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VIETNAM’S NATIONAL STANDARD
SCAFFOLDING - SAFETY REQUIREMENTS
Foreword
The TCVN 13662:2023 is developed on the basis of consulting the ANSI/ASSE A.10.8-2011 Scaffolding - Safety requirements.
The TCVN 13662:2023 is developed by the Hanoi Architectural University, proposed by the Ministry of Construction, appraised by the Directorate for Standards, Metrology, and Quality, and publicized by the Ministry of Science and Technology.
SCAFFOLDING - SAFETY REQUIREMENTS
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The following referencing document is necessary for the application of this Standard. If a reference document is mentioned together with its publishing year, only the referenced edition shall prevail. If a reference document is not mentioned together with its publishing year, the latest version and all its amendments and revisions (if any) shall prevail
TCVN 5308:1991, Code of Practice for building safety technique.
TCVN 5935-2:2013 (IEC 60502-2:2005), Power cables with extruded insulation and their accessories for rated voltages from 1 kV (Um = 1,2 kV) up to 30 kV (Um = 36 kV) – Part 2: Cables for rated voltages from 6kV (Um = 7,2 kV) and 30 kV (UM = 36 kV)
TCVN 7755:2007, Plywood
TCVN 7802-1:2007 (ISO 10333-1:2000), Part 1: Full-body harnesses
TCVN 7802-2:2007 (ISO 10333-2:2000), Part 2: Lanayards and energy absorber
TCVN 7802-3:2007 (ISO 10333-3 :2000), Part 3: Self-retracting lifelines
TCVN 8044:2014 (ISO 3129:2012), Wood – Sampling methods and general requirements for physical a nd mechanical testing of small clear wood specimens
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In this Standard, the following definitions are used:
3.1
Scaffold
Means a structure system placed on stable base, suspended, anchored, or leaned towards a structure to enable employees to work at a position higher than ground level or fixed floor surface
3.2
Wood pole scaffold
Means a scaffold whose pole or entirety is made of wood (see Figure A.1)
3.3
Tube and coupler scaffold
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3.4
System scaffold - Modular systems
Means a scaffold consisting of steel poles which wedgelocks have been welded onto, etc. with a determined scaffolding width (generally 500 mm). The wedgelocks facilitate installation of bearers, runners, and other fabricated accessories with compatible couplers (see Figure A.3)
3.5
Fabricated tubular frame scaffold
Means a scaffold erected from fabricated steel tubes, joints, crossbraces (see Figure A.4). Fabricated tubular steel frames are usually standard “H” frame or “A” frame which is also referred to as pal scaffolding. Fabricated tubular frame scaffolds shall be referred to as frame scaffolds
3.6
Single pole scaffold
Means scaffold that surrounds exterior wall and consists of a single row of poles on the outside. Working platforms are positioned on bearers on one side and runners on the other. Runners are held in place by single poles. The inside of bearers leans against and is anchored in or onto the walls. Single pole scaffolds are usually tube and coupler scaffolds or wood pole scaffolds or wood poles
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Double pole scaffold
Means scaffold that consists of two rows of poles which allow it to stand independently or by anchoring to a structure. Double pole scaffolds shall be referred to as independent scaffolds if they are not anchored to a structure. Double pole scaffolds consist of two rows of poles, bearers, runners, working platforms, and braces (see Figure A.3 and Figure A.4)
3.8
Manually propelled mobile scaffold
Means scaffold that is placed on wheels and propelled manually (see Figure A.6)
3.9
Prefabricated mobile scaffold
Means a mobile scaffold manufactured and delivered with all necessary parts for assembly (see Figure A.7)
3.10
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Means a small, highly-mobile prefabricated mobile scaffold for indoor use only. Mobile work stand must not be fitted with mechanism that allows height of the stand to be raised. Working platform of mobile work stand must be prefabricated platforms made specifically for the mobile work stand and only facilitate height adjustment within a permissible range (see Figure A.8)
3.11
Bricklayers’ square scaffolds
Means a scaffold composed of framed squares which support a light and moderate duty working platform (see Figure A.9)
3.12
Horse scaffold
Means a scaffold consisting of construction horse supporting light to moderate duty working platforms (see Figure A.10)
3.13
Pump jack scaffold
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3.14
Adjustable scaffold
Means a scaffold consisting of elevating carriages and material platforms and capable of having its height manually adjusted (see Figure A.12)
3.15
Ladder jack scaffold
Means a light duty ladder scaffold consisting of working platforms attached to ladders via console brackets (there are 2 types of ladder: non-adjustable ladders and adjustable ladders (see Figure A.13))
3.16
Outrigger scaffold
Means a scaffold consisting of a working platform supported by outrigger beams extending from the wall or main structure. The fixed ends of these outrigger beams are fixed to the main structure or other structures (see Figure A.14)
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Carpenter’s bracket scaffold
Means a scaffold consisting of metal console brackets fixed to main structure or structure wall and supporting wooden working platform (see Figure A.15)
3.18
Window jack scaffold
Means a scaffold and working platform supported by console brackets resting on open windows of main structure (see Figure A.16)
3.19
Crossbraces
Mean 2 diagonal braces connected to one another by hinges in the middle to form an “X”, bracing fabricated scaffolding or poles or both (see Figure A.4)
3.20
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Means a length-wise horizontal member fixed to poles to create primary connection. Runner/ledger occasionally locates below and supports bearer/transom (see Figure A.2 and Figure A.17)
3.21
Bearer/transom
Means a horizontal member which is maybe supported by runner/ledger and supporting working platforms. Bearer/transom and runner/ledger create a work level (see Figure A.2 and Figure A.17)
3.22
Putlog
Means a horizontal member resting perpendicularly on the 2 runners/ledgers (of independent scaffolds) or resting perpendicularly on a runner/ledger and on wall of main structure (of single pole scaffolds). Putlog and bearer/transom located on the same work level of a scaffold create sufficient width which facilitates plank. Putlogs are designed to receive concentrated load or uniformly distribute load from planks (Figure A.17)
3.23
Brace
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3.24
Coupler
Means a device holding other members of the scaffold in place. Figure A.2 depicts double couplers for holding perpendicular members together, swivel couplers holding members at any angle together.
3.25
Bracket form scaffold
Means a structure consisting of wooden or metal triangular brackets attached to walls and supporting planks thereby creating working platform for employees to work with formwork or pour concrete (see Figure A.18)
3.26
Tie
Means a member connecting the scaffold to the structure or structure elements and stabilizing the scaffold (see Figure A.19)
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Elevating carriage
Means a structure capable of sliding along a shaft to lift or lower working platforms by means of hoist (see Figure A.12)
3.28
Suspended scaffold
Means a scaffold suspended from an overhead supporting structure by steel cable or ropes, is capable of being lifted and lowered by manually operated or powered hoist, is referred to as “suspended scaffold” in order to distinguish from fixed suspended scaffold. Depending on the type of hoist and whether or not rotation resistant cable is employed, there are 3 types of suspended scaffold:
(1) Manually-operated suspended scaffold
Means a scaffold suspended by cable from an overhead supporting structure, installed and operating to lift or lower working platforms to desirable locations by means of manually-operated hoist;
(2) Powered suspended scaffold
Means a scaffold suspended by cable from an overhead supporting structure, installed and operating to lift or lower working platforms to desirable locations by powered hoist (electrically or hydraulic or pneumatically);
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Means a two-point suspended scaffold (see Figure A.23).
3.29
Boatswains’ chair
Means a seat-type suspended scaffold designed to support one employee in a sitting position (see Figure A.20)
3.30
Boatswains’ stand
Means a standing-type suspended scaffold design to support one employee in a standing position (see Figure A.21)
3.31
Single-point suspended scaffold
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3.32
Two-point suspended scaffold
Means a scaffold where working platforms are suspended by two cables originating from two points where the working platforms are lifted or lowered to desirable working locations by hoist or pulley. (see Figure A.23)
3.33
Modular suspended platform
Means a platform erected from two or more modular fabricated working platforms. The length of working platforms can be adjusted by adding or removing modular working platforms. Working platforms may employ the use of angled modules to facilitate specific angles (see Figure A.24)
3.34
Masons’ adjustable multiple-point suspension scaffold
Means a scaffold consisting of one continuous working platform supported by bearers and putlogs, suspended by at least 3 steel cables from an overhead structure, allowing employees to reach desirable working positions
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Multiple-level suspended scaffold
Means a scaffold consisting of working platforms located in multiple levels and anchored to the same cable system. This system can be supported by at least two points (see Figure A.26)
3.36
Catenary scaffold
Means a suspended scaffold consisting of a platform supported by two horizontal and parallel ropes attached to structural members of a building or other structure. Vertical suspension is required to prevent deflection of working platform (see Figure A.27)
3.37
Float scaffold
Means a scaffold consisting of a working platform beneath which is reinforced by crossbraces and suspended from an overhead girder or similar structure by means of cable. Working platform is suspended by 2 parallel cables and 2 parallel bearers (see Figure A.28)
3.38
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Means a scaffold suspended from an overhead structure by means of cables, chains, or other tensile structure (see Figure A.29 and Figure A.30)
3.39
Needle beam scaffold
Means a scaffold consisting of a working platform resting on 2 needle beams which are hung by cables (see Figure A.31)
3.40
Platform
Means a general term describing a flat surface on a scaffold consisting of one or many working platforms. A platform can be a working platform or an access platform
3.41
Working platform
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3.42
Access platform
Means a platform serving as passage to working platform but not including working platform. Access platform can be sloped or horizontal (Figure A.33)
3.43
Platform unit
Means a general term depicting the smallest member capable of working on its own or being erected to create a working platform or an access platform. A platform unit can be a sawn wood plank, a wood laminated plank, a scaffold, or a metal fabricated platform (see Figure A.34)
3.44
Plank
Means a sawn wood plank, a wood laminated plank, or a fabricated platform. The plank types are listed below:
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Means a platform unit with the smallest dimensions for use by 1 or more than 1 employee or for uniform load distribution. Metal plank may have dimensions similar to those of wood planks;
3.44.2
Wood laminated plank
Means a platform unit made from laminated wood. Wood laminated plank must be designed and manufactured to ensure proper conformity and quality for use in scaffolding;
3.44.3
Sawn wood plank
Means a platform unit made from sawn wood. Sawn wood plank must be designed and manufactured to ensure proper conformity and quality for use in scaffolding. A working sawn wood plank must have sufficient dimensions so that its load-bearing capacity is equal to or greater than total weight of an employee and materials.
3.45
Scaffold deck
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3.46
Fabricated platform for one-person
Means a fabricated platform unit intended for one employee and comes in 2 types: fixed-length and extended. A fabricated work platform must be capable of withstanding weight of one employee and maximum permissible weight of materials
3.47
Fabricated platform for
two-person
Means a fabricated work platform capable of withstanding load
of two employees and maximum permissible weight of materials. This type of
platform is usually used in freestanding ladder scaffold, extended freestanding
ladder scaffold, ladder jack scaffold, or combined with cable locking mechanism
to become a part of suspended scaffold. A fabricated platform for use by two
employees must have a minimum width of 500 mm
3.48
Fabricated platform for three-person
Means a fabricated platform for use by three employees and maximum permissible weight of materials. These type of work platforms can be combined with cable locking mechanism to act as a part of suspended scaffold or directly anchored to bearers/transoms to create a working level at which point they also act as runner/ledger
3.49
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Special-purpose scaffold deck or fabricated platform is a type of platform and plank whose design and installation are altered relative to general platforms and planks in order to serve a specific purpose
3.50
Maximum intended load
Means total load of people, materials, equipment, and tools
3.51
Design load
Means maximum intended load of scaffold. Design load includes total load of employees, materials, and equipment positioned on the load-bearing subjects
3.52
Failure
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3.53
Working load
Means load of people, materials, and equipment on the scaffold
3.54
Load rating
Means maximum load depending on load capacity of the scaffold
3.54.1
Heavy duty
Means a scaffold designed and installed with working load of 375 kg/m2, used in wall construction and plastering where working load consists of load of employees, bricks and plaster
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Medium duty
Means a scaffold designed and installed with working load of 250 kg/m2, used in construction and plastering where working load consists of load of employees and plastering materials
3.54.3
Light duty
Means a scaffold designed and installed with working capacity of 125 kg/m2, used to facilitate working employees and equipment but not materials
3.54.4
Special duty
Means a scaffold design and installed to support special materials Designing of scaffold, working platform, and joints of special duty scaffold must conform to the load capacities mentioned above
3.55
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Means a scaffold design tested with design load in order to prove that the scaffold is capable of withstanding intended load with corresponding safety factor
3.56
Personal fall-arrest system
Means a combination of equipment and system to prevent falling when working at heights
3.57
Anchorage
Means a point sufficiently rigid to anchor lifelines, lanyards, deceleration devices of personal fall-arrest system or a point connecting a structure or member to a lifting device
3.58
Full-body harnesses
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3.59
Lanyard
Means a rope made from flexible materials anchoring full-body harnesses to anchorage or to lifeline, securing and suspending falling person (see Figure A.35)
3.60
Lifeline
Means a vertical or a horizontal line serving as anchorage for lanyard (see Figure A.35)
3.61
Fall protection
Means a system design to prevent people and objects from falling while working at heights
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Safety screen
Means a nylon mesh stretched, facing the exterior of the scaffold, and positioned at an angle below working platform. Safety screen must be able to catch falling person and prevent objects from falling to the ground (see Figure A.36)
3.63
Catch fan or catch platform
Catch fan or catch platform is usually positioned on all sides of working platform, especially when the scaffold is positioned above walking streets or roads (see Figure A.37)
3.64
Guardrail system
Means a system installed along open sides and both ends of scaffold plank. Guardrail system consists of: toprails (guardrails), midrails or crossbraces, vertical members for installation, and accessories. Guardrail system of working platforms that contain materials must also be fitted with toeboards or safety screen (Figure A.38)
3.65
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Means the topmost horizontal rail of guardrail system
3.66
Midrail
Means the middle rail of guardrail system, is installed parallel to and close to toprail and working platform
3.67
Toeboard
Means a board covering the sides of working platform. Toeboards prevent materials and equipment from falling out of working platform.
3.68
Open sides and ends
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3.69
Angulated roping
Means a scaffold suspension system where distance from overhead anchorage to structure surface is lower than that from anchorage on working platforms to structure surface and where the suspended scaffold always rests on the sides of the structure while moving vertically.
3.70
Babbitted fastening
Means a method of fastening cable ends and creating cable loop where cable ends are looped into metal tubes and held in place by babbitt alloy
3.71
building face roller - roller bumper
Means a guided roller designed to allow suspended scaffold to make partial contact with construction exterior or wall exterior
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Electrical ground
Is otherwise referred to a ground wire, means a wire connecting an electrical circuit or electrical appliances with the ground to prevent electrical shock. In some circumstances, electrical ground connects electrical circuit or electrical appliances with a conductive element (usually a conductive metal) at working position
3.73
Eye splicing
Means a loop-type cable end fastened by weaving the loose end back into the cable segment. Is primarily used for suspension cable (see Figure A.39)
3.74
Guy
Means a rope, a chain, or a cable stabilizing and guiding working platforms vertically. Guys act as rotation resistant cable
3.75
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Means anchorage located intermittently along vertical surface of structure exterior to keep working platform close to the structure exterior
3.76
Roof hook
Means an equipment for anchoring overhead suspension cable system of two-point suspended scaffolds, single-point suspended scaffold or boatswains’ chair to structure ledges or other overhead members (see Figure A.44)
3.77
Pulley
Means a system consisting of fixed pulleys, mobile pulleys, and cables and operating on the principle where force advantage is proportional to cable quantity. Pulley is used to lift and lower suspended scaffold
3.78
Stirrup
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3.79
Swaged fitting
Means a method of processing steel cable ends by cold-rolling threaded couplers on the steel cable end
3.80
Trolley line
Means a horizontal steel cable anchoring to the scaffold, clips, secondary brakes, or secondary scaffold for fastening fall-protection lanyards
3.81
Vertical pickup
Means a vertical line fastened to an overhead supporting structure to control deflection of horizontal cables supporting working platforms of catenary scaffold (see Figure A.26)
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Wire rope clip
Means a cable end fastened by “U” bolt wire rope clip to form a loop (see Figure A.41)
3.83
Zinced fastening
Means a method of fastening cable end and creating cable loop where cable end weaves back into the tube and held in place by lead
3.84
Hoist
Means an equipment for lifting and lowering a suspended scaffold. Hoist can be manually operated or power operated (power transmission is usually electric transmission, see Figure A.42)
3.85
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Means a system for controlling operation processes such as initiating, stopping, redirecting, accelerating, decelerating, or maintaining speed of moving parts
3.86
Operating device
Means a button, a lever, or other manual device used to activate transmission system of the scaffold
3.87
Primary brake
Means a hoist brake used to stop loaded hoist in normal conditions
3.88
Prime mover
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3.89
Safety device
Means an automatic mechanism preventing free fall of working platform
3.90
Secondary brake
Means a hoist brake used only to stop falling of the working platform in emergencies
3.91
Traction drum hoist
Means a hoist with unchanged number of cable wraps on the drum (cable is retracted to the drum as it is released). Traction drum hoist is designed to lift and lower objects by utilizing friction between the drum and the cable
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Winding drum
Means a drum lifting or lowering the scaffold by retracting or releasing cable from the drum’s surface. There are two types of winding drum: winding drum with helical groove with one cable wrap layer and plain winding drum with multiple cable wrap layers. In reality, the multi-layer plain drum is more popular (see Figure A.43)
3.93
Tieback
Means a line connecting anchorage with load-bearing equipment of the scaffold. Tieback is commonly used in suspended scaffolding for fastening hook or suspension device to a perpendicular anchorage (see Figure A.44)
3.94
Competent person
Means a person with sufficient knowledge to identify and predict potential dangers on construction sites and in the vicinity Means a person with sufficient knowledge to identify working conditions that do not comply with occupational safety and hygiene. Means a person entitled to make timely decisions to eliminate occupational safety and hygiene risks.
3.95
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Means a person who:
+ Holds license to practice issued by competent authority or professional title relating to scaffolding;
+ Has in-depth knowledge, receives professional training, and is experienced in successfully dealing with issues relating to scaffolding and working on scaffold.
4 General requirements for all types of scaffold
4.1 Scaffold must be installed, erected, commissioned, and maintained in a manner that complies with manufacturers’ technical specifications and safety requirements, indicators under this Standard in order to ensure safety for employees.
4.2 Spacing between parts of scaffold must be measured from the center of said parts.
4.3 Parts of scaffold must meet safety requirements and indicators under this Standard and design technical specifications such as load-bearing capacity, dimensions and weight. Parts of scaffold must be designed and installed with sufficient load-bearing capability in order to withstand design load.
4.4 Base plates of poles must be sufficiently rigid, complete, and capable of withstanding the highest intended load in addition to weight of the scaffold. Porous materials such as empty containers or loose bricks must not be used as base plates.
4.5 If scaffold is anchored to structural members, the members must be primary members, sufficiently rigid, or other members with similar load-bearing capability. Scaffold anchoring components must be designed to withstand load without causing the scaffold to overload.
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1) The scaffold is being installed or dismantled;
2) The scaffold is located indoors where ground area for scaffold placement is surrounded by walls or in structures such as elevator shafts or stairwells;
3) All employees are equipped with personal fall-arrest system and fastened to lifeline.
4.6.1 Toprail must be more than 900 mm and less than 1.200 mm away from the working platform.
4.6.2 Distance between poles to which guardrails are installed must not exceed 3 m, unless otherwise designed specifically by a qualified person.
4.6.3 Toeboards must have a minimum height of 90 mm from the topmost surface of working platform. Toeboards must be able to withstand a minimum horizontal outward force of 225N.
4.6.4 Materials of toprails and midrails are considered satisfactory if the toprails and midrails are not damaged or destroyed after being tested with 900 N of downward and outward force. Testing with upward force is not required.
4.6.5 If crossbraces are used instead of midrails, the junction between the braces must be 500 mm to 750 mm away from the surface of working platform.
4.6.6 If crossbraces are used in addition to midrails, the junction between crossbraces must be 900 mm to 1200 mm away from the surface of working platform. Vertical poles must be at most 1400 mm in height.
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4.6.8 If materials are taller than toeboards and there are people occupying spaces below the working platform, safety screen is required. Safety screens must cover the space between toprails and toeboards and run along all open sides of the working platform. Spaces protected by safety screen are not required to be fitted with midrails.
4.6.9 Guardrail system is not required on the side that adjoins the wall or structure member if the distance from the scaffold to the wall is less than 300 mm. In regard to suspended scaffold, guardrail system is not required on the side that adjoins the wall or structure member if the distance from the scaffold to the wall is less than 250 mm.
4.7 Safety factor for the purpose of calculating scaffold load is four, meaning the scaffold must be able to withstand its own weight and four times the design load. Safety factor of guardrail system and suspension cable that are exceptions must be calculated depending on load-bearing capability for specific requirements. Wooden scaffold members and wooden braces must be designed in a manner that complies with 4.12.
4.8 Scaffold must not shift horizontally or change structurally during use or while occupied by people unless specifically designed so.
4.9 Scaffolding parts that have been damaged or lost their load-bearing capacity must be removed. Scaffold containing parts that have been damaged or lost their load-bearing capacity must not be used unless the parts have been repaired or replaced and verified by a qualified person.
4.10 Do not exceed design load. If fabricated or modular scaffold is used, manufacturers' instructions must be adhered to.
4.11 Wood for use in wood scaffold must:
(a) have appropriate quality;
(b) be in good conditions;
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(d) not be painted or treated so as to make defects difficult to be visually distinguished.
4.12 When designing wood scaffold members and joints, respective instructions must be complied with.
4.13 Do not use wood members that are damaged or deformed by termites, rotten, or otherwise affected by chemicals regardless of whether the wood is new or used. Undamaged wood members can be reused.
4.14 When anchoring scaffold to fixed members of the structure, anchor bolts or similar anchoring solutions are required. Scaffold must not be anchored to insufficiently rigid members.
4.15 Scaffold joints must be adequate in both dimension and quantity in order to ensure design intensity of the scaffold.
4.16 All working platforms and intermediate landings must be formed by tightly arranged planks that meet all requirements below:
1) The planks must be fitted as close to one another as possible. Gaps created by any 2 planks must not exceed 10 mm.
2) Planks of standard dimensions are allowed to be combined with planks of non-standard dimensions to form working platforms.
4.17 Either end of straight planks must exceed the centerline of bearers/transoms by at least 150 mm and at most 300 mm or be secured to the bearers/transoms.
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4.19 Unless scaffold is being installed or dismantled, access to and from working platforms of scaffold must be facilitated by:
1) Wood ladders, metal ladders, or reinforced plastic ladders.
2) Climbing steps on fabricated frame scaffold where the gap between any steps does not exceed 400 mm and the width of any step is not lower than 200 mm. Clear area of climbing steps must be large enough to allow people to grip and stand on.
3) Metal ladders with hooks of the same type as the fabricated scaffold.
4) Stairs of the same type as the scaffold
5) Passages from adjacent buildings or hoists capable of human transportation.
4.20 The distance from working platform to the first step of climbing frame must be lower than 400 mm. Ladders must be erected in a manner that they do not cause the scaffold to tumble.
4.21 Externally installed hoists are not advised for human transportation as they can cause the scaffold to tumble. When ascending or descending the scaffold with ladders or climbing frame, climbers must use both hands, wear uses, have clean heads that are not stained to prevent slip.
4.22 If ladders are fitted with safety devices, these safety devices must be tested once the ladders are erected to ensure that they are not damaged and cannot cause the scaffold to tumble.
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- Access platforms or intermediate landings must be located inside the scaffold;
- Vertical clearance between any two adjacent access platforms or intermediate landings must not exceed 4 m or 2 scaffolding levels;
- Access platforms or intermediate landings must be tiled;
- Guardrail system is required along open side of access platforms or intermediate landings;
- Or personal fall-arrest system is required.
Do not use crossbraces as means of ascending, descending the scaffold.
4.23 Base plates and poles of the scaffold must be straight, firmly braced, and prevented from rotating and moving.
4.24 If equipment secured to scaffold is used to lift and lower materials, the equipment must be fitted with load limiting instruments. Scaffold where equipment for lifting, lowering materials is secured to must be prevented from tumbling caused by the secured equipment.
4.25 If risk of falling objects is present, roofs are required and the height of which must not exceed 2,75 m from the surface of working platform.
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4.27 Working platforms and access platforms on scaffold must be non-slip. Working on slippery surface on scaffold is prohibited.
4.28 Do not stack tools, materials, debris or scraps in a manner that violates safety.
4.29 Cables, ropes, and other lines must be protected from corrosion if they are used on scaffold where corrosive materials, chemicals are present or in areas with atmospheric corrosion.
4.30 Cables and ropes used in suspended scaffold must be able to withstand 6 times the maximum intended load.
4.31 If scaffold is located where corrosive chemicals are present, appropriate corrosion protective measures compliant with manufacturers’ instructions are required.
4.32 Protective measures for scaffold parts are required if they are close to heat sources, especially suspension cables, lanyards, and anchoring lines. Suspension cables, lanyards, and anchoring lines that have been exposed to heat sources must not be reused.
4.33 Do not use ladders or stools to gain additional height while working on working platforms, unless otherwise calculated and designed by a qualified person.
4.34 Recalculation and redesign are required if scaffold is partially or entirely enclosed. Add wind load on the enclosed section in order to calculate quantity, location, and ties so that the structure can withstand wind load. Braces must have sufficient load-bearing capability and be able to withstand additional load in form of wind load without being deformed or destroyed.
4.35 Independent scaffold with height to width ratio of more than 4 must be braced, stabilized, or anchored (scaffold height is determined from toprails to the ground or floor).
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4.37 Qualified person must regulate situations where personal fall-arrest system is required during installation, dismantlement, and use of scaffold and employees working on scaffold must strictly comply with these regulations. Personal fall-arrest system must comply with TCVN 7802-1:2007 (ISO 1033-1), TCVN 7802-2:2007 (ISO 1033-2) and TCVN 7802-3: 2007 (ISO 1033-3).
4.38 Exceptions can apply to scaffold types not mentioned under this Standard.
4.39 All sides of open sides of scaffold must not be sharp or pointy to prevent cut injury.
4.40 Metal members of scaffold must not be used as conductor.
4.41 During installation, use, and dismantlement of scaffold located close to power lines (below 5 m, including low-voltage line), electricity safety measures such as safety screen are required and consensus of electricity and power line authority is required.
4.42 Pole scaffold dismantlement must start from the top of the scaffold. Ties and anchoring lines must not be dismantled until the scaffold dismantlement process reaches said anchoring members and anchoring lines. Dismantled parts and components of scaffold must be lowered gradually and must not be dropped or thrown. Undismantled sections of scaffold must be stabilized throughout the dismantlement process.
4.43 Employees installing and dismantling scaffold must undergo training, adhere to safety requirements, and be properly equipped with personal protective equipment. Prior to conducting work, employees must be introduced to installation location, indicators of safety violations, and safety procedures corresponding to the type of scaffold. Provide refresher training if necessary.
4.44 Employees installing and dismantling scaffold must possess license to practice. Supervisors are required throughout scaffold installation, use, and dismantlement.
4.45 A competent person must visually inspect all scaffold structure before each use and after each incident that potentially affects scaffold quality.
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4.46.1 If the scaffold passes the inspection, the notice must specify: “Giàn giáo đã được người có thẩm quyền kiểm định và cho phép sử dụng, thời gian kiểm định/tên người có thẩm quyền kiểm định” (Scaffold inspected and permitted by competent person for use, date of inspection/name of competent person);
4.46.2 If the scaffold passes the inspection, the notice must specify: “Giàn giáo không hoàn chỉnh, chưa sẵn sàng sử dụng (lý do, thời gian kiểm định/tên người có thẩm quyền kiểm định)” (Scaffold incomplete, not ready for use (reason, date of inspection/name of competent person)); or
4.46.3 If the scaffold passes the inspection, the notice must specify: “Giàn giáo này không an toàn, không đủ điều kiện sử dụng. Không sử dụng giàn giáo khi chưa có sự cấp phép của cơ quan có thẩm quyền” (Unsafe, unsatisfactory scaffold. Do not use this scaffold without permission of competent authority).
5 Working platform and platform unit
5.1.1 Design and manufacturing requirements of working platform
5.1.1.1 Design must be adequate and accurate in order to maintain safety of working platform under load. Materials selected for manufacturing working platforms must have the correct load-bearing capability and protected from corrosion in normal working conditions.
5.1.1.2 Fabricated working platforms and scaffold decks must be designed in a way that they can support load equal to four times the maximum intended load plus their own weight.
5.1.1.3 Console brackets of platform units must not be used unless specifically designed for such use.
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5.1.2.1 Load rating of platforms created by erecting platform units must not be greater than the lowest load rating of platform units.
5.1.2.2 Requirements for human load
5.1.2.2.1 Design load of working platforms shall be calculated for one, two, or three persons where combined load of a person and equipment is considered 125 kg. Each platform unit must be capable of supporting at least one person as follows:
5.1.2.2.2 Working platform for one person must be designed and erected in a way that the platform is able to support 125 kg positioned in the middle of the platform.
5.1.2.2.3 Working platform for two persons must be designed and erected in a way that the platform is able to support 250 kg, of which 125 kg is located 0,45 m to the left and 125 kg is located 0,45 m to the right of the centerline of the working platform.
5.1.2.2.4 Working platform for three persons must be designed and erected in a way that the platform is able to support 375 kg, of which 125 kg is located 0,45 m to the left, 125 kg is located in the middle, and 125 kg is located 0,45 m to the right of the centerline of the working platform.
5.1.2.3 Requirements for uniformly distributed load
5.1.2.3.1 All types of working platforms and platform units designed to support uniformly distributed load must be able to support point load of at least one person according to 5.1.2.2.2.
5.1.2.3.2 Working platforms and platform units satisfying requirements relating to human load under 5.1.2.2 can be designed to carry uniformly distributed load. Requirements regarding uniformly distributed load and requirements regarding human load are independent of the other and are not applied simultaneously.
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5.1.2.3.4 Medium duty working platforms must be designed to withstand uniformly distributed load of 250 kg/m2.
5.1.2.3.5 Heavy duty working platforms must be designed to withstand uniformly distributed load of 375 kg/m2.
5.1.2.3.6 Specialized working platforms are platforms designed and manufactured to withstand uniformly distributed load and not mentioned under 5.1.2.3.3, 5.1.2.3.4, and 5.1.2.3.5.
5.2 Requirements regarding metal and wood planks
5.2.1 Each metal or wood plank whose supported span is 3 m must be capable of supporting a person’s weight of 125 kg in the middle of the plank.
5.2.2 Under the effect of design load, deflection in the middle of the bay under calculated load must not exceed 1/60 of the supported span.
5.2.3 If planks are used in combination with ladder scaffold, appropriate types of ladder are required.
5.2.4 Sawn wood planks must have similar load rating to that of general planks. Load rating of sawn wood planks must be verified by competent authority and shown via load rating labels.
5.2.5 Sawn wood planks shall be classified and identified for elastic modulus in static bending according to TCVN 8048-4:2014 (ISO 3349).
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5.2.7 Maximum supported span of sawn wood planks shall conform to design and manufacturers’ instructions on the basis of reliability calculation for wood planks.
5.2.8 Sawn wood planks must be used in high and well-ventilated areas. Sawn wood planks that contain fresh cut wood or are used in environment with high humidity, calculation of stress and inspection must comply with 4.12 and take into account wood humidity.
5.2.9 Laminated wood manufacturers must identify and publish technical characteristics of wood laminated planks which serve as the basis for calculation and design of working platforms.
5.2.10 Laminated wood planks must be verified for conformity (meaning that laminated wood planks conform to this Standard). Conformity verification must be performed by a competent independent body which is permitted by a competent authority.
5.2.11 Supported span of wood planks must be determined and published by manufacturers.
5.2.12 Wood surface must not be obscured by pain or other cover, other than a few location on the side for the purpose of specifying code and technical specifications. Surface treating is allowed for the purpose of periodic fire prevention and roughness as long the materials are transparent and light-transmitting.
5.2.13 Metal planks must have minimum width of 150 mm, minimum length of 3000 mm, and supported span greater than 3 m.
5.2.14 Surface of metal planks must be non-slip.
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5.3.2 Scaffold deck must be fitted with hooks on both ends to stabilize and transfer load onto bearers/putlogs or hang onto suspension cable (as suspended scaffold). Hooks of scaffold decks resting on bearers/putlogs must be prevented from displacing or lifting by themselves.
5.3.3 Surface of scaffold deck must be solid steel, steel mesh, or bar assemblies. Surface of scaffold deck must be held in place by exterior frame or by crossbraces.
5.3.4. The largest gap between erected scaffold decks and the largest gap between scaffold deck surface and exterior frame must not exceed 10 mm.
5.3.5 Scaffold deck surface can sink relative to the upper surface of exterior frame.
5.3.6 Surface of metal scaffold deck must be non-slip.
5.3.7 Scaffold deck must be labeled and have load rating compliant with 5.1.2.3.
5.3.8 Scaffold deck must undergo tested design.
5.4 Fabricated working platform
5.4.1 Fabricated working platform must be able to withstand minimum point load of one person of 125 kg positioned in the middle of the platform according to and minimum uniformly distributed load of 125 kg/m2.
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Schedule 1 - Dimension and load rating of fabricated working platform
Fabricated working platform
Load rating, kg(1)
maximum length, m
Maximum width, m
Minimum width, m
For one person
125
7,2
...
...
...
0,3
For two people
250
12,0
0,75
0,3(2)
For three people
375
12,0
...
...
...
0,5
NOTE:
(1) Load rating is determined on the basis that each end of a working platform is supported by bearer with supported width of 300 mm; 0,3(2) Minimum width of working platform whose length varies from 6 m to 9 m.
5.4.3 Surface of fabricated working platform must be made from solid steel, with bars or mesh.
5.4.4 Maximum gap between the surface and exterior frame, planks must not exceed 10 mm.
5.4.5 Surface of fabricated working platform can sink relative to the upper surface of exterior frame.
5.4.6 Surface of metal fabricated working platform must be made non-slip.
5.4.7 Fabricated working platform must be labeled and have load rating compliant with 5.1.2.3.
5.4.8 When using fabricated working platform in combination with ladder scaffold, appropriate ladder is required.
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5.5 Modular fabricated working platform
See 20.13 for modular suspended scaffold
6.1 Poles must be supported by base plates. Base plates must be solid and large enough to distribute load to the surface without being deformed. Poles must be perfectly vertical.
6.2 Where wooden poles are spliced, the ends shall be squared and the upper section shall rest squarely on the lower section. Wood splice plates shall be provided on at least two adjacent sides. Splice plates must have minimum length of 1,2 m, equivalent width and no less than pole width, and extend to both poles equally. Splice plates of other materials of equivalent strength may be used.
6.3 Double wood pole scaffold must be as close to side wall of the structure as possible.
6.4 All wood poles must be firmly anchored to structure members. Double wood pole scaffold exceeds 7,5 m in length or height must be anchored to structure members where the distance between vertical and horizontal anchorage must not exceed 7,5 m.
6.5 Bearers shall be set with their greater dimensions vertical. Bearers shall be long enough to project over poles and runners by a minimum of 0,5 m.
6.6 Bearers of single pole scaffold must be reinforced by steel strips of 5 mm in thickness x 50 mm in width secured to the lower edges for the entire length of the bearers.
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6.8 Crossbracing shall be required to prevent wood pole scaffold from moving in a direction parallel to the wall or to prevent bending of poles.
6.9 Transverse braces shall be required between each pair of inner and outer poles of independent scaffold. Crossbracing shall be required on every lift at either end of independent scaffold.
6.10 Crossbracing shall be required for the entire front side of the scaffold. Diagonal braces of the front side shall only be jointed where they connect with poles.
6.11 Wood planks must satisfy requirements below:
(a) If two planks overlap, the overlapped section must be at least 300 mm in length;
(b) If two planks are abutted, each abutted end shall rest on the center line of a bearer;
(c) Each abutted end shall rest on separate bearer;
(d) Additional bearers shall be required in necessary positions to prevent platform deflection;
(e) Abutted ends of planks must be held in place by nails or steel strip.
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6.13 Guardrail system and toeboards must comply with 4.6. Safety screen must comply with 4.6.8.
6.14 Wood pole scaffold below 18 m in height shall be manufactured and erected in a manner compliant data under Schedule 2 through Schedule 7. The data is determined on the basis of one working platform level and two additional working platform levels. Wood pole scaffold above 18 m in height shall be designed by eligible organizations and manufactured, erected in a manner compliant with this design. Copies and technical specifications of scaffold must be provided for contractors and used in inspection, examination.
6.15 Maximum clearance between bearers supporting working platforms must comply with 5.2, 5.3, and 5.4 and appropriate with load of the working platforms that they support.
6.16 Fire safety measures shall be required for wood pole scaffold. Maximum height of wood pole scaffold must be lower than the maximum height achievable by firefighting apparatus.
Schedule 2 - Nominal dimension and maximum distance of parts of light-duty single pole scaffold - 125 kg/m2
Scaffold parts(1)
Maximum height(2), m
6 m
18 m
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...
≤ 125
≤ 125
Pole dimension, mm
50 x 100
100 x 100
Distance between two adjacent poles of the scaffold length-wise, mm
1800
3000
Dimension of bearer or putlog when scaffold width is less than or equal to 900 mm
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...
50 x 100
Dimension of bearer or putlog when scaffold width is between 900 mm to 1500 mm.
50 x 150
or
75 x 100
50 x 150
or
75 x 100
Dimension of runner, mm
...
...
...
30 x 230
Vertical distance between horizontal members, mm
2100
2100
Dimension of crossbraces, horizontal braces, and corner braces, mm
25 x 100
25 x 100
Dimension of braces anchored to structure, mm
25 x 100
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...
NOTE:
(1) All scaffold parts shall be measured using outer dimensions;
(2) Maximum width of the scaffold is 1500 mm.
Schedule 3 - Nominal dimension and maximum distance of parts of medium-duty single pole scaffold - 250 kg/m2
Scaffold parts(1)
Dimensions(2)
Uniformly distributed load, kg/m2
≤ 250
Maximum height of the scaffold, m
...
...
...
Pole dimension, mm
100 x 100
Distance between two adjacent poles of the scaffold length-wise, mm
2400
Dimension of bearer and putlog (non-debarked), mm
50 x 230 or 75 x 100
Distance between bearers or putlogs, equal to or less than, mm
1400
Dimension of runner (non-debarked), mm
...
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...
Vertical distance between bearers, mm
2700
Dimension of crossbraces and horizontal braces, mm
25 x 150 or 30 x 100
Dimension of crossbraces and transverse braces, mm
25 x 100
Dimension of braces anchored to structure, mm
25 x 100
NOTE:
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(2) Maximum width of the scaffold is 1500 mm.
Schedule 4 - Nominal dimension and maximum distance of parts of heavy-duty single pole scaffold - 375 kg/m2
Scaffold parts(1)
Dimensions(2)
Uniformly distributed load, kg/m2
375
Maximum height of the scaffold, m
18
Pole dimension, mm
...
...
...
Distance between two adjacent poles of the scaffold length-wise, mm
1800
Dimension of bearer and putlog (non-debarked), mm
50 x 230 or 70 x 130
Distance between bearers or putlogs, mm
1400
Dimension of runner (non-debarked), mm
50 x 230
Vertical distance between horizontal members, mm
...
...
...
Dimension of crossbraces, horizontal braces, and transverse braces, mm
50 x 100
Dimension of ties, mm
50 x 100
NOTE:
(1) All scaffold parts shall be measured using outer dimensions. See 6.15 for requirements regarding working platform planks;
(2) Maximum width of the scaffold is 1500 mm.
Schedule 5 - Nominal dimension and maximum distance of parts of light-duty double wood pole - 125 kg/m2
Scaffold parts(1)
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...
...
6
18
Uniformly distributed load, kg/m2
≤ 125
≤ 125
Pole dimension, mm
50 x 100
100 x 100
Distance between two adjacent poles of the scaffold length-wise, mm
...
...
...
3000
Maximum width of the scaffold, mm
1800
3000
Dimension of runner, mm
35 x 100
30 x 230
Dimension of bearer when scaffold width is equal to or less than 900 mm
50 x 100
...
...
...
Dimension of bearer when scaffold width is between 900 mm and 3000 mm
50 x 155 or 75 x 100
50 x 230 or 75 x 200
Vertical distance between horizontal members, mm
2100
2100
Dimension of crossbraces, horizontal braces, and transverse braces, mm
25 x 100
25 x 100
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...
25 x 100
25 x 100
NOTE: (1) All scaffold parts shall be measured using outer dimensions.
Schedule 6 - Nominal dimension and maximum distance of parts of medium-duty double wood pole - 250 kg/m2
Scaffold parts(1)
Dimensions(2)
Uniformly distributed load, kg/m2
≤ 250
Maximum height of the scaffold, m
...
...
...
Pole dimension, mm
100 x 100
Distance between two adjacent poles of the scaffold length-wise, mm
2400
Maximum width of the scaffold, mm
1800
Dimension of runner, mm
50 x 230
Vertical distance between horizontal members, mm
...
...
...
Distance between bearers, mm
2400
Dimension of bearers, mm
50 x 230 or 50 x 255
Dimension of crossbraces, mm
25 x 150 or 30 x 100
Dimension of crossbraces and transverse braces, mm
25 x 100
Dimension of ties, mm
...
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...
NOTE:
(1) All scaffold parts shall be measured using outer dimensions. Requirements regarding supported width of planks shall conform to 7.16;
(2) The values above are calculated on the basis of one working platforms and two additional plank platforms.
Schedule 7 - Nominal dimension and maximum distance of parts of heavy-duty double wood pole - 375 kg/m2
Scaffold parts(1)
Dimensions(2)
Uniformly distributed load, kg/m2
≤ 375
Maximum height of the scaffold, m
...
...
...
Pole dimension, mm
100 x 100
Distance between two adjacent poles of the scaffold length-wise, mm
1800
Maximum width of the scaffold, mm
1800
Dimension of runner, mm
50 x 230
Vertical distance between horizontal members, mm
...
...
...
Dimension of bearers (non-debarked), mm
50 x 230
Dimension of crossbraces and transverse braces, mm
50 x 100
Dimension of ties, mm
5 x 100
NOTE:
(1) All scaffold parts shall be measured using outer dimensions;
(2) The values above are calculated on the basis of one working platforms and two additional plank platforms.
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7.1 Tube and coupler scaffolds are scaffolds erected from separate tubes (carbon steel, galvanized steel or galvalume steel) and connected by couplers to form supporting structures of working platforms.
7.2 Requirements regarding loose tubes
7.2.1 Tubes of steel and plain aluminum alloy are primary parts of the scaffold with dimensions and technical characteristics compliant with Schedule 8.
7.2.2 Tubes of steel and tubes of plain aluminum alloy must not be used on the same scaffold system, except when used as non-load bearing members.
Schedule 8 - Dimensions and technical characteristics of steel tubes and aluminum tubes
Dimensions and technical characteristics
Carbon steel tube
Galvanized steel tube
Aluminum alloy tube
...
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...
48,3 (± 0,5)
48,3 (± 0,5)
48,4 (± 0,5)
Tube thickness (plain tube), mm
4 (± 0,5)
3,2 (± 0,48)
4,47 (± 0,56)
Tube thickness (welded tube), mm
4 (± 0,8)
...
...
...
-
Weight per meter in length, kg/m
4,37
3,56
1,67
Tensile strength, MPa
340
360
295
...
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...
210
215
255
Radius of gyration, mm
15,7
16
15,6
Cross sectional area, mm2
557
...
...
...
615
Moment of inertia, mm4
138000
116000
149000
Section modulus, mm3
5700
4800
6180
...
...
...
7.3.1 All scaffold couplers shall be made from stamped steel, forged steel, malleable iron, or alloy. Scaffold couplers shall not be made from gray iron. Couplers can be used to couple and connect parts of tube and coupler scaffold and other types of scaffold.
7.3.2 Couplers must have working load compliant with Schedule 9.
Schedule 9 - Safe working load of couplers
Coupler
Type of applied load
Safe working load
kN
kg
Double coupler
...
...
...
6,25
640
Swivel couplers
Longitudinal traction
6,25
640
Putlog coupler
Sheer resistance
0,59
...
...
...
Internal connector
Longitudinal tensile force
21
2140
Threaded couplers
Tensile force
3,1
315
7.4 Spacing of parts in tube and coupler scaffold
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Schedule 10 - Maximum spacing between parts in tube and coupler scaffold
Classification by load
Minimum horizontal spacing between poles, m
Maximum horizontal spacing between poles, m
Maximum vertical spacing between poles, m
Light-duty
0,5
2,4
3
...
...
...
0,95
1,8
2,4
Heavy-duty
1,175
1,275
1,8
7.10 Transverse braces of vertical surfaces must be installed:
- On at least one level for every four levels vertically;
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- Transverse braces shall be secured to exterior poles or exterior runners of the lower level and inner poles or inner runners of the upper level via swivel couplers. Points where the scaffold is anchored to the structure must be located next to transverse braces.
7.11 Front crossbraces must be fitted to the outside of exterior poles by swivel couplers from the base of the first exterior pole to create an angle of 40o - 50o. If the scaffold is extended in length, front crossbraces shall be repeated. If the scaffold is extended in height but limited in length, front crossbraces shall be fitted to form an angle of 40o - 50o from the base of the first exterior pole to the highest possible position of the last exterior pole and repeated in the opposite direction in order to reach the top of the scaffold. If front crossbraces cannot be directly anchored to poles, they can be anchored to runners as an alternative.
7.12 Tube and coupler scaffold must be firmly anchored to wall or member of the structure if the scaffold height exceeds four times the smallest dimension of the scaffold base. Steel tubes for anchoring must be firmly attached to two poles or two runners by double couplers. Vertical distance between adjacent anchorage shall not exceed 4,2 m. Horizontal distance between adjacent anchorage shall not exceed 4,8 m. Vertical distance between the last anchorage and the top of the scaffold shall not exceed three times the smallest dimension of the scaffold base or 4,2 m, whichever is lower. Horizontal distance between the last anchorage and the end of the scaffold shall not exceed one bay length or 0,9 m, whichever is lower. Anchorage must be able to prevent the scaffold from falling into or away from the structure, (see 4.34 when the scaffold is partially or entirely enclosed).
7.13 Guardrail system and toeboards of working platforms shall be installed in a manner compliant with 4.6. Safety screen shall be installed in a manner compliant with 4.6.8.
7.14 If tube and coupler scaffold surround structures with particular shapes, such as spherical tanks, chimneys, or machinery structures, etc. which cause adequate anchorage as specified above is not feasible, design instructions shall be complied with in order to achieve a stability similar to that when adequate anchorage is provided.
7.15 Access of tube and coupler scaffold shall conform to 4.19.
7.16 Maximum clearance between bearers supporting working platforms shall conform to 5.2, 5.3, and 5.4 and be suitable for load of supporting members.
8.1 Modular scaffold shall be designed to withstand scaffold load and at least four times the maximum intended load without failing. Distance between poles and runners must be suitable for applied load so that safety factors of all members are not exceeded. Scaffold manufacturers or engineers must pay attention to permissible distance between runners and between bearers.
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8.3 Poles must be vertically straight, runners and bearers must be located on horizontal plane.
8.4 If a runner is close to the lower side of midrail in modular scaffold, its installation is not mandatory. In the case above, when guardrail systems are moved to the next level, installation of the runner shall then be mandatory. Vertical distance between runners shall not exceed 2 m.
8.5 Front cross braces shall be required for modular scaffold in order to achieve sufficient rigidity according to manufacturers’ instructions.
8.6 Base level of modular scaffold must be crossbraced or protected by other appropriate measures to ensure that the base level is always flat, square cut, contains rigid connection according to manufacturers’ instructions.
8.7 All connections shall be installed and inspected for rigidity before the next level is installed.
8.8 In sections of modular scaffold that are at risk of being uplifted, poles must me firmly secured to one another vertically by couplers or equivalent measures.
8.9 Guardrail must be installed in a manner compliant with 4.6. Safety screen must be installed in a manner compliant with 4.6.8.
8.10 Access to and from modular scaffold shall satisfy 4.19.
8.11 Façade modular scaffold shall be firmly anchored to the wall or to the structure itself if scaffold height exceeds four times the smallest dimension of the base. The first anchorage must be located at the base. Vertical distance between two adjacent anchorage shall conform to values dependent on scaffold width as follows: in regard to scaffold whose width is equal to or less than 0,9 m, the distance shall not exceed 6 m; in regard to scaffold whose width is higher than 0,9 m, the distance shall not exceed 7,9 m. Vertical distance between the last anchorage and the top of the scaffold shall not exceed four times the smallest dimension of the base. Horizontal distance between two adjacent anchorage and between the last anchorage and the end of the scaffold shall not exceed 9 m. Anchorage shall be able to prevent the scaffold from falling out of and into the wall or structure (see 4.34 when the scaffold is partially or entirely covered).
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8.13 Modular scaffold above 38 m in height shall be designed by engineers with professional certification. A copy of the design shall be retained at construction site for inspection and assessment.
8.14 Modular scaffold shall be erected and dismantled by trained employees under supervision of competent person.
8.15 Scaffold parts of different manufacturers shall not be erected in the same modular scaffold.
8.16 Prior to installation, qualified person must inspect all scaffold parts. Damaged or deformed parts shall not be used and shall be removed from the construction site.
8.17 Scaffold assembly and dismantlement equipment is required according to manufacturers' instructions.
8.18 Scaffold dismantlement shall start from top to bottom and anchorage shall only be removed when all parts above it have been dismantled.
9 Fabricated tubular frame scaffold
9.1 Erected frame scaffold shall be designed to withstand its load and at least four times the maximum intended load without failing. Distance between poles and runners must be suitable for applied load so that safety factors of all members are not exceeded. Scaffold manufacturers shall provide instructions regarding permissible distance between runners and bearers.
9.2 Distance between frames and panels shall be appropriate to applied load. Manufacturers shall provide instructions regarding permissible load, bracing type, and base plate height.
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9.4 Footings of the frame close to the base shall be placed on jack base and solid base capable of withstanding the maximum load. Erected frame scaffold shall be required to have perfectly straight poles and levels located on horizontal plane.
9.5 If a frame is positioned on top of another frame, connectors shall be required so that footings of the lower frame and those of the upper frame perfectly line up.
9.6 Frames must be vertically attached to one another via couplers or equivalent measures so that scaffold uplift is prevented.
9.7 Guardrail and toeboards shall be compliant with 4.6. Safety screen shall be compliant with 4.6.8.
9.8 Access to and from scaffold shall be compliant with 4.19.
9.9 Fabricated tubular frame scaffold shall be anchored to the structure if its height exceeds four times the smallest dimension of the base. The first anchorage must be located at the base. Vertical distance between two adjacent anchorage shall be compliant with values dependent on scaffold width as follows:
- A scaffold whose width is less than 0,9 m shall have maximum distance between two anchorage of 6 m;
- A scaffold whose width is larger than 0,9 m shall have maximum distance between two anchorage of 8 m. Vertical distance between the last anchorage and the top of the scaffold shall not exceed four times the smallest dimension of the base. Horizontal distance between two adjacent anchorage and between the last anchorage and the end of the scaffold shall not exceed 9 m. Anchorage shall be able to prevent the scaffold from falling out of and into the wall or structure (see 4.34 when the scaffold is partially or entirely covered).
9.10 Maximum clearance between bearers supporting working platforms shall be compliant with 5.2, 5.3, and 5.4
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9.12 Frame scaffold shall be erected and dismantled under supervision of a qualified person.
9.13 If console frames are fixed onto a primary frame, these console frames must perfectly fit for primary frame, side members of console frames must be parallel to poles of the primary frame and surface of the console must be perpendicular to poles of the primary frame. Console frames shall not be warped relative to their regular configuration. Console platforms shall not be used to support materials or equipment and only to act as a platform for employees to stand on (other than mobile console platforms designed specifically for material transport). If console platform is used, scaffold shall be anchored to the structure or be protected from being pulled away by other measures.
9.14 Parts of fabricated tubular frame scaffolds of different manufacturers shall not be installed together, unless the parts have similar specifications, can be easily attached to one another without the use of force, and are able to retain their structure during installation and use. Scaffold parts of different manufacturers shall not be modified in order to be installed with other parts, unless a qualified person determines that such modification does not affect safe working capacity of the scaffold.
9.15 Frame and parts of scaffold shall be periodically inspected. All damaged, deformed, or corroded parts shall be replaced. Maintenance shall be implemented before use.
10 Manually propelled mobile scaffold and fabricated manually propelled mobile scaffold
10.1 Height of working platform
10.1.1 Height of freestanding mobile scaffold shall not exceed four times the smallest dimension of the base. Extension frames shall be counted towards the smallest dimension of the base. If extension frame is asymmetrical, the scaffold shall be calculated for stability and erected by a qualified person.
10.1.2 Minimum width of working platform shall be 0,5 m. Maximum gap between adjacent planks shall be 25 mm. Working platforms shall be compliant with 4.16.
10.1.3 Scaffold shall be secured by crossbraces, horizontal braces, diagonal braces, or similar measures in order to connect adjacent vertical members, maintain perpendicular connection, and prevent displacement. The first diagonal braces shall not be located at a height above 0,9 m from the wheels; the next diagonal braces shall not located at a height above 6 m from the base. Scaffold decks fitted with hooks shall be allowed as alternatives for diagonal braces. Diagonal braces shall not be installed in mobile scaffold that is less than 2 m in height and working platforms installed by scaffold decks with hooks.
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10.1.5 Working platforms shall be held in place length-wise to prevent lateral displacement.
10.1.7 Maximum clearance between bearers supporting working platforms shall conform to 5.2, 5.3, and 5.4 and be suitable for load of supporting members.
10.1.8 Guardrail system and toeboards shall be installed in a manner compliant with 4.6 and 4.6.8.
10.1.9 Access of scaffold shall be compliant with 4.19.
10.2 Requirements regarding wheels
10.2.1 Wheels shall be designed to withstand four times the calculated load.
10.2.2 Wheels shall be required to have rubber or elastic layer with guard whose minimum diameter is 0,12 m, unless otherwise specifically designed with other materials on request.
10.2.3 Wheels shall be required to have guards and locking or braking mechanisms to prevent displacement and rotation while the scaffold is required to be stationary.
10.2.4 Wheels shall be secured to scaffold footings or bottle jack attachments so that the wheels do not fall off from the joints in any circumstance.
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10.3.1 Wheels shall be locked when in use.
10.3.2 When manually moving the scaffold, the force shall be applied as close to the base as possible depending on operating conditions and stability shall be maintained. Surface where mobile platform moves shall be large enough and shall not be obstructed.
10.3.3 Moving of scaffold shall only be allowed when the scaffold is not occupied by people, materials, and equipment. Moving of scaffold where hand-held materials, tools, or equipment are present on working platforms shall be allowed as long as strict requirements under 10.3.2 and 10.3.3 are met and all conditions below are strictly adhered to:
10.3.3.1 Guardrail system and toeboards of working platforms shall be installed in a manner compliant with 4.6. Safety screen shall be installed in a manner compliant with 4.6.8.
10.3.3.2 Surface on which the scaffold moves shall be flat, inclined no more than 1,5o, free of pothole, and free of obstacles.
10.3.3.3 The smallest dimension of the base of mobile platform shall not be lower than half the height of the scaffold. If extension frame is used, dimension of extension frame shall be counted towards dimension of the base of the scaffold as long as all wheels remain contact with the floor during movement.
10.3.3.4 All tools or equipment shall be secured to working platforms before the scaffold is moved. If small tools are present, toeboards shall be required in addition to requirements above.
10.3.3.5 All employees and personnel working close to scaffold shall be advised and warned about all scaffold movement in advance.
10.3.4 Mobile scaffold shall be erected, used, and dismantled in a manner compliant with manufacturers’ instructions.
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10.4 Labeling and labeling requirements
10.4.1 Manufacturers or suppliers shall provide use instructions and label fabricated mobile scaffolds that they manufacture or supply. Each fabricated mobile scaffold must be accompanied by an instruction manual. Each fabricated mobile scaffold shall have its own unique label.
10.4.2 Labels and instruction manuals shall specifically indicate design load or maximum intended load.
10.4.3 Labels of fabricated mobile scaffold shall indicate name of manufacturers or suppliers or identifiers of manufacturers. Labels shall be stamped on metal parts of the scaffold or on metal sheets of sufficient strength or equivalent materials fixed onto the scaffold.
11.1 General requirements
Mobile work stand shall be able to withstand its own load and four times the maximum intended load.
11.2 Working height
11.2.1 Height of working platform shall not exceed three times the smallest dimension of the work stand and 1,25 m from the ground or concrete floor.
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11.2.3 Each mobile work stand shall require at least two platform units. Minimum width of a platform unit measured perpendicular to the length of a work stand shall be 0,2 m. If two platform units are assembled to create a work stand, the gap between them shall not exceed 25 mm.
11.2.4 Ascending working platforms without ladder shall be permitted if the lowest standing platform is not located at a height above 0,6 m. If working platforms are located at a height above 0,6 m, access shall be required and compliant with 4.19.
11.2.5 Mobile work stand shall be braced by crossbraces, horizontal braces, diagonal braces, by securing holding working platform in place, or via similar solutions. All bracing points shall be firmed and prevent displacement.
11.2.6 Working platform shall be protected from lateral displacement.
11.3 Wheels
11.3.1 Wheels shall be designed with sufficient dimension and load-bearing capacity to withstand four times the design load.
11.3.2 Wheels shall be lined with rubber or elastic tires where minimum rim diameter is 0,1 m, unless otherwise specifically designed with other materials on request.
11.3.3 Wheels shall be equipped with solid wheels and anti-rotation mechanisms or similar measures to lock the wheels when the scaffold is stationary.
11.3.4 Wheels shall be secured to scaffold footings or bottle jack attachments so that the wheels do not fall off from the joints in any circumstance.
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11.4.1 Wheels shall be locked when the scaffold is in use.
11.4.2 The use of mobile work stand shall only be permitted on even ground or flat concrete floor, without potholes and obstacles and when such surface is inclined no more than 1,5o.
11.4.3 Before mobile work stand is moved, all equipment and tools on working platforms shall be cleared.
11.4.4 If working platforms are occupied by people, moving of the mobile work stand shall not be allowed.
11.4.5 Fabricated mobile work stand shall be erected, used, and dismantled in accordance with manufacturers’ instructions.
11.4.6 Fabricated mobile work stand shall be inspected before and after each use.
11.5 Labeling and labeling requirements
11.5.1 Manufacturers or supplies shall provide instruction manuals and label mobile work stand that they manufacture or supply. Each fabricated mobile work stand shall be accompanied by an instruction manual.
11.5.2 Labels and instruction manuals shall specifically indicate design load or maximum intended load.
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12 Bricklayers’ square scaffolds
12.1 Distance between two legs shall not exceed 1,5 m and height shall not exceed 1,5 m.
12.2 Minimum dimension of scaffold parts shall conform to Schedule 11.
Schedule 11 - Minimum cross section area of parts of bricklayers’ square scaffold
Parts
Dimensions, mm
Ledgers or horizontal members
50 x 150
Legs
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Braces at corners
25 x 150
Braces diagonally from the center frame
25 x 150
12.3 All corners of both sides of the scaffold shall be reinforced by corner braces with dimension of 25 mm wide x 150 mm long. Length-wise sides of the scaffold shall be braced both at the front and at the back by corner braces with dimension of 25 mm x 200 mm or by other measures that provide similar strength and stability.
12.4 Legs shall not be more than 1,5 m apart from each other in case of medium-duty scaffold and no more than 2,4 m apart in case of light-duty scaffold. If two scaffolds are arranged in tiers, crossbraces connecting the upper and lower scaffolds on both sides in form of braces with dimension of 25 mm wide x 200 mm long shall be required. Such crossbraces shall connect from the bottom of the lower scaffold to the top of the upper scaffold.
12.5 Ends of planks shall rest on at least 3 bearers. The use of fabricated planks shall be allowed.
12.6 Maximum clearance between bearers shall be compliant with 5.2, 5.3, and 5.4 and appropriate to permissible load.
12.7 Bricklayers’ square scaffolds shall not be arranged more than 3 tiers. Subsequent bricklayers’ square scaffolds shall be arranged directly on top of the previous scaffold. Surface of lower scaffold shall be held in place to prevent displacement.
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113.1 Horse scaffolds shall not be arranged more than 2 tiers or 3 m.
13.2 Minimum dimensions of parts of horse scaffold shall conform to Schedule 12.
13.3 Legs shall not be more than 1,5 m apart from each other in case of medium-duty scaffold (see 5.1.2.3.4) and no more than 2,4 m apart in case of light-duty scaffold (see 5.1.2.3.3).
13.4 If scaffolds are arranged in tiers, each horse leg shall be placed directly over the leg below.
13.5 If scaffolds are arranged in tiers, the legs of each horse shall be nailed down to prevent displacement and each leg shall be held in place by diagonal braces.
13.6 Weak or defective parts shall be removed.
Schedule 12 - Minimum cross sectional area of parts of horse legs
Parts
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Bearers or horizontal members(1)
75 x 100
Legs
30 x 100
Length-wise braces of legs
25 x 150
Corner braces on top of legs
25 x 200
Diagonal braces
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NOTE: (1) Dimensions above are calculated with maximum length of 3000 mm
14.1 Jacks, braces, and accessories shall be manufactured from sheet steel and angle steel. Each jack shall require two griping mechanisms to prevent failure of any of them. Bracing members shall be sufficiently strong to support applied load.
14.2 Working platforms shall be floored adequately and held in place to prevent displacement. Flooring planks shall have a minimum thickness of 50 mm, be abutted, and not be arranged in tiers. Working platforms shall be compliant with 5.2, 5.3, and 5.4. Minimum width of primary working platform shall be 450 mm. Minimum width of material platforms shall be 300 mm. All materials on the scaffold shall be prevented from falling.
14.3 Maximum clearance between bearers supporting working platforms shall be compliant with 5.2, 5.3, and 5.4 and suitable for load of supporting members.
14.4 If the scaffold utilizes wood poles, clearance between two poles shall be equal to or less than 2 m, scaffold height shall be equal to or less than 9 m, and each pole shall only be fitted with one jack. Wood poles shall be firmly braced onto structural members by solid brackets or similar ties. Mandatory ties are top of poles, bottom of poles, and middle of poles where spacing between adjacent ties shall be equal to or less than 3 m vertically. If working platforms are lifted or lowered past a bracing member, an auxiliary bracing member located at a height no more than 1,2 from the bracing member in question shall be required and the bracing member shall be reinstalled in its original location once the working platforms have moved past it. If the scaffold utilizes metal poles which are equal to or less than 7,5 m in height, a minimum of one bracing point between the structure and the top of the pole shall be required. If the scaffold utilizes metal poles which are greater than 7,5 m in height, a minimum of two bracing points shall be required. The distance between these bracing points shall be equal to or less than 5 m from the bracing point on top of the pole. If the scaffold utilizes metal poles, auxiliary bracing points shall not be required when working platforms move past a bracing member. Height of metal pole scaffold shall be equal to or less than 15,5 m. Scaffolds that are greater than 15,5 m shall be designed by licensed engineers.
14.5 All poles shall be positioned on base plates or foundation capable of withstanding the maximum intended load.
14.6 Poles shall be prefabricated from wood or metal members. Poles can be single pieces or multiple pieces attached together. Joint between two wood poles shall be covered by 350 mm x 90 mm metal strips which are held in place by nails of 3,8 mm diameter driven 75 mm deep or by similar means. Metal strips shall have a minimum thickness of 8 mm and be punched 5 slots of 4 mm in size on each end. The abutted ends of two poles shall be located in the middle section of the strips.
14.7 If poles compose of joint wood segments, these wood segments shall be dried, straight-grained lumber with cross sectional area of 50 x 100 mm or equivalent. Joint sections of poles shall be flat and parallel to surface on which jacks are located, covering metal strips shall be held in place by nails of 3,8 mm in diameter, driven to 75 mm deep on opposite sides of the poles.
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14.9 Pump jack scaffolds shall be designed with minimum working load of 225 kg and shall only facilitate a maximum of two people working simultaneously.
14.10 Scaffold shall be fitted with guardrail system that are compliant with 4.6. Guardrail system shall not be required if employees working on the scaffold are equipped with personal fall-arrest system (see 4.37).
14.11 If material platforms are located at a height of 1 m or lower, toprails shall not be required if the platform is adequately floored, held in place, and capable of resisting 900 N force applied in all direction.
14.12 Employees shall not stand on material platforms.
14.13 Instruction panels from manufacturers that are coherent and comprehensive shall be required on the jack.
14.14 Ladder shall be required to access working platforms during use.
14.15 Guardrail system shall be placed on the ground before scaffold construction begins.
14.16 Scaffold erection and use shall not be allowed close to power lines, charged objects unless they are insulated, removed from power source, or protected by other electrical safety measures.
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15.1.1 Adjustable scaffold shall be able to withstand its own load and four times the load rating. Load applied on the platform shall not exceed plank load depending on supported span.
15.1.2 Scaffold design shall be tested as follows: Apply point load equivalent to two times the load rating on 0,4 m2 of material platform at any position, tested scaffold is freestanding (not braced), the platform is raised to the highest position, so that the entire system is capable of withstanding the load without failing, falling over, or deforming.
15.1.3 Working platforms and material platforms shall be floored with planks in a manner compliant with 4.16.
15.1.3 Scaffold access shall be required in a manner compliant with 4.19.3 through 4.19.5.
15.2 Requirements regarding hoists
15.2.1 Cogs of hoists shall be manufactured in a manner compliant with strength requirements. Gray iron shall not be allowed as cog material.
15.2.2 Ratchet mechanisms of winding drums in hoists shall be fitted with pawls and locks. Locks shall be automatically engaged when pawls are open.
15.2.3 All crank mechanisms of winding drums shall utilize tooth-like mechanism which fits to transmission system of the hoist and is engaged in case of descending motion in order to prevent the cranks from moving in opposite direction which can injure crank operators or bystanders. This locking mechanism shall be protected from external contaminants.
15.2.4 Cables shall have sufficient length so that there are at least 3 cable wraps remaining on the drum while working platform is at the lowest position.
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15.3 Requirements regarding cables
Hoisting cables shall be required to withstand six times the design load of the scaffold. Steel cables shall be compliant with 20.8.2, 20.8.8, and 20.8.10. Steel cables shall only be used in accordance with hoist manufacturers’ instructions. Steel cables shall be in single pieces and shall not be multiple pieces joint together.
15.4 Requirements regarding elevating carriages
15.4.1 Descending motion of working platforms shall only be facilitated by operators’ deliberate use of force to disengage ratchet pawls. Once the operators cease to apply force, the pawls must automatically engage to prevent unwanted descent of working platforms.
15.4.2 A safety device shall be required for each elevating carriage. This safety device shall lock the elevating carriage onto tower structure to prevent the elevating carriage from descending more than 350 mm. This safety device shall be protected from environmental impact. Safety devices that operate on the principle of free fall shall not be allowed.
15.5 Use of adjustable scaffold
15.5.1 Guardrail system and toeboards shall only be required on the backsides and ends of material platforms and working platforms. Guardrail system and toeboards shall be compliant with 4.6. Temporary dismantlement of guardrail system of material platforms shall be allowed when materials have been loaded onto the platforms as long as the guardrail system is re-installed after operation ends. Toeboards shall not be required if the scaffold is used in an enclosed space where the risk of people occupying spaces beneath the scaffold is prevented.
15.5.2 Before working platforms are fixed to suspension cable, elevating carriages shall be supported by a device that is capable of withstanding two times the design load of the scaffold.
15.5.3 Scaffold manufacturers shall provide instruction manuals that include:
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2) handling and transport procedures;
3) erection, use, and dismantlement procedures;
4) crossbracing;
5) maximum freestanding height (without being braced to the structure);
6) bracing to structural member;
7) maximum permissible height;
8) loading method;
9) maximum permissible load of elevating carriage;
10) design load of elevating carriage and parts;
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12) inspection and maintenance;
113) fall prevention during scaffold erection and dismantlement.
15.5.4 Entities using scaffold shall introduce and provide instruction manuals for employees and supervise safe use of the scaffold. In order to use and operate the scaffold, a person must:
1) read and acknowledge manufacturers’ instructions;
2) receive safety training in operation, use, and inspection of the scaffold and its parts.
15.5.5 Working on scaffold shall be prohibited in unfavorable weather conditions, storm or strong breeze. The use of roofed scaffold or enclosed scaffold shall be compliant with manufacturers’ instructions.
16.1 Single ladder, extension ladder with brackets attached, triangle ladders, extension triangle ladders shall be used as support for planks or working platforms.
16.2 General requirements
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16.2.2 Ladders that support working platforms shall be type I ladders with load rating of 115 kg or type A1 ladders with load rating of 135 kg.
16.2.3 Maximum permissible height of working platforms shall be 6 m from the platform on which ladders are located. Maximum permissible height of working platforms supported by two freestanding triangle ladders shall not exceed four times the width of ladder legs, unless the scaffold is anchored or braced. It is possible to increase width of ladder legs via the use of auxiliary legs.
16.2.4 Platform on which ladder legs rest on shall be strong enough to support ladder legs when tested load equals to four times the load applied to working platforms.
16.2.5 Platform on which ladder legs rest shall be clean and do not contain loose materials around.
16.2.6 Maximum supported span of planks shall be complaint with 5.2, 5.3, and 5.4 and compliant with permissible load.
16.2.7 Planks and working platforms shall be firmly attached to supporting structures, prevented from all lateral displacement, and rested on supporting structures. Dimension of plank and working platform sections that are rested on supporting structures shall not be lower than 300 mm, not be greater than 450 mm, and compliant with 4.18.
16.2.8 Width of working platforms shall be calculated for working platforms with special dimensions.
16.2.9 Maximum length of working platforms shall be equal to or less than 8,5 m. any situation where length of working platforms exceeds 8,5 m shall require drawing and appropriate calculations.
16.3 Ladder jack scaffold resting on structural members
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16.3.2 Minimum width of wood working platforms shall be 0,45 m and minimum width of fabricate working platforms shall be 0,3 m.
16.3.3 Scaffolds shall be designed and erected in a manner compliant with load requirements under this Standard during normal operating conditions.
16.3.4 Straight ladders shall be designed and installed so that load applies on treads and side rails. If load only applies on the treads, minimum tread depth shall be 250 mm.
16.3.5 Working platforms shall not be installed higher than the second highest tread of the ladders.
16.3.6 Working platforms shall not be installed higher than where the ladders rest to the wall.
16.3.7 Ladders shall be leaned at a 75o angle. The ratio between the distance from ladder leg to the bottom of the structure wall and working length of the ladders. Working length of ladders shall be calculated from the leg of the ladders to the resting point of the ladders.
16.3.8 Both top end and bottom end of ladders shall be firmly secured throughout scaffold erection and before use.
16.3.9 Employees working on scaffold shall be required to wear personal fall-arrest system.
16.4 Trestle ladder scaffold
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16.5 Extension trestle ladder scaffold
Working platforms shall not be installed higher than the second highest tread of the main ladder or not be installed higher than the third highest tread of the extended section.
17.1 Outrigger beams shall project no more than 1,8 m from structure surface. Inboard section of the beams, measured from the fulcrum point, shall not be less than 1,5 times the length of outboard section.
17.2 Inboard section of the beams shall be firmly secured by:
- bracing against overhead beams or ceilings;
- anchoring to lower floor via anchorage;
- both measures above simultaneously if necessary.
Inboard ends shall be firmly braced to prevent lateral movement.
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17.4 Working platforms shall be secured by nails or bolts onto beams where spacing between the working platforms does not exceed 70 mm.
17.5 Maximum clearance between bearers supporting working platforms shall conform to 5.2, 5.3, and 5.4 and be suitable for load of supporting members.
17.6 Guardrail system shall be compliant with 4.6 and 4.6.8.
17.7 Working platforms supported by outrigger beams which project more than 1,85 m from structure wall shall be designed and calculated by professional engineers with practicing license.
Schedule 13 - Minimum dimension and maximum spacing of scaffold parts on wood outrigger beams
Light-duty
Medium-duty
Maximum load, kg/m2
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250
Cross sectional area of outrigger beam, mm
50 x 255
75 x 255
Spacing between two adjacent outrigger beams, m
3
1,8
18 Carpenter’s bracket scaffold
18.1 Design
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18.1.2 Guardrail system shall be compliant with 4.6. Safety screen shall be compliant with 4.6.8.
18.1.3 There shall be no more than two working employees and no more than 35 kg of materials occupying a length-wise space of 2,4 m of working platforms.
18.2 Wood stacker bracket scaffold
18.2.1 Minimum design specifications shall be compliant with Schedule 14.
18.2.2 Stacker brackets shall be made from solid quality wood and at most 2,4 m apart from one another.
18.2.3 Horizontal beams shall be made from two beams of wood or other materials with similar strength where dimension of cross sectional area is 0,025 m high x 0,015 m wide. These wood beams shall be secured (nailed) onto opposite sites of vertical brackets attached to the wall. Outboard section of horizontal beams shall not exceed 1 m. Extreme outboard ends shall be braced and secured by two diagonal braces.
18.2.4 Diagonal braces shall be nailed or bolted onto vertical brackets at a position that is at least 0,92 m further down from the underside of main horizontal members. Diagonal braces shall be nailed or bolted onto outboard end of horizontal members at an approximate angle of 45o.
18.2.5 An auxiliary horizontal beam shall be required between two stacker brackets in order to support working platforms. Working platforms shall consist of at least two planks which shall be nailed onto horizontal members. If one end of a plank is not nailed onto horizontal members, the plank shall have sufficient length in order to extend past horizontal members by 150 mm but no more than 300 mm.
18.2.6 Maximum clearance between bearers supporting working platforms shall conform to 5.2, 5.3, and 5.4 and be suitable for load of supporting members.
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Parts
Dimensions, mm
- Vertical bracket members
50 x 100 or 50 x 150
- Horizontal bracket members
25 x 150
- Diagonal braces
25 x 150
Maximum length of bracket
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Maximum clearance between two adjacent stacker brackets
2400 (center to center)
18.3 Metal bracket scaffold
18.3.1 Metal brackets shall be prefabricated by welded or bolted parts. Fold-type brackets shall remain in open state when they are engaged by bolts or safety locks.
18.3.2 Metal brackets shall be no more than 2,4 m apart from one another.
18.3.3 Both ends of planks shall be secured by bolts or extend past the brackets by at least 150 mm but no more than 300 mm if auxiliary supporting members are not used.
18.3.4 Maximum clearance between bearers supporting working platforms shall conform to 5.2, 5.3, and 5.4 and be suitable for load of supporting members.
18.3.5 Guardrail system on working platforms shall be compliant with 4.6. Safety screen shall be compliant with 4.6.8. Minimum dimensions of parts of wood guardrail system shall be compliant with Schedule 15.
Schedule 15 - Minimum dimension of wood guardrail system installed on metal brackets capable of supporting 125 kg/m2
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Dimensions, mm
- Guardrail posts
50 x 100
- Handrails
50 x 100
- Midrails
25 x 150
- Toeboards
25 x 150
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900 to 1200
Maximum clearance between two metal brackets (appropriate with design of manufacturers)
2400
Schedule 16 - Minimum dimensions of wood bracket scaffold capable of supporting 125 kg/m2
Parts
Dimensions, mm
Cross sectional area:
- Vertical members
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- Braces
- Guardrail posts
- Midrails
- Toeboards
50 x 100 or 50 x 150
50 x 150
25 x 150
50 x 100
25 x 150
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Guardrail height
900 to 1200
Maximum bracket width
1000
Span between vertical members
2400
18.4 Wood bracket scaffold
18.4.1 Minimum dimensions shall be compliant with Schedule 16.
18.4.2 Wood bracket scaffold shall be a part of a formwork system.
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18.4.4 Planks shall be nailed onto vertical and horizontal members of the scaffold. Planks shall extend past the last horizontal members by at least 150 mm and no more than 300 mm if auxiliary supporting members are not used.
18.4.5 Maximum clearance between bearers supporting working platforms shall conform to 5.2, 5.3, and 5.4 and be suitable for load of supporting members.
19.1 Window jack scaffold shall be designed and erected so that clamping mechanisms are able to firmly grip on to windows and withstand design load.
19.2 Window jack scaffold shall only serve construction in the area around windows where the scaffold is anchored to.
19.3 Window jack scaffold shall not be used to support working platforms that bridge windows or bridge windows and other parts of scaffold.
19.4 Guardrail system compliant with 4.6 shall be required in window jack scaffold, unless fall protection is installed instead of guardrail system.
20 Suspended scaffold with hoist
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20.1.2 If the scaffold is used in areas with irregularities such as power lines, obstacles on moving paths or other nearby operating equipment, additional safety measures such as warning signs or fences shall be required to maintain safety for users.
20.1.3 In order to operate suspended scaffold with hoist, an employee must:
- Have received training and familiarized with the type of scaffold they he/she will operate;
- Have been provided with instructions and trainings regarding the use of fall-arrest devices including lifelines;
- Have been provided with instructions regarding the use of equipment available on the scaffold;
- Be placed under occupational safety control.
20.1.4 Planning and positioning of suspended scaffold shall be done under supervision of qualified and experienced person.
20.1.5 Fabricated working platforms for use in suspended scaffolds shall have minimum load rating of two working employees and minimum width of 0,5 m.
20.1.6 Measures shall be taken to prevent tools and materials from falling out of working platforms.
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20.1.9 Fall protection and emergency equipment shall not be used to temporarily suspend members while working on suspended scaffold.
20.1.10 In regard to inclined or partially inclined cables, applied forces shall be calculated as if they are applied horizontally.
20.1.11 Working platforms on two-point suspended scaffold shall not be sloped more than 1/12.
20.2 Requirements regarding suspended parts of suspended scaffold
20.2.1 All parts suspending the scaffold (such as needle beam, guardrail hooks, wall clips) and suspending members shall be able to withstand four times the load rating. Guardrail hooks and clips shall not be hooked or clipped onto guardrails if they are not meant to support load.
20.2.2 If pulley is used in order to increase lifting capability, suspension system shall be designed so that it is capable of supporting load equal to four times the load rating of hoist multiplied by pulley multiplier.
20.2.3 Guide pulley that changes cable direction less than 90o shall have inner diameter equal to or greater than ten times the cable diameter. Guide pulley that changes cable direction more than 90o shall have inner diameter equal to or greater than fifteen times the cable diameter.
20.2.4 Guardrail hooks and guardrail members for anchoring scaffold shall be so designed to withstand four times the load rating and firmly secured to tieback. Tiebacks shall be perpendicular to structure surface and anchored to firm elements. If ties are not rigid enough, two tiebacks shall be required to prevent forward and lateral motion. Tiebacks shall be required to have load bearing capability similar to that of suspension cables.
20.2.5 Console beams for suspending scaffold shall be capable of withstanding four times the load rating of hoists and anchored to prevent displacement. If inboard end of console beams are secured by counterweights, these counterweights shall be attached to the beams. Counterweights shall be solid, non-melting objects with overturning safety factor of 4. Each piece of counterweight shall have its weight displayed on it. Tiebacks shall be perpendicular to structure surface and anchored to firm elements. If ties are not rigid enough, two tiebacks shall be required to prevent forward and lateral motion. Tiebacks shall be required to have load bearing capability similar to that of suspension cables.
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20.2.7 Multiple-tier suspended scaffolds and scaffolds covered by roofs shall be required to be equipped with independent secondary suspension with strength similar to that of primary suspension. Independent secondary suspension shall be capable of suspending the entire scaffold in case of failure of primary suspension (see 20.6). Independent suspension shall be anchored to tiebacks and independent anchorage.
20.2.8 All independent secondary suspension shall be firmly attached to the scaffold via suspension devices. The suspension devices above shall have their design tested so that they hold and suspend a minimum of 125% load.
20.2.9 If suspended scaffold is used for arc welding, for the purpose of minimizing arc welding impact on suspension quality, protective measures below shall be required:
1) All cables and suspended parts shall be insulated. Cables and independent secondary cables shall not be grounded.
2) A minimum length of 1,2 m of overhead cable ends shall be coated by insulated materials. Loose hoisting cable ends shall be insulated and not make direct contact with working platforms. Free cable ends lying on working platforms shall be held in place or kept from grounding.
3) Hoist shell shall be made from insulated materials.
4) In addition, welder’s power cable shall be connected to grounding wire between the scaffold and welded elements. Dimensions of grounding wire shall be equal to or greater than those of conductor wire and not connected to conductor wire in series or between welded elements in series.
5) Welding shall be stopped if grounding wire is snapped or not connected.
6) Welding electrodes and open electrical wires shall not make contact with scaffold members and suspension system.
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20.3.1 General requirements
20.3.1.1 Maximum rated vertical speed of electric-powered suspended scaffold shall not exceed 10 m/min.
20.3.1.2 Electric hoists shall be fitted with primary brake and secondary brake (see 20.3.3 and 20.3.4).
20.3.1.3 Deceleration gearbox of electric hoists shall be compliant with 20.3.2.
20.3.1.4 Winding drums and pulleys shall be compliant with 20.3.5.
20.3.1.5 Both winding drums and friction winding or friction pulleys shall be designed to that hoists shall always be able to accommodate suspension cables at all time.
20.3.1.6 Lubricating oils shall be applied to all necessary positions to ensure that all moving parts are adequately lubricated.
20.3.1.7 In addition to provisions under this section, all motor-powered hoists shall be compliant with 20.3.7.
20.3.1.8 In addition to requirements under this section, all manually operated hoists shall be compliant with 20.7.
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1) Name of manufacturer;
2) Maximum load rating;
3) Number;
4) Technical specifications of steel cables.
20.3.1.10 Upon exiting manufacturing facilities, hoists shall be accompanied by manuals that provide operation and maintenance instructions.
20.3.1.11 Each hoist used for suspended scaffold shall have its design tested by a competent independent entity licensed by competent authority.
20.3.2 Requirements regarding deceleration gearbox
20.3.2.1 Deceleration gearbox shall be required in case of electric hoists. Deceleration gearbox shall utilize gears to decelerate (not friction) such as gear and gear shaft transmission, cylindrical gear transmission, bevel gears, or similar gear transmission types. Deceleration gearbox shall be tightly sealed or covered.
20.3.2.2 Deceleration gearbox shall be attached directly to hoisting drums. Deceleration gearbox shall not be attached to hoisting drums via rubber belts, bolts, roller chains, or other friction-based, gear-based methods.
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20.3.3 Requirements regarding primary brakes
20.3.3.1 Primary brakes shall be required in case of electric hoists. Primary brakes shall be automatically acting brakes that are normally closed, meaning the brakes will automatically close whenever power supply for main engines is shut or whenever operators stop.
20.3.3.2 Primary brakes shall be calculated to stop and support minimum load equal to 125% of load rating of hoists.
20.3.3.3 Primary brakes shall be directly connected to transmission system of hoists. Primary brakes shall not be connected to transmission system of hoists via rubber belts, bolts, roller chains, or other friction-based, gear-based methods.
20.3.4 Requirements regarding secondary brake
20.3.4.1 An automatic acting secondary brake shall be required for each hoist. Secondary brakes shall be able to stop and support minimum load equal to 125% of load rating of hoist during acceleration. Secondary brakes shall be considered instant brakes if they are capable of stopping and supporting minimum load equal to 125% of load rating of hoists where vertical braking distance does not exceed 0,3 m. Secondary brakes shall be considered non-instant brakes if they are capable of stopping and supporting minimum load equal to 125% of load rating of hoists where vertical braking distance does not exceed 0,6 m in vertical length.
20.3.4.2 In case of friction drums, secondary brakes shall directly apply on suspension cables. In case of hoists with winding drums, secondary brakes shall apply directly on suspension cables or directly on winding drums or extension of winding drums. Secondary brakes shall be separate from transmission system of hoists. Activation mechanism of secondary brakes can be separate from the brakes.
20.3.4.3 The use of secondary brakes for stopping and suspending hoists shall be prohibited unless speed limit is exceeded or secondary brakes are not closed before hoists are stopped by primary brakes in normal working conditions.
20.3.4.4 Secondary brakes shall be tested on a periodic basis under simulated conditions according to manufacturer’s instructions (see 20.20.3).
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20.3.5 Requirements regarding drums and pulleys.
20.3.5.1 Requirements regarding friction drums and friction pulleys
20.3.5.1.1 Friction drums and friction pulleys shall be designed so that steel cables are evenly distributed and cable wraps do not overlap one another. Friction drums and friction pulleys shall be equipped with mechanisms that maintain pulling force of hoists when load increases. Counterweights and free cable ends shall not be used to generate pulling force.
20.3.5.1.2 Inner diameter of friction drums and friction pulley shall be equal to or greater than eighteen times the diameter of steel cables.
20.3.5.2 Requirements regarding winding drums
20.3.5.2.1 Winding drums shall be fitted with fastening mechanisms for cables. Fastening mechanisms shall be able to withstand four times the load rating of hoists. (see 20.8.11.4 for requirements for steel cable fastening mechanisms.)
20.3.5.2.2 Winding drums shall be fitted with unwinding mechanisms.
20.3.5.2.3 Minimum number of wraps on drums while working platforms are at the lowest position shall be 4.
20.3.5.2.4 Minimum diameter of drums shall be equal to or greater than ten times the cable diameter.
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20.3.6 Energy transmission system
20.3.6.1 Gasoline-powered hoists shall not be allowed.
20.3.6.2 Electric-powered hoists shall be allowed as long as requirements under electricity safety standards and this Standard are adhered to. Electric motor shall be accompanied by labels which specify minimum technical specifications of:
- Name of manufacturer;
- Voltage;
- Intensity;
- Frequency; and
- Rated capacity.
20.3.6.3 Pneumatic, hydraulic, diesel-powered hoists shall be allowed as long as this Standard is adhered to.
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20.3.7.1 Each electric hoist shall be fitted with a separate control system. If the control system utilizes buttons, the amount of force necessary to press the buttons shall remain unchanged. If control system utilizes predetermined stop, automatic locks shall be required to engage when the system is shut down or protection against unintended control. If control system utilizes levers, either the type requiring unchanged activating force or the type with predetermined stop shall be required.
20.3.7.2 Manual operating scheme shall be allowed for electric hoists. If powered hoist is fitted with manual operating scheme, the manual operating scheme shall be designed so that each hoist requires no more than one personal manually operating it. A mechanism for shutting off prime movers during operation shall be required. Manufacturers shall provide use instructions of manual operating scheme and power switch instructions before the use of manually operated hoist is permitted.
20.3.8 Manual operation of powered hoist
20.3.8..1 Manual operating scheme shall be fitted with speed limiter to prevent hoists from moving to fast or unwinding cables too fast.
20.3.8.2 Speed limiter shall be inspected and tested upon first installation, periodically, and irregularly.
20.4 Requirements regarding electric cable and electric appliances
20.4.1 Electric cables and control system shall conform to TCVN 5935-2: 2013 (IEC 60502-2:2005).
20.4.2 Electric cables of electric hoists shall utilize neutral cables that are insulated and grounded. Electric metal boxes shall be grounded.
20.4.3 Devices that prevent excessive stretching of electric cables or similar measures shall be required. Electrical sockets shall be fitted with devices that prevent excessive stretching of cables or similar measures to prevent plugs from being pulled out of sockets. Electrical sockets shall be secured to the scaffold and prevented from all displacement.
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Personal fall-arrest system for employees working on suspended scaffold shall be compliant with 4.37 and additional requirements below:
20.5.1 Employees working on single-point suspended scaffold or two-point suspended scaffold shall be required to be equipped with personal fall-arrest system. Each part of personal fall-arrest system shall be inspected individually before use, including: full-body harnesses, lanyards, hooks, and lifelines. Lifelines shall be anchored to two anchorages which shall be separate from suspension system of the scaffold. Lifelines and anchorage shall be able to withstand a minimum load of 225 kg. Pressurized pipes and gas pipes shall not be used as anchorage.
20.6 Fall protection of suspended scaffold
20.6.1 Separate secondary suspension shall be allowed as an alternative to personal fall-arrest system in single-point suspended scaffold and two-point suspended scaffold. Separate secondary suspension shall comprise of suspension lines one end of which is anchored to independent structure while the other end is anchored to primary structure of the scaffold. Anchorage and secondary suspension shall be able to withstand load of the scaffold. Separate secondary suspension shall be fastened to working platforms by suspended devices via secondary brakes of hoists (see 20.2.8)
20.6.1.1 Tying equipment and techniques of scaffold suspension shall be calculated and designed by licensed engineers.
20.6.2 Employees working on scaffold fitted with secondary suspension shall not be required to wear lifelines. If this is the case, suspension line is allowed to be directly anchored to scaffold members and suspension line shall be short enough to prevent employees from falling over guardrails.
20.6.3 If trolley line is used, the trolley line shall be secured to supporting frames of secondary brakes or equivalent safety anchorage.
20.6.4 Two-point suspended scaffold fitted with separate secondary suspension shall be required to be fitted with guardrail system on both sides of working platforms.
20.6.5 Scaffolds with overhead cover and multiple-tiers scaffolds shall be required to be fitted with anti-rotation lines and separate secondary suspension line as depicted under 20.2.6, 20.2.7, and 20.2.8. If scaffolds above are used, all suspension lines of personal fall-arrest system on all scaffold tiers shall be anchored to scaffold members or horizontal trolley lines. Independent suspension lines shall be hung from independent anchorage to tying points on suspended scaffold.
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20.7.1 Manually operated hoists that utilize winding drums shall utilize ratchet and pawl mechanism which will lock if the ratchet ceases to rotate in the direction of lift.
20.7.2 Manually operated hoists shall be fitted with secondary brakes that act directly on cables or winding drums.
20.7.3 Hoists that utilize manually operated winding drums shall be fitted with suspension devices in order to connect suspension lines to the scaffold. Devices that clip cable ends to winding drums shall have minimum load rating equal to four times the load rating of lifting devices.
20.7.4 Hoisting cables of hoists that utilize manually operated winding drums shall have sufficient length so that a minimum of four cable wraps remains while the scaffold is at the lowest position.
20.7.5 All positions that require lubricating oils shall be adequately lubricated and greased so that all moving parts of hoists can operate smoothly at all time.
20.7.6 All manually operated hoists shall be accompanied by signs that specify:
1) Name of manufacturer;
2) Maximum load rating;
3) Machine number;
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20.7.7 Manually operated hoists upon being released shall be accompanied by operation and maintenance instructions.
20.7.8 Manually operated hoists used in suspended scaffold shall have their design tested by independent laboratories licensed by competent authority.
20.7.9 Manually operated hoists shall be fitted with speed limiter in normal operating conditions.
20.7.10 Manually operated hoists shall be fitted with levers to lower the scaffold.
20.7.11 Rapid lowering mechanisms shall not be installed or activated during installation if there are employees on the scaffold.
20.8 Requirements regarding suspension cables
20.8.1 Cables used in suspended scaffold shall be able to withstand at least six times the load rating and shall have diameter not lower than diameter under other requirements under this Standard.
20.8.2 Cables used in manually operated suspended scaffold shall have a minimum diameter of 6,5 mm.
20.8.3 Steel cables used in manually operated suspended scaffold shall have a minimum diameter of 8 mm.
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20.8.5 If there are two cable lays within a length equal to seven times the cable diameter, the cable shall not be used.
20.8.6 Free ends of steel cables shall be tied in a way that every cable section other than that contained in anchor assistance devices can be easily seen.
20.8.7 Cables shall have sufficient length so that it is possible to reach the lowest working level without running out of cables. Free ends of cables shall be welded or tied up.
20.8.8 Steel cables repaired due to defects shall not be allowed for use.
20.8.9 Cables of manually operated hoists shall be allowed to be connected by loops and clips as long as the connection is not wound into the hoists.
20.8.10 Cables shall be maintained in accordance with manufacturers’ instructions. Cables that display defects below shall be removed:
1) Steel structures that have been damaged to the point of reduced functionality and strength.
2) The cables are twisted to the point of reduced tensile strength or reduced elasticity making it difficult for the cables to be retracted to hoists or pulleys.
3) Number of visible broken wires per lay length is equal to or greater than 6 or number of visible broken wires in one strand per lay length is equal to or greater than 3.
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5) The cables show sign of failure due to contact with heat sources or electrical current.
6) The cables are entangled in secondary brakes which are activated due to exceeding the speed limit.
20.8.11 Cable connections shall be compliant with 20.8.10.1 through 20.8.10.4 below:
20.8.11.1 Free cable ends shall not be secured by metal tubes made from materials of babitt or zinc.
20.8.11.2 Fabricated accessories or hooks, wire clips shall be suitable for steel cables according to cable manufacturers, scaffold manufacturers, or qualified person’s instructions.
20.8.11.3 Wire clips shall be installed in accordance with manufacturer’s instructions. “U” clips shall not be allowed where hoists for lifting scaffolds are suspended. "U” clips shall have their guards fastened after initial load testing and refastened periodically.
20.8.11.4 Cable ties shall have minimum strength equal to 80% of that of steel cables.
20.9 Multiple-point suspended scaffold (Figure A.25)
20.9.1 Hoists of multiple-point suspended scaffold shall be compliant with 20.3 or 20.7 Manufacturers or professional engineers shall be allowed to design multiple-point suspended scaffold. Multiple-point suspended scaffold shall be erected under supervision of a qualified person.
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20.9.3 Suspension steel cables shall be compliant with 20.8 and steel cable ties shall be compliant with 20.2.
20.9.4 People occupying multiple-point suspended scaffold shall be equipped with personal fall-arrest system which shall be compliant with 20.5, except for the following cases:
1) The scaffold utilizes separate secondary suspension compliant with 20.2.7, 20.2.8, and 20.5, and
2) All sides of working platforms are fitted with guardrails.
20.9.5 If one side of working platform adjoining wall is not fitted with guardrails, all employees working on the platform shall be equipped with personal fall arrest system. Suspension lines shall be allowed to be anchored to primary elements of working platforms.
20.9.6 Guardrail system and toeboards of working platforms shall be installed in a manner compliant with 4.6. Safety screen shall be installed in a manner compliant with 4.6.8.
20.9.7 Fabricated working platforms can be connected to one another to expand length-wise and facilitate continuous movement from one working platform to another if hoist supporting frames facilitate such purpose and are designed for such purpose. Maximum number of hoists serving a fabricate working platform shall be 2. If there are more than 2 hoists serving a working platform, joints between fabricated working platforms shall be designed by engineers specializing in suspended scaffold in order to prevent overloading of suspending members.
20.10 Masons’ multiple-point suspension scaffold
20.10.1 Maximum working load shall be 75 kg/m2 and placed load shall not exceed this value.
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20.10.3 Suspension cable shall be compliant with 20.8. Steel cable shall be secured to overhead console beams and have safety factor of 6.
20.10.4 Anchorage and anchoring system shall be designed by engineers having with proper license for this type of scaffold.
20.10.5 Suspending ends of overhead beams shall be guarded by bolts or couplers.
20.10.6 Resting points of overhead beams shall be wedged with wood.
20.10.7 “U” wire clips on mobile scaffolds for fastening suspension cable shall vertically line up with hoists.
20.10.8 Working platforms of scaffold shall have minimum load equivalent to that of sawn wood plank of 50 mm thick. (see 5.2, 5.3, and 5.4 to determine maximum permissible clearance between bearers supporting planks).
20.10.9 Guardrail system shall consist of toprails, toeboards, and safety screen and shall be installed along the edges of working platforms. Toprails and toeboards shall be compliant with 4.6. Safety screen shall be installed in a manner compliant with 4.6.8. Employees working on working platform shall be equipped with personal fall-arrest system where lanyards are anchored to scaffold members.
20.10.10 If the risks of falling objects are present while employees are working on scaffold, overhead guards shall be required at a maximum height of 2,75 m from working platforms and assembled from planks of minimum thickness of 50 mm in case of sawn wood or 18 mm in case of laminated wood or materials with similar strength.
20.10.11 Scaffold shall be erected or moved to the correct position according to inspected design and use instructions under supervision of a qualified person.
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20.11.1 Minimum working load shall be 37,5 kg/m2 and placed load shall not exceed this value.
20.11.2 Scaffolds shall be fitted with hoists compliant with 20.3 or 20.7.
20.11.3 Suspension cable shall be compliant with 20.8. Steel cable shall be secured to overhead console beams and have safety factor of 6.
20.11.4 Anchorage and anchoring system shall be designed by engineers having with proper license for this type of scaffold.
20.11.5 Suspending ends of overhead beams shall be guarded by bolts or couplers.
20.11.6 Resting points of beams shall be wedged with wood.
20.11.7 Steel hooks or “U” clips for fastening suspension cables to mobile console beams shall be positioned directly above hoists.
20.11.8 Working platforms of scaffold shall have minimum load equivalent to that of sawn wood plank of 50 mm thick. (see 5.2, 5.3, and 5.4 to determine maximum permissible clearance between bearers supporting planks).
20.11.9 Guardrail system shall consist of toprails, toeboards, and safety screen and shall be installed along the edges of working platforms. Toprails and toeboards shall be compliant with 4.6. Safety screen shall be installed in a manner compliant with 4.6.8. Employees working on working platform shall be equipped with personal fall-arrest system where lanyards are anchored to scaffold members.
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20.11.11 Scaffolds shall be erected or moved to the correct position according to inspected design and use instructions under supervision of a qualified person.
20.11.12 Scaffolds whose working platforms are wider than 900 mm shall be required to be fitted with mechanisms that prevent lateral movement.
20.12 Requirements regarding two-point suspended scaffold
20.12.1 Width of working platforms of two-point suspended scaffold shall be equal to or greater than 0,45 m and equal to or less than 0,9 m and compliant with 5.4.2. Working platforms shall be fastened to hoist suspending or supporting beams. Hoist suspending or supporting beams and suspension cables shall be compliant with 20.2 and 20.8. In case of enclosed space, it is possible to use working platforms equal to or narrower than 0,3 m. Narrow working platforms shall be compliant with 20.1.5 where their installation shall be implemented under supervision of a qualified person.
20.12.2 Hoists lifting and lowering two-point suspended scaffold shall have their design tested in a manner compliant with 20.3 or 20.7.
20.12.3 Guardrail system and toeboards shall be complaint with 4.6 and safety screen shall be compliant with 4.6.8. Hoist supporting beams shall be considered guardrails if they are no more than 0,45 m away from the edge of working platforms. Edges of working platforms shall be fitted with guardrails if hoist supporting beams allow people to travel through.
20.12.4 Employees working on two-point suspended scaffold shall be equipped with personal fall-arrest system compliant with 20.5.
20.12.5 Two-point suspended scaffold shall be suspended by steel cables, ropes, or synthetic ropes. Steel cables shall be compliant with 20.8. Suspension cables shall have minimum safety factor of 6.
20.12.6 Pulleys using ropes or synthetic ropes shall be of standard type and 155 mm in dimension. A minimum of 1 set of duo pulleys and 1 set of single pulley shall be required. Pulleys and pulley sets shall be suitable with diameter of synthetic ropes. Pulley sets shall be fitted with safety hooks or tight clips.
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1) Suspension cables create an angle with the structure surface so that when the scaffold is lifted, a minimum force of 45 N is applied to the structure surface laterally by the scaffold.
2) Continuous anchoring to the structure is required;
3) Intermittent anchoring is implemented where anchoring is implemented once every 3 tiers or 15 m, whichever value is lower;
4) Scaffold is secured to working positions.
20.12.7.2 For the purpose of preventing rotation, anchoring to windows or window bars shall not be allowed. Anti-rotation shall also be facilitated by tying two ropes to the ground of the floor below. Rotation control system shall be designed and installed by a qualified person with special attention to adjustment to working platform height.
20.12.8 Two-point suspended scaffold fitted with toprails shall be fitted with separate secondary suspension. Separate secondary suspension shall be compliant with 20.2.7 and 20.2.8.
20.12.9 Two-point suspended scaffolds can be hung at the same working height without having traversable passage between them, irrespective of the case where these working platforms are at the same elevation and next to each other.
20.13 Requirements regarding fabricated two-point modular scaffold
20.13.1 Two-point suspended scaffold assembled from fabricated modules shall be compliant with 20.12.1 and 20.12.3.
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20.13.3 Working platform modules and fabricated working platform modules shall have their design tested. Design testing shall be carried out by an independent laboratory licensed by competent authority.
20.13.4 Working platform modules and assembled working platform modules shall be designed with stable safety factor equal to twice the load rating.
20.13.5 Scaffolds formed by modules that form floor with unique shapes such as cornering, zigzagging, or with multiple hoists shall be designed by manufacturers or licensed professional engineers and erected under supervision of qualified person.
20.13.6 Working platform modules or platform units shall be accompanied by instructions for arrangements and load rating of these arrangements.
20.13.6 All employees working on suspended scaffold formed by modules shall be equipped with personal fall-arrest system compliant with 20.5.
20.14 Requirements regarding multiple-tier suspended scaffold
20.14.1 Multiple-tier suspended scaffold shall be designed by licensed professional engineers.
20.14.2 Powered hoists used on multiple-tier suspended scaffold shall be compliant with 20.3 or 20.7.
20.14.3 All load-bearing members shall be fastened to each other directly and to the top of hoist support frames and shall not be suspended from the topmost working platforms.
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20.14.5 Suspension cables shall be steel cables and compliant with 20.8.
20.14.6 Guardrail system and toeboards must comply with 4.6. Safety screen must comply with 4.6.8.
20.14.7 Separate secondary suspension shall be required for multiple-tier suspended scaffold. Separate secondary suspension shall be compliant with 20.2.7 and 20.2.8.
20.14.8 Fall protection system installed in multiple-tier suspended scaffold shall be compliant with 4.37, 20.5, and 20.6.
20.14.9 Employees moving between tiers shall be equipped with personal fall-arrest system.
20.15 Requirements regarding multiple-point suspended scaffold lifted by manually operated hoists
20.15.1 Scaffold shall have working load of 37,5 kg/m2 and placed load shall not exceed this value.
20.15.2 Scaffold shall be fitted with manually operated hoists in a manner complaint with 20.7, except for cases where tandem hoists utilize two cables where the inner cable is close to the surface of the structure and the outer cable is across the working platform from the inner cable. Winding drums of tandem hoists shall wind both cables evenly so that working platforms are always perfectly horizontal.
20.15.3 Suspension cables shall be compliant with 20.8.
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20.15.5 Ends of beams shall be secured to prevent hooks from slipping off of beams.
20.15.6 Beams shall be wedged with wood.
20.15.7 Hooks or cable stabilizers on mobile beams shall perfectly line up with hoists vertically.
20.15.8 Working platforms of scaffold shall have minimum strength equivalent to 50 mm thick planks. (see 5.2, 5.3, and 5.4 to determine maximum permissible clearance between bearers supporting planks). It is permissible to use fabricated working platforms as long as there are no more than two hoists serving a working platform. Hinged connection shall be used to connect adjacent working platforms to create extended working platform.
20.15.9 Guardrail system shall consist of toprails, toeboards, and safety screen. Toprails and toeboards shall be compliant with 4.6. Safety screen shall be compliant with 4.6.8. Employees working on these working platforms shall not be required to wear personal fall-arrest system.
20.15.10 If the risks of fall object are present, roofs preventing falling objects shall be required. Such roofs shall be located at a height no more than 2,75 m from working platform and floored with 50 mm thick sawn wood planks or 18 mm thick laminated wood planks or materials with similar strength.
20.15.11 Scaffolds shall be erected or moved to the correct position according to inspected design and use instructions under supervision of a qualified person.
20.16.1 Scaffold shall have working load of 37,5 kg/m2 and placed load shall not exceed this value. Bricks, stone, and other materials shall not be placed on working platforms.
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20.16.3 Scaffold shall be suspended from steel beams, other console members, steel hooks, or steel suspension lines. Steel beams, console members, steel hooks, or steel suspension lines shall be capable of safely supporting the greatest load.
20.16.4 Suspension cables shall be compliant with 20.8.
20.16.5 Guardrail system shall consist of toprails, toeboards, and safety screen. Toprails and toeboards shall be compliant with 4.6. Safety screen shall be complaint with 4.6.8.
20.16.6 Scaffold shall be erected or moved to the correct position according to inspected design and instructions of manufacturers under supervision of a qualified person.
20.16.7 If additional reinforcement is required to increase the height of working position, technical specifications of suspension cables and scaffold structure shall be designed by engineers with certificates and in-depth understanding of the design.
20.17 Single-point suspended scaffold lifted and lowered by powered hoists
20.17.1 Suspended scaffold and hoists shall undergo tested design. Hoists shall be compliant with 20.3 or 20.7.
20.17.2 Employees working on suspended scaffold shall be equipped with personal fall-arrest system that is complaint with 20.5.
20.17.3 Two single-point suspended scaffolds can be joint to form a two-point suspended scaffold. In this case, the created two-point suspended scaffold shall be compliant with 20.12.
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20.18 Boatswains’ chairs lifted or lowered by manually operated hoists
20.18.1 Wooden chairs shall be reinforced by underside bars to prevent cracked and falling wood pieces.
20.18.2 Seat slings of ropes or synthetic ropes shall have a minimum diameter of 16 mm, be reeved through four corner holes in the seat and cross each other on the underside of the seat.
20.18.3 Slings and lifelines of boatswains’ chairs serving arc welding or brazing shall be made of steel with minimum diameter of 10 mm (see 20.2.9).
20.18.4 Employees working on boatswains' chairs shall be equipped with personal fall-arrest system that is complaint with 20.5, except for cases where personal fall-arrest system is not required.
20.18.5 Cable pulleys serving boatswains’ chairs shall fulfill requirements below:
(a) Use ball bearers of appropriate dimensions for pulley sets;
(b) Pulley sets shall be fitted with safe clipping mechanisms;
(c) Suspension lines shall form a loop at the end which is tightly wrapped;
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20.18.6 Hooks and steel members or overhead structural members for anchoring cable pulleys shall be firmly secured. Tiebacks shall be perpendicular to the structure surface and firmly anchored to primary members with sufficient load-bearing capacity.
20.18.7 Seat surface shall be designed with dimensions and materials compliant with 20.18.1. Seat surface shall be designed to withstand a load of 115 kg and only be approved after tested design has been conducted.
20.18.8 Manually operated hoists serving boatswains’ chairs shall be compliant with 20.7.
20.19 Requirements regarding electric-powered boatswains’ stand
20.19.1 Electric-powered boatswains’ stands and electric-powered hoists shall be installed by electric-powered hoist manufacturers or undergo tested design after installation to ensure that these devices are compatible with one another and cable of supporting dynamic load of 115 kg.
20.19.2 Electric-powered hoists serving boatswains’ stands shall undergo tested design and be compliant with 20.3.
20.19.3 Suspending devices and steel cables serving electric-powered boatswains’ stands shall be complaint with 20.2 and 20.8.
20.19.4 Employees working on electric-powered boatswains’ stands shall be equipped with personal fall-arrest system compliant with 20.5. Separate secondary suspension line is allowed as an alternative to lifeline if the separate secondary suspension line is compliant with 20.2.8. In this case, full-body harnesses shall be anchored to boatswains' stands.
20.20 Suspended scaffold inspection
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20.20.2 Steel cables, ropes, suspension points, working platforms, hoists, tying equipment, anchorage of personal fall-arrest system, and hooks thereof shall be inspected by a competent person prior to their installation. A competent person shall inspect the entire suspended scaffold system at least once per day. Any part of suspended scaffold that shows signs of degradation or damage shall be removed immediately. Scaffold suspension ropes that show signs of degradation or damage shall be removed immediately. Employees operating suspended scaffold shall monitor the entire system throughout use process and report all risks to a competent person.
20.20.3 Primary and secondary brakes shall be inspected as follows:
20.20.3.1 Inspection of primary and secondary brakes shall be compliant with manufacturers’ instructions and shall occur on an annual basis at most.
20.20.3.2 Inspection and testing shall also verify that the devices have passed testing with primary brakes and secondary brakes.
2020.20.3.3 If all of the tests cannot be performed at construction site, hoists shall then be dismantled entirely and transported to facilities with adequate equipment to conduct all of the tests. During the period in which hoists are dismantled for testing purposes, the entire suspended scaffold operation shall be suspended until the testing completes and hoists have been installed adequately.
20.20.3.4 If hoists or secondary brake transmission devices are removed from scaffold for testing purposes elsewhere, all parts that are directly or indirectly related to reinstallation of these devices shall be inspected before the scaffold is used.
20.21 Suspended scaffold maintenance
20.21.1 All parts that affect safety shall be maintained in accordance with maintenance procedures so that they perform their design functions properly. Suspended scaffold shall be maintained and preserved in accordance with manufacturers’ instructions. Information relating to maintenance of suspended scaffold shall be recorded to equipment use log.
20.21.2 All damaged or (mechanically and electrically) corroded parts that affect safety shall be replaced immediately. All conductor wires, sockets, and connections shall be firmly clipped.
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20.21.4 Major repair of suspended scaffold shall be implemented by qualified person and compliant with manufacturers’ instructions.
20.21.5 Parts whose function is affected if the parts are contaminated or covered in dust shall be kept clean and clear of dust at all time.
20.21.6 All parts of hoists, steel cables, and accessories thereof shall be greased and lubricated according to manufacturers’ instructions.
20.21.7 Free ends of suspension cables shall be wrapped or clipped to prevent fraying or crushing of cables. When wrapping or clipping free cable ends, cable section that has been damaged or suffered from fatigue and reduced load-bearing capability shall be removed.
20.21.8 Do not shut down safety devices or electrical protection equipment throughout operation of suspended scaffold unless doing so is necessary for testing, inspection, or maintenance. As soon as tests, inspection, and maintenance are complete, these temporarily shut down devices shall be brought back to normal operating conditions.
20.21.9 Personal fall-arrest devices shall be maintained in accordance with manufacturers’ instructions. Fall protection lines shall be tested to determine load-bearing capability or replace periodically. Do not replace any part of fall protection system without the consent of manufacturers.
21.1 All needle beam scaffolds shall comply with safety factor requirements when calculating scaffold load under 4.7 and 4.11, have minimum cross sectional area of 100 mm x 160 mm, and have the wider sides positioned vertically. It is permissible to use metal needle beams or similar types compliant with requirements under 4.7 and 4.11.
21.2 Scaffold shall utilize suspension lines or hooks and accessories with appropriate load-bearing capability and compliant with 4.30. Spacing between two wood beams with cross sectional area of 100 mm x 160 mm shall not exceed 3 m.
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21.4 Spacing between two needle beams shall be equal to or less than 2,4 if 50 mm thick sawn wood planks are used. If spacing between two needle beams is greater than 2,4 m, working platforms shall be designed in accordance with requirements applicable to special cases. Length of excess section of each plank end shall not be less than 0,15 m and shall not be greater than 0,3 m.
21.5 If one beam is higher than the other beam or if working platform is not perfectly horizontal, anchoring solutions shall be required to prevent slip or overturning.
21.6 All loose parts and accessories on the scaffold shall be placed in containers.
21.7 If one end of needle beam is supported by structural members, these members shall have sufficient load-bearing capability and satisfy safety factor when calculating scaffold load according to 4.7 and 4.11.
21.8 In erection, use, or dismantlement of needle beams at a height above 3,0 from the ground or solid platform, employees shall be equipped with personal fall-arrest system or fall protection devices or safety screen where height of the screen shall not be more than 1,8 m below the working platforms. Personal fall-arrest system or fall protection devices shall be anchored to structural members that are not scaffold members (see 4.37).
22 Interior hung scaffold (see Figure A.29 and Figure A.30)
22.1 Interior hung scaffold shall be suspended from roof members or ceiling beams.
22.2 Interior hung scaffold shall be designed to support four times the maximum intended load plus its own load. Suspension cables shall be compliant with 4.29 and 4.30 and have safety factor of 6.
22.3 A 60 mm x 230 mm wood plank shall be attached to each end of working platform to act as bearer.
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22.5 Tubes and couplers are allowed to suspend scaffold and shall be designed to withstand uniformly distributed load greater than heavy-duty scaffold with safety factor of 4.
22.6 If scaffolds are suspended by steel cables, the steel cables shall cross couplers or hooks. If steel cables are looped over beams, the cables shall be protected by soft cushion where sharp or pointy beam edges. A minimum of two wraps to overhead members and a minimum of two wraps to lower beams shall be required. Steel cable ends shall be protected from being frayed by cold stamped steel tubes which are capable of withstanding 80% of yield strength of steel cables.
22.7 All overhead suspending members shall be inspected for load-bearing capability prior to erection of the scaffold.
22.8 Toprails, midrails, and toeboards shall be compliant with 4.6. Safety screen shall be compliant with 4.6.8.
23 Swing scaffold (see Figure A.28)
23.1 Maximum number of employees working on the scaffold shall be 3 together with a small number of light-weight equipment. Scaffold shall be erected in a manner compliant with 23.2 through 23.6 unless it is designed with similar strength and rigidity.
23.2 Working platforms of laminated woods shall have minimum thickness of 19 mm, minimum width of 900 mm, and minimum length of 1800 mm.
23.3 Working platforms shall be supported by at least two bearers of solid sawn wood without knots and fissures and of dimension of 50 x 100 mm or 25 x 250 mm. Supporting members shall extend past working platforms towards both sides by at least 150 mm. Bearers shall be firmly attached to working platforms.
23.4 Open sides of working platforms shall be fitted with 20 x 40 mm toeboards of wood or similar materials.
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- Four rope ends are firmly anchored to overhead suspending members;
- Each rope is tied to one end of bearers, fixed to the underside of the working platform to the remaining end of the bearers where it is tied to the bearers;
- Remaining length of rope end after being tied to bearers shall be sufficient for the rope to be tied to suspending members.
23.6 All employees erecting, using, or dismantling scaffold where working platforms are higher than the ground or the floor by 2,5 m shall be equipped with fall protection devices. Lanyards shall be anchored to lifelines. Lifelines shall be secured to structures independent from the scaffold (see 4.37).
24 Catenary scaffold (see Figure A.27)
24.1 Both ends of working platforms shall be anchored to horizontal cables that are strong enough to prevent working platforms from falling if any of the cables break. Working platforms shall have minimum width of 0,5 m.
24.2 Horizontal steel cables shall be anchored to members that can withstand cable tension. Horizontal cable tension shall be equal to or less than 9 kN. Maximum spacing between cables offering protection against deflection shall be 1,5 m. Horizontal cables shall be continuous. Horizontal cables shall have minimum diameter of 12 mm, be manufactured from cold-rolled steel, and have safety factor equal to six times the design load.
24.3 Instructions of cable manufacturers regarding cable protection measures and use of cable suspension accessories shall be adhered to.
24.4 Working platforms shall be designed with working load of 25 kg and occupied by no more than two people simultaneously. The number of working platforms per scaffold shall be equal to or less than two and the number of working platforms between two vertical suspension lines shall not be greater than one.
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24.6 Employees working on scaffold shall be equipped with personal fall-arrest devices if there are risks of falling and if working platforms is at least 3 m above the ground or the floor. Lanyards of personal fall-arrest devices shall be secured to anchorage that is independent from the scaffold. If lanyards are vertical or horizontal, anchoring ends of these lanyards shall be anchored to members independent from the scaffold.
24.7 Ladders granting access to working platforms shall be required.
24.8 Catenary scaffold shall be designed by professionally licensed engineers and erected under supervision of a qualified person.
25.1 If slope of roof ladder is greater than 3:12, requirements under 25.2 and 25.4 shall be complied with.
25.2 Treads shall be at least 250 mm wide, at least 40 mm thick and fitted with all width-wise braces. Tread rise height shall be uniform and not exceed 600 mm. Braces shall be at least 25 mm thick x 30 mm wide. Braces shall be secured beneath treads.
25.3 Roof ladders shall extend from the ridge of the roof to the awning and be secured to the roof by rigid hooks or similar solutions.
25.4 Each roof ladder shall be fitted with a lifeline. Employees shall be required to wear personal fall-arrest devices whose lanyards are connected to lifeline.
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