Tiêu chuẩn TCVN 13662:2023 về Giàn giáo - Yêu cầu an toàn

• Số hiệu: TCVN13662:2023
• Loại văn bản: Tiêu chuẩn Việt Nam
• Nơi ban hành: ***
• Người ký: ***
• Ngày ban hành: Năm 2023

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.

5.4.9 Fabricated working platform must undergo tested design.

5.5 Modular fabricated working platform

See 20.13 for modular suspended scaffold

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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.

6.7 Runners must have minimum length exceeding that of a lift height. Runners must not be installed in the middle of the bay. Runners must be secured onto outer edges of poles to form support for bearers.

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.

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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.

6.12. When platforms are being moved to the next level, the existing platform shall be left undisturbed until the new bearers have been set in place and braced prior to receiving the new platforms.

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.

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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/m^2

Scaffold parts^(1)

Maximum height^(2), m

6 m

18 m

Uniformly distributed load, kg/m^2

≤ 125

≤ 125

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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

50 x 100

50 x 100

Dimension of bearer or putlog when scaffold width is between 900 mm to 1500 mm.

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or

75 x 100

50 x 150

or

75 x 100

Dimension of runner, mm

25 x 100

30 x 230

Vertical distance between horizontal members, mm

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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

25 x 100

NOTE:

(1) All scaffold parts shall be measured using outer dimensions;

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Schedule 3 - Nominal dimension and maximum distance of parts of medium-duty single pole scaffold - 250 kg/m^2

Scaffold parts^(1)

Dimensions^(2)

Uniformly distributed load, kg/m^2

≤ 250

Maximum height of the scaffold, m

18

Pole dimension, mm

100 x 100

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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

50 x 230

Vertical distance between bearers, mm

2700

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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:

(1) All scaffold parts shall be measured using outer dimensions;

(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/m^2

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Dimensions^(2)

Uniformly distributed load, kg/m^2

375

Maximum height of the scaffold, m

18

Pole dimension, mm

100 x 100

Distance between two adjacent poles of the scaffold length-wise, mm

1800

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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

1900

Dimension of crossbraces, horizontal braces, and transverse braces, mm

50 x 100

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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/m^2

Scaffold parts^(1)

Maximum height, m

6

18

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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

Maximum width of the scaffold, mm

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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

50 x 100

Dimension of bearer when scaffold width is between 900 mm and 3000 mm

50 x 155 or 75 x 100

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Vertical distance between horizontal members, mm

2100

2100

Dimension of crossbraces, horizontal braces, and transverse braces, mm

25 x 100

25 x 100

Dimension of ties, mm

25 x 100

25 x 100

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Schedule 6 - Nominal dimension and maximum distance of parts of medium-duty double wood pole - 250 kg/m^2

Scaffold parts^(1)

Dimensions^(2)

Uniformly distributed load, kg/m^2

≤ 250

Maximum height of the scaffold, m

18

Pole dimension, mm

100 x 100

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2400

Maximum width of the scaffold, mm

1800

Dimension of runner, mm

50 x 230

Vertical distance between horizontal members, mm

1800

Distance between bearers, mm

2400

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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

25 x 100

NOTE:

(1) All scaffold parts shall be measured using outer dimensions. Requirements regarding supported width of planks shall conform to 7.16;

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Schedule 7 - Nominal dimension and maximum distance of parts of heavy-duty double wood pole - 375 kg/m^2

Scaffold parts^(1)

Dimensions(2)

Uniformly distributed load, kg/m^2

≤ 375

Maximum height of the scaffold, m

18 m

Pole dimension, mm

100 x 100

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1800

Maximum width of the scaffold, mm

1800

Dimension of runner, mm

50 x 230

Vertical distance between horizontal members, mm

1300

Dimension of bearers (non-debarked), mm

50 x 230

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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.

7. Tube and coupler scaffold

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

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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

Outer diameter, mm

48,3 (± 0,5)

48,3 (± 0,5)

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Tube thickness (plain tube), mm

4 (± 0,5)

3,2 (± 0,48)

4,47 (± 0,56)

Tube thickness (welded tube), mm

4 (± 0,8)

3,2 (± 0,32)

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Weight per meter in length, kg/m

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3,56

1,67

Tensile strength, MPa

340

360

295

Yield strength, MPa

210

215

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Radius of gyration, mm

15,7

16

15,6

Cross sectional area, mm^2

557

453

615

Moment of inertia, mm^4

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116000

149000

Section modulus, mm^3

5700

4800

6180

7.3 Requirements regarding couplers:

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.

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Coupler

Type of applied load

Safe working load

kN

kg

Double coupler

Longitudinal traction

6,25

640

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Longitudinal traction

6,25

640

Putlog coupler

Sheer resistance

0,59

60

Internal connector

Longitudinal tensile force

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2140

Threaded couplers

Tensile force

3,1

315

7.4 Spacing of parts in tube and coupler scaffold

Depends on load according to Schedule 10.

Schedule 10 - Maximum spacing between parts in tube and coupler scaffold

Classification by load

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Maximum horizontal spacing between poles, m

Maximum vertical spacing between poles, m

Light-duty

0,5

2,4

3

Medium-duty

0,95

1,8

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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;

- In at least one for every three sets of posts horizontally;

- 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 40^o - 50^o. 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 40^o - 50^o 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.

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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 Modular scaffold

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.

8.2 All poles must be placed on pump jacks and wood base plates or sufficiently rigid surface capable of supporting pole weight and maximum intended load of the scaffold. Couplers of poles must vertically line up.

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.

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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).

8.12 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.

8.13 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.

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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.

9.3 Erected fabricated steel tubes or panels shall be braced by crossbraces or diagonal braces or both in order to hold parts in place horizontally and vertically. Crossbraces shall have sufficient dimension so that vertical members are always perpendicular to horizontal plane and line up. Bracing points shall be manufactured for rigidity.

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.

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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

9.11 Frame scaffold which is above 38 m in height shall be designed by eligible entity as per the law. A copy of the design and technical specifications shall be retained at the construction site for inspection and assessment purposes.

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.

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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.

10.1.4 If adjustable height is required for working platforms, pole joints shall be fitted with bottle jacks. If bottle jacks are not fitted to pole joints, bottle jacks shall be required at the footings of the scaffold with minimum length of 150 mm. Maximum distance between the jacks and the upper side of the wheels shall be 300 mm.

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.

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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.

10.3 Requirements regarding use of mobile scaffold

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.

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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.

10.3.5 Dimension of working platforms on mobile scaffold shall not exceed that of the footings, unless other solutions are applied to increase stability such as extension frame or similar solutions.

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.

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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 Mobile work stand

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.

11.2.2 Fabricated working platforms can create work stands of varying heights where the distance between these work stands shall not exceed 0,4 m. If this distance exceeds 0,4 m, employees shall not allowed to stand on these work stands.

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.

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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.

11.4 Use of mobile work stand

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 1,5^o.

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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.

11.5.3 Labels shall specify name of manufacturers or name of 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 mobile work stand.

12 Bricklayers’ square scaffolds

12.1 Distance between two legs shall not exceed 1,5 m and height shall not exceed 1,5 m.

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Schedule 11 - Minimum cross section area of parts of bricklayers’ square scaffold

Parts

Dimensions, mm

Ledgers or horizontal members

50 x 150

Legs

50 x 150

Braces at corners

25 x 150

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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.

12.8 Bricklayers’ square scaffold shall be erected on a sufficiently strong and flat surface.

13 Horse scaffold

113.1 Horse scaffolds shall not be arranged more than 2 tiers or 3 m.

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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

Dimensions, mm

Bearers or horizontal members^(1)

75 x 100

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30 x 100

Length-wise braces of legs

25 x 150

Corner braces on top of legs

25 x 200

Diagonal braces

30 x 100

NOTE: ^(1) Dimensions above are calculated with maximum length of 3000 mm

14 Pump jack scaffold

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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.

14.8 Wood poles with dimension of 100 mm x 100 mm shall be single pieces.

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).

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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.

15 Adjustable scaffold

15.1 General requirements

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 m^2 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.

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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.

15.2.5 Hoists shall utilize appropriate cable clips. Cable clips shall have minimum strength equivalent to 80% of yield strength of the cables. Cable ends shall be tied in accordance with manufacturers’ instructions. Wire rope clip shall not be allowed.

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.

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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:

1) deployment procedures;

2) handling and transport procedures;

3) erection, use, and dismantlement procedures;

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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;

11) working platform ascending and descending procedures;

12) inspection and maintenance;

113) fall prevention during scaffold erection and dismantlement.

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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 Ladder jack scaffold

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

16.2.1 Total weight of employees, planks, supporting system, and materials on working platforms shall not exceed load bearing capability of the ladders.

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.

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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

16.3.1 Scaffolds whose working platforms are wood planks or framed wood planks shall only facilitate one person working. Scaffolds with fabricated working platforms shall only facilitate two people working as long as each person is standing on half of the platform span.

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.

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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 75^o 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

Working platforms shall not be installed higher than the second highest tread of the ladders.

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.

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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.

17.3 Outrigger scaffold shall be erected in accordance with parameters under Schedule 13, unless designed by professional engineers with practicing license. Outrigger scaffolds designed by professional engineers with practicing license shall be manufactured and erected in a manner compliant with the design. Photocopies of detailed drawings and technical specifications regarding dimensions and spacing between elements shall be stored at construction sites.

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.

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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/m^2

125

250

Cross sectional area of outrigger beam, mm

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75 x 255

Spacing between two adjacent outrigger beams, m

3

1,8

18 Carpenter’s bracket scaffold

18.1 Design

18.1.1 Brackets shall be made from wood or other appropriate materials such as steel or aluminum alloy with known strength characteristics. Working platforms shall be designed so that they can withstand minimum load of 125 kg/m^2.

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.

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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 45^o.

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.

Schedule 14 - Minimum dimensions of wood stacker bracket scaffold capable of supporting 125 kg/m^2

Parts

Dimensions, mm

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50 x 100 or 50 x 150

- Horizontal bracket members

25 x 150

- Diagonal braces

25 x 150

Maximum length of bracket

1000 (unsupported)

Maximum clearance between two adjacent stacker brackets

2400 (center to center)

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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/m^2

Parts

Dimensions, mm

- Guardrail posts

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- Handrails

50 x 100

- Midrails

25 x 150

- Toeboards

25 x 150

Guardrail height

900 to 1200

Maximum clearance between two metal brackets (appropriate with design of manufacturers)

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Schedule 16 - Minimum dimensions of wood bracket scaffold capable of supporting 125 kg/m^2

Parts

Dimensions, mm

Cross sectional area:

- Vertical members

- Horizontal members

- Braces

- Guardrail posts

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- Toeboards

50 x 100 or 50 x 150

50 x 150

25 x 150

50 x 100

25 x 150

25 x 150

Guardrail height

900 to 1200

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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.

18.4.3 Wood brackets shall be triangular in shape.

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.

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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

20.1 General provisions

20.1.1 Materials, parts, and equipment used in erecting suspended scaffolds with hoists shall be compliant with this Standard and acceptable technical experience.

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:

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- 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.

20.1.7 All parts such as bolts, guards, joints, locks, steel cables, beams, and suspended equipment shall be maintained to meet quality and adapt to all working conditions. All parts above shall be inspected for quality before each installation and on a periodic basis throughout use process (see 20.20).

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.

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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 90^o shall have inner diameter equal to or greater than ten times the cable diameter. Guide pulley that changes cable direction more than 90^o 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.

20.2.6 Anti-rotation mechanisms shall be required to prevent scaffold rotation. Working platforms of suspended scaffold shall be surrounded by guardrail system and toeboards (see 4.6 and 20.12.3)

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.

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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.

20.3 Requirements regarding electric hoists

20.3.1 General requirements

20.3.1.1 Maximum rated vertical speed of electric-powered suspended scaffold shall not exceed 10 m/min.

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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.

20.3.1.9 Each hoist shall be fitted with panels that contain information on:

1) Name of manufacturer;

2) Maximum load rating;

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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.

20.3.2.3 Gear transmission of deceleration gearbox shall be compliant with gear manufacturing standards and have minimum transmission coefficient of 1.

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.

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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).

20.3.4.5 Secondary brakes shall be placed in enclosed spaces.

20.3.5 Requirements regarding drums and pulleys.

20.3.5.1 Requirements regarding friction drums and friction pulleys

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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.

20.3.5.2.5 Electric hoists that utilize winding drums shall be fitted with tensioning mechanism to keep the cables from becoming entangled when not carrying load.

20.3.6 Energy transmission system

20.3.6.1 Gasoline-powered hoists shall not be allowed.

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- 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.

20.3.7 Requirements regarding control of powered hoist

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.

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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.

20.5 Requirements regarding personal fall-arrest system

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.

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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.

20.7 Requirements regarding manually operated hoists

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.

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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;

4) Technical characteristics of hoisting cables (specifications can be written on the signs which will be hung on cable ends).

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.

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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.

20.8.4 Steel cables shall be lubricated as they are manufactured.

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.

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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.

4) Cables are corroded, eroded, having lost its lubrication layer, or crushed where thickness of the crushed section is less than 1/3 of outer diameter of the cables.

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.

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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.

20.9.2 Cables suspending scaffold shall be fastened to hoist supporting frames, bearers supporting working platforms, or other members compliant with 20.2.1.

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:

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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/m^2 and placed load shall not exceed this value.

20.10.2 Scaffolds shall be fitted with hoists compliant with 20.3 or 20.7.

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.

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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.

20.11 Light-duty mason’s multiple point scaffold

20.11.1 Minimum working load shall be 37,5 kg/m^2 and placed load shall not exceed this value.

20.11.2 Scaffolds shall be fitted with hoists compliant with 20.3 or 20.7.

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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.

20.11.10 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.

20.11.11 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.

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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.

20.12.7.1 Rotation of scaffolds shall be minimized by one of the solutions below or similar solutions:

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;

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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.

20.13.2 Tools, hoist support frames, connections, and other accessories shall be compliant with 20.2, 20.12.2, and 20.12.3. Hoist support frames that allow people to move below shall be required to be fitted with guardrail system on the edges.

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.

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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.

20.14.4 All platform units shall be complaint with Article 5.

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.

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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.

20.15.4 Anchorage and cable ties shall be designed by professional engineers. Engineers designing anchorage and cable ties shall be required to have knowledge regarding this type of scaffold.

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.

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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 Multiple-point suspended scaffold lifted and lowered by manually operated hoists or powered hoists

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.

20.16.2 Hoists (manually operated or powered) and their suspending devices shall undergo tested design and be compliant with 20.3 or 20.7.

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.

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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.

20.17.4 Suspension cables and solutions shall be compliant with 20.8.

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.

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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;

(d) Suspension lines shall be of synthetic ropes of 16 mm in diameter; or ropes with similar strength and durability characteristics.

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.

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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

20.20.1 Suspended scaffolds, after being erected, shall be inspected immediately at construction sites where the scaffolds are used. Inspection shall be carried out by inspectors licensed to carry out inspection of the respective type of suspended scaffolds. The inspection aims to ensure that all suspension cables, ropes, suspending points, working platforms, hoists, suspending and tying equipment, anchorage of personal fall-arrest system and hooks thereof are compliant with this Standard. Hoists shall be inspected before each installation and before each redeployment, undergo test run after each installation and each redeployment in permissible procedures of a qualified person.

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:

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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.

20.21.3 All parts of electrical system and moving cables shall be removed if they are significantly damaged or corroded.

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.

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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 Needle beam scaffolds

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.

21.3 Suspension cables shall be anchored to needle beams by hooks or by tying with eye splices. Free ends of suspension cables shall be held in place by tying into a loop or a knot.

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.

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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.

22.4 Maximum permissible spacing between bearers supporting working platforms shall be compliant with 5.2, 5.3, and 5.4 and appropriate with permissible load.

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.

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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.

23.5 Working platforms shall be suspended by ropes or synthetic ropes of minimum diameter of 25 mm or similar. Suspension ropes shall not be degraded, damaged, corroded by chemical substances, or otherwise defective. Rope connection shall be secure enough to prevent working platforms from moving or sliding. Each scaffold shall only be suspended by two continuous ropes in a manner compliant with requirements below:

- 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;

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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.

24.5 Vertical suspension lines shall be ropes, synthetic ropes, or steel cables. Vertical suspension lines and connection shall be calculated and designed to withstand intended load.

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.

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25 Roof ladder

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.