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  Tube and Coupler
Tube and CouplerTube and coupler scaffolds are so-named because they are built from tubing connected by coupling devices. Due to their strength, they are frequently used where heavy loads need to be carried, or where multiple platforms must reach several stories high. Their versatility, which enables them to be assembled in multiple directions in a variety of settings, also makes them hard to build correctly. Note: The requirements on this page are specific to tube and coupler scaffolds only. For requirements that apply to all types of supported scaffolds, please refer to the Frame or Fabricated module of this eTool.


General Requirements
  • When platforms are being moved to the next level, the existing platform must be left undisturbed until the new bearers have been:

    • Set in place, and

    • Braced before receiving the new platform. [1926.452(b)(1)]
  • Couplers must be made of a structural metal, such as:

    • Drop-forged steel,

    • Malleable iron, or

    • Structural-grade aluminum. [1926.452(b)(9)]
  • The use of couplers made from gray cast iron is prohibited. [1926.452(b)(9)]

  • Tube and coupler scaffolds over 125 feet in height must be:

    • Designed by a registered professional engineer, and

    • Constructed and loaded in accordance with that design. [1926.452(b)(10)] See Appendix A for non-mandatory examples of design and loading criteria.


Bracing
  • Transverse bracing forming an "X" across the width of the scaffold must be installed at the scaffold ends, and at least at:

    • Every third set of posts horizontally (measured from only one end), and

    • Every fourth runner vertically. [1926.452(b)(2)]
  • Bracing must extend upward diagonally to opposite sides of the scaffold, such as from the inner posts or runners to the next outer posts or runners, or vice versa (see diagram). [create diagram] [1926.452(b)(2)]

  • Building ties must:

    • Be installed at the bearer levels between the transverse bracing, and

    • Meet the requirements of 1926.451(c)(1). [1926.452(b)(2)]
  • On straight run scaffolds, longitudinal bracing across the inner and outer rows of posts must:

    • Be installed diagonally in both directions, and

    • Extend upward from the base of the end posts to the top of the scaffold at approximately a 45-degree angle. [1926.452(b)(3)]
  • On scaffolds whose length is greater than their height, longitudinal bracing must be repeated beginning at least at every fifth post. [1926.452(b)(3)]

  • On scaffolds whose length is less than their height, longitudinal bracing must be installed from the base of the end posts upward to the opposite end posts, and then in alternating directions until reaching the top of the scaffold. [create diagram] [1926.452)(b)(3)]

  • Bracing must be installed as close as possible to the intersection of the bearer and post or runner and post. [1926.452(b)(3)].

  • Where conditions do not permit the attachment of bracing to posts, bracing must be attached to the runners as close to the post as possible. [1926.452(b)(4)]


Bearers
  • Bearers must be installed transversely between posts. [1926.452(b)(5)]

  • When bearers are coupled to posts, the inboard coupler must:

    • Bear directly on the runner coupler, and

    • Be as close to the posts as possible. [1926.452(b)(5)]
  • Bearers must extend beyond the posts and runners, and provide full contact with the coupler. [1926.452(b)(6)]

  • The bottom bearers must be located as close to the base as possible. [1926.452(b)(8)]


Runners
  • Runners must be installed along the length of the scaffold, located at level heights on both the inside and outside posts. [1926.452(b)(7)]

  • On outside posts, tube and coupler guardrails and midrails may be used in lieu of outside runners. [1926.452(b)(7)]

  • Runners on straight runs must be:

    • Interlocked to form continuous lengths, and

    • Coupled to each post. [1926.452(b)(8)]
  • The bottom runners must be located as close to the base as possible. [1926.452(b)(8)]


Non-mandatory Guidelines

Minimum Size of Members
1926 Subpart L Appendix A (2)(b)

  Light Duty Medium Duty Heavy Duty
Maximum Intended Load 25 pounds/foot² 50 pounds/foot² 75 pounds/foot²
Posts, runners, and braces

NOTE: Longitudinal diagonal bracing must be installed at an angle of 45° (±5°).		 Nominal 2 inches (1.9 inches) OD steel tube or pipe Nominal 2 inches (1.9 inches) OD steel tube or pipe Nominal 2 inches (1.9 inches) OD steel tube or pipe
Bearers

NOTE: Bearers must be installed in the direction of the shorter dimension.		 Nominal 2 inches (1.9 inches) OD steel tube or pipe and a maximum post spacing of 4 feet x 10 feet Nominal 2 inches (1.9 inches) OD steel tube or pipe and a maximum post spacing of 4 feet x 7 feet
or
Nominal 2½ inches (2.375 inches) OD steel tube or pipe and a maximum post spacing of 6 feet x 8 feet.		 Nominal 2½ inches (2.375 inches) OD steel tube or pipe and a maximum post spacing of 6 feet x 6 feet
Maximum runner spacing vertically 6 feet 6 inches 6 feet 6 inches 6 feet 6 inches

Maximum Number of Planked Levels
1926 Subpart L Appendix A (2)(b)

Maximum Number of Additional Planked Levels
  Light Duty Medium Duty Heavy Duty  
Number of Working Levels       Maximum Height of Scaffold
1 16 11 6 125 feet
2 11 1 0 125 feet
3 6 0 0 125 feet
4 1 0 0 125 feet
 
 
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