Tube and Coupler Scaffolds

A tube and coupler scaffold is a supported or suspended scaffold consisting of a platform(s) supported by tubing, erected with coupling devices that connect uprights, braces, bearers, and runners.

Tube and coupler scaffolds must adhere to the following criteria:

• 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 prior to receiving the new platforms.
• Tube and coupler scaffolds over 125 feet in height must be designed by a registered professional engineer, and must be constructed and loaded in accordance with such design. Consult 29 CFR 1926 Subpart L, Appendix A for how to comply with design and loading requirements for tube and coupler scaffolds under 125 feet in height.
• 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. Bracing must extend diagonally from the inner or outer posts or runners upward to the next outer or inner posts or runners. Building ties must be installed at the bearer levels between the transverse bracing.
• On straight run scaffolds, longitudinal bracing across the inner and outer rows of posts must be installed diagonally in both directions, and must extend from the base of the end posts upward to the top of the scaffold at approximately a 45-degree angle.
  • On scaffolds whose length is greater than their height, such bracing must be repeated beginning at least at every fifth post.
  • On scaffolds whose length is less than their height, such 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.
  • Bracing must be installed as close as possible to the intersection of the bearer and post or runner and post.
• Where conditions preclude the attachment of bracing to posts, bracing must be attached to the runners as close to the post as possible.
• Bearers must be installed transversely between posts, and when coupled to the posts, must have the inboard coupler bear directly on the runner coupler. When the bearers are coupled to the runners, the couplers must be as close to the posts as possible.
• Bearers must extend beyond the posts and runners, and must provide full contact with the coupler.
• Runners must be installed along the length of the scaffold, located on both the inside and outside posts at level heights. (When tube and coupler guardrails and midrails are used on outside posts, they may be used in lieu of outside runners.)
• Runners must be interlocked on straight runs to form continuous lengths, and must be coupled to each post. The bottom runners and bearers must be located as close to the base as possible.
• Couplers must be of a structural metal, such as drop-forged steel, malleable iron, or structural grade aluminum. The use of gray cast iron is prohibited.

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