Michigan Administrative Code › Department - Labor and Economic Opportunity › MIOSHA › General Industry and Construction Safety and Occupational Health Standards › Occupational Health Standards › Part 12 - SCAFFOLDS AND SCAFFOLD PLATFORMS › FLOOR AND GROUND SUPPORTED SCAFFOLDS › Section R. 408.41223 - Tube and coupler scaffolds

Current through Vol. 24-12, July 15, 2024
Rule 1223.
(1)
						A tube and coupler scaffold shall have all posts, bearers, runners, and bracing
						of not less than a nominal 2-inch (1.90 inches outside dimension) steel tubing
						or equivalent.
(2) The material
						used for couplers shall be of a structural type, such as a drop-forged steel,
						malleable iron, or structural grade aluminum. Dissimilar metals shall not be
						used.
(3) The posts of a tube and
						coupler scaffold shall not be spaced more than 6 feet apart in width and not
						more than 10 feet along the length for a light-duty rated scaffold, 8 feet
						along the length for a medium-duty rated scaffold, and 6 feet along the length
						for a heavy-duty rated scaffold.
(4) Drawings and specifications for a tube
						and coupler scaffold over 125 feet in height above the base plate shall be
						designed by a qualified engineer who is knowledgeable in scaffolding. Drawings
						and specifications shall be readily available at the jobsite. A scaffold that
						is less than 125 feet in height shall conform to the requirements of table
						3.
(5) Runners shall be erected
						along the length of the scaffold and located on both the inside and the outside
						posts at even heights. When tube and coupler guardrails and midrails are used
						on outside posts, they may be used in place of outside runners. Runners shall
						be interlocked to form a continuous length and coupled to each post. The bottom
						runner shall be located as close to the base as possible. The runners shall be
						placed not more than 6 feet 6 inches on centers.
(6) A bearer shall be installed transversely
						between posts and shall be securely coupled either to a post bearing on a
						runner coupler or directly to a runner and shall be kept as close to the post
						as possible.
(7) A bearer shall be
						not less than 4 inches, but not more than 12 inches, longer than the post
						spacing or runner spacing. A bearer may be cantilevered for use as brackets to
						carry 2 2-inch by 10-inch planks. The bearer for a cantilevered section shall
						be not more than 24 inches and the section shall be limited to 25 pounds per
						square foot.
(8) Cross bracing
						shall be installed across the width of the scaffold at both ends and at least
						every third set of posts horizontally and every fourth runner vertically. The
						bracing shall extend diagonally from the inner and outer runners upward to the
						next outer and inner runners.
(9)
						Longitudinal diagonal bracing on the outer rows of poles shall be installed at
						a 45-degree angle from near the base of the first outer post upward to the
						extreme top of the scaffold. Where the longitudinal length of the scaffold
						permits, the bracing shall be duplicated beginning at every fifth post. In a
						similar manner, longitudinal diagonal bracing shall also be installed from the
						last post extending back and upward toward the first post. Where conditions
						preclude the attachment of this bracing to the posts, it may be attached to the
						runners.
(10) Guys, ties, and
						braces shall be installed according to the scaffold manufacturers
						recommendations or at the closest horizontal member to the 4-to-1 ratio height
						and be repeated vertically at locations of horizontal members every 20 feet
						(6.1 meters) or less thereafter for a scaffold 3 feet (0.91 meters) wide or
						less and every 26 feet (7.9 meters) or less thereafter for a scaffold more than
						3 feet (0.9 meters) wide. The top guy, tie, or brace of a completed scaffold
						shall be placed no farther than a 4-to-1 ratio from the top. The top guys,
						ties, and braces shall be installed at each end of the scaffold and at
						horizontal intervals of not more than 30 feet (9.1 meters), measured from 1
						end, not both, towards the other end. Outriggers, when used, may be considered
						a part of the base dimension. The outriggers shall be installed on both sides
						of the scaffold at each frame line.
(11) Table 3 reads as follows:
TABLE 3
TUBE AND COUPLER SCAFFOLDS
LIGHT DUTY
MEDIUM
HEAVY
Maximum uniformly distributed load
25 pounds per square foot
50 pounds per square foot
75 pounds per square foot
Post spacing (longitudinal)
10 feet
8 feet
6 feet
Post spacing (transverse)
6 feet
6 feet
6 feet
Work levels
1
2
3
1
2
1
Maximum allowable additional planked
										levels
8
4
0
6
0
6
Maximum height (feet)
125
125
91
125
75
125