1. (1) All vertical, horizontal and diagonal members of tube and coupler metal scaffolds shall be securely fastened together with approved safe locking devices to form positive connections.

2. (2) The use of grey cast iron fittings in such scaffolds is prohibited.

   (c) Runners.

3. (1) Every tube and coupler metal scaffold shall be provided with a ledger or runner of metal tubing locked end to end with fittings to form a continuous length of the scaffold. Such runner shall be secured to each intersecting post of the scaffold with approved couplers or clamps.
4. (2) Runners shall be placed not more than six feet, six inches on centers vertically.

5. (3) The bottom runner of any such scaffold shall be located as close to the base of the scaffold as possible.

   (d) Bearers or putlogs.

6. (1) The bearers or putlogs of such scaffolds shall be installed transversely between the posts. They shall be securely coupled to the posts and shall bear on the runner couplers. When such bearers or putlogs are coupled directly to the runners, the couplers shall be kept as close to the posts as possible.
7. (2) The bearers or putlogs shall be located at each set of posts, at each level and at each intermediate level where a working platform has been installed.

8. (3) Each bearer or putlog shall be of sufficient length to provide an overhang of at least four inches but not more than 12 inches beyond the inside and outside posts.

   (e) Bracing.

9. (1) Cross bracing shall be installed across the width of every tube and coupler scaffold at every third set of posts horizontally and at every fourth runner vertically. Such bracing shall extend diagonally from the inner and outer runners in an upward direction to the next outer and inner runners.
10. (2) Longitudinal bracing shall be installed on every tube and coupler scaffold. Such bracing shall run from a point near the base of the first outer post upward at an approximate 45 degree angle to the extreme top of the scaffold.
11. (3) Where the length of the scaffold continues beyond such longitudinal bracing, such bracing shall be duplicated, beginning at every fifth post.
12. (4) In a similar manner, such longitudinal bracing shall also be installed to run from a point near the base of the last post upward at an approximate 45 degree angle toward the first post to the extreme top of the scaffold.
13. (5) Where the height of any such scaffold is greater than its length, additional longitudinal bracing shall be installed at a point on the first post at the same elevation as the top of the lower longitudinal bracing. Such additional bracing shall run in an upward direction at an angle of approximately 45 degrees to the top of the scaffold. Such additional bracing shall also be installed in a similar manner starting from the outer end or last post at the same elevation.

14. (6) Where conditions prevent the attachment of such longitudinal bracing to the posts, such bracing may be attached to the runners of the scaffold.

    (f) Light duty tube and coupler scaffolds.

    All posts, bearers, runners and bracing used for light duty tube and coupler scaffolds shall be constructed of nominal two-inch O.D. steel tubing. The posts of any such scaffold shall be spaced not more than six feet apart by 10 feet along the length of the scaffold.

    (g) Medium duty tube and coupler scaffolds.

    All posts, runners and bracing of medium duty tube and coupler scaffolds shall be constructed of nominal two-inch O.D. steel tubing. Where the posts are spaced not more than six feet apart by eight feet along the length of such scaffold, the bearers shall be constructed of nominal two and one-half inch O.D. steel tubing. Where the posts are spaced not more than five feet apart by eight feet along the length of such scaffold, the bearers shall be constructed of nominal two-inch O.D. steel tubing.

    (h) Heavy duty tube and coupler scaffolds.

    All posts, bearers, runners and bracing of heavy duty tube and coupler scaffolds shall be constructed of nominal two and one-half inch O.D. steel tubing. The posts of such a scaffold shall be spaced not more than six feet apart by six feet, six inches along the length of the scaffold.

(a) Structural members.

The structural members of tube and coupler scaffolds shall be constructed of steel tubing.

(b) Couplers.