1919.73—Unit proof test and examination of derricks.
(a)
Unit proof tests of derricks shall be carried out at the same times as are specified in § 1919.71(a) for cranes.
(b)
Unit proof load tests and safe working load ratings shall be based on the design load ratings at the ranges of boom angles or operating radii. Unit proof loads shall exceed the safe working load as follows:
| Safe working load | Proof Load |
|---|---|
| Up to 20 tons | 25 percent in excess. |
| 20-50 tons | 5 tons in excess. |
| Over 50 tons | 10 percent in excess. |
Proof loads shall be applied at the designed maximum and minimum boom angles or radii, or, if this is impracticable, as close to these as practicable. The angles or radii of test shall be stated in the certificate of test. Proof loads shall be swung as far as possible in both directions. The weight of all auxiliary handling devices shall be considered a part of the load.
(c)
After satisfactory completion of a unit proof load test, the derrick and all component parts thereof shall be carefully examined in accordance with the requirements of § 1919.71(d), as far as applicable.