Safe Working Load | Proof Load |
To 20 tons | 25% in excess |
20-50 tons | 5 tons in excess |
Over 50 tons | 10% in excess of manufacturer's recommended lifting capacity. |
Proof load must be applied at the designed maximum and minimum boom angles or radii, or if this is impractical, as close to these as practical. The angles or radii of test must be stated in the certificate of test. Proof loads must be swung as far as possible in all directions. The weight of auxiliary handling devices such as spreader bars, robots, clams, magnets, or other gear must be considered a part of the load. Brakes must be tested by holding the proof load suspended without other mechanical assistance. After satisfactory completion of a unit proof load test the derrick and all component parts thereof must be carefully examined and nondestructive tests may be conducted to assure that the equipment is safe for use and has not been damaged in the unit proof load testing process.
(4) Unit proof load tests for cranes must be carried out with the boom in the least stable direction relative to the mounting, based on the manufacturer's specifications.
(5) Unit proof load tests for cranes must be based on the manufacturer's load ratings for the conditions of use and must, except in the case of bridge type cranes utilizing a trolley, consist of application of a proof load of ten percent in excess of the load ratings at maximum and minimum radius, and at such intermediate radii as the certifying authority may deem necessary in the circumstances. (The manufacturer's load ratings are usually based upon percentage of tipping loads under some conditions and upon limitations of structural competence at others, as well as on other criteria such as type of crane mounting, whether or not outriggers are used, etc. Some cranes utilizing a trolley may have only one load rating assigned and applicable at any outreach. It is important that the manufacturer's ratings be used.) Trolley equipped cranes must be subject to a proof load of twenty-five percent in excess of the manufacturer's load rating. In cases of foreign manufacture, the manufacturer's specifications must be subject to approval by the certifying authority. The weight of all auxiliary handling devices such as magnets, hooks, slings, and clamshell buckets must be considered part of the load.
(6) If the operation in which equipment is engaged never utilizes more than a fraction of the safe working load rating, the owner of the equipment may, at their option, have the crane or derrick certified for and operated at a lesser maximum safe working load in keeping with the use and based on radius and other pertinent factors, however, the equipment concerned must be physically capable of operation at the original load rating and the load reduction must not be for the purpose of avoiding correction of any deficiency.
(7) Safe working load ratings must not be increased beyond the manufacturer's ratings or original design limitations without prior approval by the accredited certification agency. Such prior approval must be based on the manufacturer's approval of such increase or documented engineering design analysis or both. All necessary structural changes must be completed prior to approval by the accredited certification agency.
[Statutory Authority: RCW
49.17.010,
49.17.040,
49.17.050,
49.17.060. WSR 15-24-102, § 296-56-60097, filed 12/1/15, effective 1/5/16. Statutory Authority: RCW
49.17.040. WSR 99-02-024, § 296-56-60097, filed 12/30/98, effective 3/30/99. Statutory Authority: Chapter
49.17 RCW. WSR 95-04-007, § 296-56-60097, filed 1/18/95, effective 3/1/95. Statutory Authority: RCW
49.17.040 and
49.17.050. WSR 86-03-064 (Order 86-02), § 296-56-60097, filed 1/17/86; WSR 85-01-022 (Order 84-24), § 296-56-60097, filed 12/11/84.]