Proof Load

Disclaimer: The information on this page has not been checked by an independent person. Use this information at your own risk.


Proof Load testing is the process of applying a load to equipment which is greater than the Safe Working Load (SWL) or Working Load Limit (WLL) to ensure it is safe. This should be conducted before the equipment is used for the first time, after modification or repair and at least once every 5 years.


The load to which you should test will vary depending on the equipment designed, client requirements and the standards they use - as I am based in the UK, I will use the rules indicated in DNV 2.22 October 2011, section '2.3 Test Loads'


For Cranes and derrick rigs table 12-1 [note 1 tonne = 1000kg]



Safe Working Load (SWL) Test Load
Up to 20 tonnes 25% in excess of the SWL
Exceeding 20 tonnes, but not exceeding 50 tonnes 5 tonnes in excess of the SWL
Above 50 tonnes 10% in excess of the SWL


Proof Load Test calculator for DNV 2.22 October 2011 Table 12-1




For Lifting Beams table 12-2 [note 1 tonne = 1000kg]


Safe Working Load (SWL) Test Load
Up to 10 tonnes 2 x SWL
Exceeding 10 tonnes, but not exceeding 160 tonnes (1.04 x SWL)+9.6
Above 160 tonnes 1.1 x SWL


Proof Load Test calculator for DNV 2.22 October 2011 Table 12-2