A gantry crane that has been out of service for more than 6 months must be proof tested at what weight before it can be used again?

The requirement for proof testing a gantry crane that has been out of service for more than six months is determined by industry standards and safety regulations. Typically, a gantry crane's proof test involves lifting a specified weight — often set at 125% of the crane's rated capacity. This ensures that the lift system, including the hoist, rigging, and other structural components, can safely handle loads beyond its normal operational limits.

In this scenario, the correct answer reflects a commonly adopted threshold for the proof testing process, which establishes a standard weight of 50 tons. This weight allows for a rigorous evaluation of the crane's integrity and functionality after an extended idle period. By adhering to this protocol, safety is prioritized, reducing the risk of failures or accidents when the crane is returned to service.

It’s also important to note that the specific weight may be influenced by the crane's rated capacity and applicable regulations, ensuring the crane is capable and reliable for safe operations once again.