Proof test

Such a structure is often subjected to loads above those expected in actual use, demonstrating safety and design margin.

[3] Cranes and derricks are proof tested when called on for potentially dangerous load levels or high-valued cargoes.

[4][5] Similarly, items which are smaller and more common (rope and cable, slings, shackles and eyes) are nevertheless in the load path and a failure risk if not tested.

[6] Testing generally involves lifting weight or drawing tension equal to or greater than design levels.

[8] Vessels which may be a failure risk, such as utility-scale water towers, chemical-handling equipment,[9] or very-high-pressure storage tanks, may be proof tested.

Rocket stage tankage, being high-valued and often the vehicle's primary structure, are proof-tested when redesigned,[10] and may be tested at the unit level.

[11] Testing involves exposure to higher gauge pressures than design levels, or in some cases, pulling harder vacuum.

Large calibre arms, such as artillery, will in general use an inert solid projectile (the proof shot); although water, sand or iron (powder) filled versions can be found for testing recoil systems.

For both small arms and heavy weapons, the gun is fired remotely and then examined; if undamaged, it is assumed to be safe for normal use and a proof mark is added to the barrel.

A small arms proof round is loaded to a higher than normal service pressure, stressing both the gun barrel and breech during firing.

This can be due to a heavy projectile fired using the standard propelling charge, the standard projectile fired with a different propellant type or weight, or combinations of charge and bullet weight to give the required proofing pressure.

[13] Some of the signs actually used are: The standard proof test consists of firing two overloaded cartridges that produce 25% more chamber pressure than the C.I.P.

[14] Before the year 2006 the standard test consisted of firing two overloaded cartridges producing 30% more chamber pressure then the C.I.P.

Readings will be taken of chamber pressure by copper crusher, or piezo electric gauges and velocity by Doppler radar (in-bore or aeroballistic), or photocell counter chronographs.

As failure of an aircraft structure or substructure may be catastrophic, demonstration of designs or of in-service units is performed via proof testing.

[17] Failure of sail rigging is no longer as catastrophic, but may still lead to damage, injury and loss of vehicle functions.