black powder proof

[Jorden]

Todays topic for argument; should black powder revolvers have the wedge proofed?

[dromia]

Depends on how you would have it "proofed"?

Checking a gun for possible failures is a good idea, however the way things are "proven" under the current regime is totally useless as an indicator of anything other than it didn't break/explode that time when an overpressure round was deliberately fired through the gun.

[ukrifleman]

I had a conversation on the range some time ago with a club member who was an aeronautical engineer, when the subject got around to stress testing of components.
He said that any individual component that was stress tested and passed was never used, but all the other units in the batch were deemed to be fit for purpose.

[dromia]

Aye no one in their right mind would deem an over stressed part to be safe, except the lunatics in the proof house.

[billgatese30]

I had a conversation on the range some time ago with a club member who was an aeronautical engineer, when the subject got around to stress testing of components.
He said that any individual component that was stress tested and passed was never used, but all the other units in the batch were deemed to be fit for purpose.

Yet with the pressure equipment directive, all vessels over a certain pressure volume (i.e. A combination of volume and pressure) must be tested at greater than maximum SWP before being placed on the market. Strange how approaches differ by industry.

[FredB]

Pressure vessels are not early subject to regular cyclic stresses. The problem with overstressed proof tests is that the fatigue life of the test piece is radically shortened.
Fred

[Plumose]

Does the emptying and filling of pressure vessels daily count as regular cyclic stress, as that is what happens with scuba cylinders at a busy dive centre?
My standard cylinders have a working pressure of 232bar and test pressure of over 300bar (I would have to look at one to get the exact pressure), the test is filling to the higher pressure and checking or plastic deformation

[billgatese30]

PED checks are normally at least 1.5 times working pressure and they certainly see pressure cycling when operating depending on the component. Things like desiccant air dryers will dump pressure from one tower to re-generate etc.

[FredB]

Cyclic stress means that the stresses are reversed, compressive to tensile. The proof test on a pressure vessel may actually improve its life. As the overpressue test is released. Residual compressive stresses may be left in the inner skin of the vessel. The pressures are very small compared to those experienced b a gun barrel where the complex shape around the breach area,bolt and firing pin are most likely to suffer.
Fred