How pitted is too pitted?

[Peter69_56]

I agree with you form the point that operational testing vs a correctly done hydro. If done correctly the tanks you reference should never be hydro'd because they would have failed pre hydro visual inspection.

Exactly, inspect and only if it passes then hydro.

However, just because it passes hydro today does not mean that its fail safe for 12 months (OZ) or in the case of the rest of the world 5 years. There have been cases where tanks have failed not long after being hydro'd. Perhaps the inspection missed something, or perhaps they were badly treated after hydro, or perhaps an internal weakness finally fails due to the last hydro overpressurising one too many times. People seem to think that hydro is a fail safe, if it passes hydro it must be A1. I was taught that the critical job is inspection, if you miss something, it might pass hydro one last time but that overpressurisation is the final straw. One would hope if it was going to fail it would during hydro, but NOT always. A good and genuine full inspection is the most critical component, with hydro being secondary.

 

[2airishuman]

I'm not sure we're all talking about the same thing.

In the USA, the federal goverment requires something that is called "cylinder requalification," which is performed by an authorized testing facility, and which has two possible outcomes: Pass, and Fail. If the cylinder passes, the cylinder is permanently marked with the month, year, and identification of the test facility. If the cylinder fails, it is permanently marked "condemned" or rendered unusable. The requalification process involves a visual inspection and a hydrostatic test, and for pre-1990 aluminum cylinders, a visual eddy test.

Usually people call this entire process "hydro" even though there's more to it than that.

In the USA we also have a voluntary annual tank inspection which is typically called "VIP," an acronym for "visual inspection program." Though not enforced by law, nearly all fill stations require it. Standards and extent of testing varies widely. Many but not all inspectors are trained through PSI, equipment used varies, etc.

Now, where does the point you're trying to make fit into that?

 

[Peter69_56]

Ok in OZ we inspect and hydro yearly, and the cylinder passes or fails based on both those tests.

Is the US mandatory testing 5 yearly, and the yearly visual only a voluntary test?

So I guess in OZ, as we inspect and hydro yearly, my point is the inspection is the most critical check as that usually shows up most defects. It can pass a hydro with a visual defect if missed, but wont pass a visual inspection just because it passes a hydro.

I agree with you that most think tank testing is hydro, when in fact its inspection and hydro.