diver1369

"Not through .... but it does not require much corrosion for a cylinder to fail the visual inspection that goes along with a hydro test. I don't have access to the British Standard for dive cylinder inspections... anyone in the business able to recall how much of a wormhole will result in failure of the cylinder?
Steve"


Not a professional, but:

CGA C6.1 Std (AL): if wall thickness is .2" (5.08mm) or greater (most SCUBA 3AL cyls), general corrosion may remove up to 0.030" (0.76mm) and individual pits may be up to .060" before the cylinder should be removed from service.

Line corrosion of 6 inches or more in AL, regardless of depth, should render the cylinder unserviceable (per Luxfer).

In steel cylinders, line corrosion 6" or greater, and over .020" (.51mm) deep will be reason for failure of the cylinder. Individual pits in steel are generally left to the inspector's judgement becasue they may result in a leak, but not a rupture (per PSI and CGA). The pit inspection disc that PSI sells only goes up to 0.10 inch, which suggests that is at or over the maximum pit depth that requires such 'judgement'.

Personally, I'm a bit more picky than the stds for any tank I dive (or inspect for others).

BTW, dielectric thread compound will remove the concern of AL tank threads and non-AL valve stems.

john