SurfLung wrote:-Finally, he said a failed cylinder should have the DOT ratings stamped out and the threads rendered useless.
The statement above is only partially correct.
If by “failed” he means the cylinder must be condemned in accordance to 49 CFR Ch. I, 180.205, Nt.:
(
1) A cylinder
must be condemned when—
(iv) For a DOT specification cylinder,
other than a DOT 4E aluminum cylinder
or a special permit cylinder, permanent
expansion exceeds 10 percent of
total expansion.
Then the following applies:
(2) When a cylinder must be condemned,
the requalifier must—
(i) Stamp a series of X’s over the
DOT specification number and the
marked pressure or stamp ‘‘CONDEMNED’’
on the shoulder, top head,
or neck using a steel stamp;
(iii) As an alternative to the stamping
or labeling as described in this
paragraph (i)(2), at the direction of the
owner, the requalifier may render the
cylinder incapable of holding pressure.
Notice the bolded portion of the last paragraph. If a requalifier does this: “the threads rendered useless” without the “the direction of the owner”, he in essence has destroyed property without the owners authorization.
The DOT numbers belong to the DOT and therefore can be revoked (destroyed) by the DOT, but destroying the tank threads requires the owner’s authorization and it should be obtained in writing.
CFRs can be a bit confusing, but a hydro test operator should know better than talking about destroying cylinder threads without owners permission... that is inexcusable.
Note: there is a distinct difference between a cylinder that must be “condemned” from a “cylinder rejection”. Cylinder rejection is covered in 49 CFR Ch. I, 180.205 (h).
SurfLung wrote:
- The same questions to a local dive shop owner I know pretty well came back with the following:
"I have had 4 tanks fail the hydro test. Three of them I could identify myself, I could see the cracks (aluminum? - Eb). The other one was a 2250 tank and I knew there was nothing wrong with it, so I sent it to a different hydro place and it passed. I’m sure they tested it as a 3000 tank & that’s why it failed at the first place. I guess it’s your call if you want to spend the money. But, they really are trying to get all these odd number psi tanks off the market. They just want the standard tanks to be 2250 or 3000 psi. It’s a lot of work to switch their machines to test these different tanks." (So the industry may be pre-disposed to failing our vintage 1800 and 1880 psi tanks?)
Your local dive shop owner has no clue of what he is talking about.
A professional hydro station (that does more than just Scuba tanks) will test cylinders of many different pressures (fire extinguishers, life raft cylinders, O2 cylinders, CO2 cylinders, argon, helium, nitrogen, etc.). Most type 3AA O2 cylinders have a stamped pressure of 2015 psi (with the + then 2216 psi). I think most CO2 cylinders are stamped 1800 psi.
From this statement: “It’s a lot of work to switch their machines to test these different tanks”, I can tell you that he has never seen how a hydro test is done. There is nothing to switch. The operator only needs to determine the test pressure for the particular tank and then he takes up to that pressure (he has to record all that information). Most hydro stations that I have dealt with have a posted table (right on the console) with all the common tank pressures with the test pressure next to it.
