PCDC Storage bottle blows

[Tom Smedley]

It is almost impossible to hydro one of the large cylinders. The test that is probably most recommended is a hammer test. The tank is emptied and struck with an appropriate size hammer. If the metal rings like a bell it is most likely healthy but if there is a dull thud it is not. Do a Google search on compressed gas hammer test.

Just the cost of transporting a large cylinder to a hydro facility would be enormous - that is if you could find a facility that would be able to do the test. I don't think our local fire-extinguisher folks would be able to.

Let's hope for most of the dive shops in the world that OSHA does not get involved with this incident but I fear they will. I've worked directly for the US government since 1967 and the fact that they screw up anything they touch hasn't changed.

 

[Leadking]

2) A hammer test consists of tapping a cylinder a light blow with a suitably sized hammer. A cylinder emptied of liquid content, with a clean internal surface, standing free, will have a clear ring. Cylinders with internal corrosion with give a duller ring dependent upon the amount of corrosion and accumulation of foreign material. Such cylinders shall be investigated. The hammer test is very sensitive and is an easy, quick, and convenient test that can be made without removing the valve before each charging. It is an invaluable indicator of internal corrosion.

 

[mike_s]

the question also lies in what was the cylinder that ruptured rated at and what was it filled to? (I guess all this will come out in the investigation).

 

[mkutyna]

I'm pretty sure that tumbling is out of the question for those large bank bottles as well yes? Is a vis is used to determine if it should be taken out of service or not? Sure, you can open the bottle up and look inside all you want but I doubt you'd be able to do anything about any minor corrosion if you happen to see any.

 

[Hallmac]

True about tumbling, it is not cost effective. We have used a whip once. The key is preventing as much moisture from entering as possible. Testing often, and crying when you have to take them out of service...

 

[jviehe]

I'm pretty sure that tumbling is out of the question for those large bank bottles as well yes? Is a vis is used to determine if it should be taken out of service or not? Sure, you can open the bottle up and look inside all you want but I doubt you'd be able to do anything about any minor corrosion if you happen to see any.

Good point. How do you ensure nitrox banks are 02 clean?

 

[mike_s]

Good point. How do you ensure nitrox banks are 02 clean?

for the above store, PCDC, they don't have o2 clean air.

they blend, (or whatever) before they get to the banked storage. So they are never introducing "pure o2" into their storage tanks. (from what Gomez told me a few years ago when he was showing me their system. someone correct me if anything has changed in the last 2 years.).

 

[FredT]

I'm pretty sure that tumbling is out of the question for those large bank bottles as well yes? Is a vis is used to determine if it should be taken out of service or not? Sure, you can open the bottle up and look inside all you want but I doubt you'd be able to do anything about any minor corrosion if you happen to see any.

ANY long straight bottle can be tumbled with a little "think outside the box" ingenuity. Two house trailer axles (easily rented) a pair of railroad ties and car or golf cart can be combined to make a functional tumbler for big tanks. Getting the media in and out is the hard part.

Cost effective, probably not, as by the time it fails the hammer test you may have a scrap bottle anyway. An agitated acid rinse could be done for a couple hundred $ of materials and tools though. Both would require a crane of some sort to dismount and drain the bottles though.

 

[Leadking]

unusual construction compared to scuba tanks. Note the top rim and the welded sidewall
Got pictures fowarded to me today!

http://s871.photobucket.com/albums/ab278/THEleadking/

cannot get pictures to load-click on the url

 

[FredT]

Those 2 photos don't show anything obvious. The seam split adjacent to the weld at the edge of the heat effected zone, just like it's supposed to. The end cap appears to have a weld metal failure, but to determine if this was a primary or secondary failure will take a lot more investigation. That will take a few days of stereo microscope work at least to nail down the exact crack initiation point(s), then it starts to get interesting.