Tank Question..

[gasdiver]

http://cgi.ebay.com/36-PC-1-4-Letter...item45efb19adb

It would not be the first time I've seen this...

[Superlyte27]

I have a set... But I used to hydro tanks.
Today, I'd be afraid of blowing up.

[JS1scuba]

That's something nice to say but it is oddly not how steel tanks are sold - pick pretty much any website, sales brochure etc. Now, it may be true the tank is not guarenteed to pass, but the expectation is certainly created. Certainly, no one told me to expect to throw them away after 5 years when I bought them.

I don't sell anywhere near the volume of cylinders i did in the earlier part of this decade but I've yet to see any manufacturer or website or brochure intimate that a cylinder will pass a hydro test after it has been in service. Most will warranty from manufacturers defects for 1 year but that's about it.

In most basic scuba certification courses the discussion of equipment, visual inspection and hydrostatic test and the service intervals for each are clearly outlined in manuals and course materials.

You may be referring to the 100,000 cycle test that Luxfer states on its website describing the manufacture process. It subjects one in 100 cylinders to a 100,000 cycle hydraulic test at the service pressure. This is done in an oil bath with a hydraulic pump that "cycles the pressure" 100,000 times. This is usually part of a batch test at manufacture time. It is not any indication that the cylinder will pass a hydrostatic test at 5/3rd service pressure 5 years from the time of the manufacture. It just ensures that the cylinder you buy today is free from possible defects.

You have been around a while. I seriously doubt that you believe that a manufacturer can guarantee a cylinder will pass a hydro test. I own at the moment close to 100 cylinders add to it another 100 or so i have owned and then given away to friends or traded out. I've probably had about 10 over the years fail hydro. Our facility hydro-tests about 8,000 cylinders of all types in a year. Scuba cylinders by far fail more often than industrial cylinders, but even so only about 20 of all types may fail in a years worth of cylinder test.

It's just how that game is played. Most of the time they pass, sometimes they don't. I think if you can get 15 years out of a cylinder one has done well. More even better.

I'm not defending the Worthington cylinders. They have been inconsistent in scuba for the 6 years they have been around. The inconsistencies have been in neck turning, height, and even on some diameter. It's not critical for singles but it is for doubles.

Sorry your tanks did not pass.

Cheers
JDS

[Sludge]

I've worked for one shop for over fifteen years, another for five, and every cylinder we have sent out for hydro has passed. I wonder if they're incompetent.

[gasdiver]

I picked up 4 of my tanks from the hydro shop today all passed. Two AL 80's with original hydro date of 7/76 and 11/77. Two steel 104's with original hydro date of 11/88. This thread had me worried about the steels, but now I'm convinced they'll last another 20...

[diveongas]

Joel, I just had two X7-100s fail on their first hydro with initial test dates of August 2005 and September 2005. I am not aware of them ever being overfilled - at least more than the usual 200 psi over until they cool - even in North FL. They have also not seen a great number of cycles as they have not been my go to tanks. Worthington has a procedure that is essentially identical the PST procedure but it only indireclty references the need to re-zero the burette, thus my concern is that both tanks failed due to a failure to properly perform the round out proceduce prior to the test.

My understanding of the need for this procedure with heat treated special permit tanks is that they are no longer perfectly round in cross section following the heat treatment process. Consequently when brought up to pressure, the tank does round out and increases its internal volume - but is not doing so do to excessive permanent expansion. That expansion due to normal rounding of the tank, if not properly zeroed out is what causes tanks to 'fail' a hydro test if the round out process is not properly done.

I have not gotten the test report back from the shop yet but when I get it, what do you recommend?

I always print out the PST test PDF and tape it to each E-7 series tank that I get tested. I use Hagemeyer (12 bucks), the guys there have cabinets filled with bulletins and do it right. Still by taping the instructions on each tank you protect against a guy's brain not kicking into gear, or nothing.

[diveongas]

It's just how that game is played. Most of the time they pass, sometimes they don't. I think if you can get 15 years out of a cylinder one has done well. More even better.

I'm not defending the Worthington cylinders. They have been inconsistent in scuba for the 6 years they have been around. The inconsistencies have been in neck turning, height, and even on some diameter. It's not critical for singles but it is for doubles.

Cheers
JDS

I have 8 PST 72 steels, all dating to the 1960s and they have passed hydro every time. They are, however, inconsistent. Two tanks from the same lot (20# apart) have a 3/8 differnce in length! I had them banded and used as doubles. I kept boots on them, with a spacer in one of the boots, which probably earns a stroke badge, but at least they would stand uprigtht on the boat or a dock.

Aluminum is for lawn chairs. In my experience, steel tanks seem to be alot like old soldiers, "Old steels never die, they just rust away."

[FW]

I have been diving over 50 years, and the only tank of mine that failed hydro was a steel "72" with obvious rust and pitting inside. My PST 104s have an orighnal hydro of 1977, and I have some 72s that are even older.

[DA Aquamaster]

I'm not defending the Worthington cylinders. They have been inconsistent in scuba for the 6 years they have been around. The inconsistencies have been in neck turning, height, and even on some diameter. It's not critical for singles but it is for doubles.

Sorry your tanks did not pass.

Joel I really don't care about incoinsitencies in beck height OAL or shoulder profile - in my experience I have found that I can talk to the distributor explain they will be doubled and they do a pretty good job of hand selecting them That type of "inconsistency" is not the same as having a 5 year old clean as a whistle inside steel tank with no history of damage or abuse fail at the first hydro test. That is not inconsistency it is just piss poor quality.

But again, I suspect the issue here is a RIN with his head completely up his ass on proper test procedures. Again based on 25 years owning an averae of about 20 tanks and given about 5 years of experience working with a RIN a failure of a non abused/non rusted steel tank is exceptionally rare and to have 2 out of 2 fail is extremely unlikely. Personally, I am really glad [I] did not send all 4 as I'd bet that the failure rate would have been 4 out of 4 with this particular RIN.

I'm experiencing some delays in getting the actual test results but it will be interesting to see what the numbers look like.

[Sludge]

My problem with Worthington is that when we could no longer get PSTs, we ordered a dozen Worthingtons and every single one was terribly rusted around the neck and threads.