Questions about LP72 tanks

[TrimixToo]

No burn marks or signs of trauma as far as I can see.

The other cylinder was 3% PE.
FWIW, they both had similar EE values.

Wow. I have an even dozen LP72s, some so old they have ICC numbers and the shoulders are crowded with hydro stamps. I get an average of two tested every year. None have ever failed. 30% is just remarkable. Remind me never to get you to buy a tank on my behalf! ;-)

 

[Tracy]

I would reccomend a different retester. I have bought and sold over 200 steel 72s in the last 5 years. I have had two fail hydro. I have had many fail visual inspection, but your 30% failure rate points me towards a bad retester. My perm expansions on the four 72s that tested this week were .9%, 1.1%, .6%, 1.4%. Those are normal numbers.

Had yet another LP72 tank fail hydro. Supposedly failed even with the round-out procedure applied.

This time I had a matched pair that I found banded together with manifold. same born date (67), same last hydro (72), same interior/exterior visual condition.

One passed. Failure came back with 22.8% PE.

My failure rate on these tanks is about 30%. Not worth the trouble.

 

[Bob DBF]

Find another hydro shop.

I'll have to add to the general theme, I haven't run across an old 72 that wouldn't pass hydro if the had passed the visual. My experience is only the 7 in my fleet now, including a 1/2" pipe thread with an ICC stamp, and another half dozen or so over the years.



Bob

 

[guruboy]

If a tank has over 10% PE at 90% test pressure during the "leak" check, does that fail hydro?

 

[Bob DBF]

If a tank "fails" at 90% test pressure during the "leak" check, does that fail hydro?

Probably just drive the tester nuts trying to find a leak that doesn't exist.

Since it is not a hydro test yet it didn't fail a hydro test.


Bob

 

[guruboy]

I should have been more clear. I meant if a tank has too much PE at 90% test pressure.

 

[runsongas]

Technically no, but unless if it was the prestretch or there was a leak, it would in all likelihood fail at the subsequent full pressure test

 

[scubafanatic]

I would reccomend a different retester. I have bought and sold over 200 steel 72s in the last 5 years. I have had two fail hydro. I have had many fail visual inspection, but your 30% failure rate points me towards a bad retester. My perm expansions on the four 72s that tested this week were .9%, 1.1%, .6%, 1.4%. Those are normal numbers.

Agreed, there is definitely a problem with that retester. One wonders how many poor, innocent tanks they've 'killed' over all these years ? I've got approx 2 dozen tanks, mostly expensive steels, and I'd have a fit if I experienced the tank fatality rates you're experiencing! I have my tanks hydro-ed at Scubatoys or Lone Star Scuba (Ft. Worth, TX) and I have yet to lose even one tank to either visual or hydro test failure. With a personal tank fleet value approaching $ 10 K, I'm not wanting some clueless dive ship getting anywhere near my tanks!

 

[guruboy]

This isn't a dive shop. No dive shop I know of in Dallas does hydro in-house.

I take my tanks directly to Koetter Fire Protection in Dallas. Most dive shops in the area use them.

The other major one is probably Cylinder Services. There are a few more smaller ones around I've heard of, including one guy who supposedly has a mobile hydro test rig in his trailer.

 

[ScubaBunga]

2 / PST >>>> 0.171 inches / 28.88 Lbs / 70.5 cu ft of air (@ STP) / REE = 58.6
4 / PST >>>> 0.181 inches / 30.11 Lbs / 70.8 cu ft of air (@ STP) / REE = 61.5
5 / Norris >> 0.179 inches / 29.73 Lbs / 71.4 cu ft of air (@ STP) / REE = 60.7
6 / PST >>>> 0.173 inches / 30.43 Lbs / 70.9 cu ft of air (@ STP) / REE = 58.7

OK I know this is an old thread, but I've recently found a hydro tester that MAY + stamp my old 72's.. I'm a bit confused on the stated PST ree value 58.4 and the values found above which are greater than 58.4. I thought to get the +, the tank had to have a value LESS than the posted value??
In addition to that - if the average REE is determined by a set of tanks, is there a % less than average that allows the pass as using the average, 50% of tanks would fail to pass...

Anyone have time to explain what it is I'm missing? I now have 14 steel 72's. Half are in hydro, half have been sitting for over 15 years but most look great, I just haven't taken them in yet. Now that I may be able to get a +, the ones that have not seen use, may see it soon (as I don't want to re-hydro tanks that are still good for a few years).
Thanks!