Tanks...which ones can't be re-hydro'ed?

[Stu S.]

We know the DOT has instructions for hydro facilities. Who sets the rules for the dive store? I had an older Aqua-Lung aluminum tank; it had been in my family for years. It was always stored with a little air in it, and passed all tests like new.

My favorite dive shop closed, and the next closest guy made a remark like: "We fail all of those". No sense taking it to be rejected without any real inspection. I sold it to a diver in Tennessee, who was using one just like it and was pleased to have a pair.

If testing is of value, shouldn't the results be uniform, regardless of the state the tank is in?

 

[halocline]

We know the DOT has instructions for hydro facilities. Who sets the rules for the dive store?......snip.....
If testing is of value, shouldn't the results be uniform, regardless of the state the tank is in?

That's a good question, and the problem is that a dive shop does not have to fill a tank that they don't want to. They can refuse to sell a fill to anyone they want, for whatever reason they want, basically. (apart from cases of racial or other discriminatory practices)

As far as DOT rules for hydro facilities, despite those rules and procedures there are all sorts of stories about seemingly improper behavior among hydro testers, I even have one of my own. As divers without compressors, we are somewhat at the mercy of these guys.

I am REALLY glad I now work on my own regs; I can't imagine tolerating paying for badly done reg service. (when I can do that myself)

 

[Stu S.]

Hey, Matt.

The large number of cylinders failing VIP at this shop gave me reason to believe that there were "false failures". So, instead of ending the day with a piece of scrap, the cylinder went to a place where it is still useful.

 

[Scared Silly]

There are no rules or laws for dive shops unless they are hydro tester as well (few are). There are dive industry standards but they do not need to be followed. As such, in FL many shops have seemed to adopted their own rules. As was said, they are free to do what they want but it leaves a bad taste for many divers because there is no consistency.

I have personally seen shops that will not fill any cylinder older than 20 years old. Others say no AL cylinders made before 1990 or 1989. About the only practice I think is okay is to say we do not fill 6351 cylinders. At least then it gives some indication that the staff know how to id a cylinder.

 

[bronk]

Why not let the regulators and insurance carriers have a say. They have the stats to be able to dictate what is statistically safe or not. Beyond the stats, properly trained personnel should be able to make the judgement on the suitability of a particular peice of equipment or in this case a tank. For old tanks a visual is not enough, hence the need for eddy current testing. However the equipment is somewhat expensive (however in the scope of the cost of dive gear, not outrageous). It is probalby worth seeking out a shop that has the equipment to do the full job in the case where the local shop refuses.
Categorically refusing to fill a tank without reulatlory restricions or coverage restrictions smacks of either: fear (rumors of all pre 1990 tanks being bad) or a push for more equipment sales. To me, that would be a reason to find another shop to patronize.

 

[oxyhacker]

But even if they are a hydrotester as well the rules only apply to them when they are doing hydrotests, so they are free to enforce their own wise or nutty rules the rest of the time, as when doing visuals that are not part of a hydro.

BTW I asked the DOT once whether hydroshops were allowed to refuse to test certain kinds of cylinders just because they didn't like them. I was told they are - that if they accept a tank for requalification they have to perform the requalification according the DOT rules, that is to say, they can't arbitrarily decide to fail tanks at 8% instead of 10% or test at 4/5ths rather than 3/5thss but if they decide they won't test 6351 tanks, or red tanks, that is no concern of the DOT.

There are no rules or laws for dive shops unless they are hydro tester as well (few are). There are dive industry standards but they do not need to be followed. As such, in FL many shops have seemed to adopted their own rules. As was said, they are free to do what they want but it leaves a bad taste for many divers because there is no consistency.

I have personally seen shops that will not fill any cylinder older than 20 years old. Others say no AL cylinders made before 1990 or 1989. About the only practice I think is okay is to say we do not fill 6351 cylinders. At least then it gives some indication that the staff know how to id a cylinder.

 

[rjack321]

I have personally seen shops that will not fill any cylinder older than 20 years old. Others say no AL cylinders made before 1990 or 1989. About the only practice I think is okay is to say we do not fill 6351 cylinders. At least then it gives some indication that the staff know how to id a cylinder.

\

Its unfortunate that 6351 was phased out differently in different tank sizes at different times. This is quite impractical at the individual fill/cylinder level.

 

[Rick Christ]

OK Guys

Here is the info. This whole thing started on Aug 8, 2002. The DOT issued HM220D (see attached) the bulletin stated that only poisonous gas is prohibit for use in a 6351-T6 alloy cylinder because of SLC. The dive industry only read the first two sentences of HM220D, then pulled their skirts up over their heads, and ran screaming down the road like a bunch of frighten little girls. Many of your LDS used this misinformation to sell you a new tank when it was not justified. Because your, LDS has more knowledge about cylinders then the engineer, scientist and metallurgist at the manufacturer, DOT, PHMAS and OHSA.

In Jan 2007 the DOT came out with the final ruling (HM220F) the reader digest version is, if there is a crack into one thread, the tank can be return to service, if the crack propagates into two threads the cylinder must be condemned and Eddy currents have to be preformed. The bulletin HM220F has now be absorbed into 49CFR 180.209m.

The last information I have received from Mark Gresham President of PSI. Only 24 cylinders out of about seven million 6351-T6 have turned into a hand grenade. The problem is similar to a 747 crashing, everyone hears about every single incident.

FYI, this number that is used to describe these cylinders 6351-T6. The T6 stands for the temper of the alloy, these cylinders were designed if they fail, to crack, vent and not explode. The 24 that did explode, something happen to these 24 cylinders that changed the temper of the alloy.

In 1985 at Smith Diving, Mpls. One Sat morning a 82-83 Luxfer cylinder did split below the threads in the fill station on me, this tank did vent, it blew the ceiling panels off the ceiling, blew water up into the rafters. It did not explode. This is how the cylinder was designed to function. Now I am saying that if you are at the site of one of these incidents, that you will say it!, you will do it! and then you go and change your shorts. It is about three times worst then a burst disk going off. I know of two more that have cracked in the fill stations here in the Keys, which did not explode. If you are coming to the Keys, I have LDS in KW & Marathon that will fill 6351-T6.

About 37 to 40 percent of the seven million 6351-T6 tanks are truly found with cracks. There are a much larger percentage of these tanks that are false positives. I have been taking many of these rejected cylinders, cutting the tops off them and inspecting them by VE and NDT and finding no cracks. Most of the cracked 6351-T6 have been taken out of service by this time, the remaining ones are mostly sound and in good shape but we need to continue to inspect and eddy current these things.

Here is the part that the diving public does not know, 6061-T6 alloy are starting to show up with SLC. I know of 14 currently. One was a Catilina. The local medical o2 supplier is saying that they have I bunch of them on site, I have not been able to inspect them as of this time.

I have been telling everyone in the dive business to buy these fill stations that will protect the tank fillers, most of the compressor manufacturers make them. I do not understand why the dive industry did not switch to these fill stations when the 6351-T6 SLC problem came out in 2002.

 

[SparticleBrane]

Here's the best policy:
Don't fill 6351 cylinders, and if you own some, ditch 'em.

 

[Rick Christ]

BTW I asked the DOT once whether hydroshops were allowed to refuse to test certain kinds of cylinders just because they didn't like them. I was told they are - that if they accept a tank for requalification they have to perform the requalification according the DOT rules, that is to say, they can't arbitrarily decide to fail tanks at 8% instead of 10% or test at 4/5ths rather than 3/5thss but if they decide they won't test 6351 tanks, or red tanks, that is no concern of the DOT.

I believe that this is going to be revisited because the issue of the 6351-T6 has now been absorbed into 49CFR 180.209m. I do not believe that a DOT Requalifier will be allowed to pick and choose what part of the CFR that they agree with and what part they don't want to follow. This would be absurdly foolish and the DOT would loose all control