Old Tanks-Advice

[tom2004]

A close friend gave me this tank and i was wondering if it was still useable. I was going to get a visual and hydro test sometime this week. The one thing im concerned about is the tank was used in the 80's. Is it too old to use in 2007? Here are some pictures...

 

[Scared Silly]

Yes, it is still usable if it passes three inspections: Visual, Eddy Current, and Hydro.

Note this cylinder is made from AL6351 which is suspectable to what is known as stress load cracking. Here is a link to the advisory and current regs:

http://hazmat.dot.gov/pubs/reports/cylinder/3al_advisory.pdf

http://a257.g.akamaitech.net/7/257/2422/01jan20061800/edocket.access.gpo.gov/2006/pdf/E6-14255.pdf

Some dive shops are paranoid about filling cylinders made from AL6351 and refuse to do so.

Mods - please lock this thread so we do have yet another thread concerning AL6351

 

[DennisW]

What Scared said. The tank is perfectly fine if it passes the tests mentioned above.

My credentials:

Diving Technologies International; Pressure Cylinder Inspection Certificate #198

 

[JEScholz]

Yes, it is still usable if it passes three inspections: Visual, Eddy Current, and Hydro.

Note this cylinder is made from AL6351 which is suspectable to what is known as stress load cracking. Here is a link to the advisory and current regs:

http://hazmat.dot.gov/pubs/reports/c...l_advisory.pdf

http://a257.g.akamaitech.net/7/257/2...f/E6-14255.pdf

Some dive shops are paranoid about filling cylinders made from AL6351 and refuse to do so.

Mods - please lock this thread so we do have yet another thread concerning AL6351

With the DOT 3AL 3000 markings, what makes you say it is a AL6351 tank?

 

[kb2ehj]

With the DOT 3AL 3000 markings, what makes you say it is a AL6351 tank?



Because all Luxfer tanks made from 6/88 backwards were made with it. From my understanding only Luxfer used this alloy. Catalina used there own alloy (I might be wrong on this but I think that is the case)

 

[DA Aquamaster]

All Catalina tanks were made using 6061-T6 alloy and are not subject to sustained load cracking issues (although they may end up being subjected to visual plus/eddy current testing now due to their pre -1990 age and older eddy current equipment can produce false positives for cracks, so it is important that the tester know what they are doing and confirm the results to eliminate false positives.)

------

The following is a list taken from a DOT safety bulletin several years ago indicating what tanks were made from 6351-T6 alloy and that consequently should definitely be visual plus inspected due the potential for sustained load cracks.

All DOT-3AL tanks manufactured under one of the following exemptions or special permits: 6498, 7042, 8107, 8364, 8422 (Most of these tanks should have been restamped "3AL" a decade or so ago as the DOT directed that the previous exempt aluminum tanks that were standardized under the "3AL" clasification be restamped at the next hydro date.)
All composite cylinders manufactured under one of the following exemptions: 7235, 8023, 8115
All Walter Kidde DOT-3AL scuba tanks. (All Walter Kidde tanks were made from 6351-T6 alloy. Walter Kidde continued tank production until 1991 so a post 1988 date on a Walter Kidde tank does not mean it is 6061-T6 alloy)
All Cliff Impact DOT-3AL scuba tanks made before July 1990.
All Luxfer 80.8 cu. ft. scuba tanks (S80.8) made before May 1987.
All Luxfer 72 and 100 cu. ft. scuba tanks (S72, S100) made before August 1987.
All Luxfer 80 cu. ft. scuba tanks (S80) made before January 1988.
All Luxfer 50 and 92 cu. ft. scuba tanks (S50, S92) made before April 1988.
All Luxfer 30 and 63 cu. ft scuba tanks (S30, S63) made before May 1988.
All Luxfer 40 cu. ft. scuba tanks (S40) made before June 1988.
All other scuba tanks made in the US before February 1990 (except Catalina, which never used 6351-T6 alloy in any of its tanks).
All scuba tanks not made in the US.

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May 1988 is the often quoted cut off date for tanks made from 6351 alloy, but the most commonly seen Luxfer S80 tanks were all being made from 6061-T6 alloy by January 1988 and the cut off really refers to the month by which all Luxfer production had been switched to 6061-T6 alloy with the last 6351-T6 Luxfer tanks being S40's produced in May 1988.

More importantly, Cliff impact and Walter Kidded tanks produced thru 1990 will be encountered that are made from 6351-T6 alloy, so a blanket cut off date of May 1988 or even January 1990will not catch all the 6351-T6 tanks out there.

 

[Stu S.]

I got a similar freebie about two years ago. It was a 1973 Luxfer, in great shape. Hydro and visual cost me $24, and a good used valve was $15. All was well.

By Spring 2007, my local dive stores pretty much stopped filling these, just in case that one in a million bursts. We had just that in Orlando earlier this year, with no injuries. When the local shop owner told me that mine would probably fail VIP, before he even looked at it, I figured the deck was stacked. That tank is now being used in Tennessee.

You may wish to ask your local compressor owners if they fill these before you invest in it. Fortunately, my investment paid off, as I saved money for two years and sold at a profit.

Happy diving!

 

[DennisW]

By Spring 2007, my local dive stores pretty much stopped filling these, just in case that one in a million bursts. We had just that in Orlando earlier this year, with no injuries.

I wonder if that tank had passed hydro and a Vis plus. If it had, it is the only known (to my knowledge, DA Aquamaster could pipe in here) 6351-T6 alloy tank to have failed catastrophically after passing the proper testing.

 

[DA Aquamaster]

I agree, there have been zero failures of properly inspected 6351-T6 tanks since the introduction of eddy current testing.

In fact the most recent DOT regulation on the issue now only requires testing at the hydro test due to the very slow growth of sustained load cracks and the effectiveness of eddy current testing in catching them early.

Ocassionally, you will hear about a catastrophic failure, but it invariably involves someone dropping an O2 filled tank on its valve, or where the tank has not been properly inspected in years, or some type of grossly abusive situation where the alloy of the tank was irrellevent to the darwinian process that occurs when stupid people play with high pressure gas cylinders.

In my opinion the refusal by dive shops to fill 6351-T6 tanks is based on ignorance, greed, paranoia or a mix of the three. None are good traits for a dive shop.

 

[Stu S.]

Here's what Seminole Scuba, Lake Mary, Florida Says:

IMPORTANT NOTICE

AN INCREASING NUMBER OF ACCIDENTS INVOLVING SCUBA TANKS MANUFACTURED WITH ALUMINUM ALLOY 6351 HAVE BEEN REPORTED IN FLORIDA, THE MOST RECENT BEING HERE IN ORLANDO. AN ALUMINUM 80 CF TANK MANUFACTURED IN 1987 EXPLODED CAUSING EXTENSIVE DAMAGE TO A DIVE SHOP. THE POTENTIAL FOR SERIOUS INJURY IS REAL AND SHOULD BE ANTICIPATED BY TANK OWNERS EVERYWHERE.

THIS ALLOY HAS BEEN FOUND TO BE UNSTABLE. THE VISUAL INSPECTION AND HYDROSTATIC TESTING OF THESE TANKS REQUIRES SPECIAL PROCEDURES AND EQUIPMENT THAT CANNOT BE RELIABLY GUARANTEED.

EFFECTIVE IMMEDIATELY, SEMINOLE SCUBA WILL NOT FILL OR SERVICE ALUMINUM SCUBA TANKS OF ANY SIZE MANUFACTURED PRIOR TO 1988. THIS POLICY HAS BEEN IN PLACE IN VARIOUS REGIONS OF FLORIDA FOR SEVERAL YEARS.

VIEW THE COMPLETE LIST OF TANKS EFFECTED - http://www.scubabomb.freeservers.com/List.htm.

My tank didn't turn instantly weak because some guy said it was "effected".

Anyway, the word around here is "We don't fill those any more, you'll have to buy a new one". When that other shop told me that most of them failed, I figured they were in cahoots. Compressor owners have the upper hand. Either I can buy a new one, rent, or quit diving.

I sold the oldie to a diver out-of-state. I bought two new ones. The guy I regularly get air from is miffed that I didn't buy them from him. GEEZ!

So the moral of the story is call around before you invest in an older aluminum cylinder. I had a good tank. It was like swimming into a tide of BS.