gene8084
Diver
Posts: 12
Joined: Sun Nov 01, 2009 8:03 pm
First Name: Gene

Just curious - old tanks

Wed Feb 08, 2017 11:51 pm

I've been to a few shops in New England that will no longer fill tanks over xx years in age, steel or aluminum -- regardless of hydro/visual status.

I'm not one to put anyone at risk, but having a few older tanks (oldest Scott AAA), a nice AL 50 my wife used to use and my 80 CU FT USD, along with an interest in the steel 72's that periodically become available, just wondering what you all do?

My first "new tank" USD, Luxfer 10-85 stands in my office with 1000 PSI remaining as a decoration and used to check regs and pressure gauges from time to time. It's honestly seen relatively few fills in it's long life (32 years) to be standing in the corner.
You do not have the required permissions to view the files attached to this post.

User avatar
luis
VDH Moderator
Posts: 1747
Joined: Thu Jun 30, 2005 9:28 pm
First Name: Luis
Location: Maine

Re: Just curious - old tanks

Thu Feb 09, 2017 8:25 am

Steel tanks can be of any age, and they are just fine. I have steel tanks from 1957 and there is nothing wrong with them. Most of my steel 72 are from the 60's or 70's. Steel doesn’t age. The 3AA steel cylinders from the early 40’s or 50’s will have the same material properties as one manufactured in 2017. The only thing that will change its structural properties is fire or rust, and a hydro and VIP will catch both defects.

In theory aluminum tanks should be OK, but before 1989 they were made of an alloy (6351) that is known to have a “structural defect”. It is a well know structural defect in the alloy itself and the DOT has developed some risk mitigation NDT (non-destructive testing) for early detection of the sustain load cracking (SLC) that are developing on these cylinder necks, but it is just a risk mitigation step driven by economics.

I knew a guy (a good friend of a friend of mine) that died in Cozumel 2 years ago due to a crack failure in a 6351 cylinder. The cylinder ruptured and it ripped his leg mid-thigh. He bled to death before anyone could do anything about it.

I also know of two cylinders in two different states that went through all the proper NDT and they still missed the cracks. It was pure luck that the cylinder didn’t have a catastrophic rupture, like the one that killed Juan in Cozumel.

Personally, I will not take the risk with a cylinder with type that has a well established structural defect. The benefits is just not worth the risk.

Where in New England are you?
In Maine I have no problems filling any steel tanks, but pre-1989 aluminum is on its way out.

Note: this probably needs to be moved to the tank section
Luis

Buceador con escafandra autónoma clásica.

User avatar
Bryan
Plank Owner
Posts: 5279
Joined: Fri Jun 24, 2005 11:40 am
First Name: Bryan
Location: Wesley Chapel Florida
Contact: Website

Re: Just curious - old tanks

Thu Feb 09, 2017 8:29 am

Millions of articles and arguments on the Aluminum cylinders with the potential to suffer sustained load cracking made from 6351 Alloy.
You can read for days and days on the subject. Few dive shops are going to fill a pre 1990 Aluminum cylinder. Most of them won't even look at it twice as it's simply not worth the risk to them.

http://www.luxfercylinders.com/support/ ... inum-alloy

Steel cylinder regardless of age are safe to fill as long as they have been hydro tested, visually inspected and filled only to their rated pressures. Once again this is at the discretion of the dive shop if they want to do this or not.

This is one of the "hot" topics discussed and argued all over the net. There are several folks on here with much more detailed knowledge than I have on the subject.
Doing it right should include some common sense, not just blindly following specs and instructions. .Gary D, AWAP on SB

User avatar
SurfLung
Master Diver
Posts: 1763
Joined: Sat Jan 01, 2011 2:03 pm
First Name: Eben
Location: Alexandria, MN
Contact: Website

Re: Just curious - old tanks

Thu Feb 09, 2017 11:01 am

- It goes against a frugal nature to throw away old aluminum Scuba tanks. I had a set of Twin 50s from about 1972-3 that had barely been used over the years and looked like new inside. After reading and hearing the horror stories I worried about these tanks. I got them inspected regularly and didn't want to part with them for sentimental reasons. Then finally one of them failed the Eddy test. And it was actually a big relief to tell the dive shop to just retire them both.
- Last time I checked, you could buy brand new aluminum 60s and 80s from Joe Diver online for only $125 without the valve. Awfully cheap insurance to just replace those old tanks with new. :)
SurfLung
The Freedom and Simplicity of Vintage Equipment and
Vintage Diving Technique are Why I Got Back Into Diving.

User avatar
ScubaLawyer
Master Diver
Posts: 1649
Joined: Thu Apr 08, 2010 11:25 am
First Name: Mark
Location: Laguna Beach, CA

Re: Just curious - old tanks

Thu Feb 09, 2017 11:23 am

Even though my beloved yellow aluminum twin 50s I got new in the mid-1970s recently passed hydro and eddy tests, one developed a leak at the neck that, try as I might, I could not source. They now sit lonely and forlorn in a corner of my garage. I'm sure I'll get rid of them soon but every time I look at them I remember another grand adventure we had together. Mark
"The diver who collects specimens of underwater life has fun and becomes a keen underwater observer. .. seek slow-moving or attached organisms such as corals, starfish, or shelled creatures." (Golden Guide to Scuba Diving, 1968) :D

User avatar
luis
VDH Moderator
Posts: 1747
Joined: Thu Jun 30, 2005 9:28 pm
First Name: Luis
Location: Maine

Re: Just curious - old tanks

Thu Feb 09, 2017 3:51 pm

ScubaLawyer wrote:Even though my beloved yellow aluminum twin 50s I got new in the mid-1970s recently passed hydro and eddy tests, one developed a leak at the neck that, try as I might, I could not source. They now sit lonely and forlorn in a corner of my garage. I'm sure I'll get rid of them soon but every time I look at them I remember another grand adventure we had together. Mark
When you submerge it in water, where are the bubbles coming from, the O-ring seal are or from a crack in the metal surface. Even if it is from the O-ring area, the leak path can still be due to a very fine crack right under the O-ring.


The two cases that I mentioned above, they detected air leaking from a crack that was not detected by either the VIP or the eddy current testing (after they were hydro-ed). One of the cases was at an LDS here in Portland and the other in Rhode Island.
Luis

Buceador con escafandra autónoma clásica.

User avatar
ScubaLawyer
Master Diver
Posts: 1649
Joined: Thu Apr 08, 2010 11:25 am
First Name: Mark
Location: Laguna Beach, CA

Re: Just curious - old tanks

Thu Feb 09, 2017 4:04 pm

luis wrote:
ScubaLawyer wrote:Even though my beloved yellow aluminum twin 50s I got new in the mid-1970s recently passed hydro and eddy tests, one developed a leak at the neck that, try as I might, I could not source. They now sit lonely and forlorn in a corner of my garage. I'm sure I'll get rid of them soon but every time I look at them I remember another grand adventure we had together. Mark
When you submerge it in water, where are the bubbles coming from, the O-ring seal are or from a crack in the metal surface. Even if it is from the O-ring area, the leak path can still be due to a very fine crack right under the O-ring.


The two cases that I mentioned above, they detected air leaking from a crack that was not detected by either the VIP or the eddy current testing (after they were hydro-ed). One of the cases was at an LDS here in Portland and the other in Rhode Island.
Oring area. I've carefully sanded, dremmeled, etc the interior neck / seal area but no luck. I ran a thread cleaner tap through. It can't get any more virginal looking. I can just make out a faint vertical line coming up the threads and into the flat Oring seal area. Looks more like discoloration than anything but that is right where the bubbles are coming out so I gotta figure it's a Crack. Funny thing is it bubbles at 3000psi but not at 2500psi. Frickin' bloody stupid dive gear......
"The diver who collects specimens of underwater life has fun and becomes a keen underwater observer. .. seek slow-moving or attached organisms such as corals, starfish, or shelled creatures." (Golden Guide to Scuba Diving, 1968) :D

User avatar
captain
Plank Owner
Posts: 1440
Joined: Mon Jul 04, 2005 11:32 am
Location: LaPlace, LA

Re: Just curious - old tanks

Fri Feb 10, 2017 11:13 am

A dye penetrant test will reveal a crack.
Captain

User avatar
antique diver
Master Diver
Posts: 2210
Joined: Sun Dec 10, 2006 12:50 pm
First Name: Bill
Location: North-Central Texas

Re: Just curious - old tanks

Fri Feb 10, 2017 11:35 am

About ten years ago I took thirteen old 6351 aluminum cylinders to a recycle place and sold for scrap. Just not worth the risk to mess with them anymore. A friend in Belize wanted to give me more for them and pay the freight to get them there. I couldn't do that, knowing they would probably get put to use and NEVER inspected again.

We found too many cracked ones over the years for me to ever trust them again. If only one in million came apart under pressure that is too many to risk life and limbs for when there is a known and documented problem.

We stopped filling them long ago, but to keep customers a little happier would always just loan them a free rental for the weekend if they were going diving and we had to refuse to fill theirs. It helped them understand when we showed a cracked cylinder cut open to reveal neck cracks from the inside. No one ever really objected to our policy after seeing that.
The older I get the better I was.

User avatar
ScubaLawyer
Master Diver
Posts: 1649
Joined: Thu Apr 08, 2010 11:25 am
First Name: Mark
Location: Laguna Beach, CA

Re: Just curious - old tanks

Fri Feb 10, 2017 12:54 pm

Bill, I agree with you it is better to be safe than sorry. I understand these old alloy AL tanks are supposed to be useable with a passed eddy tests, and mine did pass, but I hear stories like mine with weird leaks all the time. Captain, thanks for the tip but after countless hours I refuse to invest another minute dealing with this particular tank. It is officially retired. Not to say I can easily toss this set of twin 50s out. I hauled them all over the western Pacific and south east Asia when I lived over there in the late 1980s. I dove for lobster on Cortez Bank with them back in the 1970s. Plus they have this battle-worn cool factor that everyone comments on. What's that dear, get rid of all the crap in the garage I will never use again? Never. Well maybe someday. Ok, I'll get right on it.

Stay safe. Mark
"The diver who collects specimens of underwater life has fun and becomes a keen underwater observer. .. seek slow-moving or attached organisms such as corals, starfish, or shelled creatures." (Golden Guide to Scuba Diving, 1968) :D

gene8084
Diver
Posts: 12
Joined: Sun Nov 01, 2009 8:03 pm
First Name: Gene

Re: Just curious - old tanks

Fri Feb 10, 2017 7:23 pm

I'm in Connecticut, 30 minutes south of Hartford. One of the shops I frequent is in Wallingford. There's another in Jamestown, R.I that I stop by for a fill when diving near Fort Wetherill. https://goo.gl/68TALU

I probably should clarify a bit,
1. I'm not pushing to get my old USD filled, but was more interested in the popular wisdom on vintage steel.
2. My ~55+- Scott has a 1-1/4" thread with a reducer for a 3/4" valve. In hindsight I believe at least one of the shops said they won't fill a tank with a reducer anymore. It may not have been that they wouldn't fill an old steel.

I did pickup a new LP steel a couple years ago, but haven't found a vintage back pack that'll support the larger diameter tank.

Thanks all for you comments and perspectives.

Gene

swimjim
Master Diver
Posts: 1694
Joined: Thu Mar 23, 2006 12:28 am
First Name: Jim
Location: Belgium WI

Re: Just curious - old tanks

Fri Feb 10, 2017 7:43 pm

A number of years ago when the last dive shop pissed me off, I cut them all out of the loop as far as tanks were concerned. I have a really good hydro facility close by. I have talked to the guy that actually does my tanks and he knows his stuff. He told me they don't deal with too many pre '89 Al tanks so for them it doesn't make sense to keep their Eddy current machine calibrated and up and running. I had four pre 89 Luxfer tanks and I simply scrapped them out. I have a couple of 1956 steel 72's. One is a Rene. They all pass no problem. I like steel tanks better anyway. Less weight on the weight belt required. Just plain better buoyancy characteristics. Just a better tank. It's too bad they don't make them anymore. Fortunately there are many still around. If you are willing to get the old ones up to snuff, you will have great tanks for longer then you will be diving. In short, you could put them in your will. Now that's a tank!

Jim

User avatar
antique diver
Master Diver
Posts: 2210
Joined: Sun Dec 10, 2006 12:50 pm
First Name: Bill
Location: North-Central Texas

Re: Just curious - old tanks

Fri Feb 10, 2017 9:14 pm

ScubaLawyer wrote:Bill, I agree with you it is better to be safe than sorry. I understand these old alloy AL tanks are supposed to be useable with a passed eddy tests, and mine did pass, but I hear stories like mine with weird leaks all the time. Captain, thanks for the tip but after countless hours I refuse to invest another minute dealing with this particular tank. It is officially retired. Not to say I can easily toss this set of twin 50s out. I hauled them all over the western Pacific and south east Asia when I lived over there in the late 1980s. I dove for lobster on Cortez Bank with them back in the 1970s. Plus they have this battle-worn cool factor that everyone comments on. What's that dear, get rid of all the crap in the garage I will never use again? Never. Well maybe someday. Ok, I'll get right on it.

Stay safe. Mark
Mark, I understand your sentimental attachments to cool old stuff with a history. I've got it bad... just ask Francie about our storage building spaces and our garage. Bill: "Yes, honey.... I said I would clean out the garage. You don't have to keep reminding me every 6 months". Did I get that line from someone else on the forum? If so, thanks for letting me borrow it. It drives the wife crazy.
The older I get the better I was.

User avatar
SurfLung
Master Diver
Posts: 1763
Joined: Sat Jan 01, 2011 2:03 pm
First Name: Eben
Location: Alexandria, MN
Contact: Website

Re: Just curious - old tanks

Tue Feb 14, 2017 10:44 am

captain wrote:A dye penetrant test will reveal a crack.
Captain, would that be the same as MagnaFlux?

- I have a couple of aluminum 80s I bought as a "Navy Surplus" set off Ebay and didn't know for sure if they were the good aluminum or the bad. I checked the Luxfer FAQs and found a simple way to tell: If the mfg date is any year up to '88, they are the bad 6351aluminum. After 1988, all Luxfer were the good 6061 alloy. So, I checked the dates of my AL 80s and they were mfg in '89... Whew! That was close!
http://www.luxfercylinders.com/support/ ... -alloy-slc

- FYI... Luxfer said that initially they had a few reports of the good 6061 tanks failing the Eddy test. They recalled those tanks and inspected them thoroughly to find zero SLC cracks. They state categorically that the 6061 is not susceptible to SLC cracking.
http://www.luxfercylinders.com/support/ ... change-slc

- Finally about Eddy Testing... They approve a bunch of different Eddy Testing machines for the old bad aluminum but they only approve one machine for the 6061 aluminum. Apparently the other machines give false negatives with the 6061 tanks.
http://www.luxfercylinders.com/support/ ... inspection
SurfLung
The Freedom and Simplicity of Vintage Equipment and
Vintage Diving Technique are Why I Got Back Into Diving.

User avatar
captain
Plank Owner
Posts: 1440
Joined: Mon Jul 04, 2005 11:32 am
Location: LaPlace, LA

Re: Just curious - old tanks

Tue Feb 14, 2017 11:13 am

No, magnaflux will not work on aluminum.
This is dye penetrant. It is pretty simple to do.

https://www.pegasusautoracing.com/produ ... RecID=1207
Captain

Return to “Tanks and Valves”

Who is online

Users browsing this forum: No registered users and 29 guests