Walter Kidde tanks -- returns, hydrostatic testing

[pasley]

pescador775 once bubbled...
Here's a datum for all. I am the original owner of a 1972 USD aluminum 80 mfgt by ALCAN. I use the tank for shop air, portable source for air tools, etc. It is almost always full or close to it. In other words, it has sat on my shop floor for 30 years, full or air. It has passed every hydro and inspection and is still used frequently. In this capacity it is one of the most useful things that I have owned. I fill the tank from my compressor in case anyone is wondering.

There is no argument that a well care for and properly maintained tank can provide many years of service.

The question here refers to tanks made of 3AL allumimum alloy 6351-T6 which was not used until the late 70's, as opposed to your tank made in the early 70's. Note that CATALINA never used the suspect alloy.

Tanks made of aluminum alloy 6351-T6 have exploded resulting in one death, and seveal injuries to both people and property.

You do not mention to what presure you are filling your tank. Does your air compressor fill the tank to 3000 PSI? If not, then what is your normal fill pressue? Most home and shop compressors fill only to realitivly low pressures of under 500 psi.

Last of all, I assume you are having your tank inspected annually and hydroed every 5 year for both your safety and that of your employees.
http://hazmat.dot.gov/rules/not99_11.htm

 

[pasley]

pescador775 once bubbled...
'Suspect' is in the eye of the beholder. The story goes that tanks made from 6531 alloy were at fault. However, it appears that during the years '82-83 something went wrong at the foundry where lead inclusions enjoined the alloy in such a way as to promote crack spreading and sudden failure, particularly in thick sections, eg the neck.

This tank was made in 1987 http://archives.mundoacuatico.com/jan02/01janupperkeysdivecaptain.PDF well after your lead issue years.

I had not heard the story about lead. It is an interesting theory.

From what I have read the issue was the Alumimum alloy and how repeated hot filling of the tank may have altered the structure of the alloy. The heating and cooling if you will can change the properties of metal. Metal is often heated and then cooled until it reaches the desired temper and then it is quenched in a dunk tank to establish desired properties in the metal (yes, I know this is not a technical explaination, but it gets the idea across and will do for this discussion). You will see on many Semi Trucks a notice on the frame not to drill or weld as the heat generated would alter the properties of the metal.

If the problem could truly be narrowed down to just that year (82-83), would not DOT have just issued a safety notice for that year group? Instead DOT issued a safty of use notice on the alloy and no longer approvs it for mfg of high pressure tanks.

DOT conducted metalurgy test on the failed tanks and determined the cause to be Sustained Load Cracking (SLC). If there were impurities in the alloy these test should have found them I would think.

 

[pescador775]

My '72 USD tank is mfgt under special permit 6498 which is the 6351 alloy. The technical opinion regarding lead does not fall into the category of theory, not entirely. This particular alloy contained lead as part of its specification, it is not an impurity. The alloy seemed to give no problem if the lead was distributed evenly throughout the billet. The theory part has more to do with why only some of these tanks fail (17 explosions among 25 million tanks). Metallurgists have pointed to uneven distribution known as lead inclusions. This seemed to occur particularly with WK tanks and the years 82-83. However, CYA Walter Kidde tanks of all years draw negative attention, however safe. I wouldn't fill one, personally even though, intellectually, I know that they are likely to pass inspection.

The issue is quite complicated. Of the 17 explosions worldwide about 5 have been scuba tanks, the rest wire wound or glass wound scba tanks. I'm not too sure of the technology here but you get the idea. The scba tanks are mostly 4500 psi types.

Even though few of all types have failed there have been more than a few that have shown small cracks in the neck threads. The cracks take many years to develop and can be detected visually (tricky) or by special equipment (a source of false positives unfortunately). Luxfer is of the opinion that actual failures are not likely in any tanks that are filled to 3000 psi or less. You asked about my personal tank, it is always filled to 3000 psi and contains whatever pressure exists on a particular day, usually 2500 or greater.

Kidde made the 6351 tanks until 1989 although others ceased using this metal in 1988.

Pesky

 

[MikeFerrara]

In theory SLC should show visual/visual+ signs long enough before failure to be found in anual inspection before they blow.

Since I visual and fill my own tanks I would keep using one of these tanks if I had any left.

I was a little more gunshy when I had a shop though. Who wants to risk their life and property filling a tank.

We never went as far as to refuse to fill them but I don't blame those who do.

Now, I wouldn't fill one unless I was the one to do the visual (I send them out for visual plus)

 

[pescador775]

Paisley, I'm a little surprised that the dive shop guy tried to fill the Kidde tank. That explosion occurred in 2000, only a year after Kidde tanks were publically implicated in similar explosions which, incidentally, occurred in Florida. Calendar year 1999 was when the issue really hit the fan and my data are from that era. I haven't paid much attention since. So, with your ref that brings the total to 6 scuba tanks and includes an 87 model Kidde. If anyone has more info it would be of interest.

 

[muck63]

Hi all, Just was told today that my 1983 walter kiddie al 80. Will no longer be hydroed ,the place that hydros the tanks will not even look at these tanks any more. It was bad enough that only one dive shop here would fill them but, now they can no longer be hydroed .I have 3 of these tanks that can no longer be used.Seems like luxfer should step up to the plate and take care of this. Now that they wont even hydro them.

 

[Boogie711]

Why do you want a company to "step up to the plate" and compensate you for a 20 year old piece of dive gear? I'd say you got 20 years of service out of the thing - move on dude.

 

[pescador775]

What has Luxfer to do with Walter Kidde? (not 'Kiddie'). Why does anybody owe you anything? I have a 20 year old SUV. I don't expect I'll be complaining if it doesn't meet current emission requirements.

 

[pasley]

Luxfer offered a $50.00 rebate to owners of their tanks for a year. I agree with pescador775, why are you not asking Walter Kiddie to step up to the plate? I also agree, 20 years old, you have already gotten your value out of these tanks. Would you go after Ford if your 20 year old car could no longer get parts or had mechanical problems? You have to figure that any vessle under pressure of 3,000 pounds per square inch will at some time stop being safe to fill or will fail hydro. In this case, a new (at the time) alloy had an unexpected reaction to the heat of some operators overfill them and then experienced catastropic failures. Bottom line, there is at present no reason why your LDS should refuse to hydro them or fill them (mind you I respect there right to refuse to do so, I know I personally would too). There are others business that conduct hydros, go to them.

 

[The Chairman]

Sounds like "E-Bay" time...