Cracks in newer Aluminum tanks

[akscubaduck1]

I had a friend come in for a second opinion on two Luxfur tanks. 1 AL 80 first hydro 2007, 1 AL 40 (I think) first hydro 1993, both of them cracked in the shoulder area just below the threads. Two tanks same owner.
Anybody seen this before?
I thought maybe both were over filled or factory defects.
Any thoughts?

 

[WD8CDH]

The process of forming the neck or both steel and aluminum tanks sometimes creates small folds in the surface of the material. The folds are often confused with cracks but they are not degrading the structural integrity of the tank and they don't spread like cracks.

 

[carrielsal]

I had a friend come in for a second opinion on two Luxfur tanks. 1 AL 80 first hydro 2007, 1 AL 40 (I think) first hydro 1993, both of them cracked in the shoulder area just below the threads. Two tanks same owner.
Anybody seen this before?
I thought maybe both were over filled or factory defects.
Any thoughts?

Has your friend tried contacting Luxfer?

Carrie

 

[GrumpyOldGuy]

The process of forming the neck or both steel and aluminum tanks sometimes creates small folds in the surface of the material. The folds are often confused with cracks but they are not degrading the structural integrity of the tank and they don't spread like cracks.

I recently has a newer AL80 "fail" VIP for a crack in the threads, only for it later to be identified as a harmless fold by a more respected inspector. I would get a 2nd opinion before dumping the tanks.

 

[Lone Frogman]

Luxfer: Sustained-load Cracking FAQ

 

[carrielsal]

Luxfer: Sustained-load Cracking FAQ

The tanks don't fall in that range. United States: 1972 through mid-1988

 

[Lone Frogman]

Guess you didn't read all of it.

 

[Scared Silly]

They could be cracks but more than likely as said folds in the metal. Can be hard to tell. All else fails send them to Luxfer for inspection.

 

[The Chairman]

Guess you didn't read all of it.

I just did and his statement is accurate. They haven't used that alloy since 1988. Did I miss something?

 

[Lone Frogman]

Paragraph 10 ? I had a buddy with a similar problem during a VIP he ended up having to get Luxfer involved.

10. If Luxfer 6061-alloy cylinders are not susceptible to SLC, why has Luxfer exchanged 6061 cylinders that have been reported to have cracks?

After the introduction of eddy-current technology, Luxfer received reports of cracking in 6061-alloy cylinders. We accepted returns on about 1,200 of these cylinders to conduct extensive tests. Not a single cylinder was found to be cracked.
On Luxfer 6061-alloy cylinders, eddy-current devices sometimes show harmless "indications" that lead to "false-positive" readings for SLC.