Folds vs cracks on tank threads?

[GrumpyOldGuy]

I had a tank fail visual, it was a 3 year old Catalina AL80. The person doing the inspection (PSI trained) said there were cracks across multiple threads. My eyes are not that good and I am not an expert, so I did not really question, but was very supprised.

So when I got back home, I got a second opinion at my LDS (also PSI trained). He stated it was not cracked, but merely folds from the manufacturing process. In his opinion, it was a non-issue and he passed the tank.

Can anyone really explain the difference between folds and cracks. Does this happen often (false fails on visual)?

Thanks

 

[Chugwhump]

WOW! Only three years old?
I have never heard of an unabused Catalina having this issue.
My initial reaction is that you got a poor test the first time, and a proper read the second time.
I have nothing to add, but I will be watching this thread to try and learn something.
Thanks for posting this.
Chug

 

[rstofer]

Call Catalina! They may be interested in this tank regardless of whether the issue is a 'fold', 'crack' or non-issue. If there is an issue, they will probably replace the tank. This kind of think is unheard of. If there was a problem, it would be all over the Internet!

Richard

 

[Leadking]

I had a tank fail visual, it was a 3 year old Catalina AL80. The person doing the inspection (PSI trained) said there were cracks across multiple threads. My eyes are not that good and I am not an expert, so I did not really question, but was very supprised.

So when I got back home, I got a second opinion at my LDS (also PSI trained). He stated it was not cracked, but merely folds from the manufacturing process. In his opinion, it was a non-issue and he passed the tank.

Can anyone really explain the difference between folds and cracks. Does this happen often (false fails on visual)?

Thanks

A fold is where the metal actually folds upon itself but is structurally intact. A crack is a structural failure where the metal's crystalline structure (how the metal binds to itself) is failing. Folds are quite common. An eddy current test should be used if a question of crack or fold is encountered.

 

[mongodives]

Thats why I took PSI's course, so I would know what to inspect for and inspect my own tanks.

 

[NorthWoodsDiver]

Your PSI trained inspectors may have a means to photograph the issue, you could at least ask and then we could all learn from it.

The threads at the bottom of the tank opening are usually only partial threads because of the irregularity in the tank so seeing a valley that goes up through 2 or 3 threads wouldn't be unheard of and a visual v.s. an eddy would likely make things easier to distinguish.

clean the threads well and inspect it for yourself, if possible try and get a photo but my guess is its perfectly fine especially knowing its a newer catalina tank.

 

[Couv]

Catalina has a good site: Catalina Cylinders then click on Tech Support and have a good look around, they have info neck inspection, folds, cracks, etc.

 

[Doc Harry]

Keep us informed and post a photo if you can. I'd like to see this.

 

[GrumpyOldGuy]

Thanks for the education.

The Catalina site was interesting (thanks Couv). I suspect that the first VIP (done by someone who is primaraly a fill opertator) was overly cautious and classified the fold as a crack. To my untrained eye it looked like it did cross 2 threads (which means it can be returned as a manufacturing defect as I read it), but there are still more than the minimum number of perfect threads left and otherwise it is in good shape.

I wish I could share a photo - I simply did not think of this at the time and the tank is now full. I am going to double check with my LDS that passed the tank, if he agress it is 2 or more threads I will empty the cylinder, take whatever picture I can and contact Catalina for an RMA.

Thanks again

 

[knotical]

Also check out this document:
http://www.luxfercylinders.com/downloads/docs/scubaguide.pdf