What is this new annual inspection device?

[Doug B]

Took some tanks in for annual and hydro this weekend. LDS has a new visual inspection machine. This machine checks each individual thread in the neck. The LDS owner said that he is now failing a lot more tanks during annual inspection. Certain brands more than others. I guess that's good, in theory it keeps him safer when he's filling tanks.

The device looks like a threaded plug that screws into the threads of the neck - and it's wired into some sort of computer interface.

I'm interested in learning more about the device. Anybody know what this new device may be called? Who makes it?

D

[captain]

It's called a LDS moneymaker machine. A pipe plug, some wire and a lap top and I could whip you up one.

[Luis H]

It actually sounds like the third generation eddy current machine.

The latest eddy current machine, if it is properly used on aluminum tanks can be a lot more reliable than the previous eddy current testers. Since it has a direct computer interface the technician will have much better documentation for future reference and to share with the owner of the cylinder.

The machine in itself should not be failing any more tanks than is proper, if it is properly used and calibrated. But, this type of instrumentation is far from being fool proof.

The operator should also use a high magnification mirror or even better the high magnification periscopes to double check if there are really any cracks or if it is tool marks on the threads, etc.

Condemning a good tank is not only irresponsible; it is actually illegal if the tank is mark in any way. There is some tolerance for small errors, but I would be very suspicious of an inspector that is all of a sudden failing many tanks.

There are reasons we have codes and regulations.

You can do a search for tank eddy current testers. There are two manufacturers of this type of testers, but the last I heard only one of the companies had the unit with the computer interface.

My understanding is that this newer machines are supposed to detect if it is aluminum alloy 6351 or 6061 and perform a correct test accordingly.

Eddy current testing does not really apply to steel tanks.


Added:
If it is not the latest eddy current machine, I would be very interesting on finding out what they are talking about. I am not aware of any other device used for checking tank threads.

[JahJahwarrior]

http://www.visualplus.net/

[Doug B]

Originally Posted by JahJahwarrior

http://www.visualplus.net/

Yep... it is eddy current inspection. This looks like what the guy showed me. Thanks for the help.

[in_cavediver]

I'd be very leary of this. Eddy current testing is good and should be done but if he is failing a lot of 6061 tanks with no visible cracks - I'd definitely get another opinion. These tanks don't have a history of thread cracks so you shouldn't see a lot of positives. If he is doing mostly 6351 tanks - I'm not suprised. That said, those tanks are getting rarer as divers can't get fills.

These devices are only as good as the operater using it. Have a bad or ill informed operator and you'll get bad results. Also realize the DOT mandated eddy current testing on 6351 tanks but not on 6061 tanks. There is a fine line being walked here to fail a tank using a device that is not required by law and during a procedure not required by law. If it is simply a no-sticker fail he's probably OK. If he is damaging the threads or Xing out the markings, he's potentially in a world of hurt liability wise. (I'd personally demand a new tank for that)

[cajunfla]

Any time your LDS uses one of the eddy current testers, ask to see the certification of the testing operator. With the military, eddy current falls under NDI, NON-DESTRUCTIVE INSPECTION. NDI requires certification schooling, not just buying a machine and reading the how-to manual.

[Doug B]

Thanks guys,
I'm actually very familiar with eddy current inspection, magnetic particle, and dye penetrant inspection techniques..... we do a lot of it on aircraft parts.

I really just wanted/needed the link to the company that makes the hardware for the threads. I'm interested in it for non-scuba reasons.

Doug