1970 US Diver's LP72 - Lined or not?

[halocline]

It can not pass VIP according to DOT regs because you can not inspect for damage under the lining.

See how easy it is for mis-information to get perpetuated? In your defense, there are undoubtedly many hydrotesters at licensed test shops that think the same thing. Probably an accurate statement would be "It will be more difficult to get a lined tank inspected and filled at a dive shop because so many shops think that the lining means VIP failure"

Regarding these particular tanks, the inside looks great to me, I didn't see any evidence of a lining, and I'm not sure why you tumbled for so long, but you sure got 'em clean.

 

[WB2GLP]

If the tank did have a lining, it would have taken days not hours to tumble it out. The bottom of a lined tank is particularly difficult to tumble out unless your tumbler can incline/decline. I did it once and probably wouldn't bother doing it again.

 

[halocline]

That's pretty funny, bragging about a 5 year warranty on steel tanks. I have one LP72 that had a USD label and it was not lined.

 

[kwinter]

See how easy it is for mis-information to get perpetuated? In your defense, there are undoubtedly many hydrotesters at licensed test shops that think the same thing. Probably an accurate statement would be "It will be more difficult to get a lined tank inspected and filled at a dive shop because so many shops think that the lining means VIP failure"

Regarding these particular tanks, the inside looks great to me, I didn't see any evidence of a lining, and I'm not sure why you tumbled for so long, but you sure got 'em clean.

I'm not sure where you think the inaccuracy was in my statement. It's not the lining that is prohibited. It's the inability to visualize the metal under the lining that keeps the tank from passing VIP. I guess if someone made a perfectly clear lining, it would still be possible to inspect.


Please pardon any typos. Sent from my iPhone using Tapatalk

 

[Luis H]

Most internal linings that I have inspected are smooth enough that they would show any rust under them.

Keep in mind that the expansion coefficient of rust can range between 2.2 and 6.4 (I will be glad to provide references for that data), therefore, any rust under the liner should show as a blister.

The hardest thing that I have found is inspecting some of the dark coatings. Even with a very bright light, it is sometimes hard to judge how smooth is the surface due to the way the light reflects from the coating.

I personally own three white coated cylinders and one with a dark brown coat. The white coated cylinders are the easiest cylinders to inspect (even easier than non-coated). That dark brown one I have to look at it a lot more carefully and move the light all over the place to get a good look at how smooth is the surface.

When I worked at a dive shop (also a licensed hydro facility) we used to inspect lot of lined cylinder (in the 70's and a early 80's).

 

[captain]

As I wrote in post 9 and Luis said above. If the lining is smooth with no blisters ( like you see when rust forms under paint on a car ) or flaking it should not be an issue. I have a lined tank that passes hydro and inspection every time.

 

[KD8NPB]

Well.

Looks like I have some REALLY clean Grade E air service cylinders. lol.

Just kinda accelerates my plans to make a continuous blender... ~144cf is a perfect amount of gas for a 100 ft dive on EAN28 (max ppO2 target: 1.2...better bent than tox'ed!)