coatings and plus ratings on steel tanks

[gbray]

Here I go again. I just came across another LP steel 72. I had my LDS look inside and It is in great condition (I looked also). It is a PST and has a brown coating on the inside. Anyone know what that is? Can it be O2 cleaned? I went thru this before but the coating was white and flaking. the original hydro was 1971.

My second question has been asked before but I don't know where to find it. My LDS tells me they don't do plus ratings anymore but I seem to remember reading they do if you have a certain spec on a tank. Can someone refresh my memory on this or tell me where to find it?

Thanks

 

[zider]

Do some searching in the tanks subforum to find the REE number for your particular tanks. This number is required by the operator to perform the + rating. If your LDS doesn't do + ratings, start making calls around the area to gas distributors or fire safety companies and see if you can find someone who will do the + rating for you. If you are friendly with the guys at your shop you might also see if they would be willing to fill your tanks to the higher capacity without the + rating. These tanks are commonly overfilled and can easily take the extra load. Hope this helps.

 

[rstofer]

The official REE number for PST LP 72's was linked over in the Tanks subforum. Many hydro shops already have this information. After all, that is the business they are in. If your LDS doesn't do '+' ratings, they just aren't really in the business.

Still, it might not be a big difference: 65 CF vs 72 CF. Either way, it's not a lot of gas.

It isn't just LP 72s that are '+' rated. Many, if not most, LP cylinders need a '+' rating to get to rated CF.

Richard

 

[Cave Diver]

Have a look at this thread, it may give you some insight: http://www.scubaboard.com/forums/tanks-valves-bands/256232-how-handle-mysterious-tank-coating.html

 

[Gilldiver]

If the coating is intact and not flaking or blistered they should be fine, but many shops will not pass them for VIP and tell you they have to be condemned. Don't believe them, just find another shop. Tanks with good condition coatings have no reason to be removed or condemned.

But, I would not use them for PP blended NITROX, as it is an organic coating that could cause problems.

If you want to get the resin out, have them tumbled, but for media use 3 pounds of 1-2.5 inch Stainless Steel deck screws to cut the resin off, then normal media for a clean up.

 

[Polar_diver]

The ''+'' stamping allows for a 10% overfill. US DOT and Canadian TC do not allow a ''+'' to be stamped on cylinder that were not originally tested up to this specs. However, in Canada, cylinders manufactured after 1993 are automatically qualified to have +10% unless there is a ''K'' stamped after the service pressure stamped in BAR.
On an other subject, chances that a gas company accept to hydro scuba cylinders are slim. They have plenty of work with their own cylinders... Take it from a guy in this business!

 

[syntaxerrorsix]

Also keep in mind that the rated volume of the tank is only met with the 10% overfill.