Removing Paint From LP72

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Stripper wise from HD, they carry an orange base stripper that is supposed to be relatively safe compared to aircraft stripper. I used it on an old aluminum tank recently, worked pretty well and you rinse it with water.
 
Keep in mind on the old LP72s you may possibly find either of:
1) Paint.
2) A layer of vinyl.

The vinyl plasti-dip like substance was often applied over galvanizing, and was thought to be the bee's knees in tank protection.

Paint can be removed with stripper or sandblasting. If I am redoing a painted cylinder, I put a junk valve on it and give it to a sandblasting shop, and $40 later I have a bare steel cylinder that's ready for primer.
 
I have removed vinyl from cylinders by drawing a knife down the length of the cylinder and scraping it off in strips. I am not aware of any stripper that will lift vinyl.
 
I have removed vinyl from cylinders by drawing a knife down the length of the cylinder and scraping it off in strips. I am not aware of any stripper that will lift vinyl.

Cap...

Commercially available ''strippers'' will remove vinyl easier than some of the ''old school'' nitro cellulose and epoxy finishes...

These new strippers love plastic/vinyl...

The vinyl softens up and you can peel it off like cellophane...

Cutting strips with a ''utility or other type of sharp knife permanently marks the tank walls...you may also gouge/cut through the thin zinc coating exposing the carbon steel tank to rapid corrosion problems especially if used in salt water...

Keep in mind you are not only removing ''color''...you're removing ''protection''...

Currently...especially with technical divers...any cylinder coating...other than zinc...is frowned upon...in years gone by...manufacturers ''coated'' tanks...because ''paint'' was a cheap form of protection...with few exceptions...''modern cylinder coatings'' are applied because some folks like purple and lime green...but the coating offers little in the way of protection to the cylinder...and can even be a detriment to the cylinder once the coating starts to chip and peel and allows salt water intrusion...

This is the primary reason why removing tank stickers annually during visual inspection...including NITROX/DIL/OXYGEN bands is so important...especially for tanks used in salt water...

As far as steel cylinders...galvanized...is always superior...to...non-galvanized/painted...

When I get tanks back from the re-hydro shop...I always remove any loose zinc from around the area of the new re-hydro stamp...mask off a little rectangle...and coat the ''re-stamp'' area with a colored epoxy...which replaces the ''protection'' previously provided by the zinc coating...which was chipped off when the tank was stamped...

Best...

Warren
 
Made some progress on this tonight. Warmed the cylinder up and scraped and peeled the vinyl coating off. It's about 3/4 done.
 

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I don’t know what your plans are for the valve, but it looks like that might have an old uni-directional burst disc. If you are able to get that working, be sure that gets changed if that is the case.
 
I don’t know what your plans are for the valve, but it looks like that might have an old uni-directional burst disc. If you are able to get that working, be sure that gets changed if that is the case.

I'm planning to replace the valve with a K valve. A couple of out of hydro aluminum 80s are going to donate their valves to this tank and my other LP72.

What's a unidirectional burst disc? How does it differ from a modern burst disc?
 
When a modern disc bursts, the release of pressure is in three opposing directions to avoid imparting any directional force/momentum to the cylinder.
 
The unidirectional burst disc has one single hole that comes out the front of the plug. If the burst disc ever blew while someone was standing in front of it it would be like getting shot, plus the pressure makes the tank take off sideways.
The ones now have a few pressure release holes on the sides of the hex parts of the plug so if it blows the pressure comes out the sides out of a few holes so a lot safer.
 
Cap...

Commercially available ''strippers'' will remove vinyl easier than some of the ''old school'' nitro cellulose and epoxy finishes...

These new strippers love plastic/vinyl...

The vinyl softens up and you can peel it off like cellophane...

Cutting strips with a ''utility or other type of sharp knife permanently marks the tank walls...you may also gouge/cut through the thin zinc coating exposing the carbon steel tank to rapid corrosion problems especially if used in salt water...

Keep in mind you are not only removing ''color''...you're removing ''protection''...

Currently...especially with technical divers...any cylinder coating...other than zinc...is frowned upon...in years gone by...manufacturers ''coated'' tanks...because ''paint'' was a cheap form of protection...with few exceptions...''modern cylinder coatings'' are applied because some folks like purple and lime green...but the coating offers little in the way of protection to the cylinder...and can even be a detriment to the cylinder once the coating starts to chip and peel and allows salt water intrusion...

This is the primary reason why removing tank stickers annually during visual inspection...including NITROX/DIL/OXYGEN bands is so important...especially for tanks used in salt water...

As far as steel cylinders...galvanized...is always superior...to...non-galvanized/painted...

When I get tanks back from the re-hydro shop...I always remove any loose zinc from around the area of the new re-hydro stamp...mask off a little rectangle...and coat the ''re-stamp'' area with a colored epoxy...which replaces the ''protection'' previously provided by the zinc coating...which was chipped off when the tank was stamped...

Best...

Warren

Rustproof steel protection by hot-dip galvanizing Corbec

Since corrosion is an electrochemical process, it will attack the surrounding zinc rather than the exposed steel. Contrary to other types of processes claiming to provide corrosion protection, it is not required to touch-up noticeable cracks, flaws or gaps on galvanized coatings as they are self-healing.
 

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