Tank that has been engraved

[dlitz]

A buddy of mine just took his wife's alum 80's to get them hydro'd. A few years ago, a friend of hers took an engraving pencil and engraved a flower on the outside of the tank (about 3" in dia). He was told that the tank cannot be hydrostat tested because of the engraving. Is this correct? I would think that the stamps that they do on the tanks to ID the hydro would do more damage to the tank than the engraving. The engraving is very shallow, about .001" deep.

 

[helimvee]

That does seem odd, given that most tanks have nicks and scratches that deep. The only way to know for sure is to take them to your LDS and ask.

 

[j yaeger]

that seems absolutely bogus!!
you're right,the hard mark is a hell of a lot deeper than an engraving tool!!!
anyone else??
good luck
yaeg

 

[paddler3d]

I want to say there may be some truth to what you are told. The only people that are allowed to 'engrave' a tank are the hydro folks and they stamp it on the crown, which is the thickest part of the tank.

 

[Luis H]

Was the engraving on the neck or the side?

The stamping can only be done on the neck were the metal is substantially thicker. If you stamp the side you ruined/ condemned the tank.

There is a very specific pass /fail criteria for the maximum depth of a single gouge and of a series of gouges or indentations. The allowable pit/ gouge sizes are specified on CGA (Compressed Gas Association) documents that are invoked by the DOT Code of Federal Regulations.


If the tank was engraved on the side wall, I would guess that no one will pass it (even if it very shallow), engraving on the neck used to be acceptable, but since it is not a standard stamp I can see why someone will not accept it.

 

[KVDIVR]

A buddy of mine just took his wife's alum 80's to get them hydro'd. A few years ago, a friend of hers took an engraving pencil and engraved a flower on the outside of the tank (about 3" in dia). He was told that the tank cannot be hydrostat tested because of the engraving. Is this correct? I would think that the stamps that they do on the tanks to ID the hydro would do more damage to the tank than the engraving. The engraving is very shallow, about .001" deep.

Hmm, not having seen the cylinder I can just tell you as a hydrotester that nothing like a hydro stamp is allowed on the sidewalls of any cylinder. For example if a hydro shop stamps the cyl off the crown onto the cyl wall it is no longer a legal cyl. A hydro shop a few years back side stamped a whole pile of cyl's on the walls and the DOT recalled and condemned all the cyl's.
There is criteria for how big and how deep a dent or pit can be but that all changes when it adds up to a line longer than 6 inches. Can you send me a real good closeup of the work? On Feb 24th I am heading to class to renew my hydro license and would love to bring this topic to the DOT trainer with close up photos.
Dave
Advanced Hydrotest Inc
FL

 

[Stu S.]

.001 inch is half the thickness of a human hair. There are firms that grit blast a tank's exterior and that would probably remove or obscure that marking. These scratches are probably not as deep as some dive shop induced scratches on many tanks.

Your tank is not dangerous, but perhaps rules are rules.

 

[lowviz]

A buddy of mine just took his wife's alum 80's to get them hydro'd. A few years ago, a friend of hers took an engraving pencil and engraved a flower on the outside of the tank (about 3" in dia). He was told that the tank cannot be hydrostat tested because of the engraving. Is this correct? I would think that the stamps that they do on the tanks to ID the hydro would do more damage to the tank than the engraving. The engraving is very shallow, about .001" deep.

Hand grinder & wire cup-brush, repaint.

 

[dlitz]

Thanks all who responded. I think the engraving is on the side. It has been a while since I saw the tank. I will have him send some pictures when he gets it back.

 

[oxyhacker]

Funny thing is, if one looks at it as an unauthorized marking then the tank should be condemned since only the tank manufacturer and hydro shop are authorized to put markings on a tank. However, if you think of it as a scratch, it is probably legal since it (if really as trival as you describe it) isn't deep enough to condemn the tank since the limit for tank gouges is .020 to .030 (depending on material and manufacturer). If it is really as trivial as you say, it should be possible to polish it out using a not-to-aggressive abrasive, or just cover it up with a sticker. But if it is deeper, that could be dangerous!

I sure wouldn't take a grinder of similar power tool to it, because then you will be removing significant amount of metal, to say nothing of leaving a wavy surface that will be a dead giveaway that it was done.

Note that getting a dive shop's opinion will not be a totally satisfactory solution, as every dive shop it is ever taken to for a fill for the rest of its life will have its own opinion, some may fill it and others some won't, - and some will try to condemn it on the spot!