Hydro testing?

[SueMermaid]

I know this is an elementary question, but how often do you need to have your tanks hydro tested?

I have always understood that you have to get a visual inspection annually, and a hydro test every ?5? years in order to get fills.
Is this correct?

 

[washow88]

As of Saturday night 9:07 the answer is yes. (Tomorrow it may be a different answer)

 

[Bob3]

If you cheat, you can use one of those big 300 cu ft shop tanks, they only need a hydro every 10 years.:tease:

Interesting side note: there in no "law" in the US (Canada yes) that requires a scuba tank to be hydroed (just like pressure ratings). ICC rules apply to bottles used in interstate commerce.
Good luck finding a shop that'll go along with that though.

 

[The Chairman]

and they require a hydrostatic testing every 5 years. The law is to follow the DOT guidelines... and thats their guidlines here.

 

[roakey]

Bob3 once bubbled...
If you cheat, you can use one of those big 300 cu ft shop tanks, they only need a hydro every 10 years

Actually it's not cheating; what you're referring to is "star service" where a five pointed star is stamped after the hydro date. However, in order to qualify for star service, the cylinder must be moved to fill, and hammer tested each and every time before it's filled. Most shops have star service cylinders in their cascades, which means they DO NOT qualify for star service because they're filled in place, and are not hammer tested before each fill.

Caution: Shops don't like it when you point this out to them.

Roak

 

[SueMermaid]

Well, now I don't feel so dumb for posing the question. ut:

I took my tanks in yesterday for a visual inspection and fill to a new dive shop, (yes, I defected from my regular shop, shame on me), and the woman at the front desk told me they were WAY overdue (they were last hydro tested in '99) and that I should have them hydroed "at least" every two years.
Hm. I would think all that stamping would weaken the metal.

 

[The Chairman]

or they spoke wrong. Hydrostatic testing is to be done every 5 years... not every 2.

 

[washow88]

SueMermaid

washow88 once bubbled...
As of Saturday night 9:07 the answer is yes. (Tomorrow it may be a different answer)

I think the dive shop changed it to a different answer.

 

[FredT]

US and Canada goes every 5 years on most commercial and dive tanks. Fiberwound tanks similar to those used by fire departments for SCBA bottles are only to be hydroed twice (15 year max life) and generally are to be destroyed if immersed even ONCE!

Bahamain rules do not require hydro EVER! AS of 5 years ago there were no facilities to do them in the country. Tanks whos owners wanted them hydroed had to be shipped back to the states to get them done.

If I remember correclty Austrralia and NZ have their own rules requiring and annual hydro.

As a rule of thumb an aluminim bottle "needs" hydro if it's painted, as some paint methods can siginificantly weaken the metal. Many fill stations will not fill a "home finished" aluminum bottle unless it has a hydro stamp through the paint, for VERY good reason. A heat damaged AL bottle won't fail until about 2000 psi is in the tank, then it lets go like a bomb.

Other than a paint job annual (or semi-annual for heavily used tanks) VIPs with a valve rebuild and hydro every 5 years is good.

Steel tanks are on the same schedule, but additional hydros are in order after tumbling if significant corrosion seen in the tank is the reason it was tumbled. Painting isn't a hydro issue on Steel tanks.

ANY tank should be visualed if the pressure in it is lowered to the point the reg can be removed without turning off the valve. Water intrusion is a BAAAADDD thing in any tank.

AS a small defense, if the tanks were Luxfers originally dated before 8-87 or Walter Kidde aluminum tanks of any date more frequent hydros may be justified due to a metal quality issue in those tanks. The more frequent hydros are not mandatory for those tanks though. Of course the next thing you have to do is find ANOTHER LDS if the tanks don't fit that exception. Any shop doing VIPs should damn well know the rules!

FT

 

[Bob3]

... "at least" every two years.

As already pointed out, we all suspect that the dive shop is trying to hose you.
The only time I've heard about short interval hydrotesting (other than for suspected damage) was when the Navy started using aluminum tanks. They required a 1 (or 2, can't remember) year interval. It's at 5 yrs now, like the steels.
Next time you need a hydro, call up a fire extinguisher joint, that's *probably* where the dive shop brings them anyway. Be sure to ask them if they've done scuba tanks though, they may not "fast dry" the insides, which is desireable for steel tanks. (avoids the "flash rust")

I would think all that stamping would weaken the metal...

If a tank gets stamped on the side & not up above the "shoulder", it effectively trashes out the tank & will fail the 1-year annual visual as well as the visual part of the 5 year hydro.

... law is to follow the DOT guidelines...

I haven't heard of any statutes in effect making it a crime to go without hydro or to overfill.
I know Canada has them though.
Disclaimer:
I am not advocating running around w/o hydros, just pointing out the loophole.