Issues with hydro retesting of galvanized steel tanks/cylinders

[rjack321]

No, it is not related to the shape when manufactured. It is related to the zinc bonded layer changing the expansion properties of the bi-metal cylinder versus steel alone.
The support page at XS Scuba contains multiple documents and a video with an explanation of the Worthington testing issue. Skip ahead to 3:30 if you don’t want to watch the whole thing.
Changes to the hydro retest — XS Scuba

Thanks that was good!

I was close that expansion was being measured erroneously. Its just all over and not due to original shape. Funny thing is I think my hydrotester (who is actually very good about the pre-test protocols) told me the false banana story.

But that really calls into question how a PST or Worthington HDG cylinder can be "bimetallic" but somehow Faber's HDG process is avoiding the issue. So I suspect we'll see some bulletins from faber right as their 1st production runs are coming up for hydro.

 

[rjack321]

Those changes apply to the 3442 tanks, I have a pair of original hydro 1999 HP100s that are 3500 tanks, under the E9791 permit. Any differences?

They do the 90% roundout protocol so that they are "pre-expanded" and then once the test pressure is applied their isn't enough additional expansion to register as "permanent"

 

[JackD342]

Those changes apply to the 3442 tanks, I have a pair of original hydro 1999 HP100s that are 3500 tanks, under the E9791 permit. Any differences?

I don’t think 9791 tanks are galvanized, right? I know less of them. Here are two links you can check out.
http://www.hydro-test.com/files/RESindustrydocs/PST-E9791-Bulletin.pdf
https://www.phmsa.dot.gov/approvals...ile-serve/offer/SP9791.pdf/offerserver/SP9791

 

[AustinV]

I don’t think 9791 tanks are galvanized, right? I know less of them. Here are two links you can check out.
http://www.hydro-test.com/files/RESindustrydocs/PST-E9791-Bulletin.pdf
https://www.phmsa.dot.gov/approvals...ile-serve/offer/SP9791.pdf/offerserver/SP9791

Thanks for those. Thought they were galvanized, but I am not original owner and they are pretty old, so don't know...

Will be sending this paperwork in with them when they go for hydro though, thanks for the links.

 

[rhwestfall]

Yeah, 3442 (3AA) tanks have a formalized procedure, the LP (3A) have a guideline as a BMP for requalification....

 

[rjack321]

I don’t think 9791 tanks are galvanized, right? I know less of them. Here are two links you can check out.
http://www.hydro-test.com/files/RESindustrydocs/PST-E9791-Bulletin.pdf
https://www.phmsa.dot.gov/approvals...ile-serve/offer/SP9791.pdf/offerserver/SP9791

They are all hot dipped yes
I have 2 of these hp3500s

 

[rhwestfall]

Repeating, The roundout procedure MUST be done with 3AA, so it isn't a problem.... If they didn't do it, they are in violation of the CFR...

LP tanks is the issue....


(unless they do not follow the "stabiilization" component, and just use the minimum time)

 

[Basking Ridge Diver]

I can only speak for myself - I have had LP 85s (10 yrs old?), LP 72s (your tanks) and AL80s (old and new) and AL19s (newish) go in this year and they all passed the Hydro. I went to a Fire and Safety location - I have used them before and have not had any issues.

The only time I had an issue was when I went through an LDS and they lost a tank (sentimental value - my first tank I was certified with) - they gave me a new one begrudgingly but I wanted my old tank back. Never found it...

When I can I skip the LDS and go to the source... good luck

 

[lowviz]

I can only speak for myself - I have had LP 85s (10 yrs old?), LP 72s (your tanks) and AL80s (old and new) and AL19s (newish) go in this year and they all passed the Hydro.

Not anymore, they are now your tanks. IIRC those are from the 60's/70's no? Those girls have some history and miles on them from the owner previous to me!

They should last damn near forever. Keep water out of them and have them hydro'ed by a reputable retester. The rounding/round-out/stabilization procedure should be used, if it isn't then your tanks are being tested to an unfair standard.

Some new-to-steel posters appear to be a bit uncertain about hot dipped steel tanks. NO worries. The real threat is from uninformed retesters. This is what I was trying to point out. They are the same people who can trash your aluminum cylinders due to similar ignorance or laziness. All aluminum tanks older than...

If the rounding procedure is performed properly, a tank that should fail will fail and a tank that should pass will pass. I ask nothing more than that.

When I can I skip the LDS and go to the source...

I get facetime with my current LDS and urge them to have my tanks treated properly. I have a lot of steel tanks, start failing them and I look for a new shop who will be my advocate for having them properly tested.

Communication.
If at the hydro facility itself, try to ask if they have experience testing these cylinders.
If through an LDS, ask if they have any track record of sending these cylinders out.

Agree with both. Make it known that you are informed and not some patsy who is just going to take mistreatment without any push-back.

 

[runsongas]

Repeating, The roundout procedure MUST be done with 3AA, so it isn't a problem.... If they didn't do it, they are in violation of the CFR...

LP tanks is the issue....


(unless they do not follow the "stabiilization" component, and just use the minimum time)

The CFR does not require use of the roundout procedure for 3AA tanks.