Worthington hydro

[Leadking]

Tank galvanising is not galvanising at all.


IT IS THE APPLICATION OF ZINC PAINT INVOLVING HEAT.

B.S.

Worthington tanks are hot dipped galvanized. The tanks are dipped in a vat of molten zinc. Faber tanks are flame spray galvanized. A zinc rod is heated to melting and blown onto the finish.

If you are going to post, have some knowledge of what you are posting, or a least ask a question.

 

[captain]

Well there are at tens of thousands of 3AA tanks on their 10th hydro and least a few hundred 3AA tanks close to their ~20th hydro (100yrs old!). 3AAs just don't up and fail on their first hydro like the exemption and 3AL tanks occasionally do. Consisently lasting a couple of lifetimes = "overbuilt" to me. I think Henry Ford had the same definition.

Other than for scuba cylinders most if not all steel cylinders are not galvanized. 3AA commercial gas cylinders are not galvanized so making that comparison is not valid. Also at the time when the primary diving cylinder was the galvanized 72 the knowledge base of testers regarding galvanized cylinders was probably greater than those who came after the AL80 became the predominate cylinder and steel tanks were not in as common use until the tech era and the need for larger steel cylinders.

 

[rjack321]

Other than for scuba cylinders most if not all steel cylinders are not galvanized. 3AA commercial gas cylinders are not galvanized so making that comparison is not valid. Also at the time when the primary diving cylinder was the galvanized 72 the knowledge base of testers regarding galvanized cylinders was probably greater than those who came after the AL80 became the predominate cylinder and steel tanks were not in as common use until the tech era and the need for larger steel cylinders.

Sure. But this thread has been reincarnated dozens of times here: "My exemption series tank failed its first hydro..." It virtually always comes down to a failure to round out.

How many "My 3AA (galvanized or not) tank failed its first hydro" threads can you find?

Since 3AA hot dipped galvanized tanks are not failing hydros at even 5% of the rate of exemption series tanks, it is logically not a function of the galvanizing or the failure to round out 3AA galvanized cylinders regardless of PST's blanket bulletin. That bulletin was written at a time when the only scuba tanks PST made were exemption series tanks. While it does retroactively apply to steel 72s made before that date, those galvanized 3AA cylinders were passing normal hydros just fine anyway.

Most galvanized PST 72s had between 2 and 4 hydro cycles before PST even marketed exemption tanks in ~1992. Since they predate the round out memo and weren't inexplicably failing hydros left and right before it was ever written, that again validates that galvanizing is not the critical element, its the relatively lightweight construction and high test pressures of exemption series tanks which are the issue.

Compare the mass and wall thickness of a 3442psi exemption series tank to a 3AA 3180+ rated tank and the latter is remarkably heavier. Sure they use different steel, but the 3AA tank needs no round outs to pass while the lighter e-series tank will reliably fail if the round out is skipped - at the same test pressures too.

 

[Luis H]

There is no question that the Special Permit tanks are designed with a higher allowable wall stress.

There is also no question that 3AA steel tanks benefit from the round out procedure. I started operating a hydro station in the early 70’s (before I got my engineering degrees) and even though that I haven’t regularly worked with one in the past 30 years, I have seen the difference on steel 72 test results with and with out the round out procedure.

On average a steel 72 that does not get the round out procedure will test with a permanent expansion result of 5% or higher. Often between 6% and 8% and as mentioned they are also more likely to fail (>10%). I had three tanks condemned by a hydro station once. I did report them to the DOT for several code violations.

Most 3AA tanks that go through the round out procedure will pass with residual permanent expansion down in the 1% to 3% range. The difference is dramatic and in my opinion it is irresponsible for a hydro tester to perform a test without the proper pretest procedure (as specified by the manufacturer).

The purpose of the test is to validate the material elastic condition, not to test a geometry change.

Now, I understand that most hydro testers do not have a background in structural engineering (like I do) and do not understand the mechanics behind a cylindrical pressure vessel. Therefore, without going to far out of my way, I try to educate as many hydro testers as I can. Note: part of my professional experience includes pressure vessel design.

In the old days (when I worked at the dive shop with the hydro facility) we didn’t call it a round out procedure, because the manufacturers were not requiring it as a round out procedure. We used to call it a leak check procedure. We used to do it for most tanks because the hydro chamber cover in many stations started with a threaded pipe fitting that often had to be checked for leaks. So by default it was not uncommon to do a similar procedure (it wasn’t always 90% of test pressure, but it was close).

 

[NJScubaDoc]

Of the three LP 95 Steel Worthington that were sent out all three failed hydro...

My dive shop contacted Worthington/XS and long story short they are replacing the tanks free of charge, all I have to pay is shipping.

The Hydro facility was contacted by Worthington/XS and was found to be doing the hydro as they should and as I was told the failures are a result of certain tanks being double dipped in zinc for added corrosion protection, this extra bit of zinc is what is causing the failures.

Apparently Worthington/XS is trying to get the DOT to amend the parameters for pass/fail on these tanks so this doesn't happen again.

Anywho, I'm just glad they did the right thing and my tanks are getting replaced.

Anyone who has an issue with their Worthingtons should get their dive shop to document the date of purchase, take photos of the rejected tanks, hopefully your shop is reputable that they don't overfill the tanks and have them contact Worthington/XS...they should do the right thing.

 

[redacted]

The Hydro facility was contacted by Worthington/XS and was found to be doing the hydro as they should and as I was told the failures are a result of certain tanks being double dipped in zinc for added corrosion protection, this extra bit of zinc is what is causing the failures.

That explanation is a little disturbing. It sound like the 840ºF molten zinc bath is knocking the tank so out of round that even the round out process is not able to correct for the out of round produced during manufacture. Maybe a good paint job and a little treatable exterior rust is not so bad.:confused.

 

[UaVaj]

That explanation is a little disturbing. It sound like the 840ºF molten zinc bath is knocking the tank so out of round that even the round out process is not able to correct for the out of round produced during manufacture. Maybe a good paint job and a little treatable exterior rust is not so bad.:confused.

 

[DA Aquamaster]

Of the three LP 95 Steel Worthington that were sent out all three failed hydro...

My dive shop contacted Worthington/XS and long story short they are replacing the tanks free of charge, all I have to pay is shipping.

The Hydro facility was contacted by Worthington/XS and was found to be doing the hydro as they should and as I was told the failures are a result of certain tanks being double dipped in zinc for added corrosion protection, this extra bit of zinc is what is causing the failures.

Apparently Worthington/XS is trying to get the DOT to amend the parameters for pass/fail on these tanks so this doesn't happen again.

Anywho, I'm just glad they did the right thing and my tanks are getting replaced.

Anyone who has an issue with their Worthingtons should get their dive shop to document the date of purchase, take photos of the rejected tanks, hopefully your shop is reputable that they don't overfill the tanks and have them contact Worthington/XS...they should do the right thing.

This is roughly consistent with my experience. Worthington has replaced my two failed X7-100s after getting pictures of the tank markings and the test results as well as a written statement on the tank history basically asserting they have not been abused.

Total cost to me was $72 for shipping. A lot better than $700 to replace the tanks.

Regardless of why the tanks failed and whether Worthington or the test facility my have been at fault, I have a hard time complaining about the customer service I have gotten from XS Scuba and Worthington. I buy from then again with no qualms.

 

[NJScubaDoc]

Regardless of why the tanks failed and whether Worthington or the test facility my have been at fault, I have a hard time complaining about the customer service I have gotten from XS Scuba and Worthington. I buy from then again with no qualms.

Agreed :cool3:

 

[05sportsman]

Is is known to any "knowledgeable" hydro operator that you have to do the 80% pretest on a exemption galvanized tank. Just for brain food, many companies have certain "test procedures" for you to follow, Structural Composites Industries (SCBA) is one of them. I had the owner of a dive shop in Fl call and say the Hydro Facility failed all 7 of his PST tanks on their first hydro!!