How bad is the pitting on this tank?

[Wookie]

Wookie - What is PSI, please? See, I'm not the type to take someone's word for it ( :ignore: ), I want to know WHY - what are the physics.

PSI is Professional Scuba Inspectors up in Washington state. They are very nice folks, and they are the folks that DOT consults with regarding scuba. Love them or hate them, they are the scuba cylinder experts. There are lot of other folks that know a lot about cylinders, but PSI made a business of it, and they are the likely training agency you would go to if you wanted to learn how to inspect a cylinder. TDI also offers a program. 'Nuff said. They are not likely to discuss specifics of a manufacturer with you directly, as you haven't been one of their inspectors for 15 years, but if you sent them (Mark Gresham) an e-mail asking why too thick of a coating of Galvanizing on a random steel cylinder might cause it to fail hydro, he might send some reference material your way.

I understand your need to know the why's of things. I married one of your type. In some cases, however, I just punch the "I believe" button and go from there. Even if someone explained it to me, I'd just forget it during the next small business crisis.

 

[Dsix36]

Wookie - What is PSI, please? See, I'm not the type to take someone's word for it ( :ignore: ), I want to know WHY - what are the physics.

OK, I might not be Wookie but:

PSI WEBSITE

You are welcome.

 

[Lenaxia]

Thanks for the heads up on that Wookie! I am greatly enlightened about those tanks now. I wasn't aware that worthington had so many problems with hydro faiures

And in a few months I may very well be interested in another HP100 or HP120 (or maybe both!), I'll remember to hit you up to see if you want to let go of some. They supposedly have a limited lifetime warranty so worst case they replace one right?

 

[scubafanatic]

....yes Frank, is has been too long, hasn't it ? If I didn't have to schedule vacation time at work with a fair amount of advance notice, I'd have enjoyed visiting ya this weekend....maybe shoot some Lionfish too! I did have my eye on the FG Coral Spawning trip you're running, but I couldn't get off Friday 8/19 (others had already claimed the available hours for that day), so no go.

I make it a point to have all my hydros handled by tech-savvy shops (Surface Interval Scuba in Grand Prarie or Lone Star Scuba in Ft. Worth) that actually have a clue where to take steel scuba tanks for proper hydros, I've got 3 (I think) PST's just out of hydro I need to take in as soon as I burn off their Nitrox fills at the lake, but so far I've had good luck getting my steels hydroed properly, knock-on-wood!

I just got back (2 weeks ago) from a week on Belize/Sun Dancer, they special reserved me a Faber LP 95, which is a sweet little recreational tank, but I did decide to take a couple of regs in for annuals that I'd used on that trip as I spotted rust powder all over the 1st stage inlet filters, guess I should have expected that (third world country/steel tanks/tropical salt water environment)...and the tank exterior had a bit of rust in places but not much...bottom line, although not happy with having to do 2 more annuals on 2 regs that I'd JUST had annuals done a few days before my trip, I was VERY happy to have the LP 95, so I'll just have to build that post trip expense into future such trips when I rent a steel in a tropical/third world environment.

On my Sun Dancer trip, I had a bit of drama with a crew member of the trip who suddenly, on day 3 of the trip, decided to start short filling me on my Faber, so he dropped me from 3200 psi fills down to 2400 psi fills, saying I was going to blow up the boat!....which pissed me off big time! After a heated argument on the dive deck, he gave in and topped me off on that dive, then short filled me again on the night dive....which led me to have a nice little hour long heart to heart discussion with the captain that night, who told the crew to fill me up to the same 3100-3200 psi the AL 80 divers were all getting. So I was OK the rest of the trip, unless it was Brandon's turn to do the fills, in which case I had to follow up behind him and have another crew member top me off, which they were fine with...and one apologized to me for my having issues with Brandon.......I'm soon submitting my trip survey back to Sun Dancer where I will let the company know the good, the bad, and the ugly of my experience.....aside from my clash with Brandon, the rest of the trip was just fine, but I'd never knowingly return on a Dancer fleet trip where he was going to be aboard, and many other guests felt the same way (he was very cold/distant/uncaring/arrogant) and only warmed up a little when it was time to settle up and pay out tips!

Hey, Dude, Long time, no see. Why don't you hop in the car and come drill some moorings in at Stetson with us for the next 3 days?

Anyway, Worthington recently changed hands again, and I'm hoping that the new owner will pay more attention to detail. They have a good reputation in the industry, they also bought Hymark, which is now Worthington Aluminum. My problem is not any new cylinders, it's the cylinders I already own. When Luxfer got out of the small scuba cylinder business, I switched to Hymark for my 40's. When the dozen I bought came in, I condemned 4 of them right away, and the vendo
r made good on them. Of the 4 replacements, I condemned 1 and by that time Hymark had gone under. I use these 40's for hi mixtures of O2, and the pitting inside is atrocious. I will have to condemn them all this year and replace them all with Luxfers. None of the pits are big, they are loke sponge. Nothing that would condemn any other cylinder, and I'm sure that they would have been fine with air, but I don't put air in them, and I think that the Oxygen is actually attacking the cylinders.

As far as steels go, I think that the PST's are fine if they keep getting their exemption. I think Worthingtons are fine if you go through the special procedure to make sure they pass hydro. Fabers are fine if you don't mind them rusting. Whatever you do, steel cylindes are a problem. I can see rust, however, and do something about it. I can't see a potential hydro failure on account of the hydro station not following a special procedure on a 3AA cylinder. The damn thing should work as advertised. Although Fabers have their drawbacks, I can see the drawback happening and do something about it. I can't do anything about failed procedures.

 

[captain]

The fact is if the PST or Worthington round out procedure is not followed there is a higher probability the cylinder will fail especially if it has been empty for several days prior to the hydro.
Ask Luis about his tanks that failed because the procedure wasn't followed and the replacement cylinders the tester bought him.
Scuba cylinders are just about the only cylinders that are hot dipped galvanized. It's not the galvanize it self but the process that slightly alters the cylinders shape. The procedure returns the cylinder to it's correct shape right before the hydro test.

 

[Wookie]

The fact is if the PST or Worthington round out procedure is not followed there is a higher probability the cylinder will fail especially if it has been empty for several days prior to the hydro.
Ask Luis about his tanks that failed because the procedure wasn't followed and the replacement cylinders the tester bought him.
Scuba cylinders are just about the only cylinders that are hot dipped galvanized. It's not the galvanize it self but the process that slightly alters the cylinders shape. The procedure returns the cylinder to it's correct shape right before the hydro test.

I think me asking Luis anything might result in him experiencing a apoplectic seizure of some sort, but I'm sorry he had cylinder failure. I didn't know it was the actual process of hot dipping that caused the problems. As I said, there are lots of folks out there that know about cylinders. Fabers are hot dipped before painting. Different process, perhaps?

 

[PhilEllis]

RECENT HYDRO TEST PROCEDURE CHANGE FOR WORTHINGTON SP CYLINDERS!

The DOT and TC testing specifications have just recently been changed for all Worthington SP14157 (In Canada, the TC-SU 4957) cylinders. These are the 3442 PSI cylinders. With this new change, the cylinders will no longer be failed as a result of the Permanent Expansion specification. They will be evaluated only on REE number.

This is a very recent change and will result in FAR fewer failures of the special permit cylinders.

XS Scuba - Cylinder Info

This link provides the necessary information to evaluate the changes. Go to 178.37 b (i) B in the specification to see the change.

Thanks
Phil Ellis

 

[captain]

I think me asking Luis anything might result in him experiencing a apoplectic seizure of some sort, but I'm sorry he had cylinder failure. I didn't know it was the actual process of hot dipping that caused the problems. As I said, there are lots of folks out there that know about cylinders. Fabers are hot dipped before painting. Different process, perhaps?

I am not 100% sure but I think the Fabers are sprayed with molten zinc not hot dipped. It s a more porous coating and not as durable as hot dip galvanize.

http://www.plattbros.com/zincwire-moreabout.php

 

[Jax]

The DOT and TC testing specifications have just recently been changed for all Worthington SP14157 (In Canada, the TC-SU 4957) cylinders. These are the 3442 PSI cylinders. With this new change, the cylinders will no longer be failed as a result of the Permanent Expansion specification. They will be evaluated only on REE number.

Thanks
Phil Ellis

Next question!

How does one know what kind of alloy the tank is? the SP14157 , or that #### aluminum alloy that people wont fill anymore?

 

[Wookie]

Next question!

How does one know what kind of alloy the tank is? the SP14157 , or that #### aluminum alloy that people wont fill anymore?

For the alloy, you'd have to go back to the manufacturer. You're talking apples and oranges here, though. SP is (I think) a special permit. That allows a company to make a cylinder without conforming to the regulations for an already accepted method of manufacture. For instance, let's say a manufacturer wants to use a carbon fiber wrapped aluminum cylinder for scuba. That type of cylinder exists for paint ball, and also for storage of helium, for instance, but isn't approved for scuba. The manufacturer wants to break into a new market, so he writes a special permit and submits it to DOT for approval. DOT approves (or rejects) the permit and off the manufacturer goes selling his carbon fiber wrapped cylinders for scuba. The permit has a end of life, which I think is 5 years. If the permit is allowed to expire (PST is no longer in business, so their permit threatened to expire), hydrostatic tests may no longer be done on those cylinders, therefore they may not be filled, therefore they are scrap metal, unless someone comes along and gets the permit renewed. Someone did this for PST tanks, and they are good for 5 more years. Standard cylinders that meet DOT specs are stamped with a code that tells the hydro inspector/retester how to re-inspect the cylinder. Steel cylinders are 3AA, aluminum cylinders are 3AL.

The alloy is what the cylinder is made of. Aluminum cylinders could be made of alloy 6061 or 6351. Depending on the manufacturer, either alloy could have been made under either the 3AL standard, or a special permit. The Spree's structural members are made of 6061. Luxfer made 3AL cylinders from alloy 6351 prior to 1988. Walter Kidde made all of their Special Permit cylinders from alloy 6351. Catalina never made a alloy 6351 cylinder. Alloy is also important in steel cylinders. The amount of iron, chromium, and other metals in the mix makes up the alloy. Alloys are NOT created equal. The folks who scream that their Faber LP85 is the same cylinder as their Faber HP100 is the same as the European 300 BAR version so it's OK to overfill the LP85 are wrong, because the alloys are different. Some alloys are just stronger than others. And it doesn't really matter if the cylinder can or cannot handle the extra pressure, it's just plain illegal for a fill station to overfill a cylinder that will be transported.

But that's another troll for another time.