Aluminum Hydro Problem

[Ontario Diver]

Where did you get that info from? I just picked up some tanks yesterday and the operator there told me he tested tanks to 5/3rds working pressure.

That is from Canadian Standards Association Standard B339-02 Cylinders, Spheres, and Tubes for the Transportation of Dangerous Goods.

This is the standard set for Canada by Transport Canada and the TDG. Some old tanks are grandfathered to 5/3 but 3/2 is the standard.

BTW - I am half owner of a hydro testing facility. I do a lot of hydros... OK not enough.

 

[wedivebc]

That is from Canadian Standards Association Standard B339-02 Cylinders, Spheres, and Tubes for the Transportation of Dangerous Goods.

This is the standard set for Canada by Transport Canada and the TDG. Some old tanks are grandfathered to 5/3 but 3/2 is the standard.

BTW - I am half owner of a hydro testing facility. I do a lot of hydros... OK not enough.

Thanks, not having much luck finding that document on line but I'll take your word for it.

 

[Ontario Diver]

Thanks, not having much luck finding that document on line but I'll take your word for it.

You won't find it on the net. CSA sells all of thier documents. They aren't cheap but I am required by law to have a copy.

 

[oxyhacker]

Like in the US, where the DOT regs don't give the details on hydrotesting, but "reference into law" certain CGA (Compressed Gas Association) publications. A complete set of the 5 or so "pamphlets" concerning hydrotesting and tank inspection cost about $250, so you there's no way to be sure what the law is without shelling out the $250 to the CGA.

BTW if you are a CGA member (which I believe includes just working for a company that is a member of the CGA) you can download them for free in .pdf - any CGA members here?

You won't find it on the net. CSA sells all of thier documents. They aren't cheap but I am required by law to have a copy.

 

[Ontario Diver]

Here ya go Dave....

http://www.csa-intl.org/onlinestore/ISO_Search_Results.asp?query=b339

$95.00 Canadian. And it can double as a sleep aid.

 

[wedivebc]

Here ya go Dave....

http://www.csa-intl.org/onlinestore/ISO_Search_Results.asp?query=b339

$95.00 Canadian. And it can double as a sleep aid.

Thanks OD, I really was willing to take your word for it though.

 

[DA Aquamaster]

The steel tanks that you are referring to had a vinyl coating applied to the inner surface. The problem is that if the vinyl sleeve gets a pinhole in it, water gets in and the visual inspector cannot see the pitting. PSI standards call for a failure on any tank that you cannot see the metal to check for pitting.

Condemning the tank is a little drastic and also unneccesary. You can tumble the tank to remove the coating and then complete the VIP.

 

[DA Aquamaster]

HELLO ........ how many people here remember the reason we switched to alumminum from steel ...... STEEL RUSTS ..... and have a 1000/1 failure rate compared to alumminum. I seen steel tanks that were in hydro and had a VIP sticker on them blow up ..... that was one reason we started filling tanks in cement block horsetrofs to keep the damage down at the dive shop .............

Gotta disagree with you there. Steel does rust but flash rust is harmless can be removed before it becomes a problem (hides pits etc). A pit caused by rust is a problem and will result in the tank being condemned but it generally takes water in the tank and a missed VIP to get one to form.

In the past, many compressors tended to leave a lot to be desired in terms of dry air. Poor fill techniques combined with water baths also had the potential to force water droplets into the tanks. In either case, flash rust accumulated faster, more frequent tumbling was required and pits were more common. With modern compressors and filters, and doing my own fills to ensure the whip and valve are dry, I have very little problem with flash rust and tumble my tanks every other hydro instead of, in some cases, every other year.

We had a whole bunch of welding tanks in the shop last week for hydro testing made in 1912 and 1913. They are still going strong and the only real issue is finding fresh spots on the shoulders to stamp yet another date. Obviously, sustained load cracking is never going to be an issue like it is with AL tanks and assuming you keep water out of the tank, do annual VIP's and tumble the tank when needed to remove flash rust, a 50 plus year tank life should be readily achievable with steel tanks.

 

[Ontario Diver]

Condemning the tank is a little drastic and also unneccesary. You can tumble the tank to remove the coating and then complete the VIP.

True enough. But most customer's aren't willing to pay what I charge to do this for an "old steel tank". It screws up the media that I use so it is expensive.