Tank welding safety

By Tom400CFI Date 05-01-2003 17:17

My question is about finding info/data/regulations, etc on repair welding on tanks. Any info on this is greatly appreciated.

Here is more specific info; We have a waste oil tank at work, and it was located in the "pit". Wanting to create more room in the pit for working. We decided to remove the 400 gallon tank. In preperation, we had the tank emptied to lighten it. The day we went to romve the tank we decided the easiest way to lift it would be to weld a hook on the top, and lift from that point. That was the first of several very bad decisions that led to a pretty major explosion. The Tank actually held, but blew up like a ballon (still looks like one), filled half of the 4 bay shop with fire for about 5 seconds, and burned the welder fairly severely.

SO, what I'm looking for is specs, data, info, etc on welding on tanks that have, have had, oil, diesel fuel, etc. in them. I have welded brakets onto (full) diesel fuel tanks before with no issues. But I want to know th etechnically correct way to do this, so I can put it in the safety manual here, and prevent this type of accident again. Thank you in advance for your input.
-Tom

By chall

Date 05-01-2003 17:51

API have a few pubs related to this topic. 2015 and 2217A deal with personnel safety and accident prevention (explosions and fire).

I think you will find they include strong statements regarding your responsibility to comply with federal & state requirements, confined space entry, etc.

Charles Hall

By jwright650 (*****)

Date 05-01-2003 18:13

Could you lift the tank with slings instead of having to weld on a hook?
John Wright

PS. I'm sorry to hear about your welder, I hope he recovers soon.

By TimGary (****)

Date 05-02-2003 11:43

The National Fire Protection Association issues NFPA 306, Standard for the Control of Gas Hazards on Vessels. This Standard is used by the ABS and the Coast Guard to detail the regulations for welding on or entering tanks.

Also, AWS has a couple of publications that may be of use:
http://www.aws.org/cgi-bin/shop/flyall.html?mv_arg=F4%2e1%3a1999
and
http://www.aws.org/cgi-bin/shop/flyall.html?mv_arg=F4%2e1%3a1999

What safety precautions did you guys take before welding on your waste oil tank?

Tim

By billvanderhoof (****)

Date 05-03-2003 04:37

Most tanks have plumbing fittings on top- weld the hook to a pipe nipple and screw it into the tank. Stay in a spot where nothing falls on you if that fitting pulls out of the tank.

No worse condition could exist (in this area) than a tank which has just been emptied since the act of emptying it will suck it full of fresh air. Fire (and explosion) requires fuel , oxidizer and a source of ignition. Safety requires the elimination of one of these. Welding practically guarantees the source of ignition so the fuel or the oxidizer are all that is left. Remove one or the other and explosion is impossible. Keep in mind that just vaporizing the paint on the inside of an apparently clean barrel is said to be enough to fuel an explosion.

Best wishes to your welder and good luck to you in your quest
Bill

By Tom400CFI Date 05-05-2003 15:24

Thanks for the replies.
Charles Hall, I couldn't find the documents you listed from API. Is that American Petroleum Inst??

We discussed using slings, but dut to the location, and design of the tank, getting slings under, and up the other side was not a viable option. To get slings under/around this tank would have required lifting it -the original task. Anyway, that doesn't matter because really I'm looking ahead here at documenting the proper proceedure for welding on a tank, so thanks to those that listed sources for that data.

We know all the (many) mistakes that were made that led up to this accident. The problem was that nobody thought about the task thoroughly enough -the concept of vapors/fire was completely overlooked even though we are all aware of that scenario. A classic example of, "well this will only take a second" thought process.

The welder is doing well. I think he is going to recover pretty quickly (considering the severity of what happend). We talked to him yesterday, and he was doing very well. I feel good about that. Thanks again to all for the responses.
-Tom

By G.S.Crisi (****)

Date 05-07-2003 00:27

Yes, API is the American Petroleum Institute, located in Washington DC, whose site is www.api.org
Apart from the documents mentioned by Charles Hall, you'll find a "Recommended practice for welding tanks which have contained petroleum products", whose number I don't remember now.
If you have any difficulty in identifying those documents, just give them (API) a call and they will give you every possible assistance.
Giovanni S. Crisi
Sao Paulo - Brazil