Welding on a fuel tank

RENNWAGEN · Post by **RENNWAGEN** » Wed May 16, 2007 6:34 pm

What precautions need to be taken before welding on a fuel tank. I want to modify my tank for fuel injection, it has been empty for about 12 months would a good wash with hot water and detergent be enough?

Post by **david58** » Wed May 16, 2007 9:07 pm

No the fumes are what causes the explosion. I don't really want to give advice that will kill or mame you. I welded up a gas tank once it was filled with water caution because it can still explode.

crvc · Post by **crvc** » Thu May 17, 2007 7:23 am

Why do you need to modify the gas tank? I had a fuel-injected 914 which had basically a type 4 engine. The fuel line was pressurized but not the gas tank.

64bug · Post by **64bug** » Thu May 17, 2007 5:27 pm

Because your car was already fuel injected, hes making his to work for injection... (return line and probaly bigger out)

mightymanx · Post by **mightymanx** » Thu May 17, 2007 10:55 pm

try this old threat it tells you my method among others.

http://www.shoptalkforums.com/viewtopic ... highlight=

crvc · Post by **crvc** » Fri May 18, 2007 7:57 am

I'd forgotten that the 914 had a return loop taking gas from the fuel pump back to the tank. So why not add a Y connection to the existing outflow tube?

A_67vdub · Post by **A_67vdub** » Fri May 18, 2007 8:54 am

At the very minimum take it to a shop to be hot tanked to strip everything out of it. If it has any kind of coating on the inside it will booger up your weld anyway.

FWIW this question has been asked on the welding forum I frequent and the general consensus over there is "NO DON'T DO IT". There are a lot of profesional welders who won't do it. That should tell you something.

sammyphsyco · Post by **sammyphsyco** » Sat May 19, 2007 3:37 am

For a fire or explosion to occur you need 3 things. Fuel, oxygen/oxidizer, and a source of ignition. Eliminate any one of these and your relativly safe. Since we are talking about welding there will be a source of ignition present. That leaves fuel and oxygen to deal with. If you wash out the tank with water/soap that helps alot, next remove the oxygen with an inert gas. Tail pipe emmisons from a gas or diesel engine work as do Co2, argon etc..... Fill the tank with your inert gas of choice and have at it, AT YOUR OWN RISK!!!!!!!!!!!!!!!!

At my job I from time to time weld pinhole leaks on fuel tankers. We make sure diesel was the last load in the tank, then fill them with exhaust from the truck. Next the hole gets welded closed and retested for air tightness.

Its not rocket science! you just have to be DAMN SURE of yourself and what you are doing. If you are not 125% sure THEN DON'T DO IT!

mightymanx · Post by **mightymanx** » Sat May 19, 2007 11:03 am

sammyphsyco wrote:For a fire or explosion to occur you need 3 things. Fuel, oxygen/oxidizer, and a source of ignition. Eliminate any one of these and your relativly safe. Since we are talking about welding there will be a source of ignition present. That leaves fuel and oxygen to deal with. If you wash out the tank with water/soap that helps alot, next remove the oxygen with an inert gas. Tail pipe emmisons from a gas or diesel engine work as do Co2, argon etc..... Fill the tank with your inert gas of choice and have at it, AT YOUR OWN RISK!!!!!!!!!!!!!!!!

At my job I from time to time weld pinhole leaks on fuel tankers. We make sure diesel was the last load in the tank, then fill them with exhaust from the truck. Next the hole gets welded closed and retested for air tightness.

Its not rocket science! you just have to be DAMN SURE of yourself and what you are doing. If you are not 125% sure THEN DON'T DO IT!

what he said but i use dry ice I crush it up toss it in and let it "melt" for a while and they co2 makes a blanket