What is the trick to making leak free welds?

franklin2 · Aug 19, 2014

I thought it could not be done. I have seen people try to weld cracked steel hydraulic lines on tractors, forklifts, backhoes, etc. and they never were successful.

So, we had a skid steer with a backhoe attachment. It had steel lines running up the arm, with hoses at the flex joints. One of these metal lines cracked and fluid was going everywhere. My Dad took the line off and went to a machine shop where he thought they could make another line. When we got there the guy smiles and said "oh, I got a guy who can weld that". I thought to myself no way. A young boy came out, took the line, adjusted his mig welder a little bit, welded the line and then gave it back. $20 later we are on our way, and I looked at the line, he had run a bead right over the crack. Installed it and it worked great. I was floored, as many times as I have seen this tried, and have tried it myself, I could not believe it worked.

A couple of weeks ago I had the A/C compressor clutch fly apart on my mini van, and one of the flat springs came around and was hitting one of my steel refrigeration lines, cutting a little hole in it. Encouraged by what I saw on the hydraulic line, I got my mig out, cleaned the line really good, set the amps low, and welded it. No burn through or anything. But it had a pinhole leak. I welded it again. Pinhole leak. Frustrated, I smeared some JB weld over the welded area, and it has held ever since. But I am bummed out that I could not weld it and it be leak free.

What is the trick to welding these lines and they be leak free? I know it can be done now.

rswyan · Aug 19, 2014

The guy to ask would be the kid who did it successfully ...

KubotainNH · Aug 19, 2014

This would be better in the welding section. I would like to see the answers.

http://www.tractorbynet.com/forums/welding/

k0ua · Aug 19, 2014

Most people weld up things like you mentioned with TIG. But if you can do it with MIG, good deal. Apparently the kid has the technique down. I would ask him about it. In this case I would think TIG would be much easier to weld a split in a line.

Many years ago I brought an old company van to a repair shop with the passenger seat about to fall out from the rust and cracked steel all around the seat mount. The guy hunted around for some dirty coat hanger wire and proceeded to weld it up with an ace/ox torch, and did one heck of a job. The seat was still solid when we traded it off years later. So sometimes it is not the welder it is the weldor.

mfreund · Aug 19, 2014

Coat hanger is a fantastic filler rod for oxy-act welding.

Baby Grand · Aug 19, 2014

I used to MIG rolled, 20 gage steel sheet to make vacuum tanks for a company that made OEM equipment for the dry cleaning industry. Once I knew I could do it, it was easy. Convincing myself that I could do it took a lot of adjustment of heat, feed rate and technique. Convincing the shop foreman that I could do almost gave me an ulcer until I figured it out.

Egon · Aug 19, 2014

Proper courses and practice.

firemanmike69 · Aug 19, 2014

Practice, practice,practice,practice. I used to work in an oil truck fab shop making the trucks that deliver fuel oil it took about about 6 months before you could get a pipe leak free the first time and as soon as you were getting real good you'd have one that leaked bad for one reason or another to bring your ego back to size. Took 3 years to get them leak free every time no matter what

SPIKER · Aug 19, 2014

Take a bit of skill and a lot of practice with correct filler material and welder (tool) that is good too.

I can to it (or could when I was doing it on regular basis) but one thing to remember is to over weld the start/stop points when doing it. Start welding well beyond the the crack on solid material and work OVER the crack and keep welding PAST the spot the weld ends. FIRST clean out ALL the oil, heat it with torch if need be and remove grease paint ahead of time. If it is heavy or higher pressure grinding out the crack some on thicker material is needed with multiple passes each one overlapping start and stop points.

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