Brazing aluminum irrigation pipe.

[James Sorochan]

Been irrigating all summer with practically no rain up here. Got a few pinhole and small cracks in the pipes that leak and make a mess. Tried some aluminum brazing rod and a small propane bottle but couldn’t get it to stick. Then grabbed the map gas bottle with same results. Finally went and dragged the big Oxy/acetylene and still failed. I’m trying to fix the leaks in place am guessing that I need to pull all the pipes apart and get them into the shop because I’m loosing to much heat to the rest of the pipe absorbing to much heat? Not sure what to do next. JB weld? Appreciate any help here, thanks.

 

[Georgia Iron]

Does the pipe still have water in it? Or some moisture near the area, I have seen that cause copper to sweat incorrectly. Your welds have spiders in some of them, might be building steam pressure and venting... Do you have some silver brazing wire 65%?

 

[Tyler d4c]

You need some tig action imo. If I can weld up holes in crydy fuel tanks and make them hold surely can weld that up

 

[James Sorochan]

Georgia Iron. The pipe might have some water in the bottom of the pipe. I can pull the pipe apart if needed. I don't have any silver brazing wire or a tig welder. We have a regular Miller suitcase welder. The wall thickness of the pipe is really thin so I end up blowing a hole through the pipe before I can get the rod to stick.

 

[willie59]

Believe it or not aluminum is one of the hardest metals to weld simply because it is obsessively picky about being clean. Brand spanking new aluminum is not bad, but aged, dirty, oxidized aluminum will fight you tooth and nail. As mentioned by Tyler, TIG is by far the best process because you can control it, MIG, stick, and braze is much harder. Even if you clean the outer surface well to weld it, once you apply heat the inner contaminants will pop through and compromise the weld. We frequently weld damaged pontoons on pontoon boats and the contaminants that penetrate the aluminum make it very difficult to weld even with TIG.

 

[Welder Dave]

Yeah, welding would be very difficult. Even an experienced Tig welder sometimes has to weld and grind the weld out a few times to get rid of all the impurities in the aluminum. I'm not sure what grade of aluminum irrigation pipe is or even if it's generally considered weldable. Some aluminum is heat treated and trying to weld it will just result in additional cracking. I seem to recall reading irrigation pipe is difficult to weld successfully. Small aluminum boats that are riveted are an example of aluminum that can't be welded.
I think what I'd try to do is wrap the pipe with something like fiberglass cloth (long strips that will completely wrap the pipe) and use either fiberglass resin or an epoxy to stop the leaks. Devcon probably has an epoxy or a place that sells boat repair products would have fiberglass products. Being pipe makes it easy to wrap instead of trying to just patch it. A polishing pad in a grinder or something like a Scotchbrite pad (not sure if they make something similar to Scotchbrite for a grinder) could be used to thoroughly clean the pipe. I wouldn't use a sanding disc because the pipe is too thin. Just make sure the pipe is completely dry and clean.

 

[Georgia Iron]

Try this, it is cheap and works, make sure the water is gone.

https://www.amazon.com/Uniweld-UAB-Aluma-BrazeTM-Aluminum-Brazing/dp/B0BLHW8SW4/ref=psdc_3021459011_t2_B002Z5Q7SC

ALUMA-BRAZE ALL-IN-ONE Flux Cored Aluminum Brazing Alloy

ALUMA-BRAZE ALL-IN-ONE Flux Cored Aluminum Brazing Alloy

www.amazon.com

Uniweld HT44 Twister 2 Self-Igniting Hand Torch - Propane or MAP PRO | eBay

Uniweld HT44 Twister 2 Self-Igniting Hand Torch - Propane or MAP PRO.

www.ebay.com

Your mapp gas torch should work. If you need one the above is the link.

 

[Old Doug]

I have been learning how to torch weld aluminum . I got some rods that have a flux core they work but take some practice . I also have a Henrob,cobra,Dillon,Detroit torch . The video that came with it make it look easy. One thing i would like to try is cobalt blue welding glasses . They say you can see when the base metal is about to melt.

 

[Delmer]

JBweld. Dirty aluminum has to be cleaned nearly perfectly to weld or braze. Buy the big tubes of JBweld, or use quart cans of resin and fiberglass cloth like Dave said. You don't need anything like belzona for leaky irrigation pipe.

 

[Welder Dave]

I think wrapping in addition to epoxy or resin will hold everything tight and prevent the patch from coming loose over time.

 

[James Sorochan]

It started to rain finally. Must be from the hurricane down in SoCal. Don't have to irrigate for a couple days or so. I blobbed some JBweld on a couple small leaks. Might find some rubber tube and some SS clamps to reinforce the whole thing. I'll try it in a couple days to see if it at least reduces the amount of water. I think if I have time this fall after the irrigation district shuts off the water I'll tie onto the waterline that feeds these laydown pipes and burry some pvc pie with risers. Thanks everyone for your help, appreciate hearing from you all.

 

[Welder Dave]

Even wrapping self adhesive fiberglass tape around the pipe in addition to the JB weld would give additional strength to the JB weld. You wouldn't have an epoxy patch that could work loose over time. Much easier than clamps and rubber tubing.

 

[terex herder]

For typical low pressure silicone caulk will do fine. If this pipe has enough pressure the joints have to be banded together it may not work over 1/4 inch holes.

Gas welding aluminum is a fine, and tough, art. Even with blue goggles about the time you think it's getting hot enough it falls out.

Irrigation pipe is typically T0 temper 6061, so easily weldable. The pipe is welded from coiled flat stock with an automated tig torch at the manufacturer.

I have never been successful with any of the aluminum brazing mass market fillers.