Can you braze a hydraulic line?

[59 Sons]

I have a split steel hydraulic line on my Kubota M59. I ordered and have the replacement line. After two days disassembling my tractor, I have realized it is impossible to remove and replace the line. It was apperantly installed early in the construction of the tractor and never intended to be replaced. Which would have been fine if the materials had been higher quality. It was not damaged, it failed. So now I'm thinking I will have to cut the old one out and have a flexible line built on to the Kubota ends. That got me thinking they might have to braze hose fittings onto my cut tubes. So can I braze over the material defect in my tube?? I braze copper lines regularly and brass and steel fittings occasionally. I usually use a 45-55* silver braze with flux on steel or dissimilar metals. Sometimes I will cap with a 15* silver just to beef it up. Any reason I can't do this on a steel hydraulic line??

 

[RickB]

No.

 

[4570Man]

I welded a steel line because the wrong one got ordered and I didn’t want to wait any longer. It worked and continued to work the remainder of the time I had that machine.

 

[mrmikey]

Is the line split? I wouldn't hesitate to silver solder a patch over it, gonna be hard tho as the oil is going to want to be pulled into the heat. Can the bad section be cut out and a compression fitting be used to couple a piece in?
Another option would be to cut the line out, get a new one and cut it in two in an easy place to get to and join it with a compression union....................Mike

 

[mikester]

Lines are brazed at the factory, I wouldn't attempt brazing a line in place - especially with residual oil in it.

 

[Michael In Tennessee]

A hydraulic shop can likely flare the cut off ends to accept common hose ends. That or supply hose ends/adapters for the existing tractor ports.

 

[orezok]

Can the bad section be cut out and a compression fitting be used to couple a piece in?
Another option would be to cut the line out, get a new one and cut it in two in an easy place to get to and join it with a compression union....................Mike

I’m guessing you meant flare fitting not compression. Compression can’t handle hydraulic pressure.

 

[metalbender]

Have a stainless flex line made at a hydraulic shop.

 

[ovrszd]

I welded a steel line because the wrong one got ordered and I didn’t want to wait any longer. It worked and continued to work the remainder of the time I had that machine.

My old TLB has several steel lines that are brazed. I've did a couple of them.

 

[EddieWalker]

One of the metal hydraulic lines for my dozer split. My neighbor happened to stop by while I was taking it off and he said that he could weld it with a coat hanger. He used a gas acetylene torch and the metal coat hanger, and it's held perfectly for over a decade now.

 

[Egon]

I’m guessing you meant flare fitting not compression. Compression can’t handle hydraulic pressure.

Compression fittings are the perfect choice for high pressure applications. In combination with a high pressure tubing material like steel, large compression fittings can often be used at pressures in excess of 10,000 psig.

Fittings do come in different ratings. The local hardware store will likely not have the higher rated ones.

 

[Sawyer Rob]

Maybe you aren't suppose to ?, but I've done it on a farm tractor steel line and it held just fine.

SR

 

[yomax4]

I had a FEL tube pinch and when I straightened it out it cracked. I blew it out with solvent and then air and silver brazed it 14 years ago.

 

[ovrszd]

Sounds like the biggest challenge is the inability to remove it. Will be hard to purge it and clean the interior so the repair will bond to the cleaned metal.

 

[59 Sons]

Thank you everyone for your replies. The space constraints around this tube pretty much eliminate the option of having any other fittings such as compression fittings or couplers that one would have to get a tool on to solve the problem. I will blow the fluid out of the line with nitrogen. Still mulling over the feasibility of getting a solvent through the line... Sand it down to bare metal and try brazing it.

 

[TractorGuy]

I have a steel line I mig welded on my backhoe several years ago that is holding up fine. BUT I was able to remove and clean it. I also had easy access to weld all the way around.

I don't see a problem with brazing a line IF you could get at it and get it clean to start with. Not having room to even use a compression fitting seems like it would make brazing difficult.

 

[59 Sons]

By the way, just to eliminate any confusion. I have the tube disconnected at both ends. It will move an inch or so but it is about 4 ft long with compound bends and angled sections on both ends.

 

[59 Sons]

It's definitely not going to be fun.

 

[etpm]

Since you already know how to silver braze clean well with solvent and braze a patch over the split. Since the tube is defective in at least the split area I wouldn't just braze it, I think a patch is necessary.
Eric

 

[ovrszd]

It's definitely not going to be fun.

But having the ends disconnected makes purging the line more effective.

I've got faith in your ability to fix this line. Please post the results.