Welding a cylinder

Just2quickz28 · May 9, 2011

Over this weekend I noticed that the cylinder on my log splitter was weeping fluid at the back welded base. Its only dripping a very small amount after running for a while and the cylinder gets hot. Splitter is a high end manufactured unit from the late 70s, everything but the cylinder has been replaced over the past 5 years. Should this be welded? If yes then whats the chances of it leaking somewhere else later, would the money be better spent on a new cylinder since I do not trust my welding skills on this type of project.

Picture of the type of cylinder.

cjfling · May 9, 2011

Long story short, we had some welding done on our cylinder where one of the ports were and it's been running fine for years. Since you said your splitter is old, check the rod for pitting and keep in mind that over years the seals can start leaking and have to be replaced. If you are looking at those type of costs, replacing the cyclinder might be the way to go. If you think your cyclinder is good otherwise, pay a welder to weld it. You don't want to fool around with something under that kind of presure.

jml755 · May 9, 2011

If it's just a small spot, I would think you could get away with welding it. Since it's at the end away from seals, ruining them shouldn't be an issue. If you don't trust your welding skills, just braze it. Don't know why fixing this would increase "chances of it leaking somewhere else later". Plus, if you're even considering replacing it, then what have you got to lose by attempting a repair? I'd make sure it's empty, clean and well prepped. Go for it.

crazyal · May 9, 2011

The biggest issue will be the oil in the crack. To weld it you'll want to make sure it's free of oil or your weld will not be strong. You may also want to take a 4 1/2" grinder and grind the crack out.

Just2quickz28 · May 9, 2011

I just had the cylinders seals redone last year and only have maybe 20 hours on it since.
I thought of replacing since I would have to pay for a repair and do not want to waste money and time. I doubt my 110v hobby welder would be able to get a good weld on this.

KBL3830 · May 9, 2011

If it's small brazing can work, I grazed a full pressure (2500psi) steel hydraulic line on my old backhoe 10 years ago, it was the first thing I ever brazed and it's still holding

Speedfreak · May 10, 2011

I just took my cylinder off of my hoe to have it welded and the shop guy told me to leave the cylinder on next time and put pressure on it so it pulls the oil away from the crack. When I get the seals away from the crack clean it with a solvent of my choice then use a cutting blade on my 4.5 inch grinder and make a 1/8 to 3/16 deep v grove in the cylinder where the crack is and fill it completely with my little 110 volt welder. Keep making overlapping circles until the v grove is heaping full of weld. NOT flux core mig but gas mig will work fine. I haven't tried it yet but I can't wait for a cylinder to crack so I can try it. His "professional" weld looks like he filled it with a mig. and he has been in business for 40 years. He also said if it was a big spot to weld wrap a towel around the cylinder about mid way and soak it with water just before welding to make sure heat doesn't make it to the seals.

The worse thing that can happen is your have to take it off and have it welded at the shop.

cowski · May 10, 2011

i would not weld it with a mig .mig welds can be porous .i was always told not to mig weld pressure.if i was welding it ,i would burn the oil off with a torch grind it out and weld it with 7018.you can pull the rod out where you do not melt the o rings. good luck

Grayson Klassen · May 10, 2011

I have mig welded cylinders before, in fact cut off old fittings and welded new ones in place. The welds held just fine at full pressure. If it is just a weep I would just clean it up with a flap disc and put a small bubble of weld over the weep. Not sure why someone would say mig welds are porous, any weld is porous if not done correctly.

The watch out for is too much heat and you can warp the cylinder and make travel sticky in one area.

Gary Fowler · May 10, 2011

We weld pressure pipe all the time with MIG, TIG and Stick. All of them are susceptible to porosity if contaminated with oil, paint, rust etc. MIG and TIG are more so than stick, but any welding needs to be done on clean metal. Oil will cause pin hole weld to form in the cooling puddle if not removed. Make sure that the pressure in the cylinder that is produced from heat of the weld has somewhere to go other than the pin hole that you are trying to weld up, grind a slight groove in the joint where it is leaking using grinding wheel like 4" grinder with 1/8" or even 1/4" disc. You dont need to grind all the way thru the cylinder wall. An 1/8" deep groove when welded properly will hold the pressure well. After grinding the groove, preheat it with a torch to burn out any oil and put some E7018 stick electrode in the groove. Make at least 2 light passes rather than one heavy pass. Watch for the tell tale flare from you stop. IF you see a little flare burning briefly or a little venting smoke when you stop welding, you have a pinhole and need to grind it back out and start over.