The other day I asked for suggestions about repairing a badly bent line and the responses were informative and mixed. Since then, I've found another Eaton/Weatherhead product that is a hose end/ ¾ ferrule. So I have lots of choices: Weld on a fitting. Braze on a fitting Silver solder that fitting. Use the ferrule fitting. What is the difference between braze and silver solder from strength and vibration perspective ? A Master plumber said vibration was a bad idea with ferrule type fittings. What do you think ? I'm avoiding welding because I'm not very good at it and there is only a generator where the machine is. Thanks for sharing your experiences and opinions.
We had a hole in a line on the boom of a cat excavator. We silver soldered it until the new one came in. Have used compression type fittings on our pull pan with good luck.
Yair . . . Pixie . Many original hydraulic fittings were assembled with silver solder and there used to be ferrules available for joining pipe. A couple would be very easy to spin up on a lathe and you could replace the bent section with a piece of identical pipe. Silver soldering is a simple process but you would need oxy and you should use what we call "bluetip" which is 50/60 per cent silver and will suck right in there when the heat is right provided you leave a bit of clearance and have the joint well fluxed. Cheers.
I have brazed many a steel line over the years, with good results if I didn't get careless with surface prep. I used the Weatherhead compression fitting hose ends (what you are calling ferrule fittings) to replumb an entire A-W motorgrader restoration project with no problems, but that was only a 2500 psi system. For the last couple of years, I have been using the Eaton compression fittings that go to standard JIC males with real good results. It doesn't hurt that they only take 2 wrenches and a tubing cutter to install, in minutes. They can be used with any male JIC fitting, so you are not as limited as you are with the hose ends. The part # for a 3/4" is FC2875-12. For other sizes, just change the dash number. Good luck, Mitch
The problem these days is that very few systems run on as low a pressure as 2500psi like Mitch describes. 3500psi would be kind of normal, 4-5,000psi would not be extraordinary. With pressure like that you have to be VERY careful what you're doing. As a company-wide policy we do not allow any type of repairs or modifications to steel hydraulic lines. I have my own opinion about that policy but will not voice it here .........
Silver brazing (we all use the term "silver solder") is better than using normal brazing rod and much more expensive. The result is stronger and the silver acts as a wetting agent to aid proper adhesion to the steel parts. YMMV
Yair . . . Nige makes a very valid point about the increase in what are considered to be "normal" operating pressures. I really am in no position to comment and too lazy to research the subject but generally speaking high grade "silver solder" and sleeves was the preferred repair method even for such items as injector lines and we used it to fabricate the very complex arrangement required to get 5000 psi to the hovercraft lift fans . . . the tubes ran within the aerodynamically shaped air flow straighteners and there was no room for conventional fittings. Cheers
I suppose silver solder works real well on new pieces but nothing works better than an arc welder and skilled operator for time sensitive repairs. If I am repairing a cracked fitting, I drain the pressure off the line and remove it. A blow off with ether and then air pressure works best. I'll grind the crack down some and shine the surrounding area if possible and then weld up the problem. Tensile strength on brass is only around 2,500 PSI so a perfect pass is only good to that working pressure. If you put that on you will never be able to go back and silver solder or weld over it. Mechanical fittings work well enough for the low to medium pressure and flow systems. When you are working with high flows and pressures in extreme duty cycle items like big excavators I generally prefer to replace whole lines or fittings rather than trying to weld them back together.
Thanks very much for your thoughtful responses ! Ya, I'm thinking a Cat …even a little 307 probably runs more than 2500 psi. I like the simplicity of the compression/ferrule fitting and it's available locally.( ¾ was available… measured today and line is ⅞" plus a little paint ) The parts store is trying to tell me that '98/2' ( tin/silver) is silver solder ( package says 8,000 pounds tensile strength). I'm not falling for that right off… and they don't have the fitting to solder on…. Which got me wondering how they can measure the strength of something as thin as a solder joint and how that really applies…. I'm going to go talk to a couple heavy equip mechanics tomorrow and see if they are willing to share their secrets or parts . A friendly and good welder will be in town next week so I'm still weighing options. It is a personal use machine but I don't want to be fixing it all the time !! ( I have other machines to fix, too LOL ) Joan
Just remember that "pounds tensile strength " isn't the same as psi ...........
Brazing is not dependent on tensile strength but on shear strength, the fitting has to pull off to fail. That's how I've heard it explained anyway. 98% tin is called silver solder when plumbing with copper pipe, but the silver solder I think you want is actually a brazing rod, needs more than a little propane torch to use.
Since your not working on an antique, obsolete, mfgr closed up 50 yrs ago piece, why not just replace with new and be done with all the struggle and possibility of failing in an inopportune moment. Or even calling a salvage place and buying a used line.
There are no salvage places around. I'm guessing the new lines would be more than $500. Kind of out of my budget. It is presently one line, the length of the boom; about 18-20 feet. Solders are usually kind of soft so it's hard for me to picture their strength.
Yair . . . Just to add to the discussion. The "blue tip" I mentioned is apparently 45% silver, I thought it was higher. It is the stuff I use to join bandsaw blades and I can't ever imagine it blowing out of a properly constructed hydraulic fitting if correctly applied . . . it is very easy to work on pipes, band saw blades not so much. Cheers.
Forget the word solder, it's a type of brazing rod that is used just like any other brazing rod, in this case with a sleeve of some sort.
Also have had good results repairing steel Hydraulic lines & fittings with arc welding . Generally use 6011 rod . Have had good results brazing smaller thin wall hydro lines as well . Lost count of how many times we have done it . Works fine until the operator lets a tree limb rip the line off again . LOL !
I've either welded or brazed more that I care to remember. It works well if you can get the oil off & clean them up. I just did another one today.
I have never had very good luck with brazing and prefer to tig weld personally. I guess my biggest problem is knowing how to do it right. With the proper guidance or instruction and technique brazing would probably be easier but i had a line one that i tried brazing 4 times and still had pin hole leaks so i cut out all the braze, made a patch piece to cover the hole and welded around it. I carry a Hi-Freq box on my truck that plugs right into my big blue and away i go. usually the hardest part is getting the line off and on.
I've brazed a ton of hyd lines in the field. The biggest issue is getting it clean enough. Just a tiny bit of oil or grease left in the joint/crack and you'll get pinholes that **** oil.
maybe that is my problem. I always figured the open flame would burn the contaminates out lol
Interesting discussion that has inspired me to "fix" a partially crushed steel line on my 570 A grader. Discovered this damage a few years back, but as it was still allowing enough fluid through to operate the moldboard slide I let it go. After a recent circle adjustment, I discovered how it came to be crushed by a 1 1/2 inch backup wrench. Apparently some one was underneath the circle with a one inch drive impact and it wasn't noticed that the backup was up against the steel hydraulic lines while they were pounding away from below. I wondered if they ever noticed it. The damage was about one inch on both lines. Because these lines are contoured to and tight against the draft frame they are fairly exact in measurements and bends, (about eight bends per line), it was a bit of a puzzle to extract them in the right way. My concern with the compression fitting fix was that the result would push the lines away from the frame about 1/4 inch for about eight to ten inches of line. thus slightly changing their geometry, resulting in ???? I was thinking that a brazed sleeve would be the best fix. The hydraulic shop did not know about this type of fix and did not want to experiment. They suggested a compression fitting repair or, if I wanted to spent more $$$, new lines at three to four times the cost. I opted for the compressing fitting as I thought it might work in that particular area where there was more room for flexing it out and away from the frame. Well it wasn't much fun reattaching those lines but after a couple of hours and some hammer and wedge work I got the hard connections installed and now only have to attach the flex lines to test it out. I decided to wait a day before I finished up because now I'm thinking that I should have blown out the lines before I made the hard connections to the circle manifold. It was a professional shop, but **** happens and it is now my responsibility to see it done correctly. I'll finish today and take a picture.
OK here are pixs of the fix: A close up of the compression fittings. The lower one leaked and I had to loosen, wedge and reset the fitting while watching my new hydraulic fluid drain out. Bigger picture Overall picture of lines with wrench at left side. These lines are steel and precisely made with eight bends front to back from the factory. Net result is that the lines were for the blade tilt and after the leak got fixed it did not improve on the performance of the moldboard slide and may have created a problem down the road for vibration induced leaks. Perhaps a foot or so of flexhose would have worked better. Some kind of soldered sleeve would be my choice of a good fix. We'll see. Did trace the moldboard slide problem to a shimming issue and fixed that. Got to know my grader better. Whup!!!
I wouldn't advise a beginner to do it but I have had repeated succes welding steel lines... Nice and steady using 7018 rods... I always make a point that it is a temporary repair on invoices... Of course, it never is tho.