I`ve got an up coming project to repair a crack about a foot long in the water jacket that surrounds the cylinder of one of those large single cylinder oilfield engines,that in the old days were used to run multiple pumping unit off rod lines. I think it is a Fairbanks-Morse engine,about 20 to 25 horsepower. The crack runs paralell to the cylinder. The company that wants this repaired,I`ve worked for for nearly 25 years and the owner is fairly knowledgable about welding. He asked me if I`ve ever welded cast iron before and I said yes. He said he wanted me to repair the crack,and I said I would braze it. I hardly got the words out of my mouth and he said nope,it won`t hold. I was kind of suprised at his response and told him from my experience in repairing cast it would definetly work and hold. In my 25 years of welding I`ve had excellent success brazing cast iron and cast steel,whereas in welding even with the best cast iron welding rod persistent cracks can at times be a problem. I mentioned in welding the higher the nickel content the better. He said no,that I need to use a rod that contains aluminum,bronze and something else, he couldn`t remember the third metal. I never heard of this,the composition of the welding rod containing aluminum for repairing cast iron,and I told him such.He said in brazing you get the localized area too hot and not with welding. This suprised me and I told him the welding arc which melted the rod to form the weld was hotter than the flame of the torch. Back to an earlier point, in my experience,brazing produces a stronger bond than most non-welders realize. Welding may be stronger I don`t know,but for a water jacket I thought brazing would be sufficient. I realize I may learn something from his suggestion, I`m always willing to learn no matter how little or much knowledge the other person may have. I am always learning something. Doing portable welding in the oilfield a person gets all kinds of jobs. Oh,also when we were speaking an old timer over heard our conversation and he also said braze it,once again the owner said it won`t hold. I`ll do it the way the owner says because he`s the one paying the bill,and like I said maybe I`ll learn something,if I do I will be very suprised, partly because,a welding rod containing aluminum to repair cast.I just like to fix something right the first time and do a good job at it. Thank You and any and all suggestions, advice and any experience you may relay is greatly appreciated.
I'm retired now but when I had my shop my "old timer" employees would refuse to do anything but braze weld cracks. I never had a problem. I recently ran across a broken axel housing on a farm tractor that we did 30 years ago, stll running.
Pass on this job. If this guy won't let you do what you know is best and are familiar with tell him to go elsewhere.
He probably had a failure from a bad weld or an inproper application years ago and that set his mindset.
Good luck.
Thanks for your reply. I called an oilfield welder that I know who is well known and one of the best in the business here in Michigan where I am and he also said brazing would be the way to go. If the owner won`t budge on this project I think I will just pass on it. I like to use a procedure that I know will work,rather than try one unheard of. Oh, and that welder I called said he never heard of that particular rod used to repair cast.
Usually [99.9%] of the time the owner lets me do things as I see fit,but this time he wants it his way, probably because he said he has over $38,000 invested in it. Thanks again.
Ni Rod ,or Gas weld with hemotox flux and cast rod if you can find it
NMWELDING
You are correct that brazing will hold. It may even hold better than NiRod. However;
I would advise against brazing a water jacket unless it is a sleeved engine that you can remove the sleeve from. The uneven heat expansion between the inner and outer casting frequently causes further cracks when brazing is used. The area to be heated with brazing is very much larger that the small spot heated with Arc Welding. The thermal expansion causes additional cracking internally due to the structural rigidity and low tensile strength.The welding arc is hotter, but it is localized.
If you can heat both the inside and the outside walls and all the interlocking tenons uniformly and evenly at the same time, and cool them evenly, then I would consider brazing. The best way way to do this might be to braze weld it in an open flame oven. I do not know why aluminum bronze was suggested. Most of the old Fairbanks Morse engines were "Good Gray Castings".
When welding with NiRod, use little or no preheat. You should only weld 3/4 inch at a time, and then let it cool to ambient before the next pass. Skip around for the next pass.
Metal Locking is a good welding alternative.
SMAW with Ni-Rod 99 would be my suggested repair process.
Joe Kane
Joe Kane may have something here. Many years ago I tried to braze a small crack in a bronze casting. When I heated it cracks went off in all directions turning that thing to scrap.
I agree! Go with the Nickel 99%.
By darren 
Date 08-19-2008 19:17
Edited 08-19-2008 19:26
what is metal locking?
never heard of before, sounds interesting.
darren
p.s. i looked it up but still don't get all the particulars. how does it keep the crack for seeping?
About 20 years ago I got a call from a contractor building a water treatment plant close to my shop. He had a section of 24" ductile iron pipe that need a steel conection ring welded on the end of the pipe for some kind of clamp they used to make a final field conection. When I got on site he gave me the repair procedure that the pipe manufacturer had sent to him. It said to use 3/16" aluminum bronze or 55 nickel stick rod. So I went to my local weld suppliers and they had never heard of aluminum bronze electrodes, after some searching they located some but it would have taken to long to get it in because I was under the gun to get the job started. I did the job with the nickel rod and ran a 3 pass fillet weld around the ring to get the desired weld size that was specified and all went good. I think I saved the repair procedure from the pipe manufacture. I will look tomorrow when I get to work, maybe it could have some information that you can use.
Thanks for all input. Any and all advice,suggestions and experience is much appreciated.
Do a search on 309L stainless used to repair cast iron. It works great!!
oh and dont forget to drill the crack to keep it from continuing to migrate while expanding and contracting
