Wednesday afternoon I was contacted by a customer to try to "fix" a boiler in a government building. I asked the typical questions to try to prepare for the job. They were not sure where or why the boiler was leaking. Didn't know the material either. Oddly it was on the fourth floor penthouse in the middle of a complex instead of the basement or ground floor level. Set up was fun.
When we arrived I saw that it was a cast iron vertical sectional boiler (very common in commercial buildings) and was leaking out of the side section. I sent after some cast iron welding rods at the local supply. NLW9960 ENi-C1 (googled them and they are made in China)) is all the info I have on the rods. After excavation and preheat I tried the rods and could not get them to weld (WAF) worth a flip. Tried DCEN, DCEP, AC, hot, cold, medium, helicoil- ok I'm making stuff up now.
Anyhow they would not work. I've welded some cast iron before with good results and know a little about it though not an expert. That's the reason for this post. Any ideas on how to repair this crack? I welded it cold and hot, peen-ed and half bead temper. I brought 309 and it was only slightly better. 7018 would stick to the cast and actually welded OK but as you would expect it cracked at all fusion lines. I was prepared to use SMAW only due to no info and very limited time to try to repair the leak. No brazing, tig, mig attempts were made.
This is a link to a similar boiler.
http://www.weil-mclain.com/downloads/literature/gasoil/808894lit.pdfpage 3 and 8 give a good idea of design.
The puddle would eat away the base metal, ball up and fall to the floor. Very humiliating :)
I left then with a nice looking E7018 4" wide X 1" pad weld with a full crack on the top and bottom.
I told them up front that it was not likely that it could be repaired successfully by welding and no guarantee was made. They already have a replacement section an order but I don't think it will be here soon and if I can regroup I will try again. Like you, I don't like to fail.
Thanks in advance and hope you have a great Thanksgiving!