welding cast iron radiator

Well I finished the week off by trying to weld a plug into a old (75 yrs or so ) heating radiator, the boss told me too use 309L SMAW and a couple hundred degrees preheat. That failed miserably so I cleaned everything off and tried a higher preheat temperature and allowed the heat to soak for a minute before welding. Well it was a total failure, I did notice the second time around that the base metal appeared to be evaporating as the arc approached, very strange behaviour indeed. On Both attempts the weld cracked as soon as welding stopped even with preheat around 500F, and it appeared as though the weld could be pulled off by hand.
I am starting to think the radiators may be unweldable or possibly just difficult. Monday I will attempt the repair with a Cast Iron rod. failing that I will suggest a threaded plug instead of a welded in one.
I was hoping that someone here may have successfuly repaired one of these old radiators and would be willing to share their technique. I will only have a hour monday to make another attempt before the owner tells them it can not be welded, and I would like to actually make this work,,,very stubborn!!
Thanks for any help or suggestions,( except solar heating )
John

If the radiator is a cast iron radiator then you will have a much better chance of success welding it with cast iron rod. 309 L is a stainless rod and I have no Idea why that would have been suggested for welding cast iron??
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Actually I am not sure why stainless was suggested, never gave it a second thought, had too many other things to get done. I did check it out earlier today and I can find no reference to using 309L for welding cast iron, there is an older reference to using 18-8 for cast but nothing else along those lines.
John
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Sounds like you have a lot of water corrosion on the inside of the metal. You might be better off brazing it than welding it.
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Well come to think of it now there was a strange smell while welding and extreme porosity on the first weld, I think I will fire up the TIG machine and do a little brazing in the morning. At least it should be a little more forgiving, one thing about failures in welding you can learn alot from them
Have a good week everyone
John
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On Sun, 25 Jan 2004 03:31:41 GMT, Ernie Leimkuhler
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I've found that my cast iron repairs got a lot better when I switched from using mechanical cleaning with a wire brush to electrolytic de-rusting.
-- Die Gotterspammerung - Junkmail of the Gods

I would use Cronatron 211 1/8" specifically for cast repairs. Small 1/2" welds with allot of peening. If not available then a ni-rod or go to the tried and true, brass with oxy-acet.
A
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On Tue, 27 Jan 2004 04:00:53 GMT, Aaron wrote:
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Hi Aaron, I've used the Cronatron 211 and have some opinions that might be of interest. Keep in mind that I'm an amateur welder and have little experience with cast iron.
I found the C 211 to be spectacular on GOOD iron. V'ing out properly is critical. The weld seems to want to pile up, and it's difficult to get it to flow into the surrounding material. It's controlable with a little practice, as long as you don't dilly-dally.
On an old thin iron that has been subjected to heat or water, the results were disappointing. The Cronatron salesman warned me of this -- something about the composition of the old material having less iron and more carbon, and the carbon just burning away. I tend to believe him, as the results were exactly as he described.
Cracking can also be a problem on old thin material. Don't be afraid to take days to complete the weld.
Finally, if you're not dead-set on welding, keep the possibility of brazing in mind.

Well I did get the radiator welded and leak free finally, used a couple of Ceritanium rods that where kicking around. Made especially for cast iron.
I know I know my were they not used right from the beginning, would you believe to save money?
There was a very interesting problem with the cast iron appearing to evaporate in the arc which a first for me, one of the guys at work did find an old reference to welding these old radiators and they mention the standards of brazing and CI rods with a note" virtually unweldable" at the end of the paragraph.
The weld was completed by removing most of the stainless steel filler, just enough was left to act as a cushion between the mild steel and cast iron. Welds were short with no preheat and plenty of peening. After 24 hours the radiator did not leak mind you this was without pressure. By this weekend they will have it up and running so hopefully they let us know if it worked or not.
John
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