Repairing Cast Iron Floor Drain Cover


Old 02-11-15, 07:10 PM
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Repairing Cast Iron Floor Drain Cover

I haven't done much with cast iron, but I do have a mig welder and am fairly proficient with it on steel and aluminum. This Cast Iron drain cover has one of its corners broken off. I thought I might just build it back up with the mig but thought I might get some expert advice before I proceeded. I thought I read somewhere that you should heat up the cast iron first. Is that true?
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Old 02-11-15, 09:02 PM
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I seem to recall that cast iron cannot withstand thermal shock and will destruct from the concentrated heat of a welder. You could try to pre heat it but I'm not sure how you could get it to a high enough temp.
Old 02-11-15, 09:06 PM
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No expert, but grandpa used to braze cast iron with nickel welding rod. I suppose he preheated it with the torch before brazing. I know there are special mig rods made just for cast.
Old 02-12-15, 03:35 AM
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I'm a self taught amateur welder I've welded cast iron with a stick welder a few times but with mixed results although I never have tried to build up a corner [just repair cracks] Probably the best advice I've gotten from a pro welder was 'it's already broke so it's not like you can hurt it, go head and see what you can do'
Old 02-12-15, 07:45 AM
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Brazing or stick welding with nickel would be my first choice. For just one small repair it's not worth buying a whole pack of nickel rods so you might consider taking it to a weld shop on a Friday afternoon with a 6 pack in hand.

If you want to try with your mig I would pre-heat the part as much as possible. Even if you don't have an oxy-acetylene I would get the work area as hot as possible with a propane or MAP gas torch.
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