welding a cast iron wood stove box.

[out in the shop]

i got a call today from a repeat customer, he has a 6 in crack in the fire box of a wood stove. besides the basics...pre,post heat, drilling holes at end of crack ect. is there any complications due to the heating cycles and expansion , contraction. i was going to tig, with either cast iron rod or ss wire....whats your take? thanks in advance todd

[Aeroweld]

Considering the application, I would be concerned about the different expansion and contraction rates of the filler compaired to the original cast when the stove is in use. Me thinks there is a better than average chance the stove will crack again right next to the weld.

When you say "cast iron rod" do you mean actual cast iron rod or one of the alloys recommended for TIG welding cast? I definately wouldn't use stainless.

[Rocky D]

I'd hafta agree with Aero on this one. Stainless and NI rod have different expansion rates than cast iron, and would prolly crack right out after the first few heating cycles. O/A would be a good way to go, and you may also do it with cast rod with TIG,...dunno on that latter, since I've never done it...just educated guessing.

[out in the shop]

thanks for your replies, the reason i mentioned ss, was becuase an ol timer taught me ss wire and cast get along due to the nickel, but i do have cast iron wire.and yes an alloy designed for ci repair

[moe1942]

I have the same problem but didn't weld. Odds are in the stoves favor. I stop drilled the crack, Veed it out and put a special wood stove putty in the crack which hardens like JB weld after firing. It can be painted and lasts the heating season.

The reason the stove cracked there stacks the odds against a successful weld.

You could also rivet a patch over the crack but don't buck the rivets down tight. Use slightly oversized rivet holes..

[bob.celeste]

I have the same problem but didn't weld. Odds are in the stoves favor. I stop drilled the crack, Veed it out and put a special wood stove putty in the crack which hardens like JB weld after firing. It can be painted and lasts the heating season.

..

Moe, I have exactly the same problem, mine is a crack in the door of a Jotul made in 1977 and only cracked this morning from a creosle fire on the inside of the door. What did you use? Was it JB Weld? How long was the stove out of service till it could be relit?

Thanks, Bob (1944)

[usmcpop]

Various stove cements and sealers are available. The Rutland brand stuff should be easy to find. Their regular furnace cement is supposed to take an hour to dry before you fire it up slowly. I've used that type of stuff to seal the corners of an old antique multi-piece stove and it held up well.

http://www.sandhillwholesale.com/repair-maintenance-products-cement-mortar-silicone-stove-lining-c-5_33.html

http://www.rutland.com/category.php?category_id=5

Hey, check out this old tip from a 1939 Popular Science magazine. Use coarse steel wool and furnace cement to repair big holes:

http://books.google.com/books?id=ny0DAAAAMBAJ&pg=PA139

[chenry]

brazing ?

99% nickle rod ?

[Sandy]

Depending on the age of the stove it is quite possible that it is made from white cast which isn't real conducive to any type of welding. Real common when stoves were stoves and the only source of heat. Cast isn't just one category called 'cast'. :)