On 14/07/2011 10:44, Matty F wrote:
I cut up a piece of cast iron to fit the missing lug on this pipe:
http://i52.tinypic.com/35aryqe.jpg
That's a one inch hole in the other lug.

The pipe to start with:
http://i54.tinypic.com/dhekj7.jpg

Some expert welder will weld the lug on. I suppose he will have to
grind bits off the new piece in order to weld right to the middle.
I'll drill a new hole after the welding is finished.
I've not seen cast iron welded before. Anything to worry about?

I would be extremely pessimistic of any result. Cast iron can be welded
in the manner described by other posters, but I would expect re-cracking
of the flange through the force exerted by the bolts when assembled.

I would be more tempted to make a mild steel flange of the same size,
cut the old one off and braze or weld the end of the pipe onto the new
flange.

Are you sure it's cast iron? Is the material too hard to file?