On Thu, 14 Jul 2011 04:06:36 -0700, Matty F wrote:

On Jul 14, 11:00 pm, cynic wrote:

Cast is VERY difficult to weld properly. the usual way is to slowly
heat the piece up to red hot, weld it with appropriate rods and cool it
down slowly. Unless you know someone with the right skills its going to
be expensive.
I'd be inclined to try brazing then make a shaped clamp plate to go
over the flange and once complete hide it with paint. Is it an exhaust
pipe from some static engine or something else?

The pipe is bolted inside a firebox that's red hot and contains steam at
110 psi.

Is replacing the entire pipe* an option? My (limited) understanding of
welding cast iron is that quite often it can break again in the future,
particularly in high stress environments, and it looks like that pipe as
a whole has had a hard life (understandable, given where it came from).

* either with something manufactured to be identical to the original, or
- in a restoration context - with something that performs the same
function, where you'll keep the damaged original in storage as part of
the project.

cheers

Jules