On Thu, 14 Jul 2011 03:04:09 -0700 (PDT), Matty F
wrote:

On Jul 14, 9:58 pm, Peter Parry wrote:

Brazing is often preferred with unknown materials as cracking after
welding is very common.

The pipe is cast iron.

Sorry, I meant unknown type of cast iron. It has several forms some
of which are unweldable because the welding changes the characteristic
of the cast iron making it very brittle and cracking inevitable.
..