I have a leaking steel pipe that supplies warm water to radiators in my house.

A plumber dropped by and said it would be easiest to cut the bad part away and
weld a replacement. The pipe is about 2 inches thick.

The replacement is about two feet.

The plumber gave me a quote of about $2000 which I promptly refused.

What about using a fiberglass or something else? I'd rather just cut the cracked
steelpipe part away and weld a copper replacement part. Any ideas?