Fillet weld must have back purge in stainless steel?

Date 06-25-2009 12:41

Crashproj,
What are you actually asking ?

"are you guys really doin this kind of stuff..."

"Us guys" generally follow the clients specifications, the codes / standards and good work practices.
A good welder can usually weld a fillet weld (eg. reinforcing pad) on the outside of a stainless pipe without causing oxidation on the inside of a pipe.
A less competent welder may weld too hot and cause oxidation.
Cheers,
Shane

By 803056

Date 06-25-2009 20:22

The thickness of the pipe wall and the welding process (heat input) will influence the maximum temperature attained on the pipe ID. Temperatures above 400 degrees F will typically result in some level of discoloration.

Whether the discoloration is unacceptable is determined by the customer and what is specified in the project specification.

Best regards - Al

By crashproj (*)

Date 06-25-2009 20:48

Al,

I agree with you Al.. when heat input is the one will influence the discoloration and not the purging gas.

thanks and regards,

By crashproj (*)

Date 06-25-2009 20:31

shane sorry...

What i mean , is it necessary to have a back purge when welding on stainless pipe with a fillet weld?

"A good welder can usually weld a fillet weld (eg. reinforcing pad) on the outside of a stainless pipe without causing oxidation on the inside of a pipe."

So it is not mandatory to have a back purge on a fillet weld, actually the thickness of the run pipe is 7.9 mm same thickness for the reinforcement pad we completed 2 spools without back purging and no oxidation on the inside of a pipe.

regards