SMAW root welding of duplex SS P/W

By Alnmouth Date 08-28-2005 14:21

SMAW root welding of duplex SS -31803 pipe work.

To save the complication of back purging of tie-in welds in duplex SS contractor has proposed SMAW process for root welding.

Service is none sour wet hydrocarbon gas with CO2, any comments on suitability?

By - Date 08-28-2005 22:27

If you are using the SMAW process to avoid purging the weld, you need to reconsider. Unless you are using a double vee groove weld configuration, and going to grind the back side and backweld, you are going to have "sugar" and that is unacceptable. I will send you a couple of papers and Avesta's "How to Weld Avesta 2205" if you will provide your e-mail address.

Chuck

By jiweiming (**)

Date 09-03-2005 05:39

so,Chuck,would u kindly enough to send me these papers?thanks.
in addition,have u ever used plasma arc gouge if u choose SMAW or SAW process?
jimmy

By - Date 09-03-2005 11:55

Hi Jimmy,
The papers will be forthcoming.
Regardless of the welding process, the root must be protected from the oxidation in the atmosphere. If not, one should be prepared to remove the oxide layer from the inside of the root pass. Actually, plasma arc gouging is probably the preferred method of removing this oxide layer. Heavy grinding can cause localized heat stress, which can, if done improperly, cause microscopic crevices that can lead to cracks. It's unlikely with Duplex, but not impossible.
I'll need your e-mail address in order to send you the papers.

Chuck