what is the difference 4130 weld inlay with SS316 or INC625

[yudhichen]

everyone,
Does anyone know what is the difference between adding inlay on 4130 body with SS316 or INC625?
so far i've seen these two inlays being used on wellhead equipment. but i dont know what's the advantage on one with respect to another. from what perspective we could say it's better.

thank you

 

[SJones]

Advantage of 316: cheaper

Advantage of 625: more corrosion resistant; does not require a different alloy for the first layer

The choice is down to what service the material is expected to see and whether 316 can tolerate it.

Steve Jones
Corrosion Management Consultant

http://www.linkedin.com/pub/8/83b/b04

All answers are personal opinions only and are in no way connected with any employer.

 

[yudhichen]

Thank's for the reply sir....noted...
is there any specific parameter that become edge point on 316 which considered as a limit before we decide to use 625?
i guess its located at environment constraint in general???

regards

yudhi

 

[OGMetEngr]

If it's for sour service, I'd suggest taking a look at NACE MR0175 / ISO15156. This document specifies limits for 316 such as temperature, H2S partial pressure, and chlorides. Your main culprit for 316 is chloride-induced stress corrosion cracking (CISCC). Also of concern is sulfide stress cracking (SSC).

Again, like SJones stated, depends on application which one would be better.

 

[OGMetEngr]

Also, besides cracking problems, there are localized corrosion problems that are more prevalent with 316 over 625 such as pitting and crevice corrosion. Depends on environment.

 

[yudhichen]

Thanx OGMetEngr & SJones.
I'll dig deeper at NACE MR0175.....
really appreciate your reply.

regards

yudhi