A few questions on this interesting topic as well as on the suggestions imparted as below.
- How do you perform local PWHT on a fully fabricated pressure vessel? If that's the case , every weld joint (L-Seam, C-Seam, Nozzle Welds ) has to be individually wrapped by heating coils. Is that possible after fabrication of entire vessel?
- Restoration of Duplex clad is usually done after barrier layer by 309L. 2209 electrode/filler may be used also right from the first layer for restoration of clad.
- PWHT of 51 mm thick Duplex clad vessel would encompass the following PWHT cycle easily:-
- Ambient to 300 Deg C-Unlimited heating, 300 Deg C /Hr. Hold at 300 Deg c for uniform equalization of temperature
- From 300 Deg C to 600 Deg C – ROH 40-50 Deg C /Hr- would involve- easily 4 hrs of heating cycle
- Soak 2 600-620 Deg C- for 2 hrs easily
Hence depending on the size of the vessel, a heating cycle of 7-8 hrs easily would be required between 300- Deg C to 600 Deg C. Same would be case for cooling . Hence a PWHT .stress relief temperature @ 600 Deg C could be quite harmful. Typically 300-700 Deg C is the formation range of various intermetallic phases for Duplex S.S.
It would be nice to know the decision taken by the originator of this query , for education of all concerned.
Thanks.
P.Goswami.P.Eng, IWE.
Independent & Consulting Welding & Metallurgical Specialist
Linkedin: https://www.linkedin.com/in/pradip-goswami-2999855/
Email:pgoswami@rogers.com,pradip.goswami@gmail.com
Cell/Whasapp:1-905-9793232
From: materials-welding@googlegroups.com <materials-welding@googlegroups.com> On Behalf Of Customer Care
Sent: July 11, 2020 10:13 PM
To: materials-welding@googlegroups.com
Subject: RE: [MW:31136] CS with Duplex SS (S31803) clad vessel PWHT?
Hi,
You can realize the dissimilar welding (CS 516 Gr.70) + Cladding (S31803) with PWHT following these steps:
-As the base metal of CS have 51 mm of thickness, apply preheating about 175 °C and maintain it during the welding. Use filler for CS type E/7018 (depending welding process).
-Buttering the CS with austenitic filler metal (e.g., E/309L) and remove clad S31803 with grinding, 2" side and side of the weld joint. Realize localized PWHT over the weld metal and HAZ only, about 625 °C during one and half hours.
- Weld the S31803 clad using duplex filler like E/2209.
Ramon Briceno
Senior Metallurgical Engineer / Oil & Gas
Sent from Mail for Windows 10
From: Materials & Welding
Sent: Saturday, July 11, 2020 6:42 AM
To: Materials & Welding
Subject: [MW:31131] CS with Duplex SS (S31803) clad vessel PWHT?
ASME Sec VIII div1
SA516 Gr 70 - 51mm thickness+S31803 clad
any experience on duplex clad vessel PWHT?
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