Re: [MW:33549] HEAT EXCHANGER CONSTRUCTION

Hi,
In general, DSS weld overlay is not recommended in CS due to cracking and other weldability issues. Moreover, Tube sheet forging with heavy weld overlay requires stress relieving too. 
However, stress relieving is not recommended for DSS, Hence in my opinion DSS weld overlay on TS to be replaced with Alloy 625 weld overlay wherein all these these issues related to weldability & PWHT will be solved.
Regards,
Prabhu.





From: Vishwas Keskar Welding Manager WELDING <vvkeskar123@gmail.com>
Sent: Thu, 06 Oct 2022 09:52:15
To: Materials & Welding <materials-welding@googlegroups.com>
Subject: [MW:33541] HEAT EXCHANGER CONSTRUCTION

Dear Experts 

One of HEX involves  following MOCs -

HEX tubes - SA 789 TYP 32205 

Tubesheet -SA 266 CL 2 CS - Tube sheet IS cladded with TYP S32205  overlay.

Shell side - CS -SA 516 GR 70 - 75mm thk 

Channel side - CS- SA 516 GR 70 - 75 mm thk 

PWHT is required for  Tube sheet to Shell welding and Tube sheet to Channel welding. These are butt welds with CS Weld metal .

PWHT is not required for  Tube sheet to HEX Tube  welding due to DSS tube to DSS cladding.

 

Pl advice for the  care that shall be taken during PWHT  of Tube sheet to Shell welding and Tube sheet to Channel welding.

 

Thanks and regards

Vishwas - IWE

International Welding Engineer

 

 

 

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