PWHT required for tubesheet repairs

[virjil]

We have a 42 mm thick tubesheet which was a part of a fixed tubesheet type heat exchanger. Due to shell cracking failure, the shell to the tubesheet welds failed by transverse cracks. We completely cut open the shell for us to replace it at the same time, we desire to recover the tube bundle. Upon penetrant testing inspection on the tubesheet, the cracks that we identified on the welds penetrated the tubesheet. We repaired the transverse cracks on the tubesheet by grinding out the cracks. Based on our inspection, the cracks did not reach a depth of more than 1/2". After weld build up using GTAW, do we need to PWHT the entire tubesheet? Am I correct in specifying GTAW as the weld technique for the build up?

 

[metengr]

The requirements for PWHT depend on the materials of construction. What is the tubesheet material? The welding process that was used is fine.

Once you have identified the tubesheet material, go to Section VIII, Div 1 of the ASME Boiler and Pressure Vessel Code and locate the requirements for PWHT based on the tubesheet material.

If PWHT is required by Code, the PWHT can be localized depending on the number of repair areas. Also, the time for PWHT will be dictated by repair depth to the tubesheet not the thickness of the tubesheet.

 

[virjil]

Thanks Sir. By the way, the tubesheet material is SA-266-2. I will consult our ASME B&PV Code as you recommended.