Repair of hydogen affected damages

[mthakur]

We have taken out a high temp H2 service U-tube exchagner for repair after two years of service. The weld between channel to nozzles made in F22 Cl3 have cracks in the welding as detected by TOFT. There are no apparent damages seen on nozzles or shell forging. We need to gouge out both nozzles completely to ensure all defects are removed before they are welded back.

I would like to know what NDT should be performed on shell and also nozzles faces after they have been removed to ensure they are free from hydrogen attack.

 

[metengr]

Wet fluorescent magnetic particle testing (MT) of the weld prep and surrounding base material.