Weld repair of A216 WCB valve without PWHT (Cavity 75 x 38 mm)

[Inspectengr]

We have A216 WCB valve (Thickness of the part to be repaired is more than 100 mm)

At current, due to cracks in bolt holes the excavated are is 75 x 38 mm with depth of 40 mm approximately

As per A216 WCB Section 10 Repair by Welding

10.3 Castings containing any repair weld that exceeds 20 % of the wall thickness or 1 in. [25 mm], whichever is smaller, or that exceeds approximately 10 in.2[65 cm2] in area, or that was made to correct hydrostatic test defects, shall be stress relieved or heat treated after welding. This mandatory stress relief or heat treatment shall be in accordance with the procedure qualification used.

Our case has crossed thickness percentage and wall thickness but area is less than 65 cm2.

If we see API-570 it suggests 8.2.4 Preheat or Controlled Deposition Welding Methods as Alternatives to Postweld Heat Treatment.

Now question is:
Can we employ API-570 and carry out Preheat or Controlled deposition welding in lieu of PWHT or since it is a casting we have to go with A216 WCB requirement.

-THe valve is under repair after a few years (3~5 years) of service.

 

[TugboatEng]

Welding inside surfaces without preheat is problematic. As the weld cools it shrinks towards the center and the overlay can pull away from the surface and crack.