Please note that during PWHT (after cladding on Valve bore) monitoring process, it was observed that temperature was exceeded the required value i.e. Reqd. 600̊C whereas observed 780̊C. The soaking period was 4 Hrs.
This discrepancy is mainly due to faulty control instrument and negligence of technician. Eventually, valve body was tested for hardness and found to be (150-160 BHN) less than the minimum hardness value i.e. 197 BHN (contract specs).
Details: The reference standard - API 6A, Material- AISI 4130 with internal bore cladding with Inco 625 overlay.
Is there any additional mechanical testing required? Can we reject the valve? Can we go for an additional heat treatment to obtain required hardness (min 197 BHN)?
I would like to have your advice on way forward.