Hi,
For Pno 4 (let say P11 grade ),Achieving hardness and toughness without PWHT is really a challenging task.
Preheat temp and methodology plays a vital role.
Try to use induction heating!
If the impact test at minus 29 C is required, then there is not point in trying without a PWHT.
Yes, for the cap pass , temper bead techniques will help greatly .
In PQR we can do things with lot of care and somehow achieve the required results , but in production each and every joint needs to welded with same care , which may not be easy to do.
Hence, in my opinion going with PWHT is a good option. Check API RP 582, It mandates. ( I presumed API RP 582 will also be applicable)
Regards,
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Regards,
Sudhakar K CEng MWeldI,IWE.
Welding & Metallurgical Engineer,
Email: sudhak...@gmail.com.