we used WPS with Impact tested to weld LTCS with 60 inch Diameter and Wall thickness is 16mm, now Observed less Separation between two pressure containing welds (Required separation is =155mm, actual is =74mm) in this cause Project specification requirement is PWHT (stress release) but WPS not available for PWHT and Impact

In this cause we planned to establish new WPS with PWHT and Impact Test,
my question is what thickness of the Test coupon is suitable for PWHT and Impact range coverage

dear all,

i have a WPS and PQR  for 6 mm thickness for HSAW and SMAW welding. The same WPS is eligible to produce 5 mm thickness also.