Our company is going to qualify a welding procedure on a 1/4"thick plate coupon of SA-387 P91 material welded with the GTAW process using ER-NiCr-3 filler rod in the 1G position with no PWHT.We will use a 99.90% argon mixture for shielding and backing.Preheat will be 200 degrees F and interpass...
If a welder qualifies on a .625"(5/8") thick coupon with F3 to 1/8" and filled the rest of the way with F4 with a minimum of 3 layers his qulifications are as follows for production welding.
F4- Unlimited thickness with backing
F3-unlimited thickness with backing
F3-1/4" without backing
Refer...
