This is a code-critical pipe welding procedure for chrome-moly (P11) piping — the kind of WPS that takes a welding engineer hours to draft manually. The procedure uses a GTAW root pass with SMAW fill and cap on 6" Schedule 80 A335 P11 pipe in the 6G position (45° inclined, fixed). Chrome-moly requires strict preheat maintenance at 300°F and mandatory PWHT at 1,350°F. IronKit generated the full WPS including the dual-process parameters, interpass limits, and PWHT hold time — details that are easy to get wrong when writing by hand. The welding supervisor at a Gulf Coast contractor said this was the first WPS generator that got the P11 PWHT window right on the first try.
Frequently Asked Questions
Why does P11 chrome-moly require PWHT?
Chrome-moly steels (P-4 group) develop hard, brittle microstructures in the heat-affected zone during welding. PWHT at 1,350°F tempers the martensite back to a ductile structure and relieves residual stress. Skipping PWHT on P11 piping is a code violation and a safety risk.
What is the 6G position?
6G is the most restrictive pipe position — the pipe is fixed at a 45° angle and cannot be rotated. A welder certified in 6G is qualified for all other pipe positions (1G through 6GR) per ASME QW-461.9. It is the industry standard qualification test for pipe welders.
Why use GTAW root + SMAW fill?
GTAW provides the best root pass quality on open-root pipe joints — clean fusion, no inclusions, and controllable penetration. SMAW fill and cap is faster than all-GTAW and produces acceptable mechanical properties on chrome-moly. This combination is standard practice for code-grade pipe welding.
Does IronKit calculate PWHT hold time?
Yes. IronKit calculates hold time based on the wall thickness (1 hr/inch, 30 min minimum) per ASME Section IX. For 0.432" wall P11 pipe, the hold time is 30 minutes minimum.