API 570 Piping Inspector Practice Test 2026 - Comprehensive Exam Preparation

The amount a WPS can cover, when it’s qualified by a PQR coupon, is up to twice the plate thickness used in that coupon. Since the PQR coupon thickness is T, the WPS is valid for welds on plate up to 2T. This ensures the welding parameters proven on the coupon can be applied to somewhat thicker material without re-qualifying, while thicker sections beyond 2T would require another PQR to extend the WPS. So the maximum allowed thickness on the WPS is 2T.