SCWI cheat sheet

A welder performance qualification tests a welder's skill using a qualified WPS; it is separate from procedure qualification, which tests the procedure.

Essential variables for welder qualification commonly include process, position, base-metal thickness, filler-metal classification, backing, and vertical progression; changes beyond code limits require requalification.

AWS D1.1 position rule: a 3G vertical-groove qualification also qualifies 1G and 2G, but not 4G; a 4G qualification qualifies 1G, 2G, and 4G.

ASME IX: a groove-weld test qualifies the welder for groove and fillet welds within the qualified ranges; a fillet-only test qualifies only fillet welds.

Qualification validity: under common codes, a welder's qualification lapses after six months without welding with the qualified process; requalification or an approved extension is required.

Test coupon acceptance: visual examination and bend tests, or permitted radiographic examination, must meet code criteria; defects exceeding limits fail the test and may require retesting per code.

Records must show welder ID, process, position, thickness range, filler metal, code, test date, and results; production welding must stay within those limits.

A WPS is a written instruction; a PQR is the supporting test record. Production welding must use a WPS supported by a PQR or by prequalified status.

Procedure essential variables include process, base-metal P-number or group, thickness range, filler F-number or A-number, preheat, PWHT, position, and electrical characteristics; changes outside ranges require requalification.

ASME IX procedure qualification limits both base-metal thickness and deposited weld-metal thickness; the WPS range must reflect both limits, not just coupon thickness.

A tensile test specimen generally must reach the minimum specified tensile strength of the base metal; failure below that value is a qualification failure.

Bend tests evaluate ductility and soundness; side bends are commonly used for thick coupons, while face and root bends are used for thinner coupons.

AWS D1.1 prequalified WPSs are allowed only when all prequalified conditions are met; any deviation requires procedure qualification testing.

Impact qualification requires testing at the specified temperature with code-specified specimen location and acceptance energy; base metal, heat-affected zone, and weld metal may each be tested.

Welding coordination ensures that qualified WPSs, qualified welders, approved filler metals, and correct inspection requirements are available before production begins.

Document control must prevent use of superseded WPS revisions or drawings; only approved documents should be at the work site.

Traceability links each joint to base-metal heat number, filler lot, WPS revision, welder ID, and inspection results.

Nonconformance reports record the requirement, the actual condition, disposition such as repair, rework, accept, or reject, and corrective action.

Low-hydrogen electrodes require holding ovens after opening and rebaking per manufacturer limits; exposure time and temperature must be controlled.

Preheat and interpass temperatures are measured with calibrated instruments at code- or procedure-specified locations and recorded.

Welding and inspection equipment must be within calibration; out-of-calibration instruments can invalidate test results and require rework of affected inspections.

NDT method selection matches the expected discontinuity, geometry, material, and code; no single method detects all discontinuities.

RT is suited to volumetric internal discontinuities; UT is suited to planar and internal discontinuities; PT and MT are surface or near-surface methods.

MT applies only to ferromagnetic materials; magnetization direction should be approximately perpendicular to the expected discontinuity orientation.

PT requires a nonporous, clean surface and controlled dwell and development times; it detects surface-breaking discontinuities only.

NDT personnel must be certified by method and level under the applicable scheme, such as ASNT SNT-TC-1A, CP-189, or ISO 9712.

NDT procedures specify technique, equipment, calibration, scanning, and acceptance criteria; the acceptance standard must match the construction code.

NDT reports should record method, procedure, equipment, calibration, examiner, locations, results, and acceptance standard.