A heavy frame conducts heat away differently from a thin corrugated panel. The welder must form the required fusion boundary without losing the thin sheet’s oil-retaining continuity. A procedure suited to equal-thickness flat plates may not represent this joint. [1]
Draw the actual corrugation root, frame contact and access. Identify sheet thickness, fit-up and restraint. Local gaps and curvature can change the thermal and mechanical conditions along the seam.
| Joint condition | Risk to investigate | Evidence |
|---|---|---|
| Heavy member removes heat | Incomplete fusion at its face | Representative section and qualified process |
| Thin member heats rapidly | Burn-through or loss of section | Process window and final continuity |
| Variable corrugation fit | Changing root gap and weld access | Fit-up map along the actual seam |
| High restraint | Distortion or crack-related conditions | Sequence and dimensional evidence |
Qualify the competing constraints together
A heat-input change can improve one interface while worsening another. Review current, speed, process and technique through the qualified welding plan rather than selecting one generic higher or lower setting.
Representative trial joints should reproduce corrugation geometry and frame heat sink, not just the nominal thickness pair. Examine the relevant fusion faces and sheet continuity on the sample.
Choose NDT using material, weld thickness, welding process, quality requirements and demonstrated coverage. NDT acceptance levels are not a detailed one-to-one translation of weld quality levels. [2]
Screen the thickness mismatch in qualification
Assumptions: a 1.2 mm corrugated panel joins a 6.0 mm frame, a 5:1 thickness ratio. The supplied procedure dossier explicitly covers a thin-side member range of 3.0–12.0 mm for its defined joint/process. The panel is 1.8 mm below that lower bound, so reject the dossier as the production basis for this joint. The 6 mm frame matching its range cannot cure the thin-side exclusion. Develop an applicable qualification and a representative corrugated joint that preserves the frame heat sink, gap/access and restraint; verify thin-side fusion, continuity and final distortion. The assumed range is a dossier input, not a universal code qualification rule.
References
- U.S. Federal Highway Administration, Bridge Welding Reference Manual, FHWA-HIF-19-088, 2019.
- ISO, ISO 17635:2025, Non-destructive testing of welds — General rules for metallic materials.