Column Splice Fit-Up and Preheat Dispute
On a six-story braced frame, a field CJP groove weld completes a W14x132 column splice at a moment connection. The approved WPS calls for a 1/8-in root opening, 45° included bevel, and minimum preheat of 225°F. At 07:30 the steel temperature is 38°F and the shop has not supplied heating blankets. The fitter has set the joint with a root opening that varies from 3/16 in to 1/4 in, and one flange face is offset by 1/8 in, creating a ledge. The welder proposes to run a root pass to bridge the gap and then back-gouge to sound metal. About 30% of the joint has already been welded on the opposite side. The erector asks for an immediate decision because the crane is scheduled to move at noon. You are the special inspector.
1. What is your disposition of the fit-up and the proposed root pass? Explain the code basis and the inspection steps you would take.
Read the worked answer
Reject the fit-up as presented. The root opening exceeds the WPS value and is variable along the joint; the 1/8-in offset creates an abrupt ledge that is not addressed by the WPS. A bridge pass is not an acceptable substitute for proper fit-up because it can create lack of fusion, slag entrapment, and an irregular root profile that later NDE may not reliably detect. The first step is to stop welding, document the condition with measurements and photographs, and notify the contractor and EOR in writing. Do not give verbal approval for a field fit-up change. The joint must be re-fitted within the WPS tolerance, or the contractor must obtain an engineered repair procedure from the EOR that addresses root opening, mismatch, and access. Before welding resumes, verify bevel angle, root face, cleanliness, backing or root treatment, and that the welder is qualified for the actual joint configuration. Any existing weld on the opposite side should be treated as suspect until inspected, because it was made under the same fit-up condition.
2. How do you handle the preheat requirement at 38°F ambient, and what records do you require before welding resumes?
Read the worked answer
The WPS minimum preheat of 225°F governs; 38°F ambient does not satisfy it and does not excuse it. The contractor must supply heating blankets or another approved heat source, measure base metal temperature with a calibrated contact pyrometer at the location and distance required by the WPS, and demonstrate that the minimum preheat is maintained before the arc is struck. Preheat is not a one-time check: verify interpass temperature during welding, and confirm that the maximum interpass limit is not exceeded. Record the ambient temperature, steel temperature before heating, preheat measurement locations, interpass readings, and the time of each check. If the contractor cannot maintain preheat, stop the work. Also verify that the WPS preheat is appropriate for the base metal thickness and chemistry; if the project specification or D1.1 requires a higher preheat for the thickness or ambient condition, the higher value governs. Do not allow the welder to use the root pass as a way to warm the joint.
3. The erector argues that the 30% completed weld should be accepted because it was made by a qualified welder. How do you evaluate the existing weld?
Read the worked answer
Welder qualification does not cure a nonconforming fit-up. The completed portion must be evaluated against the same acceptance criteria as the rest of the joint, and the inspector should require visual inspection plus the NDE specified for the joint. Because the fit-up had an excessive root opening and a ledge, the existing weld is a suspect area for lack of fusion and root defects. The contractor should propose a repair procedure: gouge or grind out the suspect weld to sound metal, re-fit or repair the joint geometry per the EOR, and reweld under the approved WPS with preheat. After repair, perform the required NDE and document the results. The inspector should issue a nonconformance report, keep the EOR informed, and not allow the crane move or subsequent work to proceed on the assumption that the weld is acceptable. Acceptance is based on evidence, not on the welder's qualification card.