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Before Welding

Inspection before welding begins ensures the joint is set up correctly and the welder has the right procedure, materials, and conditions. Catching errors at this stage prevents costly rework after welding is complete. Every item below traces directly to a D1.1:2025 requirement.

• Verify the WPS is qualified or prequalified. The welding procedure specification must be either prequalified per Clause 5 or qualified by testing per Clause 6. Confirm the WPS document is available at the workstation and current for the joint being welded.
• Check base metal identification against Table 5.6 and the mill test report. Verify the base metal grade matches what the WPS specifies. Table 5.6 lists prequalified base metals and their groups. The mill test report (MTR) confirms the actual material delivered to the job.
• Verify joint fit-up matches the WPS joint detail from Figure 5.1. Root opening, groove angle, root face, and backing (if required) must match the prequalified joint detail referenced in the WPS. Tolerances for fit-up are specified in the joint detail drawings.
• Check preheat temperature meets Table 5.11 minimum. Measure preheat with a contact pyrometer or temperature-indicating crayon. The required minimum preheat depends on the base metal group, thickness, and hydrogen category of the filler metal. Preheat must be established before the arc is struck.
• Verify electrode or wire matches the WPS and Table 5.7. Confirm the filler metal classification, size, and manufacturer match the WPS. Table 5.7 lists prequalified filler metal and flux combinations for each process. Check lot numbers against storage records.
• Confirm the welder is qualified per Clause 6. The welder or welding operator must hold a current qualification for the process, position, and thickness range being welded. Qualification records should be available for review on request.

During Welding

In-process inspection monitors whether the welder is following the WPS parameters and maintaining weld quality throughout the joint. These checks happen while welding is actively in progress or between passes on multi-pass welds.

• Observe welding technique matches WPS parameters. Verify the welder is using the correct process, electrode size, polarity, and approximate parameter range (amperage, voltage, wire feed speed) specified in the WPS.
• Monitor interpass temperature does not exceed the WPS maximum. Measure interpass temperature before depositing the next pass. If the WPS or base metal specification limits interpass temperature, the weld must cool to below that limit before the next pass begins.
• Check electrode storage per Clause 7.3.2 for low-hydrogen electrodes. Low-hydrogen electrodes (E7018 and similar) must be stored in heated ovens after removal from the sealed container. Clause 7.3.2 specifies storage temperatures and maximum exposure times. Electrodes exposed beyond the allowed time must be reconditioned or discarded.
• Verify travel speed and heat input within WPS range for quenched and tempered steels per Clause 7.7. QT steels have maximum heat input limits to preserve their mechanical properties. Calculate heat input from voltage, amperage, and travel speed. Exceeding the maximum heat input can degrade the heat-affected zone toughness.
• Check cleaning between passes. Slag, spatter, and surface contaminants must be removed between passes. Incomplete slag removal is a common cause of inclusions and incomplete fusion defects in multi-pass welds.

After Welding — Visual Inspection

Visual inspection is required for all production welds under D1.1. Table 8.1 defines the acceptance criteria for eight categories of weld discontinuities. The inspector examines the completed weld surface, measures weld size, and checks profile conformance.

• No cracks permitted. Cracks of any type, size, or location are never acceptable under Table 8.1. This includes longitudinal cracks, transverse cracks, crater cracks, and cracks in the heat-affected zone. Any crack requires repair.
• Incomplete fusion is not permitted. The weld must be completely fused to the base metal at both toes and between all passes. Incomplete fusion is rejected regardless of size or length.
• Crater cracks are not permitted. Craters at weld terminations must be filled and free of cracks. Crater cracks indicate improper termination technique.
• Undercut: statically loaded members limited to 1/32 inch maximum depth. Measure undercut depth at the weld toe. For statically loaded nontubular connections, undercut exceeding 1/32 inch requires repair. Cyclically loaded connections have stricter limits.
• Porosity: sum of diameters shall not exceed 3/8 inch in any linear inch. Visible surface porosity is measured by summing the diameters of all pores within any one-inch length of weld. The total must not exceed 3/8 inch.
• Weld profiles must conform to Figure 8.2. Check for excessive convexity, insufficient leg size, excessive concavity, overlap, and insufficient throat. Figure 8.2 provides the visual reference for acceptable and unacceptable weld profiles.
• Verify weld size meets the drawing requirements. Fillet weld leg size and groove weld reinforcement must meet the minimum dimensions specified on the structural drawings. Use fillet weld gauges for measurement.

After Welding — NDE Requirements

Nondestructive examination goes beyond visual inspection to detect subsurface discontinuities that cannot be seen on the weld surface. D1.1 does not require NDE on every weld. The engineer specifies which joints require NDE and which methods to use based on the loading condition, joint criticality, and project requirements.

• Radiographic testing (RT) per Clause 8.12. RT uses X-ray or gamma-ray radiation to produce an image of the internal weld structure. It detects porosity, slag inclusions, and incomplete joint penetration. The resulting radiograph provides a permanent record of weld quality.
• Ultrasonic testing (UT) per Clause 8.14. UT uses high-frequency sound waves to detect planar discontinuities such as lack of fusion and cracks that are difficult to find with RT. Table 8.2 provides the UT acceptance and rejection criteria including indication rating and discontinuity class.
• Magnetic particle testing (MT) per Clause 8.16.1. MT detects surface and near-surface discontinuities in ferromagnetic materials. It is commonly used for fillet weld inspection, root pass inspection, and back-gouge verification where surface-breaking cracks are the primary concern.
• The engineer specifies NDE requirements in the contract documents. D1.1 Clause 1.5.1 gives the engineer authority to determine the type and extent of inspection beyond the code minimum. The contract documents should clearly state which joints require NDE, the method, and the extent of examination.

Inspector Qualifications

D1.1 Clause 8.1 requires all inspection to be performed by qualified inspectors. The code does not prescribe a specific certification program, but it requires inspectors to demonstrate competence acceptable to the engineer.

AWS QC1 and CWI certification is the most widely recognized inspector qualification in the United States. The Certified Welding Inspector (CWI) program requires a combination of education and experience, a three-part examination covering fundamentals, practical, and code application, and recertification every three years.

The engineer determines the inspection requirements per Clause 1.5.1. This includes specifying inspector qualifications, the scope of inspection, the timing of inspections, and the acceptance criteria beyond the code minimum. On most structural steel projects, CWI certification is specified as the baseline inspector qualification.

The inspector must be independent from production welding personnel. The inspector's role is verification, not supervision. The contractor remains responsible for producing welds that meet the code requirements.