What are the inspector's first steps before production welding begins?

Confirm that an applicable WPS is on site and accessible to the welder. Then verify the welder's current certification covers the process, position, and base metal being welded. Check joint fit-up against WPS tolerances, confirm preheat has been achieved and measured at the correct distance from the joint, and verify consumables are the correct type and properly stored.

How far from the weld joint should preheat be measured?

AWS D1.1:2025 requires preheat to be verified at least 3 inches (75 mm) from the point of welding on each side of the joint. Temperature-indicating crayons (Tempilstiks) or a contact thermometer are both acceptable methods. Infrared guns are unreliable on bare, reflective steel surfaces and should not be used as the sole verification method.

What electrode storage check does the CWI perform before welding?

For low-hydrogen electrodes (E7018 and similar), verify that electrodes have been stored in a heated rod oven at the manufacturer's specified temperature, or removed from a sealed hermetic container within the permitted atmospheric exposure time. AWS D1.1:2025 specifies maximum exposure limits by hydrogen designator (H4, H8, H16). Electrodes that exceed limits must be re-dried or discarded — not handed to the welder.

Should fit-up acceptance be documented before welding starts?

Yes. For joints with a hold-point inspection requirement, the inspector records fit-up acceptance by signing or initialing the fit-up inspection report before authorizing fill passes. Root opening, bevel angle, and root face dimension must all be within WPS tolerance and D1.1 groove preparation requirements before arc ignition.

CWI Pre-Weld Inspection: What to Verify Before Arc Ignition

Pre-weld CWI inspection for AWS D1.1: verify WPS coverage, joint fit-up, preheat measurement, consumable storage, and welder cert before the first arc strikes.

Every rejection found before the first arc is struck costs nothing to correct. Every rejection found after the weld is deposited costs time, money, and — if the joint is already encased in a column or covered by a deck — possibly the structural integrity of the connection. The pre-weld inspection is not a formality. It is the cheapest quality gate in the entire fabrication sequence.

This article walks through what a CWI or authorized inspector should verify before production welding begins on any structural joint under AWS D1.1:2025.

Verify the WPS Is Applicable to This Joint

The first question before any arc is struck: does an applicable WPS exist, is it in the inspector's hands (or the welder's hands, or posted at the work station), and does it actually cover what's about to happen?

Covering the joint means confirming the WPS specifies:

Process: SMAW, GMAW, FCAW-G, FCAW-S, SAW, GTAW — these are not interchangeable on a WPS. A FCAW-G procedure does not cover FCAW-S production welding, regardless of filler metal tensile strength match.
Position: A 1G or 1F WPS does not cover overhead (4G/4F) or vertical (3G/3F) welding. The inspector should confirm that the qualified position range covers the actual weld position in the structure.
Base metal group: AWS D1.1:2025 Table 6.9 assigns structural steel grades to base metal groups. A WPS qualified on one group may or may not cover another — the qualified range must be checked.
Base metal thickness: The WPS specifies a qualified thickness range for the base metal based on the thickness tested during PQR qualification. If the production joint thickness falls outside that range, a different WPS is needed.
Filler metal classification: The electrode or wire actually in the welder's hand must match the classification on the WPS, not just the strength level.

A mismatch between any of these parameters and the WPS is a procedural deficiency that cannot be corrected after the weld is deposited. Document the applicable WPS number, revision, and the joint identification in the inspection log.

For context on how essential variable changes affect WPS coverage, see WPS essential variables vs nonessential variables.

Confirm Welder Qualification

Before the welder strikes an arc, the inspector should have confirmed — or can confirm on demand — that the welder's WPQ covers:

The welding process assigned to this joint
The position in which this joint will be welded
The base metal thickness group if applicable to the WPQ scope
Continuity: AWS D1.1:2025 Clause 6.4.1 suspends qualification in any process if the welder has not used that process in production for six consecutive months. A welder who was qualified 14 months ago and hasn't welded FCAW-G since then is not currently qualified for FCAW-G — regardless of what the original WPQ says.

The continuity verification is where most shops get caught. The welder's original WPQ may look fine; the continuity log is where the gap appears. If the shop runs automated continuity tracking, the inspector can query the system. If not, the inspector needs to pull the production log and verify the last documented date of use for this process.

See AWS D1.1 welder continuity: the six-month rule for the full continuity qualification framework.

Inspect and Accept the Joint Fit-Up

Joint fit-up must be verified against both the WPS and the AWS D1.1 fabrication tolerances before any fill weld passes are deposited. The fit-up inspection is typically a hold point — the inspector must sign off before the welder proceeds.

The inspector checks:

Root opening: For prequalified groove joints, the root opening must fall within the tolerances specified in the applicable joint detail. An undersized root opening can prevent complete joint penetration; an oversized opening may change the effective throat and deposition requirements in ways the WPS doesn't account for.

Bevel angle: Groove angle affects arc access during root pass welding, especially in restricted-access locations like box column interiors. Too shallow an angle causes inclusion trapping; too steep wastes filler metal and increases distortion risk.

Root face: The land or root face dimension affects the likelihood of burn-through on the root pass. Verify it matches the joint detail tolerance.

Alignment and offset: Joint faces should be aligned within D1.1 tolerances. Significant mismatch shifts the weld center of gravity away from the design assumption.

Cleanliness: Mill scale, moisture, oil, paint, or primer within the groove may or may not be permitted depending on the joint category and WPS. If the WPS requires wire brushing or other surface preparation, it must be done before the inspector accepts fit-up.

For fit-up tolerance details, see groove weld fit-up tolerances under AWS D1.1.

Verify Preheat Has Been Achieved

Preheat is a critical pre-weld requirement for carbon and low-alloy structural steels. Its purpose is to slow the cooling rate, reduce hydrogen diffusion from the weld metal into the HAZ, and lower the risk of hydrogen-assisted cracking. Welding on cold steel without required preheat — even for a single pass — is a significant quality failure.

The inspector verifies preheat before the first arc, and the measurement must be made correctly:

Location: AWS D1.1:2025 requires preheat measurement at least 3 inches (75 mm) from the intended point of welding. This accounts for heat loss in the base metal and ensures the body of the joint — not just the surface directly under the heat source — has reached the required temperature.

Method: Temperature-indicating crayons (Tempilstiks) or a calibrated contact thermometer are the standard methods. Crayons in two temperature ratings — one just below the required preheat and one just above — let the inspector bracket the required temperature precisely. Infrared (IR) pyrometers are not reliable on bare carbon steel surfaces because the emissivity of mill scale and cleaned steel varies significantly; they may read 15–30°F low or high on the same surface depending on surface condition.

Both sides: Preheat the entire joint region, not just the groove face. Large or heavy sections require additional soak time to ensure the interior of the base metal reaches temperature, not just the surface.

Documentation: Record the measured preheat temperature, the measurement method, and the joint identification in the inspection log before sign-off.

For the underlying code requirements and carbon equivalent calculations, see preheat and interpass temperature on a WPS.

Check Consumables Before Use

The inspector should verify that the electrode, wire, or flux being used matches the WPS classification and has been stored correctly.

For low-hydrogen SMAW electrodes (E7018, E7016, E7028, and similar):

Electrodes from hermetic (vacuum-sealed) containers must be used within the manufacturer's stated atmospheric exposure limit after opening — typically 4 hours for H4 designator, 9 hours for H8, and longer for H16. If the container was opened outside the shift and the welder cannot confirm exposure time, the electrodes are suspect.
Electrodes that were stored loose or in an unlabeled coffee can are rejected until proven otherwise.
Re-drying is permitted per AWS D1.1 when the hydrogen designator and manufacturer instructions allow it — but re-drying is the welder's responsibility to request, not a field shortcut the inspector applies after the fact.

For FCAW wire and SAW flux, storage against moisture and proper conditioning per manufacturer data sheets is the baseline. Verify that the wire spool or flux hopper is from an approved lot and that the packaging was sealed until use.

For a detailed breakdown of hydrogen control requirements, see low-hydrogen electrode conditioning H4 H8 H16.

Equipment Readiness: Amperage, Voltage, and Gas Flow

The inspector is not the machine operator, but the pre-weld check should include confirmation that:

The welding machine is set to parameters within the WPS-specified ranges for amperage and voltage
For GMAW and FCAW-G, the shielding gas type matches the WPS and flow rate is within the specified range
For SAW, the flux hopper is filled with the correct flux per the WPS, and the flux is conditioned if required

These checks are often done together during the welder's own equipment setup. The inspector can verify against the WPS without interrupting the setup process.

Document the Pre-Weld Inspection

The pre-weld check has no value if it is not recorded. The inspection log for each joint should capture:

WPS number and revision used
Welder ID and WPQ number
Joint identification (member mark, weld number, or location drawing reference)
Fit-up inspection result (accepted / rejected with corrective action if applicable)
Preheat temperature measured and method used
Consumable verification (electrode lot, container type, storage confirmed)
Inspector name, certification level, and sign-off date and time

A completed pre-weld inspection record turns the inspection into a documented quality event. Without it, the best inspector in the shop still has only word-of-mouth evidence that the joint was accepted before welding began.

Rule library based on AWS D1.1:2025; verify against your governing edition.