Does my existing WPS cover in-process weld repairs?

Usually yes, if the repair process, position, and base metal match the original WPS parameters. But if access forces you into a position the original WPS doesn't qualify—for example, overhead repair on a joint the WPS qualified only in the flat position—you need a WPS that explicitly covers that position.

Can cracks be repaired without a separate repair WPS?

Crack repairs are a special case. Before any welding starts, the crack and its cause must be identified and the affected metal fully excavated to sound metal. The repair WPS is typically the same procedure used originally, but crack repairs on high-restraint or fracture-critical joints may require additional controls—preheat, buttering passes, slow cooling—that should be documented in writing before work begins.

Who must approve a weld repair under AWS D1.1?

Under AWS D1.1, the Engineer has authority over acceptance criteria and may impose additional requirements on repairs. The CWI inspects the excavation to verify sound metal and inspects the completed repair. On contract work, the owner's representative may also require notification before repairs begin—check the project specification.

What documentation is required for a completed weld repair?

At minimum: identification of the original defect and its probable cause, excavation documentation (location, depth, method of removal), the WPS used for the repair, the qualifying welder's WPQ, and all NDE records. The repair NDE method should match or exceed what was originally specified for the joint.

Repair weld procedure qualification under AWS D1.1

In-process and in-service weld repairs both need code-compliant procedures. Here's when your current WPS covers a repair — and when you need a new one.

Weld repairs happen in every fab shop and on most field projects. Porosity clusters, incomplete fusion at the root, undersized fillet legs, cracks found during final NDE — each requires welding to correct. The question a QC manager has to answer immediately: does the existing WPS cover this repair, or is a new procedure required?

AWS D1.1 doesn't treat repair welding as a categorically different operation. The same Clause 6 qualification framework applies. What changes is the specific conditions of the repair — position, access, base metal condition, and defect type — and whether those conditions fall within the existing WPS's qualified range.

When the existing WPS is sufficient

A repair that matches the original procedure parameters in process, filler, position, and preheat is covered by the existing WPS. The most common in-process repairs fall into this category:

Porosity removal and backfill in the same position
Surface slag inclusions ground out and re-welded
Undersized fillet welds built up on accessible horizontal or flat joints
Root pass repairs before fill passes have been deposited

For these, the weld sequence is: stop, mark the defect, excavate to sound metal, verify the excavation visually (the CWI should see bare, clean metal with no discoloration or lack-of-fusion boundaries), and re-weld per the original WPS. Documentation is the repair entry in the weld traveler or weld map.

The critical check is position. A WPS qualified in the flat and horizontal positions (1G and 2G) does not cover a repair that physically can only be made in the overhead position. This situation comes up on assembled structures where access to one face of a joint is blocked once the member is in place. If overhead or vertical repair is anticipated, the WPS qualification range should cover it from the start.

When you need a different or supplemental WPS

Four conditions create a need for a dedicated repair procedure or a WPS that extends the original qualification:

1. Position change. As above — if the repair position isn't in the original WPS's qualified range, either re-qualify or use a WPS that covers the repair position.

2. Change of process. Some repairs are made more practical by switching process. A SAW root pass defect may be easier to excavate and repair with SMAW. The repair process must be qualified, and essential variables under Table 6.6 apply to the repair WPS just as they do to the original. Rule library based on AWS D1.1:2025; verify against your governing edition.

3. Base metal condition after thermal cutting. Deep excavations with arc gouging followed by grinding typically restore sound metal. But on alloy steels or thick sections, the thermal cycle from gouging can affect the HAZ. If the repair is on a material with elevated carbon equivalent or hardenability, verify that preheat requirements are documented and applied to the repair — not just the original weld.

4. Cracks. Crack repairs require additional investigation before picking up the electrode. See below.

Excavation: getting to sound metal

Whatever the defect type, repair welding starts with complete removal of the defective material. AWS D1.1 requires excavation to sound metal. "Sound" means confirmed absence of cracks, porosity, or lack-of-fusion through visual examination — and by MT or PT when required or when the excavation depth warrants it.

MT or PT on the excavation floor is good practice on any crack removal, not just code-mandated. A crack can extend beyond the visible indication. Running MT on the excavation floor before welding is the only way to confirm the entire crack has been removed, and a second round of MT or PT after welding verifies no crack propagated into the repair.

Common excavation methods:

Carbon arc gouging followed by grinding: effective and fast, but leaves a light surface layer that must be ground off before welding
Grinding only: slower but produces a clean surface with no carbon contamination risk; preferred when the defect is shallow
Mechanical chipping: appropriate for small porosity clusters or slag pockets; impractical for large or deep defects

Maintain the same preheat during excavation as during welding, particularly on high-strength or thick plate. Letting the joint cool before gouging and then reheating before repair introduces a thermal cycle that can cause additional HAZ cracking if hydrogen is present.

Crack repairs: extra steps before welding

A crack doesn't appear without a cause. The three common causes in structural fabrication are hydrogen-induced cracking, solidification cracking (hot cracking), and lamellar tearing. Each has different implications for the repair approach.

Hydrogen-induced cracking is the most common cause of HAZ cracks, particularly on high-strength steel or under high restraint. Before repairing, identify whether the original WPS had adequate preheat and low-hydrogen filler. If not, the repair must correct the root cause — higher preheat, rebaked electrodes, or a different filler — not just fill the crack.

Solidification cracking (crater cracks, hot cracks in the weld metal center) points to filler chemistry or weld bead geometry. Long, narrow beads with high dilution ratios crack more readily. The repair WPS should specify bead width-to-depth ratios and consider filler substitution if the original choice was marginal.

Lamellar tearing in the base metal indicates through-thickness stress on a material with poor through-thickness ductility. A direct re-weld will tear again. Buttering passes on the base metal surface before joint welding, combined with reduced restraint where possible, are the standard mitigation.

For a thorough overview of how preheat controls cracking mechanisms, see preheat and interpass temperature on a WPS.

Post-repair NDE

The repair must be inspected to at least the same standard as the original weld. If the joint originally required radiographic testing, the repair gets radiographic testing. If MT was the original NDE method, MT is the minimum for the repair.

Common upgrade: when the original weld was VT only (as permitted for certain fillet welds) and the repair involves a suspected or confirmed crack, MT or PT on the completed repair is appropriate regardless of what the original NDE requirement was. A crack that returns after repair is a far more serious finding than the additional NDE cost.

The repair NDE record should reference the original weld ID, the defect type, the repair sequence, and the post-repair NDE result. This chain of traceability matters in audits. A completed repair with no NDE record linking back to the original defect looks like an unrepaired defect to an auditor.

For documentation requirements that survive third-party audits, see NDE documentation and the audit packet checklist and weld map traceability in production.

Tracking repairs in your WPS library

A repair WPS isn't a special document class — it's a WPS like any other, filed in the same library. The practical issue is scope: shops with large structural WPS libraries may have procedures covering flat/horizontal only, with no qualified vertical-up or overhead procedure. The repair that comes up in the field exposes the gap.

A qualification matrix showing position coverage across all active WPS procedures makes this visible before the field crew picks up the electrode. If position 4G (overhead) isn't covered by any active WPS, that's a known gap — not a surprise discovery mid-project.

See managing a welding procedure library for audit readiness and WPS Welding's qualification matrix and library management.