Weld maps and WPS traceability on fabrication drawings

A completed weld looks the same whether it was made by a qualified welder following a qualified WPS, or made without either. The documentation is what proves compliance. When an AISC-certified QC inspector or third-party auditor walks your shop floor, they ask one question for every weld: "Which WPS qualifies this, and can you show me it?"

If answering that question requires a search through a filing cabinet and some uncomfortable silence, the audit is not going well.

Weld traceability — the documented chain from weld symbol on the drawing to the applicable WPS — exists to demonstrate that the weld is sound by design, not by accident.

See: Common WPS deficiencies found in third-party fabrication audits

What a weld map is

A weld map is a drawing — either a separate document or an overlay on the fabrication drawing — that assigns a WPS reference number to each weld or class of welds on a structural member. It is sometimes called a "weld procedure reference drawing" or incorporated into a broader "weld data sheet."

A typical weld map contains:

• The structural member (beam, column, plate girder, connection) shown in plan or elevation
• Weld mark identifiers (W1, W2, W3 — or alpha-numeric codes keyed to the member mark) at each weld location
• A table in the drawing margin listing: Weld Mark → WPS Number → Process → Filler Classification → Minimum Preheat → NDE Requirement

Once created for a member type, the weld map is reused across the project as that member repeats. A W18×97 beam may appear 40 times on the structural drawings — the weld map for W18×97 connections is created once and applies to all 40.

What a weld schedule is

The weld schedule is the tabular companion to the weld map. Where the map shows location, the schedule shows parameters. A typical row:

The schedule becomes the traveling document that follows shop travelers, inspection hold-point cards, and NDE request forms through production. An inspector checking the preheat reading on W3 before welding starts looks at the weld schedule, not the WPS itself.

Building a weld map: the process

Step 1 — Identify every distinct weld

Mark up the fabrication drawings and list every weld by type. Group welds by the variables that determine which WPS covers them:

• Base metal combination (A36, A572 Gr.50, A992, A588, etc.)
• Joint type (fillet, partial joint penetration groove, complete joint penetration groove)
• Thickness range
• Position (1F, 2F, 3F, 4F for fillets; 1G, 2G, 3G, 4G for groove welds)
• Process (SMAW, FCAW-G, GMAW, SAW)

Step 2 — Match each weld to a qualified WPS

For each weld group, identify which WPS in your library qualifies it. A WPS covers a production weld when:

• The base metal(s) fall within the WPS's qualified base metal category
• The production thickness is within the WPS's qualified range, based on the PQR test plate thickness
• The position is within the WPS's qualified positions
• The filler, process, and joint type match the WPS

If no existing WPS covers a weld, you need to qualify a new procedure before welding starts — not after. An unplanned qualification event mid-project is expensive.

Step 3 — Assign weld marks and populate the schedule

Number or label each distinct weld location on the drawing. Enter the WPS reference for each into the schedule. Welds in the same category — same joint type, base metal, thickness, and position — can share a WPS row with a note covering the range.

Step 4 — Attach to the shop traveler

The weld map and schedule travel with the work order. Welders reference the WPS number and retrieve the current controlled revision from the document library. Inspectors verify correct filler, preheat, and NDE requirements before welding begins and after it ends.

See: WPS revision control: how to avoid using a superseded procedure

What auditors actually check

During an AISC certification surveillance audit, the auditor typically selects several in-progress or completed members and traces the full traceability chain for a random set of welds:

1. Drawing weld symbol → weld schedule (WPS number and NDE requirement assigned)
2. WPS number → controlled WPS document (current revision, properly signed)
3. WPS → supporting PQR (test results recorded, essential variables within range)
4. Weld log entry → welder name → active WPQ (qualification still current, continuity maintained)

If any link in that chain is missing or inconsistent, it's an audit finding. Multiple findings of the same type can affect AISC certification status. Weld maps and schedules establish link #1. Without them, the audit becomes a manual reconstruction exercise under pressure.

See: AISC certification audit readiness: what a CWI checks before the auditor arrives

The five most common weld traceability errors

Using a superseded WPS revision

A WPS was updated to add a position or change a filler classification. The shop traveler still references Revision 0. Auditors compare the revision number on the traveler to the current controlled document. A mismatch is a finding even if the WPS content change was minor.

A field weld with no assigned WPS

A welder adds a weld in the field that wasn't on the original drawing — a fit-up tab, a shim weld, a temporary clip. That weld needs a qualified WPS before it's made. "It's just a small weld" is not a compliant answer.

WPS position doesn't cover the actual weld position

The WPS is qualified 1G and 2G. The production weld is made 3G. Without a 3G-qualified procedure, the WPS doesn't cover the weld — regardless of whether the weld looks good visually or passes NDE.

Filler in the weld log doesn't match the WPS

A welder used a different electrode heat number or classification than the WPS specifies, and no one caught it before the heat entered service. If filler classification is an essential variable for the weld type, the WPS coverage is broken.

Preheat not recorded

The WPS requires 150°F minimum preheat. The welder's log line for preheat is blank. An auditor treats an empty line as "not done." The burden of proof is on the fabricator to demonstrate compliance — an unrecorded preheat is indistinguishable from a skipped one.

NDE traceability flows from the weld schedule

The weld schedule is also where NDE requirements are assigned. When an NDE technician receives a request for UT on W3 of a plate girder, the source of that requirement is the weld schedule row — not a separate NDE plan document that might be out of sync.

Keeping NDE requirements in the weld schedule rather than in a standalone NDE plan reduces the risk of the two documents diverging after a revision. If the WPS or joint design changes, one update to the weld schedule row propagates the NDE requirement change automatically.

See: Maintaining an audit-ready welding procedure library

Digital weld schedule management

Paper weld schedules work, but they create version-control problems. When a WPS is revised, every active project schedule referencing that WPS number needs updating. If a filler becomes unavailable and a WPS is amended to substitute, every schedule that referenced the old filler must change.

Digital systems with linked WPS records propagate revisions automatically — the schedule shows the current WPS content without manual re-entry. The audit-packet export in WPS Welding bundles the WPS library, PQR supporting documentation, welder qualifications, and NDE records into a single package — the documentation set an AISC QC inspector or owner's representative requests at the start of an audit.