Weld Mapping and NDE Tracking: A Field Primer

What a weld map actually is

A weld map is a controlled record of every welded joint on a project, keyed back to the isometric or structural drawing it belongs to. Each weld gets a unique weld number so it can never be confused with another. From that number you can trace the joint to its drawing, its spool or assembly, the welder who made it, the procedure used, and the inspection results.

The point of the map is traceability. If a client, an inspector, or your own QC manager points at a joint and asks who welded it and whether it passed, the answer should take seconds, not an afternoon of digging through field copies. The map is also the backbone of your inspection plan — you cannot manage what percentage of welds have been tested if you do not have a complete, numbered list of welds in the first place.

Weld numbers, joints, and welder continuity

Each weld record ties together a few essential pieces of information:

• •Weld number and joint type: a unique ID plus the joint detail (butt, socket, fillet, branch) and the drawing/iso it appears on.
• •Welder ID: the specific welder or weld operator who made the joint, recorded by their stamp or ID number.
• •WPS used: the welding procedure specification the joint was made to, so the parameters are traceable.
• •Material and size: base metal, pipe size and schedule (or member size), and filler metal as applicable.
• •Status and inspection results: fit-up, visual, and any NDE outcomes, with dates.

Welder continuity, WPS, and PQR

A welder is only allowed to make production welds within the range they are qualified for, and that qualification has to stay current. Codes generally require that a welder keep using a process within a defined window — commonly six months — or their qualification for that process lapses. Tracking the date of each welder's last qualifying weld is what "welder continuity" means, and a good weld log surfaces it automatically so you do not put an out-of-date welder on a critical joint.

Behind the welding sit two documents that get confused constantly. The WPS (welding procedure specification) is the written recipe — process, materials, joint design, electrical parameters, preheat, and so on — that tells the welder how to make the weld. The PQR (procedure qualification record) is the proof that the recipe works: it documents an actual test weld and the mechanical test results that qualify the WPS. In short, the PQR backs up the WPS, and production welds are made to the WPS. Your weld map should reference the WPS for every joint so the procedure trail is complete.

NDE methods at a high level

Non-destructive examination (NDE) checks weld quality without cutting the joint apart. The common methods, from simplest to most involved:

• •VT (visual testing): the baseline. A qualified inspector visually examines fit-up and the finished weld for profile, undercut, and surface defects. Almost every weld gets VT.
• •PT (liquid penetrant testing): a dye is drawn into surface-breaking flaws and revealed by a developer. Good for surface cracks and porosity on non-porous materials.
• •MT (magnetic particle testing): magnetizes a ferromagnetic part so iron particles gather at surface and near-surface flaws. Faster than PT but only for magnetic materials.
• •RT (radiographic testing): an X-ray or gamma image of the weld reveals internal defects like incomplete penetration, slag, or porosity. Produces a permanent film/digital record.
• •UT (ultrasonic testing): high-frequency sound finds internal flaws and can be more sensitive than RT for certain crack-like defects; phased-array UT is increasingly used in place of RT.

Sampling, rejects, and repair tracking

Most projects do not radiograph every weld. The spec sets a sampling rate — say a percentage of each welder's joints — and which methods apply to which weld categories. Many programs also use progressive sampling: if a sampled weld fails, you expand the sample (often two additional welds from the same welder, sometimes more) to find out whether the problem is isolated or systemic. That is exactly why the welder ID on every weld matters — a reject sends you straight to that welder's other joints.

When a weld is rejected, the map has to follow the repair through to closure. A defect is excavated or the joint is cut out, re-welded, and then re-examined by the same method that found the original defect (and often VT as well). Each of those steps — reject, cut-out, repair weld, re-inspection — is its own dated entry against the original weld number. A weld that was rejected and never shows a passing re-test is a hole in your turnover package, and inspectors look for exactly that.

Field PM's weld mapping ties each joint on the iso to its welder, WPS, and inspection status, tracks welder continuity, and carries rejects through repair and re-test so the count of accepted welds is always real — not a spreadsheet someone forgot to update.

The turnover data book

At the end of a weldment-heavy job, the client does not just want the pipe in the ground — they want the documentation that proves it was built right. That package is the turnover data book (sometimes called the MRB, manufacturing record book): the complete set of weld maps, weld logs, welder qualifications, WPS/PQRs, NDE reports, material test reports, and hydrotest or pressure-test records.

If your weld map has been maintained as a live record from the first joint, the data book is largely a print job. If it has not, closeout becomes weeks of reconstruction — chasing down which welder made joint 0427, whether the RT ever cleared, and where the repair report went. Build the map as you go, and the turnover book builds itself.