Pipeline construction — oil, gas and product transportation · reference card
Cross-country and plant piping welded under API 1104 and the ASME B31 transportation codes. The four monitoring pain points that cost pipeline contractors most, and which Therness signal addresses each.
A cross-country pipeline spread welds joints faster, in more varied conditions, and further from a shop than almost any other class of structural welding. The same crew that welds a clean joint at a compressor-station tie-in welds the next one in a trench in the rain, and API 1104’s qualification and acceptance framework has to hold across both.
The root pass carries most of the risk. Once fill and cap passes are on, a root-pass problem is buried under metal that has to be removed to find it, on a joint that may already be backfilled. That asymmetry — cheap to catch before the next pass, expensive after — is what makes evidence taken during welding worth more than evidence taken afterward.
Modern mainline construction increasingly welds mechanically rather than by hand, which raises production rate faster than radiographic capacity can follow. The practical question stops being whether a joint was welded correctly and becomes which of many joints a limited NDT crew should look at first, and that question is only answerable from a record made as the joint was welded — see the pipeline monitoring guide for how a camera-based record is built into an API 1104 completion package.
| Code | Why it applies |
|---|---|
| API 1104 | The primary construction code for girth welds on oil and gas transmission pipelines, covering procedure and welder qualification alongside acceptance. |
| ASME B31.4 | Transportation code for liquid pipeline systems, setting the piping design and construction envelope the girth welds sit inside. |
| ASME B31.8 | Companion transportation code for gas transmission and distribution piping systems. |
| ISO 3834-2 | Quality-system requirements a pipeline contractor's welding operation is increasingly asked to hold alongside the pipeline-specific codes. |
| Pain point | Consequence | Signal that sees it |
|---|---|---|
| Preheat and interpass conditions vary along a cross-country right-of-way | A joint welded at midday in the sun and one welded at dawn on the same spread carry different thermal histories that a settings sheet does not show. | Non-contact interpass measurement taken at the joint on every weld, not inferred from ambient conditions. |
| Root pass quality on a girth weld decides whether the rest of the joint is recoverable | A root-pass problem found only after fill and cap means excavating a completed joint on a live right-of-way. | Thermal and pool evidence captured on the root pass itself, before the next pass covers it. |
| A mechanized spread welds joints faster than a crew can radiograph them | Radiography becomes the bottleneck on production rate, and a suspect joint is identified hours after it was made. | Per-joint process evidence available immediately, so radiography is directed rather than queued. |
| Traceability across a long right-of-way spans many crews, shifts and welding rigs | Reconciling which crew, procedure and rig produced a given joint number becomes the slow part of the completion package. | Joint identifier, welder, procedure and process record joined automatically as the weld is made. |
Therness measures what happens while the arc is running — parameters, thermal signature, per-weld records — so the problems on this page surface on the shift that made them.
Progetto cofinanziato nell'ambito del PR Piemonte FSE+ 2021-2027,
Priorità I, Obiettivo Specifico a), Azione 4 – "Sostegno alla nascita delle start up"
