Line List
A line list is the master register of every numbered process pipe in a facility, with metadata including line number, size, pipe spec, service, design temperature and pressure, insulation, and the from-and-to equipment tags. It is the piping engineering peer to the I/O list and the instrument index.
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A line list is the piping discipline's master register, one row for every numbered process pipe in a facility, and it is the structural peer of the I/O list and the instrument index. Each row carries the line number in whatever convention the project uses, a form like 6-PG-101-A1 that already encodes size, service, sequence, and pipe spec, the nominal size, the pipe spec that bundles material, schedule, end connection, gasket, and bolting, the fluid service, the design and operating temperature and pressure, insulation and tracing, the from-and-to equipment tags, and the P&ID reference. The reason its accuracy matters is that the pipe spec drives procurement and construction. A carbon-steel line and a stainless line of the same size want different valves, gaskets, and welding procedures, and an error on the list propagates straight into the material take-off and the field. The most error-prone elements are spec breaks, the points, usually at a flange where one line transitions from one spec to another, and the list records the break and the drawing page that shows it. Unlike the cable schedule or the datasheet, this is data the P&ID genuinely carries. The line number, size, spec, service, and routing between equipment are drawn on the sheet, including the break notation, so a careful reading of the set produces the line list directly rather than as a downstream document that needs other sources to complete.
What columns appear on a line list.
Line number, per the project numbering convention, often size-service-sequence-spec like 6"-PG-101-A1. Nominal size. Pipe spec, which encapsulates material, schedule, end-connection, gasket, bolt material. Service, the fluid service class and process medium. Design and operating temperature and pressure. Insulation type and thickness if applicable. Heat tracing and steam-tracing requirements. From and to equipment tags. P&ID reference. Test pressure and inspection class. Material balance reference.
Why pipe-spec accuracy matters downstream.
Pipe spec drives material procurement. A 6"-CS-A106B line wants different material, different valves, different gaskets, different welding procedures than a 6"-SS316-A312 line. Errors on the line list cascade into the procurement package and into construction. Spec breaks, where one section of a line transitions from one spec to another, often at a flange are the most error-prone elements. The line list captures the break location and references the relevant P&ID page where the break is shown. Tagsight extracts line specs as drawn including the break notation.
Frequently asked.
Is the line list the same as the line schedule.
Sometimes the terms are used interchangeably. Some projects distinguish. The line list is the unique-line register. The line schedule adds detailed routing, support locations, insulation lengths, and material take-off quantities. The line list is the upstream document. The line schedule is the downstream piping-engineering document.
Does the line list show every pipe in the plant.
Generally only numbered process lines, plus utility lines, steam, water, air, nitrogen at the level the project numbers them. Tubing, sample lines, instrument air laterals, and short stub-outs typically don't get individual line numbers. They're handled at the spec or schedule level.
Who is responsible for the line list and when is it issued.
The piping lead or piping engineer owns the line list. A preliminary version is available in FEED from the P&ID set. The detailed-engineering issue incorporates pipe-spec revisions from stress and materials engineers. The IFC version is the one construction works against. Changes after IFC go through formal MOC, and each revision of the line list triggers reconciliation against the as-built P&ID mark-up.