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Key takeaways
- Most abbreviations fall into four groups: drawings and documents, components, materials and testing, and design.
- Abbreviations vary between companies, so always check the legend sheet on the project.
- The full site glossary has longer explanations of each term.
Drawings and documents
- P&ID: piping and instrumentation diagram.
- PFD: process flow diagram.
- ISO: isometric drawing.
- GA: general arrangement drawing.
- PMS: piping material specification.
- MTO: material take-off.
- BOM: bill of materials.
- IFC: issued for construction.
- IFR / IFA: issued for review / approval.
- TQ: technical query.
Components
- NPS / DN: nominal pipe size / diameter nominal.
- WN / SO / SW / BL: weld neck, slip-on, socket weld, blind flange.
- RF / RTJ / FF: raised face, ring type joint, flat face.
- BW / SW / THD: butt weld, socket weld, threaded.
- ELL / RED / TEE: elbow, reducer, tee.
- CONC / ECC: concentric, eccentric reducer.
- SPWD: spiral wound gasket.
- PSV / PRV: pressure safety valve / pressure relief valve.
- LO / LC / CSO / CSC: locked open, locked closed, car sealed open, car sealed closed.
Materials and testing
- CS / LTCS / SS / DSS / SDSS: carbon steel, low-temperature carbon steel, stainless steel, duplex, super duplex.
- CRA: corrosion-resistant alloy.
- GRE / GRP / FRP: glass-reinforced epoxy / plastic, fibre-reinforced plastic.
- CA: corrosion allowance.
- NDE / NDT: non-destructive examination / testing.
- RT / UT / MT / PT / VT: radiographic, ultrasonic, magnetic particle, penetrant, visual testing.
- PMI: positive material identification.
- PWHT: post-weld heat treatment.
- WPS / PQR / WPQ: welding procedure specification, procedure qualification record, welder performance qualification.
- MTC: mill test certificate.
Design
- DP / DT: design pressure / design temperature.
- MDMT: minimum design metal temperature.
- SMYS: specified minimum yield strength.
- BOP / TOS / COP: bottom of pipe, top of steel, centre of pipe.
- EL: elevation.
- NPSH: net positive suction head.
- AIV / FIV: acoustic-induced / flow-induced vibration.
- CUI: corrosion under insulation.
Code reference
Project legend sheets Always take precedence over general lists.
What to take back to your desk
Keep a personal list. Every time you meet a new abbreviation on a project, write it down with the project’s meaning. In six months you’ll have the most useful page in your notebook.
Educational content. Always design to your project specification.
