API piping standards
American Petroleum Institute (USA): Line pipe, oil-country tubulars, valves, tanks and in-service inspection codes for the oil and gas industry. 16 standards most used in piping, flanges, fittings, valves and materials.
| Standard | Covers | Category | On this site |
|---|---|---|---|
| API 5L | Line pipe (PSL 1 and PSL 2, grades B to X80) | Pipe | Open → |
| API 5CT | Casing and tubing | Pipe | Open → |
| API 6A | Wellhead and christmas tree equipment | Valves | – |
| API 6D | Pipeline and piping valves | Valves | – |
| API 594 | Check valves: flanged, lug, wafer and butt-welding | Valves | – |
| API 598 | Valve inspection and testing | Valves | – |
| API 600 | Steel gate valves, flanged and butt-welding ends, bolted bonnets | Valves | – |
| API 602 | Compact steel gate, globe and check valves (small bore) | Valves | – |
| API 603 | Corrosion-resistant bolted-bonnet gate valves | Valves | – |
| API 607 | Fire test for quarter-turn valves | Valves | – |
| API 608 | Metal ball valves | Valves | – |
| API 609 | Butterfly valves: double-flanged, lug and wafer | Valves | – |
| API 650 | Welded steel tanks for oil storage | Tanks | – |
| API 510 | Pressure vessel inspection code (in-service) | Testing & inspection | – |
| API 570 | Piping inspection code (in-service) | Testing & inspection | – |
| API 1104 | Welding of pipelines and related facilities | Welding | – |
Subjects are short summaries, not official titles. Always buy the current edition from the issuing body; check which edition your project specification names.
Frequently asked questions
Which API standards cover piping?
API 5L (line pipe); API 5CT (casing and tubing); API 6A (wellhead and christmas tree equipment); API 6D (pipeline and piping valves); API 594 (check valves: flanged); API 598 (valve inspection and testing) and others listed on this page.
Last updated 2026-11-02