At a Glance
Grades
B · X42 · X52 · X65 · X70
Scope
API 5L covers seamless and welded steel line pipe for use in pipeline transportation systems in the petroleum and natural gas industries. It is the dominant pipe specification for transmission, gathering, and distribution pipelines worldwide.
The specification covers pipe in two product specification levels — PSL 1 and PSL 2 — with increasing requirements for chemistry control, mechanical testing, and dimensional tolerances. It encompasses five primary grades — Grade B, X42, X52, X65, and X70 — and three manufacturing methods: seamless (SMLS), electric resistance welded (ERW), and double submerged arc welded (DSAW).
Understanding X-Grades
The X-grade number equals the minimum yield strength in ksi. X52 pipe has a specified minimum yield strength (SMYS) of 52,000 PSI. X65 = 65,000 PSI. This convention makes grade selection straightforward — pick the X-grade that satisfies your pressure design calculation. Higher X-grades allow thinner walls for the same pressure rating, reducing material cost and weight on large-diameter projects.
PSL 1 vs PSL 2
PSL 1 is the base product level — meeting minimum chemical and mechanical requirements. PSL 2 imposes stricter chemistry limits, mandatory Charpy impact testing, tighter dimensional tolerances, and additional NDE requirements. Most serious transmission projects and all sour service applications require PSL 2. The full breakdown is covered in the PSL 1 vs PSL 2 breakout module.
PSL 1 vs PSL 2 — Breakout Module
Chemistry differences · Impact testing · Sour service supplements · When to specify PSL 2
Coming Soon
Key Notes
API 5L is a line pipe standard — not a plant piping standard. For plant and process piping governed by ASME B31.3, the default specification is A106 or A53. API 5L is appropriate when a project is designed to ASME B31.4, B31.8, or equivalent pipeline codes.
Dual certification: API 5L Grade B can be dual certified to ASTM A53 Grade B and/or A106 Grade B when the pipe meets the chemistry and mechanical requirements of both standards. This is common and commercially available.
End finishes: Plain End (PE), Beveled End (BE), or Threaded End (TE). BE is standard for pipeline construction — the 30° bevel is specified for field butt welding. PE is used where ends will be field-cut or coupled.