API 5L PSL1 / PSL2 Line Pipes

The API 5L specification covers pipes to conveying oil, gas, water in the petroleum, gas and water distribution industries.

API 5L pipes may be classified according to the following criteria:

  • execution: seamless or welded (seamless pipes may be used up to 24 inches, LSAW above 24 inches, ERW up to 20 inches)
  • specification level (API PSL1, PSL2): PSL1 is a standard quality used for pipelines, whereas PSL2 sets more stringent chemical, mechanical properties, and testing requirements
  • surface finish: black, varnish painted, anti-rust oil, galvanized, coated externally (3PL) and/or lined internally
  • ends types: plain, beveled, threaded ends

The main advantages of API 5L pipe are:

  • Resistance to cracking forces that may propagate in long pipelines
  • Sour service suitability
  • Rather inexpensive and long service life (at least grades B, X42)

Size Range

API 5L pipes are available in dimensions between from 2 to 28″  (seamless execution) and up to 80″ in welded execution (generally, LSAW i.e. longitudinal submerged arc welding).

The API 5L and ASME B36.10 pipe dimensions and weights are, in fact, identical.

API 5L PIPE CHEMICAL AND MECHANICAL PROPERTIES

The yield strength of an API 5L pipe is specified with the number that follows the X in the material grade designation (in kilopounds per square inch – i.e. KSI). So, for instance, an API 5L X52 pipe has a minimum yield strength of 52 KSI.

The table shows the chemical composition of API 5L steel pipes PSL1 and PSL2 from Grade A to Grade X70, as well as their mechanical properties.
Source: API 5L specification

API 5L Equivalent Grades (ASTM, EN, DIN)

Material grades A53 Gr. B and A106 Gr. B, and also API 5L Gr. X42, are API 5L Gr. B equivalent. It is actually quite common to find on the market pipes that comply, at the same time, with all these specifications (“quadri-norm” marked pipes). While this is true in terms of chemical and mechanical properties, note that the API 5L specification sets more severe requirements and tests than those set for the two equivalent ASTM specifications.

In terms of comparison with EN pipe standards, API 5L Gr. B equivalents are EN 10216-1 P265GH (seamless) and EN 10217-1 P265 (welded) – whereas EN 10216-2 P265 GH is the EN equivalent grade for ASTM A106 Gr. B pipes.

Line Pipe Materials: Werkstoff vs EN vs API
Werkstoff/DIN EN API
1.0486   StE 285 – API 5L Grade X42
1.0562   StE 355 P355N API 5L Grade X52
1.8902   StE 420 P420N API 5L Grade X60
1.8905   StE 460 P460N API 5L Grade X70
High Yield Steel Pipes
1.0457   StE 240.7 L245NB API 5L Grade B
1.0484   StE 290.7 L290NB API 5L Grade X42
1.0582   StE 360.7 L360NB API 5L Grade X52
1.8972   StE 415.7 L415NB API 5L Grade X60
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