What are PSL1 and PSL2 in API 5L?
- Product specification level (PSL)
- A level in API 5L that sets how demanding the technical requirements are for line pipe. PSL1 is the baseline. PSL2 adds requirements for chemical composition, strength, toughness, non-destructive examination and traceability.
API 5L covers seamless and welded steel pipe for pipeline transportation systems in the petroleum and natural gas industries. It is a pipeline standard, not a plant piping standard, although the same pipe is used in both. The buyer chooses PSL1 or PSL2 on the purchase order.
| Requirement | PSL1 | PSL2 |
|---|---|---|
| Carbon, Grade B seamless (max) | 0.28 % | 0.24 % |
| Phosphorus and sulfur, Grade B (max) | P 0.030 %, S 0.030 % | P 0.025 %, S 0.015 % |
| Carbon equivalent | Not specified | Maximum set per grade (CE IIW or Pcm) |
| Yield and tensile strength | Minimum only | Minimum and maximum, plus a maximum yield-to-tensile ratio |
| Charpy impact test | Not required | Required on the pipe body and, for welded pipe, the weld |
| Non-destructive examination | As the standard requires | More extensive, with stricter acceptance |
| Traceability | Lot based | Heat based |
| Inspection certificate | As agreed in the order | EN 10204 type 3.1 or 3.2 |
| Sour service annex (H) | Not applicable | Available by order |
Figures are the Grade B limits widely published for the 45th and 46th editions. Confirm every number in the edition named on your purchase order.
PSL2 pipe is made to tighter control, so it costs more than PSL1 of the same grade and size. How much more depends on grade, size and market, so request quotes for both levels.
What do grades B, X42 to X70 mean?
In API 5L the number after X is the minimum yield strength in thousands of psi, rounded. X52 is a nominal 52,000 psi, and the standard states the exact value 52,200 psi (360 MPa). The ISO-style name for the same grade is L360, with 360 being the minimum yield in MPa.
| Grade | ISO name | Min. yield, psi (MPa) | Min. tensile, psi (MPa) |
|---|---|---|---|
| A | L210 | 30,500 (210) | 48,600 (335) |
| B | L245 | 35,500 (245) | 60,200 (415) |
| X42 | L290 | 42,100 (290) | 60,200 (415) |
| X46 | L320 | 46,400 (320) | 63,100 (435) |
| X52 | L360 | 52,200 (360) | 66,700 (460) |
| X56 | L390 | 56,600 (390) | 71,100 (490) |
| X60 | L415 | 60,200 (415) | 75,400 (520) |
| X65 | L450 | 65,300 (450) | 77,600 (535) |
| X70 | L485 | 70,300 (485) | 82,700 (570) |
Minimum values from the strength table of API 5L. PSL1 stops at X70; PSL2 also covers X80 and higher grades. PSL2 adds maximum limits not shown here.
A higher grade lets the designer use a thinner wall for the same pressure, which saves steel and weight but demands better welding control. Grades B, X42, X52, X60 and X65 are common choices for oil, gas and water lines.
ASTM A106 Grade B and API 5L Grade B have similar strength, but they are different documents with different testing. See ASTM A106 vs A53.
How do you read a full API 5L designation?
A PSL2 grade carries a letter for the delivery condition: R as rolled, N normalized, Q quenched and tempered, M thermomechanically rolled. A pipe sold as X52N is PSL2, grade X52, normalized. A grade with the suffix S is PSL2 pipe ordered to the sour service annex, and O is PSL2 pipe ordered for offshore service.
Product types appear as SMLS for seamless, HFW for high-frequency welded (called ERW in older documents), SAWL for longitudinal submerged-arc welded and SAWH for helical submerged-arc welded pipe.
A line on an order reads like this: Line pipe, API 5L PSL2, Grade X52N, SMLS, NPS 8, 8.18 mm wall, PE, 12 m random length, EN 10204 3.1. Pipe is ordered by OD and wall thickness; schedule numbers are only shorthand. See Pipe schedules explained.
When do you need PSL2, and what about sour service?
The project specification decides, not the supplier. PSL2 is common for oil and gas flowlines and transmission pipelines, higher-strength grades, low-temperature design and any service where fracture toughness matters. PSL1 is used for water lines, low-pressure gathering and many utility lines where the design basis allows it.
API 5L has annexes for special services. Annex H covers PSL2 pipe ordered for sour service, adding requirements such as hardness and testing for sulfide stress cracking and hydrogen-induced cracking. Annex J covers PSL2 pipe ordered for offshore service. Check the annex letters against your edition.
What should an RFQ for API 5L pipe state?
- API 5L with the edition, PSL level and grade including the delivery-condition suffix
- Product type: seamless or the accepted welded process
- OD and wall thickness (or NPS and schedule), length and end finish
- Special services: sour service (Annex H), offshore (Annex J) or low-temperature toughness
- Extra tests: Charpy temperature and energy, DWTT, hardness, HIC or SSC tests
- Coating, if any, and marking requirements
- Certificate type, EN 10204 3.1 or 3.2, and any third-party inspector
- Quantity, destination and Incoterm
Ask whether the pipe is also certified to another specification such as A106 or A53. Read it on the certificate. See Material test reports.
How can JJ Projects help?
JJ Projects sources line pipe to specifications such as API 5L and ASTM A106, and reviews the documents against your purchase order. Send grade, PSL, size and test requirements through Request a quote, or see steel and structural products.
Sources
- API Specification 5L, Line Pipe (46th edition announcement)
- ISO 3183, Petroleum and natural gas industries: steel pipe for pipeline transportation systems
- Project Materials, API 5L PSL1 vs PSL2
- Project Materials, API 5L pipe grades B to X80
- ISO 15156-1:2020, Materials for use in H2S-containing environments in oil and gas production