# API 5L PSL1 vs PSL2: grades and requirements > API 5L PSL2 adds tighter chemistry, strength limits, mandatory Charpy tests and heat traceability over PSL1. Grades B to X70 in psi and MPa. URL: https://jjprojectsok.com/knowledge/api-5l-psl1-vs-psl2 Español: https://jjprojectsok.com/es/knowledge/api-5l-psl1-vs-psl2 Updated: 2026-10-16 API 5L PSL2 adds tighter chemistry, strength limits, mandatory Charpy tests and heat traceability over PSL1. Grades B to X70 in psi and MPa. **In short:** API 5L defines two product specification levels for line pipe. PSL1 is the standard quality level, and PSL2 adds tighter chemistry and carbon equivalent limits, both minimum and maximum strength, mandatory Charpy impact testing and heat-based traceability. The grade number follows the minimum yield strength: X52 means a minimum yield of 52,200 psi (360 MPa). ## 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. **PSL1 and PSL2 compared** | 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. **Minimum yield and tensile strength by grade** | 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](https://jjprojectsok.com/knowledge/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](https://jjprojectsok.com/knowledge/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. > An annex does not make pipe suitable for every sour environment. The purchaser must define the H2S partial pressure, pH and temperature, as explained in the sour service guide. See [NACE MR0175 / ISO 15156 for buyers](https://jjprojectsok.com/knowledge/nace-mr0175-iso-15156-sour-service). ## 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](https://jjprojectsok.com/knowledge/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](https://jjprojectsok.com/request-a-quote), or see [steel and structural products](https://jjprojectsok.com/products/steel-structural). ## Questions ### What is the main difference between PSL1 and PSL2? PSL2 adds tighter chemistry and carbon equivalent limits, maximum as well as minimum strength, mandatory Charpy impact testing, stricter inspection and heat-based traceability. PSL1 is the baseline quality level. ### What does X52 mean on API 5L pipe? The grade has a minimum yield strength of 52,200 psi (360 MPa) and a minimum tensile strength of 66,700 psi (460 MPa). X52 is the traditional name and L360 is the ISO-style name. ### Is PSL2 required for sour service? Not by itself. Sour service pipe is normally PSL2 ordered to Annex H, but the owner's specification and ISO 15156 decide what is required. Define the environment on the order. ### Is API 5L PSL1 acceptable for plant piping? Only if the piping class allows it. Plant piping is usually A106 or A53 under ASME B31.3, and the design code limits which pipe specifications can be used. ### Can one pipe be both API 5L PSL1 and ASTM A106 Grade B? Yes, when the manufacturer's testing and marking meet both documents, and the certificate lists both. PSL2 and A106 is harder to combine because the requirements differ. ### Which certificate does PSL2 pipe come with? An inspection certificate, typically EN 10204 type 3.1, with results traced to the heat. State the type on the order and name any third-party inspector. ## Sources - [API Specification 5L, Line Pipe (46th edition announcement)](https://api.org/products-and-services/standards/important-standards-announcements/standard-5l) - ISO 3183, Petroleum and natural gas industries: steel pipe for pipeline transportation systems - [Project Materials, API 5L PSL1 vs PSL2](https://blog.projectmaterials.com/quick-answers/pipes/api-5l-psl1-vs-psl2/) - [Project Materials, API 5L pipe grades B to X80](https://blog.projectmaterials.com/pipes/api-5l-pipe) - [ISO 15156-1:2020, Materials for use in H2S-containing environments in oil and gas production](https://www.iso.org/standard/79658.html) ## Related - [Steel and structural](https://jjprojectsok.com/products/steel-structural): Carbon, alloy, stainless and copper plate, sheet, line pipe, tubing, forgings, flanges, fittings, bolting, gaskets and structural steel for industrial projects. - [Oil and gas](https://jjprojectsok.com/industries/oil-gas): Pipe, valves, vessels, exchangers, slug catchers, electrical, instrumentation and safety supply, plus engineering and project support for oil and gas. - [Procurement](https://jjprojectsok.com/services/procurement): Sourcing from manufacturers and authorized distributors, technical and commercial evaluation, purchase-order follow-up, inspection and delivery coordination. - [ASTM A106 vs A53 pipe: which one to specify](https://jjprojectsok.com/knowledge/astm-a106-vs-a53): ASTM A106 is seamless pipe for high-temperature service; A53 also covers welded pipe. Compare grades, strength, service and dual-certified pipe. - [NACE MR0175 / ISO 15156 for buyers](https://jjprojectsok.com/knowledge/nace-mr0175-iso-15156-sour-service): NACE MR0175 / ISO 15156 limits materials and hardness for H2S service to prevent cracking. Learn the three parts, 22 HRC and what a buyer must specify. - [Request a quote](https://jjprojectsok.com/request-a-quote): Request a quotation for steel, valves, refractory, electrical, safety or IT supply, or for engineering and project management. Attach drawings or a list.