API 5L and ASTM A106 are both carbon steel pipe standards — but they serve different purposes and are not interchangeable. API 5L governs line pipe for transmission pipelines; ASTM A106 governs seamless pipe for plant piping. Choosing the wrong spec can cause Aramco document rejection at Goods Receipt. Here is everything you need to know.
Use this table for a fast side-by-side overview. Detailed sections below cover each standard in depth.
| Criterion | API 5L | ASTM A106 |
|---|---|---|
| Standard body | American Petroleum Institute (API) | ASTM International |
| Primary scope | Line pipe for transmission pipelines (oil, gas, water) | Seamless pipe for high-temperature plant piping service |
| Grades available | Gr. B, X42, X46, X52, X56, X60, X65, X70, X80 | Grade A, Grade B, Grade C |
| PSL tiers | PSL1 (basic) and PSL2 (enhanced chemistry, CVN, NDE) | No PSL tiers — single product specification level |
| Manufacturing method | Seamless or ERW (Electric Resistance Welded) | Seamless only |
| Heat treatment | Not mandatory for PSL1; may be required by grade for PSL2 | Normalized or annealed after hot working (mandatory) |
| CVN impact testing | Not required for PSL1; mandatory for PSL2 at X42 and above | Not required by the standard (may be specified by PO) |
| Typical Saudi Aramco use | Gathering lines, transmission pipelines (SAES-L-032) | Plant piping, utility piping (SAES-L-108) |
API 5L and ASTM A106 Grade B share the same minimum yield strength (241 MPa) and tensile strength (414 MPa), but they are not interchangeable on Saudi Aramco projects. API 5L — published by the American Petroleum Institute — covers both seamless and ERW (Electric Resistance Welded) line pipe for the transportation of hydrocarbons in gathering and transmission pipelines; SAES-L-032 references API 5L PSL2 for all sour-service and offshore pipeline applications. ASTM A106 Grade B is exclusively seamless carbon steel pipe designed for high-temperature plant piping service up to 427°C under ASME B31.3; SAES-L-108 specifies it as the standard carbon steel pipe for Aramco process facilities. In SAEP-347 Annex 4, API 5L pipe carries material number P-002 (ERW) and P-003 (seamless), while ASTM A106 Gr.B seamless is P-001. Specifying the wrong standard triggers documentation rejection at Aramco Goods Receipt inspection.
API 5L — the American Petroleum Institute Specification for Line Pipe — covers seamless and welded pipe used in pipeline transportation systems for oil, gas, and water. The specification is published by API and is the global standard for pipeline line pipe across the Middle East, North America, Europe, and Asia.
API 5L is organized around two Product Specification Levels (PSL) that define progressively stricter chemistry, testing, and NDE requirements:
PSL1 is the entry-level product specification. Chemistry limits are broader, CVN impact testing is not required, and NDE requirements are less comprehensive. PSL1 is suitable for non-sour, non-critical pipeline service where the project specification does not mandate enhanced testing. It is rarely accepted by Saudi Aramco for hydrocarbon service.
PSL2 adds stricter carbon equivalent limits (Pcm and CE), mandatory Charpy V-Notch (CVN) impact testing, mandatory hydrostatic testing, full-length NDE (UT or radiography), and controlled carbon content. For sour service applications (H₂S environments), PSL2 additionally requires HIC (Hydrogen-Induced Cracking) testing per NACE TM0284 and SSC testing per NACE TM0177. Saudi Aramco mandates PSL2 for all hydrocarbon gathering and transmission lines.
| Grade | SMYS (MPa) | SMTS (MPa) |
|---|---|---|
| Grade B | 241 | 414 |
| X42 | 290 | 414 |
| X52 | 359 | 455 |
| X65 | 448 | 531 |
API 5L seamless pipe allows wall thickness tolerances of +20% / −12.5% of the specified wall thickness. ERW pipe has tighter rolling tolerances. PSL2 adds additional dimensional verification requirements at the pipe ends (expanded or cropped) to ensure weld fit-up quality in the field.
For sour service, high-pressure, or cyclic loading applications, seamless is preferred because it eliminates the weld seam as a potential defect initiation site. ERW pipe is acceptable for standard service at lower cost, provided the weld seam is 100% NDE inspected by UT. Saudi Aramco's SAES-L-032 specifies the permitted manufacturing method per service classification.
API 5L pipe for Saudi Aramco projects must be specified to Product Specification Level 2 (PSL2) for sour service and offshore pipeline applications under SAES-L-032. The key differences between PSL1 and PSL2 are: PSL2 has mandatory Charpy impact testing (minimum 40 J at −20°C for X52 and above), stricter chemistry limits on Mn, Si, and Cu, mandatory non-destructive examination on all seam welds for ERW pipe, and a certified maximum hardness of 22 HRC for sour service compliance. Common API 5L grades on Aramco projects include Grade B (248 MPa minimum yield) for process piping, X42, X52, and X65 for pipeline applications. In SAEP-347 Annex 4, ERW API 5L pipe carries material number P-002 and seamless API 5L is P-003. Gulf Union Ozone stocks API 5L PSL2 Grade B seamless and ERW pipe in sizes 1 inch to 24 inch NPS with EN 10204 3.1 mill test certificates and SAEP-347 Annex 4 material number references on every delivery.
ASTM A106 — formally titled Standard Specification for Seamless Carbon Steel Pipe for High-Temperature Service — covers seamless pipe for use in high-temperature and high-pressure plant piping systems. Unlike API 5L, it is exclusively seamless: no ERW or LSAW pipe is permitted under A106.
ASTM A106 specifies three grades with progressively higher minimum yield and tensile strength:
ASTM A106 Gr. B is the workhorse of refinery and petrochemical plant piping in Saudi Arabia. It is specified by Saudi Aramco's SAES-L-108 for general carbon steel piping in sizes NPS ½ through NPS 24, covering normal service temperature range up to approximately 427°C (800°F).
ASTM A106 mandates that pipe manufactured by hot-working processes must be furnished in the normalized or annealed condition, or as hot-finished. This thermal processing requirement ensures a refined, uniform grain structure that provides stable mechanical properties at elevated temperatures — the primary service condition A106 is designed for.
API 5L does not universally mandate heat treatment for PSL1; PSL2 higher grades may require normalizing or quenching and tempering depending on grade and wall thickness.
ASTM International (formerly American Society for Testing and Materials) publishes broad-scope material standards covering metals, plastics, composites, and construction materials across many industries. ASTM standards like A106 define the material composition, mechanical properties, and manufacturing process — but they are industry-agnostic.
The American Petroleum Institute publishes standards specifically for the petroleum industry. API 5L incorporates petroleum-specific requirements — including considerations for sour service, pipeline weld quality, and field installation — that ASTM A106 does not address. This is why A106 is the correct specification for refinery and plant piping, while API 5L is the correct specification for gathering and transmission pipelines.
The selection is primarily driven by the application type and the applicable Saudi Aramco Engineering Standard. Use the following guidance as a starting point — always confirm with your project PO and applicable SAES.
Saudi Aramco's engineering standards clearly delineate the two specifications by application:
Substitution Risk: Procuring ASTM A106 Gr. B when the SAES calls for API 5L PSL2 — or vice versa — is a common procurement error in Saudi Arabia. Both materials will fail Aramco's Goods Receipt inspection for documentation non-conformance. Gulf Union Ozone reviews your material requisition against the applicable SAES before confirming any order.
Choosing between API 5L and ASTM A106 on a Saudi Aramco project is determined by the piping service classification in the piping design basis. Under SAES-L-108, ASTM A106 Grade B seamless pipe is specified for all Category M toxic fluid service and standard Normal Fluid Service process piping inside plant battery limits governed by ASME B31.3. Under SAES-L-032 and SAES-L-450, API 5L PSL2 is required for gathering, transmission, and distribution pipelines outside battery limits governed by ASME B31.4 or B31.8. The design engineer reads the applicable SAES piping class to determine the correct material and SAEP-347 material number: ASTM A106 Gr.B seamless is P-001, API 5L ERW is P-002, and API 5L seamless is P-003. Specifying the wrong standard in the purchase order will trigger rejection at Aramco Goods Receipt inspection, causing project delays and third-party identity testing costs.
API 5L is the American Petroleum Institute specification for line pipe used in transmission pipelines — it covers both seamless and ERW pipe, two PSL levels (PSL1 and PSL2), and grades from Grade B up to X80. ASTM A106 is an ASTM International specification for seamless carbon steel pipe used in high-temperature service plant piping — it only covers seamless pipe in three grades (A, B, C) and has no PSL tiers. API 5L Grade B and ASTM A106 Grade B have similar minimum mechanical properties, but their chemical requirements, testing protocols, and intended service scope differ. They are not direct substitutes without engineering review.
Saudi Aramco specifies both depending on the application. SAES-L-108 (industry piping) typically calls for ASTM A106 Gr. B seamless pipe for plant piping in sizes up to NPS 24. SAES-L-032 (offshore and onshore gathering lines) and pipeline projects specify API 5L pipe, with PSL2 mandatory for sour service or HIC-prone environments. Always check the applicable SAES and Purchase Order — using API 5L where A106 is specified, or vice versa, will result in document rejection at Aramco Goods Receipt inspection.
Not automatically. API 5L Grade B and ASTM A106 Grade B have similar SMYS (35,000 psi / 241 MPa) and SMTS (60,000 psi / 414 MPa), but they differ in carbon content limits, phosphorus and sulfur maxima, heat treatment requirements, and mandatory testing. API 5L PSL2 Grade B includes mandatory CVN impact testing and stricter chemistry limits, making it more demanding than A106 Gr. B in those respects. Substitution requires written approval from the project engineer and, for Aramco projects, compliance with the applicable SAES and SAMSS. Gulf Union Ozone can advise on material equivalency for your specific purchase order.
Gulf Union Ozone stocks API 5L and ASTM A106 pipe in our Jeddah warehouse with EN 10204 Type 3.1 MTCs ready. Send your material specification, size, schedule, grade, and quantity — we confirm availability and issue your quotation within 4 business hours.