What are the ASTM standards for big diameter steel pipe in the oil and gas industry

What counts as a "big diameter" steel pipe?

In plant piping, most carbon steel pipe is supplied in nominal sizes up to roughly 24 inches. Beyond that range—typically from NPS 16 or 20 right up to 60–64 inches and beyond—the piping is generally classed as large diameter. The jump in size changes the manufacturing route: a solid billet can no longer be pierced into a seamless tube economically, so big diameter pipe is almost always produced as welded pipe formed from steel plate or strip. Three welded processes dominate: longitudinal submerged arc welding (LSAW/DSAW), spiral submerged arc welding (SSAW), and high-frequency electric resistance welding (ERW) at smaller large-diameter sizes.

Because the whole length is held together by the weld seam, the standard and the testing regime you choose matter more for large-diameter pipe than for any small size. The selection below reflects that reality.

ASTM A106/A106M: seamless pipe for high-temperature and process service

ASTM A106/A106M covers seamless carbon steel pipe intended for high-temperature service. Grades A, B, and C are specified, with Grade B (minimum yield strength 35 ksi) accounting for the majority of global orders. The standard is written mainly for refinery, petrochemical, and power plant piping governed by ASME B31.3 and B31.1, and it requires a hydrostatic test with tighter carbon and manganese controls than general-purpose grades so that the material retains adequate notch toughness after long-term exposure to elevated temperature.

One practical limitation matters for this discussion: A106 is a seamless-only standard. Because seamless manufacture becomes impractical above roughly 20–24 inches outside diameter, ASTM A106/A106M steel pipe is the natural fit for high-temperature process lines at smaller and mid sizes, while truly large-diameter transmission pipe is covered by welded specifications instead. If your application genuinely needs seamless pipe at a large diameter and high temperature, this is where the physical and economic limits of the standard show up, and a welded option should be evaluated by the responsible engineer.

ASTM A53/A53M: general-purpose seamless and welded pipe

ASTM A53 covers both seamless (Type S) and welded (Type E and F) carbon steel pipe for mechanical and pressure applications. Grade B is the most commonly specified, with the same 35 ksi minimum yield as A106 Grade B, which sometimes leads specifiers to treat the two as interchangeable. They are not: A53 is written for moderate-temperature, moderate-pressure, and general service such as water and steam distribution and light structural duty, while A106 is aimed squarely at high-temperature process piping with stricter chemistry and testing.

For large-diameter oil and gas work, A53 is a minority choice. It appears mainly in smaller lines, fire-protection water systems, and structural applications rather than in big-diameter transmission pipe. Its significance for a specifier is largely in understanding when it is a suitable, economical alternative and when it must not be substituted for a line-pipe standard.

ASTM A671/A672: electric-fusion-welded carbon steel pipe for large diameters

Where large-diameter, electric-fusion-welded carbon steel pipe is needed for elevated or moderate pressure service, ASTM A671 and A672 are directly relevant. Both cover electric fusion arc-welded pipe—longitudinal or spiral seam—in sizes NPS 16 and larger. A671 addresses atmospheric and lower-temperature service, while A672 addresses high-pressure service at moderate temperatures. Each standard is sub-divided by tensile strength class (such as CC60, CC65, and CC70) and by heat-treatment class, so the buyer can specify whether the welded pipe is supplied normalized, tempered, or otherwise conditioned to meet the required properties.

These standards are a common home for fabricated big-diameter pipes used in power, chemical, and water systems. They are, however, less frequently the governing specification for petroleum transmission than API 5L, which remains the industry default for oil and gas line pipe and is examined next.

API 5L and ISO 3183: the governing standards for oil and gas transmission line pipe

Although the question asks about ASTM standards, a complete answer for the oil and gas industry must acknowledge the leading line-pipe specification: API 5L, developed by the American Petroleum Institute and harmonized with the international standard ISO 3183. Except where a project expressly invokes a national code such as GOST or GB/T, most long-distance crude oil, natural gas, and product transmission pipe around the world is ordered to API 5L. For large diameters the standard covers ERW, LSAW/DSAW, and SSAW forms, with API 5L steel pipe in grades from B through X80 available across two product specification levels.

PSL1 provides the baseline chemistry and tensile requirements used for lower-risk gathering and distribution lines. PSL2 tightens the chemistry limits, makes Charpy V-notch impact testing of the weld seam mandatory, and imposes yield-to-tensile ratio limits—requirements that virtually every national pipeline code and major operator demands for high-pressure gas service. Combined with mechanical tests, hydrostatic testing, and, for PSL2, ultrasonic inspection of the seam weld, API 5L gives big-diameter trunk lines the fracture-toughness performance they rely on.

When ASTM standards still apply to big diameter pipe

There are several oil and gas scenarios where an ASTM requirement is written into the project specification even for large-diameter pipe. ASTM A252, for example, covers welded and seamless steel pipe piles used in offshore and onshore foundation and structural support—large-diameter piles in Grade 1, 2, and 3 are a staple of marine and geotechnical works. Likewise, ASTM A671 and A672 are sometimes invoked for big-diameter fabricated piping where the project code permits their use. Finally, many projects adopt hybrid specification strategies: pipe body to API 5L, but fittings, flanges, and welding consumables to ASTM or ASME standards.

The practical takeaway is that "ASTM" and "API 5L" are not rivals but complementary layers. ASTM supplies the process-plant and structural specifications that surround the pipeline, while API 5L supplies the line pipe itself. A well-written material take-off names both where both are needed.

Choosing the right standard for your project

The decision usually comes down to four factors: service temperature and pressure, the applicable piping or pipeline code, the required manufacturing form, and diameter. As a rule of thumb:

• Small-to-mid sizes, high-temperature process service—specify ASTM A106 Grade B.
• General moderate service and structural duty—ASTM A53 Grade B is an economical fit.
• Large-diameter oil and gas transmission lines—API 5L PSL2 X60–X70 in LSAW or SSAW form, harmonized with ISO 3183.
• Large-diameter fabricated pressure piping—consider ASTM A672 (or A671 for lower temperatures) by heat-treatment class.
• Marine and onshore foundations—ASTM A252 steel pipe piles.

If a specification on your material take-off is ambiguous, confirm the governing standard before ordering. Delivering a pipe that meets the chemical and mechanical numbers but not the code's specific testing and documentation requirements can still fail inspection at the weld-procedure and certification stage.

Quality assurance that protects a large-diameter project

Because big-diameter welded pipe carries its entire integrity in the seam, the quality regime is as important as the standard itself. Look for a supplier that combines automated forming lines, CNC machining, robotic and submerged-arc welding, and non-destructive examination such as ultrasonic and X-ray inspection. Hydrostatic testing, positive material identification, and a complete mill test certificate should accompany every heat. At EZ Steel Industrial, more than 12 quality checkpoints are applied across production, supported by ISO 9001 management, API 5L and API 5CT product certification, and PED-compliant documentation—so project teams can verify that every length meets the specified grade, dimension, and test requirements.

Supplying beyond the pipe itself, the company bundles fittings, flanges, gaskets, and fasteners so that a transmission or process project can be sourced as a coordinated package. With manufacture across carbon and alloy steel, stainless steel, and copper-nickel facilities, and staple experience reflected in featured projects from pipeline transmission to petrochemical plants and marine systems, EZ Steel Industrial supports EPC contractors and operators who need dependable large-diameter pipe and the supporting components delivered together.

What to ask your supplier before ordering

A few targeted questions can prevent expensive rework on a large-diameter order. Confirm the exact standard and whether it is PSL1 or PSL2 when API 5L is specified. Ask for the weld type (longitudinal versus spiral) and the heat-treatment class where an ASTM A671/A672 pipe is named. Verify the test scope—hydrostatic, ultrasonic, impact, and positive material identification. Finally, request the mill test certificate and third-party inspection coverage before fabrication so that quality documentation is in place from the start.

Understanding how ASTM standards and API 5L fit together makes it far easier to specify, procure, and inspect big diameter steel pipe with confidence. Get the standard right, pair it with the correct welded manufacturing route, and back it with a full testing and documentation package—and your transmission or process line is built on a specification you can defend to any auditor.