What is the difference between EN10208 steel pipe for onshore and offshore applications?

Understanding EN 10208: A Quick Overview

EN 10208 is the European standard that defines the technical delivery conditions for seamless and welded steel pipes used in the transport of combustible fluids, primarily natural gas. The standard is split into two parts that engineers and procurement teams often mix up: EN 10208-1 (Pipes of Requirement Class A) and EN 10208-2 (Pipes of Requirement Class B). A common question that comes up in pipeline projects is which part applies to onshore lines and which one to offshore lines. The short answer is that the EN 10208 series is designed mainly for on-land pipeline systems, and offshore pipelines generally fall under a different set of standards such as ISO 3183 and API 5L. Understanding the boundary between these standards — and the practical differences between Class A and Class B — is what determines whether a line pipe will be accepted by the end user, the certification body, and the inspection team on site.

What EN 10208-1 Is Used For

EN 10208-1 covers steel pipes for the on-land transport of combustible fluids, primarily in gas supply systems such as distribution networks, city gate stations, and low-to-medium pressure transmission mains. It excludes pipeline applications in the petroleum and natural gas industries, which are covered by ISO 3183, and excludes cast pipes. Class A is the entry-level requirement class within the EN 10208 family, with less stringent quality and testing requirements than Class B. The grade range typically covers L245 up to L485, and the standard applies to both seamless and welded products.

In practical terms, EN 10208-1 is the right choice when the pipeline runs above ground or is buried on stable land, where operating pressure, population density, and fracture-consequence risk are moderate. One characteristic that surprises many buyers is that no mandatory Charpy V-notch impact energy requirement is specified in EN 10208-1. This makes Class A pipes cost-effective for utility gas distribution but limits their use in colder climates or in more demanding transmission service where ductile-fracture arrest is required.

What EN 10208-2 Is Used For

EN 10208-2 covers the same family of seamless and welded steel pipes — unalloyed and alloyed, excluding stainless — but at a higher requirement level. It is intended for the transmission of combustible fluids in onshore cross-country pipelines, gathering lines, and high-pressure gas transmission systems. Class B includes stricter chemical composition limits, tighter mechanical property verification, and full traceability with mill test certificates. The grade range is again L245 to L485, but the testing regime is significantly heavier.

The big difference is the addition of mandatory Charpy V-notch impact testing at a specified test temperature. The impact energy values in EN 10208-2 are derived from EPRG (European Pipeline Research Group) recommendations and are written specifically to prevent long running shear fracture in pipelines transporting clean, dry natural gas. The standard also sets a weld efficiency factor of 1.0 for welded pipes of Class B, which means the welded joint is qualified to the full pipe body strength. For two-phase fluids, rich gas, or sour service, additional testing beyond the standard minimum may still be required by the designer.

Does EN 10208 Cover Offshore Pipelines?

This is where the title question becomes interesting. Strictly speaking, the EN 10208 series — both Part 1 and Part 2 — is written for on-land (onshore) gas pipelines. The standard itself states that pipeline transportation systems within the petroleum and natural gas industries are covered by ISO 3183, and that for offshore applications and other applications outside the scope of EN 10208-1 and 10208-2, other standards may be applicable. The most commonly used standards for offshore line pipe are ISO 3183 (the international standard for oil and gas pipeline transportation systems) and API 5L, often specified at PSL 2 level for the risers, flowlines, and trunklines that run subsea.

Offshore pipe is exposed to conditions that onshore pipe rarely faces: external hydrostatic pressure from the water column, internal pressure from production fluids, low-temperature service in deep water, fatigue from wave and current loading, and the need for corrosion-resistant line pipe coatings and anodes. These conditions drive additional requirements that the EN 10208 series does not address, including sour-service limits (HIC, SSC), strain-based design provisions, and tighter dimensional tolerances for pipeline laying. For these reasons, EN 10208 is rarely called out as the primary standard for offshore line pipe, even though the steel-making and basic pipe-making routes are very similar.

Key Technical Differences at a Glance

Looking at the two parts side by side, the main differences come down to scope, testing intensity, and intended service environment.

Scope. EN 10208-1 is for on-land gas supply systems with lower pressure and lower consequence of failure; EN 10208-2 is for transmission pipelines for combustible fluids on land with higher operating pressure. Both are onshore standards. Offshore line pipe should be specified against ISO 3183 or API 5L, not EN 10208.

Requirement class. Class A in Part 1 is the lower bar; Class B in Part 2 is the higher bar. For projects that already reference EN 10208 steel pipe in their material requisition, Class B is the more common choice for transmission service.

Charpy impact testing. Part 1 has no mandatory impact requirement; Part 2 has explicit Charpy V-notch values aimed at preventing long running shear fracture in clean, dry natural gas service.

Weld efficiency. Welded pipes in Part 2 are evaluated with a weld efficiency factor of 1.0, allowing the weld to develop full pipe body strength under qualifying procedures.

Traceability and documentation. Class B requires full MTC traceability including heat treatment, NDT coverage, and chemical analysis; Class A allows a lighter documentation package.

Relationship to ISO 3183. EN 10208-1 has effectively been replaced by EN ISO 3183:2013 in many procurement specifications, with the bulk of its requirements carried forward into ISO 3183 PSL 1 and PSL 2. EN 10208-2 content maps closely to ISO 3183 PSL 2 with additional European-specific clauses.

How to Choose the Right Pipe for Your Project

The selection should start with the design code, not the pipe standard. For a city gas distribution main operating below 16 bar, EN 10208-1 is generally sufficient and is the most economical option. For a cross-country gas transmission line operating at 40 to 80 bar, EN 10208-2 is the right baseline, and additional clauses on impact test temperature, supplementary testing, and sour service should be added by the project specification when the service conditions demand them.

For offshore developments — subsea flowlines, risers, trunklines, and export pipelines — specify against ISO 3183 or API 5L at PSL 2, with project-specific supplements covering strain capacity, fatigue, sour service (if applicable), and coating requirements. If the project crosses a beach or landfall and the line transitions between offshore and onshore sections, the offshore portion stays on ISO 3183/API 5L and the onshore portion can use EN 10208-2, with a clear material take-off boundary at the landfall valve station.

At EZ Steel Industrial, we supply L245 to L485 grade EN 10208 seamless and welded steel pipes for gas and oil transport, with documented MTCs, hydrostatic testing, and full NDT coverage to support both Class A and Class B deliveries. The same manufacturing and inspection resources are also used to produce ISO 3183 PSL 1 and PSL 2 pipe for offshore and cross-country pipeline projects, so buyers who need both onshore and offshore pipe from a single source can consolidate their material list with one mill package.

Final Thoughts

The cleanest way to remember the boundary is this: EN 10208-1 is the light-duty onshore gas pipe specification, EN 10208-2 is the heavy-duty onshore gas pipe specification, and offshore line pipe belongs to ISO 3183 or API 5L. Choosing the wrong part of the standard is one of the most common reasons for material rejection at the receiving warehouse, and the fix is almost always to upgrade to Class B, add explicit Charpy impact requirements, or move the offshore portion to a standard that was actually written for subsea service. When in doubt, the design code, the operating pressure, the test temperature, and the service fluid should drive the choice — not the project country or the mill's standard catalogue page.