BS EN 10216-1:2013 Standard For Seamless Steel Tubes

The EN 10216 Series: Five Parts Explained

EN 10216-1 is one part of a five-part series covering seamless steel tubes for pressure purposes. Each part targets a different service condition and material family. Selecting the wrong part is the most common specification error engineers make with this series.

For corrosion-resistant pressure tubing, stainless steel seamless tube is specified to EN 10216-5, which covers austenitic, austenitic-ferritic (duplex), and ferritic stainless grades. EN 10216-1 covers only non-alloy carbon steel and offers no corrosion resistance beyond what a protective coating provides.

The welded-tube counterpart to this series is EN 10217 (Welded steel tubes for pressure purposes). When welded manufacturing is acceptable and the cost saving matters, EN 10217-1 is the direct equivalent of EN 10216-1.

TR1 vs TR2: The Two Quality Levels

The TR1/TR2 distinction is the single most important decision in EN 10216-1. It determines whether the tube supports PED compliance, whether impact testing is mandatory, and which inspection document you receive.

The practical rule: if the tube goes into pressure equipment that must carry a CE mark under the Pressure Equipment Directive, specify TR2. TR1 grades explicitly do not support the Essential Requirements of the New Approach Directive 97/23/EC. TR1 is appropriate for non-PED applications, structural pressure use, and markets outside EU regulatory scope.

BS EN 10216-1 Steel Grades

The standard covers three steel grades, each available in both TR1 and TR2 quality. The designation follows EN 10027-1: the letter P indicates pressure purposes, the number indicates minimum yield strength in MPa for the thinnest wall section, and the TR suffix indicates the quality level.

Chemical Composition of BS EN 10216-1

Chemical composition is defined as cast analysis in Table 2 (TR2) and Table 3 (TR1) of the standard, expressed in % by mass. Two elements differ between the quality levels: sulfur is tighter in TR2 (0.015% vs 0.020%), and TR2 requires a minimum aluminium content of 0.020% for grain refinement.

Note on aluminium: the 0.020 % minimum total aluminium for TR2 is not applicable where the steel contains a sufficient amount of other nitrogen binding elements, which must then be reported. Aluminium is specified as a minimum for grain refinement and nitrogen fixing, not as a maximum residual limit.

Note: Steels must be fully killed, and this excludes rimming, balanced, and semi-killed steel. The open hearth (Siemens-Martin) process is not permitted unless combined with secondary steelmaking or ladle refining. The 0.70% combined cap on Cr + Cu + Mo + Ni prevents residual element accumulation from scrap-based steelmaking that would compromise weldability.

Product analysis tolerances (Option 3) permit the following deviations from the cast analysis limits of Tables 2 and 3.

Mechanical Properties of BS EN 10216-1

Mechanical properties are defined in Table 5 (TR2) and Table 6 (TR1). Tensile and elongation requirements are identical for both quality levels. The difference is that TR2 adds mandatory impact energy requirements. Yield strength decreases as wall thickness increases, reflecting the reduced cooling rate and coarser grain structure in thicker sections.

Tensile Properties (TR1 and TR2)

Upper yield strength varies by wall thickness; tensile strength and elongation are constant across the thickness range.

Impact Properties (TR2 Only)

Charpy V-notch impact testing is mandatory for TR2 at 0 °C (32 °F). The minimum average absorbed energy from three test pieces is listed below. TR1 grades carry no impact requirement.

Note: The mean of three test pieces must meet the specified value. One individual value may fall below, provided it is not less than 70% of that value. For wall thickness greater than 60 mm, mechanical properties are subject to agreement between purchaser and manufacturer.

Delivery Conditions and Manufacturing

All tubes are manufactured by a seamless process. The delivery condition depends on the forming operation and the quality level.

Option 1 allows the purchaser to require normalised or normalising-formed delivery condition for hot-formed TR1 tubes, removing the manufacturer’s discretion to supply in the as-formed condition. Cold-finished tubes are always normalised regardless of quality level, because cold working introduces residual stress and directional properties that normalising removes.

Dimensions and Tolerances

Tubes are delivered by outside diameter (D) and wall thickness (T). Preferred dimensions are selected from EN 10220 and listed in Table 7 of the standard, covering outside diameters from 10.2 mm to 711 mm and wall thicknesses from 1.6 mm to 100 mm. Dimensions outside Table 7 may be agreed.

Diameter and Wall Thickness Tolerances (Table 8)

Out-of-roundness is included in the outside diameter tolerance; eccentricity is included in the wall thickness tolerance. Wall tolerance depends on the T/D ratio.

Note: For outside diameters D ≥ 355.6 mm, the upper wall thickness may be locally exceeded by a further 5% of the wall thickness T. This local allowance accommodates the mandrel and roll wear patterns inherent in large-diameter seamless tube production.

Length Tolerances (Table 9)

Unless Option 8 is specified, tubes are delivered in random lengths with the range agreed at enquiry. For exact lengths (Option 8), the tolerances are strictly over-only:

Straightness and End Preparation

Deviation from straightness shall not exceed 0.0015 L for any tube length L, and deviation over any one metre shall not exceed 3 mm. Tubes with wall thickness up to and including 3.2 mm are delivered with square cut ends, free from excessive burrs. Option 7 covers tubes with wall thickness above 3.2 mm, which are delivered with bevelled ends at a 30° (+5°/−0°) angle and a 1.6 ± 0.8 mm root face. For wall thickness greater than 20 mm, an alternative bevel may be agreed between purchaser and manufacturer.