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In European structural steel grades, the letter S means structural steel. The number usually refers to the minimum yield strength level for the lower thickness range of the product.
For hollow sections, the complete grade name normally includes the toughness designation and the letter H, such as S235JRH, S275J0H, or S355J2H. Buyers may search for S235JR, S275JR, or S355JR, but for EN 10219 and EN 10210 hollow sections the H designation should be confirmed in the order.
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Base grade |
Common hollow section grades |
What the suffix means |
Buyer note |
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S235 |
S235JRH |
JR: impact energy at +20 C; H: hollow section |
Baseline option for lighter structural work. |
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S275 |
S275J0H, S275J2H |
J0: impact energy at 0 C; J2: impact energy at -20 C; H: hollow section |
Middle grade used where S235 is not enough but S355 is not required. |
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S355 |
S355J0H, S355J2H, S355K2H |
J0/J2/K2 indicate toughness class; H indicates hollow section |
Most common higher-strength choice for columns, piling, and export projects. |
Typical chemical composition and mechanical property comparison for EN hollow section enquiries is shown below. Values are simplified buyer-reference figures; the mill test certificate and the exact EN 10219 or EN 10210 order condition control the final acceptance.
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Grade group |
Typical max C % |
Typical max Mn % |
Typical max P/S % |
CEV note |
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S235JRH |
0.17 |
1.40 |
0.040 / 0.040 |
Lower carbon-equivalent level; generally easier welding. |
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S275J0H / S275J2H |
0.20 |
1.50 |
0.035 / 0.035 |
Higher strength than S235; check toughness class. |
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S355J0H / S355J2H / S355K2H |
0.22 |
1.60 |
0.035 / 0.035 |
Higher strength and CEV limit; welding procedure should be confirmed. |
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Grade group |
Min yield strength class |
Tensile strength range |
Elongation trend |
Typical application fit |
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S235JRH |
235 MPa class |
360-510 MPa |
Highest among the three groups |
Light frames, secondary structures, simple fabrication. |
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S275J0H / S275J2H |
275 MPa class |
410/430-560/580 MPa |
Medium |
Moderate-load structures and regional specifications. |
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S355J0H / S355J2H / S355K2H |
355 MPa class |
470-630 MPa |
Lower than S235/S275 but higher strength capacity |
Columns, piling, heavier hollow sections, export projects. |
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Grade |
General position |
Typical reason for selection |
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S235 |
Baseline structural steel |
Light structures, secondary steelwork, and lower load requirements. |
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S275 |
Middle structural grade |
Moderate structural work or regional specifications where S355 is not needed. |
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S355 |
Higher-strength structural grade |
Common for hollow sections, piles, columns, and export projects. |
S355 gives higher structural capacity than S235 or S275 in many applications. In some designs, it may help reduce section size or weight. However, buckling, deflection, weld design, connection details, and the project code can still control the final section choice.
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Application |
Typical grade choice |
Selection logic |
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Light support frame |
S235 or S275 |
Lower loads and simple fabrication may not justify S355. |
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Building hollow section columns |
S355 |
Higher structural efficiency is commonly useful. |
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Piling pipe |
S355 often specified |
Strength and project acceptance are important. |
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General fabrication |
S235/S275/S355 |
Grade depends on the drawing and load requirement. |
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European export project |
S355J2H often requested |
Common hollow section requirement with toughness confirmation. |
A higher grade is not always the better commercial choice. Buyers should consider availability, welding requirements, coating, inspection, and total project cost.
· Availability: S355 is widely available, but special size, wall thickness, or toughness combinations may need mill production.
· Fabrication: welding, cutting, bending, galvanizing, and coating requirements should be checked before ordering.
· Cost: S355 may cost more per tonne, but it can still be economical if it reduces section weight or simplifies design.
· Lead time: less common grades or toughness classes may increase production and documentation time.
Over-specification happens when a buyer requests a higher grade than the design actually needs. This can increase cost, reduce availability, and delay delivery.
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Confirm before quotation |
Example |
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Product standard |
EN 10219 or EN 10210 |
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Grade and toughness |
S355J2H, S275J0H, or project-specified condition |
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Dimensions |
OD, side length, wall thickness, length, quantity |
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Inspection |
Visual, dimensional, NDT, third-party inspection if required |
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Certificate |
EN 10204 3.1 MTC or other project requirement |
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Substitution rule |
Allowed only with written project approval |
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Question |
Answer |
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Is S355 always better than S235? |
No. S355 has a higher strength level, but S235 can be enough for light structures. The design calculation should decide. |
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Can S275 replace S355? |
Not without approval. If the drawing specifies S355, changing to S275 may reduce structural capacity and project acceptance. |
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What does J2 mean in S355J2H? |
J2 indicates an impact toughness requirement under the relevant standard. The H is commonly associated with hollow sections. |
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What is the ASTM equivalent of S355? |
There is no perfect one-to-one equivalent. Substitution requires technical review because standards, chemistry, testing, and toughness differ. |
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Is S355 the same as API 5L X52? |
No. API 5L is a line pipe standard, while S355 is a European structural steel grade. They should not be substituted without review. |
