EN10225 S355G8+M Offshore Steel Plates

Britannia Offshore Platform built with Dillinger S355G8+M TMCP Steel

Britannia Offshore Platform built with Dillinger S355G8+M TMCP Steel

EN10225 S355G8+M is a weldable structural steel for offshore structures. We hold a large stock of it together with stocks of other TMCP steels for offshore use, including S355G10+M.

Unlike many of the lower EN10225 steels S355G8+M is thermomechanically rolled and quite different to the EN10025 steels due to the addition of Nickel, Chromium and Molybdenum for the corrosion resistant properties.

For customers requiring S355G8+N we also have a large stock available with even thicker plates than S355G8+M

S355G8+M Z35 is available. Some plates are Z35 through tested at the mill according to Option 13 and come with a  Z35 designation on the MTC – S355G8+M Z35. Other plates that come without the additional Z35 test can be tested with 3rd party verification quickly and efficiently. With our stock of Dillinger plates the additional through thickness testing is reliable due to the excellent P and S values of the steel

Other offshore grades available include S355G10+MAPI 2W-50, S420G2+MS460G2+M and S460ML

Key Benefits of Buying S35G8+M from Oakley Steel

The key benefits of buying S355G8+M and S355G8+N plates from Oakley Steel are that:

  • We have a very high availability of plates on an ex-stock basis. We can deliver most requirements from our out capacity
  • S355G+M plates are the best quality from Dillinger Hutte. This means a very clean steel and physical properties that are generally better than that required by EN10225
  • Thick plates – lot of the S355G8+N and S355G10+M plates are very thick – up to 150 mm – which save significant delivery time over a mill order – and if you need several we are normally able to supply thick plates for a whole MTO.

S355G8+M Stock

S355G8+M is available ex-stock

  • Thickness:10 – 100 mm
  • Width: Up to 3.5m
  • Length: Up to 12m

S355G8+N Stock

S355G8+M is available ex-stock

  • Thickness:10 – 150 mm
  • Width: Up to 3.5m
  • Length: Up to 12m


All S355G8+M plates are according to EN10225:2009 or later. (EN10225:2001 is withdrawn)


  • Standard Number: EN10225
  • S – from structural
  • Minimum Yield at <16 mm: 355 MPa
  • G8 – to designate the steel grade
  • Thermomechanically Rolled: +M

Typical Mill

  • Dillinger Hutte
    • Dillingen
    • Dunkirk


  • Surface: EN10163-B3
  • Thickness: EN10029:10-B
  • Length & Width: EN10029:10
  • Flatness: EN10029:10-T5L

Manufacturing Process

  • Vacuum degassed
  • Full killed
  • Fine Grain Treated

Mill Tests

  • Tensile Test
  • Hardness Test
  • Impact Test: -40C or -50C
  • Deep Etch Test
  • Drop Weight Test
  • Through Thickness: EN10164 Z35
  • UT: EN10160 S1

Chemical Composition – Heat Analysis

  • Max CEV: 0.43
  • Max Pcm: 0.24
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Mechanical Properties of Offshore Steel Grades

GroupSteel GradeNumberTensile Strength <40mmTensile Strength 40<100mmYield Strength
<16mm16-25mm25-40mm40-63mm63-100mmMinimum ElongationCVN TemperatureCVN EnergyMax Thickness
3S355G8+M1.8810+M470 to 630470 to 63035535534533532522%-40C50J100mm
3S355G10+M1.8813+M470 to 630470 to 63035535534533532522%-40C50J100mm
3S420G2+M1.8857+M500 to 660480 to 64042040039038038019%-40C60J100mm
3S460G2+M1.8887+MApprox 520 to 700Approx 500 to 675460440420415405 (63 to 80)
400 (80 to 100)
This table provides the main features of the mechanical properties of different offshore grades as required by the relevant standards. It is not complete as we have not included many of the minor use cases. These may have a major impact in your application so please use this for reference purposes only and refer to an original and upto date copy of the relevant standard.

MTC Possibilities

  • EN10204:2004  3.1
  • EN10204:2004 3.2
  • EN10204:1991+A1:1995 as per ISO10474:1991

Typical 3rd Party Inspector

  • Lloyds Register of Shipping (LRS)
  • Det Norske Veritas (DNV)

You can purchase a copy of EN10225 from BSI


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