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Steel For offshore structures, Standards Comparison

Introduction

The requirements on structural steel plates for offshore structures differ because of the varying fields of application and location. Today, there are four major standards existing, beside of the shipbuilding standards,
which describe the severe requirements on structural steel plates for offshore constructions. The standards prEN 10225, BS 7191 and the material data sheets of  NORSOK (Norwegian standard) are primarily applicable in Europe (North Sea).

The API-standard is mainly applied in American and Asian areas. However, the different standards may also be used in other areas. In some parts, the standards correspond to each other. So, the Norsok standard refers to the prEN 10225 which itself is based on the BS 7191. The more the standards approach each other, the easier it will be for the steel fabricator to develop together with the engineering companies improved steel grades in an economic way.

Here you will find a comparison of the steel grade 355 in the delivery conditions normalized (N) and thermo mechanically rolled (TMCP) and also of the steel grades 420, 450 and 460 in the delivery conditions thermo- mechanically rolled and quenched and tempered (Q+T). The comparison is based on the latest revisions of the mentioned standards at the date of this  issue. *) Furthermore, you will find all weldability qualifications of Dillinger Hütte for offshore grades and all approvals for ship-building grades.

*) Remark: In order to ease the use of this document the supplementary requirements of the different standards are not listed. 

Source: Dillinger Hütte

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Grade 355 / API 2H and 2W -  chemical compositions


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Grade 355N - comparison of tensile strength, yield strength and toughness

  BS7191 EN 10225 / NORSOK API 2H Shipbuilding rules
LR / GL / NV etc.
 
355 N 355EM / EMZ S355G2+N S355G3+N S355G7+N
S355G8+N
S355G9+N
S355G10+N
API 2H-50 e. g. E 36 / EH 36
Thick. [mm]

Tensile strength Rm [MPa]

≤25 460 – 620 470 – 630 470 – 630 470 – 630 483 – 620 490 – 620
> 25 ≤40 " " " " " "
> 40 ≤100 '' - '' '' '' ''
> 100 ≤150 '' - - '' '' ''
Thick. [mm]

 Yield Strength ReH [MPa]

≤16  ≥355  ≥355  ≥355  ≥355  ≥355*)  ≥355
> 16 ≤20 '' ≥345 ≥345 '' '' ''
> 20 ≤25 '' '' '' '' '' ''
> 25 ≤40 ≥345 - '' ≥345 '' ''
> 40 ≤63  ≥340 - -  ≥335 '' ''
> 63 ≤80 ≥325 - - ≥325 ≥325*) ''
> 80 ≤100 ≥325 - - '' '' ''
> 100 ≤120 ≥315 - - '' '' ''
> 120 ≤150 ≥305 - -  ≥320 '' ''

*)Rp0.2

  BS7191 EN 10225 / NORSOK API 2H Shipbuilding rules
LR / GL / NV
 
355 N 355EM / EMZ S355G2+N S355G3+N S355G7+N
S355G8+N
S355G9+N
S355G10+N
 
API 2H-50 e. g. E 36 / EH 36
  Minimum Impact Energy Av [Joule] - transverse (average/single) - at a test temperature of
-40 oC -40 oC -40 oC -40 oC -40 oC -40 oC
Surface
All thickness
< 40 mm
< 50 mm
50 / 35
-
-
50 / 35
-
-
50 / 35
-
-
50 / 35
-
-
-
41/34
-
-
-
24/17
Quarter thick.
>40
> 50 < 70
> 70 < 150
-
-
-
-
-
-
-
-
-

-
-
-

41/34
-
-
-
27 /19
34 / 24
Mid-thickness
All thicknesses
> 40 mm
-
50 / 35
-
-
-
-
-
50 / 35
-
-
-
-

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Grade 355 TMCP – comparison of tensile strength, yield strength and Toughness

 

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355 N and TMCP – Comparison of yield to tensile strength ratios

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420/450/460 - chemical compositions


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420 / 450 / 460 TMCP – comparison of tensile strength, yield strength and toughness




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420 / 450 / 460 Q+T – comparison of tensile strength, yield strength and toughness



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420 / 450 / 460 TMCP and Q+T – comparison of yield to tensile strength ratios


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Weldability qualifications of Dillinger Hütte
for different delivery conditions and steel grades *)

N: TMCP: Q+T:
355EM / 355EMZ
Maximum qualified plate
thickness in Dillinger Hütte:
120 mm (According to BS 7191 appendix F + G)
355EM / 355EMZ
Maximum qualified plate
thickness in Dillinger Hütte:
85 mm (According to BS 7191
appendix F + G)
S420G1+Q / S420G2+Q /
S460G1+Q / S460G2+Q

Maximum qualified plate
thickness in Dillinger Hütte:
100 mm (According to EN 10225,if option 18 is chosen)
S355G7+N / S355G8+N /
S355G9 N / S355G10+N

Maximum qualified plate
thickness in Dillinger Hütte:
120 mm (According to EN 10225, if option 18 is chosen)
S355G7+M / S355G8+M /
S355G9+M / S355G10+M

Maximum qualified plate thickness in Dillinger Hütte: 85 mm (According to EN 10225, if option 18 is chosen)
450EM / 450EMZ
Maximum qualified plate
thickness in Dillinger Hütte:
100 mm (According to BS 7191appendix F + G)
  API 2W-50(T)
Maximum qualified plate thickness in Dillinger Hütte: 90 mm (According to API RP2Z, if suppl. S11 is chosen)
 
  S420G1 + M / S420G2+M /
S460G1+M / S460G2+M

Maximum qualified plate thickness in Dillinger Hütte: 100 mm (According to EN 10225, if option 18 is chosen)
 
  450EM / 450EMZ
Dillinger Hütte is qualified up to
100 mm (According to BS 7191 appendix F + G)
 
  API 2W-60
Maximum qualified plate
thickness in Dillinger Hütte: 75 mm (According to API RP2Z, if suppl. S11 is chosen)
*) Several grades require a weldability qualification according to a standard or an approval of a classification company, which is necessary for a delivery.

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Approvals of Dillinger Hütte for shipbuilding grades *)
(examples for E36 / EH36 respectively F40 / FH40)

Grade Classification Company Thickness
[mm]
Delivery
Condition
  • Detailed inquiries concerning approvals are to be
    submitted to our Quality Department.
     
  • This summary is only for information. In case of
    conflicts the original standard has to be applied.
     

  • Individual feasibility and combination of grades are a matter of an inquiry.

     

*) The shipbuilding grades
(e.g. E36 or E40) require a formal approval by the relevant classification company.

ABS-EH36

ABS-AH40
to FH40
ABS
ABS

ABS
≤100
≤65

≤44
TMCP
N

TMCP
BV-EH36
BV-E36
BV
BV
≤80
≤50
TMCP
N
NV-E36

NV-F36
DNV
DNV
DNV
≤100
≤50
≤80
TMCP
N
TMCP
GL-E36 GL
GL
≤250
≤100
N
TMCP
LR-EH36

LR-F36
LR
LR
LR
≤170
≤100
≤70
N
TMCP
TMCP
NV-A420
NV-E420

NV

≤100

TMCP

GL-A40
to E40


GL

≤100

TMCP

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