GB/T 712-2022 English PDF (GBT712-2022)

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GB/T 712-2022: Structural steel for ship and ocean engineering
GB/T 712-2022
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 77.140.50
CCS H 46
Replacing GB/T 712-2011
Structural Steel for Ship and Ocean Engineering
ISSUED ON: OCTOBER 12, 2022
IMPLEMENTED ON: MAY 1, 2023
Issued by: State Administration for Market Regulation;
Standardization Administration of the People’s Republic of China.
Table of Contents
Foreword ... 3
1 Scope ... 5
2 Normative References ... 5
3 Terms and Definitions ... 7
4 Classification and Designations ... 7
5 Order Content ... 8
6 Dimensions, Shapes and Weights ... 8
7 Technical Requirements ... 9
8 Test Methods ... 21
9 Inspection Rules ... 23
10 Packaging, Marking and Quality Certificate ... 26
Appendix A (informative) Correspondence of Each Steel Grade and Designation
Specified in the Regulations of Each Classification Society ... 27
Appendix B (normative) Steel Designations, Delivery Status and Batch Size for Impact
Test ... 31
Foreword
This document was drafted in accordance with the rules provided in GB/T 1.1-2020 Directives
for Standardization - Part 1: Rules for the Structure and Drafting of Standardizing Documents.
This document serves as a replacement of GB/T 712-2011 Ship and Ocean Engineering
Structural Steel. In comparison with GB/T 712-2011, apart from structural adjustments and
editorial modifications, the main technical changes are as follows:
a) The applicable thickness range of structural steel for ocean engineering is modified
(see Chapter 1; Chapter 1 of Version 2011);
b) A total of 3 steel grades and 10 designations of ultra-high strength 790, 890 and 960
are added (see Chapter 4);
c) The requirements for the average thickness of steel plates are added (see 6.1);
d) The requirements for the chemical composition of ultra-high strength grade steel are
modified (see Table 4; Table 4 of Version 2011);
e) The requirements for carbon equivalent of ultra-high strength steel are added (see
Table 5);
f) The requirements for vacuum degassing treatment of ultra-high strength grade steel
with through-thickness properties and 690, 790, 890 and 960 grade steel with non-
through-thickness properties are added (see 7.2);
g) The requirements for the rolling compression ratio of continuous cast billets and steel
ingots are added (see 7.2);
h) The requirements for the mechanical properties of ultra-high strength grade steel are
modified (see Table 7; Table 6 of Version 2011);
i) The requirements for the grain size of ultra-high strength grade steel are added (see
7.5);
j) The measurement method for the average thickness of steel plates is added (see 8.2);
k) The requirements for the sampling location of ultra-high strength grade steel are
modified (see 8.3; 7.4 of Version 2011);
l) The requirements for the batching of ultra-high strength grade steel are modified (see
9.2; 7.3 of Version 2011);
m) The requirements for impact inspection lot of ultra-high strength grade steel are
modified (see Appendix B; Appendix A of Version 2011);
Structural Steel for Ship and Ocean Engineering
1 Scope
This document specifies the classification and designations, order content, dimensions, shapes,
weights, technical requirements, test methods, inspection rules, packaging, marking and quality
certificate of structural steel for ship and ocean engineering.
This document is applicable to steel plates (with a thickness of not greater than 150 mm) for
the manufacturing of hull structures, such as: ocean-going, coastal and inland navigation ships
and fishing boats, etc., steel plates (with a thickness of not greater than 250 mm) for ocean
engineering structures, steel strips and shear plates with a thickness of not greater than 25.4 mm,
and profile steel with a thickness of not greater than 50 mm or steel bars with a diameter of not
greater than 50 mm (hereinafter referred to as the steel).
2 Normative References
The contents of the following documents constitute indispensable clauses of this document
through the normative references in the text. In terms of references with a specified date, only
versions with a specified date are applicable to this document. In terms of references without a
specified date, the latest version (including all the modifications) is applicable to this document.
GB/T 222 Permissible Tolerances for Chemical Composition of Steel Products
GB/T 223.5 Steel and Iron - Determination of Acid-soluble Silicon and Total Silicon Content -
Reduced Molybdosilicate Spectrophotometric Method
GB/T 223.9 Iron, Steel and Alloy - Determination of Aluminum Content - Chrome Azurol S
Photometric Method
GB/T 223.12 Methods for Chemical Analysis of Iron, Steel and Alloy - The Sodium Carbonate
Separation-diphenyl Carbazide Photometric Method for the Determination of Chromium
Content
GB/T 223.14 Methods for Chemical Analysis of Iron, Steel and Alloy - The N-benzoy-N-
phenylhydroxylamine Extraction Photometric Method for the Determination of Vanadium
Content
GB/T 223.19 Methods for Chemical Analysis of Iron, Steel and Alloy - The Neocuproine-
chloroform Extraction Photometric Method for the Determination of Copper Content
GB/T 223.23 Iron, Steel and Alloy - Determination of Nickel Content - The Dimethylglyoxime
Spectrophotometric Method
GB/T 223.25 Methods for Chemical Analysis of Iron, Steel and Alloy - The Dimethylglyoxime
Analysis of Carbon and Low-alloy Steel (routine method)
GB/T 5313 Steel Plate with Through-thickness Properties
GB/T 6394 Determination of Estimating the Average Grain Size of Metal
GB/T 8170 Rule of Rounding off for Numerical Values and Expression and Judgement of
Limiting Values
GB/T 11261 Steel and Iron - Determination of Oxygen Content - The Pulse Heating Inert Gas
Fusion-infrared Absorption Method
GB/T 17505 Steel and Steel Products - General Technical Delivery Requirements
GB/T 20066 Steel and Iron - Sampling and Preparation of Samples for the Determination of
Chemical Composition
GB/T 20123 Steel and Iron - Determination of Total Carbon and Sulfur Content Infrared
Absorption Method after Combustion in an Induction Furnace (routine method)
GB/T 20124 Steel and Iron - Determination of Nitrogen Content - Thermal Conductimetric
Method after Fusion in a Current of Inert Gas (routine method)
GB/T 20125 Low-alloy Steel - Determination of Multi-element Contents - Inductively Coupled
Plasma Atomic Emission Spectrometric Method
3 Terms and Definitions
The terms and definitions defined in GB/T 1591 are applicable to this document.
4 Classification and Designations
4.1 The classification and designations of the steel shall comply with the stipulations of Table
1. Please refer to Appendix A for a comparison of the various steel grades and designations
specified in the regulations of each classification society.
4.2 When there are requirements for the through-thickness properties of the steel, the symbols
for the required levels of through-thickness properties (Z25 and Z35) shall be added after the
designations in Table 1.
do not hinder the inspection of the surface quality, as well as inconspicuous roughness,
reticulation, scratches and other local defects caused by pressing the iron oxide scales and
rollers, but their depth shall not be greater than 0.3 mm, and the minimum allowable thickness
of the steels shall be guaranteed.
7.6.3 Surface defects of the steels are allowed to be removed by grinding. The cleaned area
shall be smooth and without edges. The thickness reduction shall not b...