GB/T 42669-2023 (English Version)

Standard No.: GB/T 42669-2023
Language: Chinese, Available in English version
Release Date: 2023
Published By: General Administration of Quality Supervision, Inspection and Quarantine of the People‘s Republic of China
Latest: GB/T 42669-2023

Scope: It specifies the grade representation method, ordering content, size, shape, weight and allowable deviation, technical requirements, test methods, inspection rules, packaging, marking and quality certificate of corrosion-resistant bulb flat steel for cargo oil tanks of crude oil ships. It is applicable to corrosion-resistant bulb flat steel for cargo oil tanks of crude oil ships (hereinafter referred to as bulb flat steel).

Introduction

1. Scope and applicability of the standard

This standard specifies the grade representation method, ordering content, size, shape, weight and allowable deviation, technical requirements, test methods, inspection rules, packaging, marking and quality certificate of corrosion-resistant bulb flat steel for cargo oil tanks of crude oil ships. It is applicable to corrosion-resistant bulb flat steel for cargo oil tanks of crude oil ships (hereinafter referred to as bulb flat steel). 0.050 ≤0.40 AH36 C: 0.50, Si: 0.60~1.60, Mn: 0.90~, P: 0.025, S: 0.050 ≤0.40 AH37 C: 0.50, Si: 0.60~1.60, Mn: 1.20~, P: 0.020, S: 0.050 ≤0.38

3. Dimensions and allowable deviations

The allowable deviations of bulb flat steel are divided into four grades according to different nominal sizes, with a maximum deviation range of ±4.0mm (applicable to >300~430mm). The allowable deviation of length is +80mm~-0mm.

4. Mechanical properties requirements

Grade	Yield strength (MPa)	Tensile strength (MPa)	Elongation after fracture (%)	Impact absorption energy (KV2/J)
A	≥235	400~520	≥22	No requirement
AH36	≥315	440~570	≥21	Longitudinal: 31, Transverse: No requirement

5. Surface quality and corrosion resistance

The surface of the bulb flat steel should not have harmful defects such as bubbles, scars, cracks, etc. The corrosion resistance should comply with the China Classification Society's "Guidelines for Inspection of Corrosion Resistant Steel Materials for Cargo Oil Tanks of Crude Oil Tankers" and IMOMSC.289(87).

6. Implementation suggestions

6.1 Suggestions for manufacturers:

Strictly control the chemical composition of raw materials in accordance with the standards, especially the addition of corrosion-resistant elements such as Ni and Cr.
Strengthen the dimensional and surface quality monitoring during the production process to ensure that the products meet the tolerance requirements.
Establish a complete test and inspection system to ensure that the mechanical properties and corrosion resistance indicators meet the standards.

6.2 Recommendations for users:

Specify technical requirements when purchasing to ensure that suppliers provide products that meet standards.
Establish strict acceptance procedures, including chemical composition, mechanical properties and corrosion resistance tests.
Perform regular maintenance inspections to ensure the safety of bulb flats during use.

GB/T 42669-2023 Referenced Document

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 20125 Low-alloy steel.Determination of multi-element contents.Inductively coupled plasma atomic emission spectrometric method
GB/T 2101 General requirment of acceptance, packaging, marking and certification for section steel
GB/T 222 Permissible tolerances for chemical composition of steel products
GB/T 223.11 Determination of chromium content in iron, steel and alloy by visual titration or potentiometric titration
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 223.18 Methods for chemical analysis of iron steel and alloy.The sodium thiosulfate separation iodimetric method for the determination of cupper 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 223.3 Methods for chemical analysis of iron, steel and alloy--The diantipyrylmethane phosphomolybdate gravimetric method for the determination of phosphorus content
GB/T 223.5 Steel and iron.Determination of acid-soluble silicon and total silicon content.Reduced molybdosilicate spectrophotometric method
GB/T 223.54 Iron, steel and alloy—Determination of nickel content—Flame atomic absorption spectrometric method
GB/T 223.60 Steel and alloys - Determination of silicon content - Gravimetric method*， 2024-04-25 Update
GB/T 223.61 Methods for chemical analysis of iron, steel and alloy--The ammonium phosphomolybdate volumetric method for the determination of phosphorus content
GB/T 223.63 Iron, steel and alloy—Determination of manganese content—Sodium (potassium) periodate spectrophotometric method
GB/T 223.64 Iron,steel and alloy.Determination of manganese content.Flame atomic absorption spectrometric method
GB/T 223.67 Iron,steel and alloy.Determination of sulfur content.Methylene blue spectrophotometric method
GB/T 223.68 Methods for chemical analysis of iron, steel and alloy. The potassium iodate titration method after combustion in the pipe furnace for the determination of sulfur content
GB/T 223.69 Iron,steel and alloy.Determination of carbon contents.Gas-volumetric method after combustion in the pipe furnace
GB/T 223.71 Methods for chemical analysis of iron, steel and alloy. The gravimetric method after combustion in the pipe furnace for the determination of carbon content
GB/T 223.72 Iron,steel and alloy.Determination of sulfur content.Gravimetric method
GB/T 223.74 Methods for chemical analysis of iron, steel and alloy. The combustion gravimetric/gas-volumetric method for the determination of combined carbon content
GB/T 223.76 Methods for chemical analysis iron,steel and alloy.The flame atomic absorption spertrometric method for the determination of vanadium content
GB/T 223.78 Methods for chemical analysis of iron,steel and alloy-Curcumin spectrophotometric method for the determination of boron content
GB/T 223.9 Iron,steel and alloy.Determination of aluminium content.Chrome azurol S photometric method
GB/T 228.1 Metallic materials—Tensile testing—Part 1: Method of test at room temperature
GB/T 229 Metallic materials—Charpy pendulum impact test method
GB/T 2975 Steel and steel products - Location and preparation of samples and test pieces for mechanical testing
GB/T 41749 General requirements for surface condition of hot-rolled sections
GB/T 4336 Determination of multi-element content in carbon steel and medium and low alloy steel Spark discharge atomic emission spectrometry (conventional method) Amendment No. 1
YB/T 081 Rule for rounding off of numberical values and judgement of testing values for technical standards of metallurgy

GB/T 42669-2023 history

2023 GB/T 42669-2023 Corrosion-resistant bulbous flat steel for cargo oil tanks of crude oil tankers