GB/T 34207-2017 in English
VALIDWide and heavy plates for offshore line pipe
- Issued on:2017-09-07
- Implemented on:2018-06-01
- File Format:PDF
- Delivery:Via email within 1~3 business days
$146.00
《GB/T 34207-2017海底管线用宽厚钢板》由TC183（全国钢标准化技术委员会）归口，TC183SC6（全国钢标准化技术委员会钢板钢带分会）执行，主管部门为中国钢铁工业协会。
Introduction
Standard Background and Significance
GB/T 34207-2017 "Wide and Thick Steel Plates for Submarine Pipelines" is an important standard formulated by China based on the characteristics of the submarine environment. It aims to regulate the production, inspection and application of wide and thick steel plates for submarine pipelines. The standard was proposed by the China Iron and Steel Association and managed by the National Steel Standardization Technical Committee. It is applicable to wide and thick steel plates for submarine pipelines with a thickness of 6mm to 45mm.
Grade representation method
| Grade composition | Example description | Dual grade system |
|---|---|---|
| L450MO/X65MO | L - pipeline steel; 450 - specified minimum total elongation strength (MPa) | For comparison of X series grades, please refer to Appendix A |
Note: The X series grades are derived from API Spec 5L-2012 "Specification for Pipeline Steel Pipes", and a dual grade system is adopted to meet the needs of domestic and foreign markets.
Chemical composition requirements
Table 1 lists the chemical composition requirements for wide and thick steel plates for submarine pipelines, including the maximum mass fractions of major elements such as carbon (C), silicon (Si), and manganese (Mn). Special attention should be paid to the following:
- For every 0.01% decrease in carbon content, the manganese content may be increased by 0.05%, but shall not exceed the upper limit.
- The total aluminum (Alt) content shall not exceed 0.060%, the nitrogen (N) content shall not exceed 0.012%, and Al/N ≥ 2:1 (not applicable to Ti-killed or Ti-treated steels).
Mechanical properties and process requirements
| Grade | Tensile test index (MPa) | Charpy impact test (J) | Drop weight tear test (DWTT) | Vickers hardness HV10 |
|---|---|---|---|---|
| L245MO/BMO | Rt0.5: 245~450; Rm: 415~760 | Single value: 60; Average: 80 | - | ≤230 |
| L450MO/X65MO | Rt0.5: 450~570; Rm: 535~760 | Single value: 90; Average value: 120 | D=2a | ≤260 |
Implementation suggestions and practical applications
1. Chemical composition control: During the production process, the content of key elements such as carbon and manganese should be strictly controlled to ensure that it meets the requirements of Table 1. For special grades, other trace elements can be added by negotiation.
2. Mechanical property verification: Focus on the Charpy impact test and drop weight tear test to ensure that the ductile-brittle transition characteristics under low temperature conditions meet the needs of the seabed environment.
3. Surface quality monitoring: Ultrasonic testing (GB/T 2970) is used to check the steel plates one by one to ensure that there are no defects such as cracks and bubbles. The surface cleanliness must meet the requirements of GB/T 14977.
4. Grain size and inclusion control: Table 4 stipulates that the grain size level of L245MO/BMO~L390MO/X56MO grades shall not be lower than level 7, and the non-metallic inclusion level (A, B, C, D) shall not exceed level 2.0.
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