GB/T 38520-2020 in English
VALIDMarine cryogenic breakaway coupling
- Issued on:2020-03-06
- Implemented on:2020-10-01
- File Format:PDF
- Delivery:Via email within 5 business days
$301.00
《GB/T 38520-2020船用超低温拉断阀》由TC137（全国船用机械标准化技术委员会）归口，主管部门为国家标准化管理委员会。
Introduction
Interpretation of the core content of the standard
This standard applies to safety devices that can automatically disconnect and seal when the hose transmission system is subjected to abnormal tension during liquefied natural gas (LNG) ship filling and barge operations. The main technical features are as follows:
| Comparison dimensions | Breaking bolt type | Cable disconnection type |
|---|---|---|
| Working principle | Bolt disconnection through preset breaking point | Clamp structure pulled off by safety pin |
| Applicable size (DN) | 16-150 | 16-250 |
| Closing time | ≤3 seconds (all must be met) | |
| Ice resistance | DN≤80 needs to resist 10mm ice layer, ＞80 needs to resist 25mm ice layer | |
Key Technical Requirements
Material Specifications
The valve body must be made of 06Cr17Ni12Mo2 austenitic stainless steel forgings and must pass the -196℃ Charpy V-type impact test (average impact energy ≥ 27J). The seals must comply with the GB/T24925 low-temperature valve material standard.
Performance indicators
- Compressive strength: no deformation or leakage under 2.4MPa hydraulic pressure
- Sealing: no leakage under 0.05MPa/1.76MPa air pressure
- Anti-static: discharge path resistance <10Ω
- Fire resistance: the soft seal remains sealed after burning
Implementation suggestions
Selection guide
For scenarios below DN150, the breaking bolt type structure is preferred, and its breaking force should be ≤ 2/3 of the tensile strength of the connecting hose; for large-size pipelines, the cable disconnection type is recommended, and the disconnection force setting must take into account both safety and prevention of misoperation.
Testing points
The low-temperature sealing test needs to be carried out in a -162℃ liquid nitrogen environment, and the pressure test needs to include 0°, 45°, and 90° multi-angle breakaway verification. The drop test requires three drops from a height of 1.5m without leakage.
Technical evolution analysis
This standard unifies the technical specifications of marine ultra-low temperature breakaway valves for the first time. Compared with traditional valves, it adds:
1) Reliability requirements under icing conditions
2) Multi-directional breakaway force verification
3) 8MPa low-temperature high-pressure impact test
It marks the further improvement of the standard system of supporting equipment for LNG ships in my country.
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