Information details
Direction of pressure relief hole for low-temperature valves
Release Time：
2025-08-21
The direction of the pressure relief hole in cryogenic valves should generally be toward the upstream side when the valve is closed to ensure safe release of abnormal pressure generated by the vaporization of the medium inside the valve cavity.
Basic principles for the direction of pressure relief holes
The design of the direction of pressure relief holes in cryogenic valves should follow the following core principles:
Toward the upstream side when the valve is closed: When the valve is closed, the relief port should connect the valve cavity to the upstream pipeline, allowing vaporized medium to safely flow back to the high-pressure side, preventing overpressure in the valve cavity or medium leakage into the environment.
Avoid directing toward the operating side: Incorrect direction may cause flammable/toxic medium leakage into maintenance areas, leading to safety incidents.
Relief direction for different valve types
Gate valves:
Single-seal gate valves typically have pressure relief holes (e.g., 3mm diameter) on the elastic gate plate, connecting the valve cavity to the upstream pipeline.
Double-seal gate valves require an external pressure-reducing valve, with the pressure relief direction determined by design.
Ball valves and globe valves:
The pressure relief direction must be clearly marked on the process flow diagram, especially when shut-off valves are installed on both ends of a control valve; the pressure relief direction should be opposite the control valve.
Installation and design considerations
Process diagram annotation: The pressure relief direction must be clearly marked on the process flow diagram and reflected in the pipeline isometric drawing.
Structural compatibility: The long-neck valve cover design must ensure that the pressure relief direction aligns with the pipeline flow direction to prevent cold energy from being conducted to the operating components.
Safety verification: After installation, a pressure test must be conducted to ensure the effectiveness of the pressure relief function.
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