1. Key selection parameters
Material corrosion resistance
Material resistant to hydrogen sulfide corrosion (such as stainless steel 316L, monel alloy) must be selected, because hydrogen sulfide in natural gas can easily cause valve corrosion failure.
It is recommended to use a fully welded structure for the valve body to eliminate the risk of external leakage.
Sealing performance
Soft seal valve: Zero internal leakage must be achieved at 1.1 times the nominal pressure (CJ3055 standard).
Hard seal valve: Allowable internal leakage <0.3DNmm³/s (for example: DN500 valve leakage ≤9ml/min).
Bidirectional sealing design is preferred to avoid medium flow direction restrictions.
Structural design
Full-bore flow channel: Reduce flow resistance to ensure smooth passage of pipeline cleaners/detectors.
Low structure height: Reduce the depth of buried installation and reduce construction costs.
Valve stem direction: Horizontal or vertical upward installation, valve stem downward is prohibited (to prevent medium leakage)
2. Working Condition Adaptation Requirements
| Parameter | Require |
|---|---|
| Work Pressure | ≤4.0MPa(Medium and low pressure conditions) |
| Temperature range | -29℃~121℃(conventional) |
| Medium characteristics | Solid content ≤5%, viscosity ≤600mm²/s |
| Drive mode | Pneumatic (automatic)/manual (emergency cut-off) |
3. Preferred valve type
Eccentric structure: Double eccentric or triple eccentric metal hard-sealed butterfly valve, resistant to high pressure difference, long life, suitable for regulation and cutting.
Operation accessories: Must be equipped with a fully enclosed opening and closing indicator to clearly indicate the valve status and prevent misoperation; it is recommended to install a limit switch or position feedback device.
4. Special considerations
Safety certification: Comply with the CJ3055 "Town Gas Valve Experiment and Inspection" standard, and give priority to API 607 fireproof certified products.
Maintenance convenience: With modular design, seals can be quickly replaced to reduce maintenance downtime.
Installation direction: There is no flow restriction for bidirectional sealing butterfly valves, but one-way sealing valves must ensure that the front of the butterfly plate faces the medium flow direction (the valve body is marked with a flow direction arrow).