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Gate Valve Middle Chamber Abnormal Pressure Rise Protection Measures
Release time:
Aug 12,2025
Gate Valve Middle Chamber Abnormal Pressure Rise Protection Measures
一. Hazards of abnormal pressure rise in the middle chamber of the gate valve
1. Valve body damage
Rupture of the valve body: when the pressure in the middle chamber exceeds the strength limit of the material, it may lead to deformation and cracking of the valve body or valve cover.
Seal failure: high pressure will squeeze the valve seat sealing surface, resulting in deformation of the metal sealing surface or soft sealing materials (such as PTFE) tear, resulting in internal or external leakage.
Valve stem jamming: the pressure pushes the gate to squeeze the valve stem, increasing the operating torque, or even causing the valve stem to break.
2．Safety risks
Media Leakage: Leakage of high temperature and high pressure media (e.g., steam, toxic gases) may cause fire, poisoning or environmental pollution.
Valve ejection: In extreme cases, broken bonnet bolts may cause the bonnet to eject, resulting in casualties.
3．System failure
Upstream and downstream equipment impact: a sudden increase in pressure in the cavity may be transmitted to the pipeline or connected equipment, resulting in system overpressure chain reaction.
二．The common causes of abnormal pressure
1.Thermal expansion of the medium: such as liquid media (water, oil) in the closed cavity heat volume expansion, a sudden increase in pressure (liquid water warming 1 ℃ pressure increase of about 0.3MPa).
2.Gasification effect: high temperature liquid vaporization (such as boiler systems), volume expansion hundreds of times.
Bidirectional sealing design: some gate valve gate bidirectional seal will be completely closed in the cavity, exacerbating the pressure buildup.
3.System pressure fluctuations: a sudden rise in upstream pressure (such as pump start and stop) and downstream shutdown.
三．Protective measures
1.Optimization of structural design
Medium cavity pressure relief device: additional pressure relief holes in the valve body or automatic pressure relief valve (such as spring-loaded safety valve), when the pressure exceeds the set value of the automatic release.
Open gate: small holes (such as balance holes) are designed on the gate to allow a small amount of media to pass through to balance the pressure, but attention should be paid to the applicable media (not applicable to the harsh sealing requirements of the working conditions).
Bonnet reinforcement design: using high-strength bolts or thickened bonnet to enhance the pressure-bearing capacity.
2.Materials and process control
Pressure-resistant materials: The valve body is made of high-strength materials (e.g. ASTM A216 WCB upgraded to A352 LCC low-temperature steel or A351 CF8M stainless steel).
Heat treatment process: eliminate casting residual stress, improve pressure resistance.
3.Operation and Maintenance
Avoid half-open state of the valve: pressure is more likely to accumulate in the middle chamber when it is half-open, it should be fully open or fully closed.
Regularly check the pressure relief device: Ensure that the pressure relief valve and exhaust valve function properly.
System pressure monitoring: install pressure gauges or sensors to monitor real-time pressure in the cavity.
4.Special working conditions to cope with
High-temperature media: use jacket insulation or heat dissipation design to reduce the expansion caused by temperature rise.
Low-temperature media: to prevent vaporization of residual liquid after the valve is closed (e.g., LNG valves need to be pre-cooled operation).
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TEL:+8618595868771
E-mail:sales@successmach.com
Address:98-1 Dengfeng Road, Shangjie District, Zhengzhou City, Henan Province