Gate valves frequently come in single- or double-wedge designs, wedge types, parallel-types, etc. The two that are most frequently used are wedge-type resilient gate valves and double-wedge wedges, both of which produce excellent sealing results.
Due to its excellent double-sided sealing, the central cavity pressure may occasionally increase abnormally. Gate valve
overpressure can have very serious repercussions. The operational stress on the pressure-bearing and operating components
(such as the stem and gate frame) will sharply increase when the central cavity of the valve experiences an abnormal pressure increase.
Problems could arise if the actuator's driving force becomes intolerable. The motor may burn out, the gate frame may break, and the stem may
fracture in severe cases. Many high pressure and large diameter gate valves experience these
phenomena frequently.
Abnormal pressure risks rise by
1. Damage to the valve The valve's nominal pressure is typically used to determine the components 'strength, including the casing, bonnet, and stem.
The opening pressure will rise exponentially when there is an abnormal pressure rise, which will cause the relevant parts 'service stress to double.
High stress areas will fracture and suffer damage when the material's actual stress exceeds the permitted stress, making it impossible for the valve to
open and damaging or scraping the entire valve.
2. System security disruption Obviously, excessive pressure on pressure-bearing components like the shell and valve bonnet is very dangerous. The weak part may first perforate, causing leakage, once there is an
overpressure situation. High-pressure fluid is frequently used to clean the packing and self-sealing ring components, which results in significant leakage. It can get even worse and even harm equipment and personnel when the media is high-temperature, toxic, or harmful gas.
3. The regular opening and closing of valves is essential for various industrial process controls, which results in significant losses to production control
processes. The system will need to be shut down for maintenance once this control is not achieved, which will result in significant losses.
Protection
1. Opening pressure relief holes inside the valve is the most cost-effective and efficient way to address abnormal pressure increases in the middle chamber. On the upstream gate's outer circle and inlet valve seat, pressure
relief holes have been installed. In order to prevent an abnormal pressure rise, the middle chamber's pressure will automatically release toward the upstream
side as the pressure in the chamber rises. This is done by always maintaining a pressure equal to that of the downstream side.
2. To control the pressure range, install a special pressure relief valve outside the gate valve's chamber. Set the main valve's rated working pressure to the
relief valves 'discharge pressure. To keep the main gate valve operating safely, the middle chamber automatically discharges to the set pressure when it is
overpressured. Double seat gate valves are silently killed by abnormal
overpressure, which poses a serious threat to the security of systems and equipment. It is important to take the necessary preventative measures when abnormal
overpressure occurs, especially for gate valves with high temperatures, high pressures, and large diameters.