The unusual pressure rise of cast steel gate valves happens strikingly and similarly in many relative applications, because the two major factors of its occurrence are similar in lots of industrial systems, that is, the system medium changes from cold state to thermal state after starting up. The gate is closed in cold state and opened in thermal state. Therefore, if no measures are taken for the system, the damage to the system caused by the unusual pressure rise is almost inevitable. This unusual pressure rise of cast steel gate valves has three hazards:
1. The damage to the valve itself
The strength of the valve shell, the bonnet and the valve stem is generally designed according to the nominal pressure of the valve. When the pressure rises abnormally, the opening pressure will increase manyfold. As a result, the service stress of related parts increases manyfold. When the actual stress of the material exceeds the allowable stress, the high stress parts will break and be damaged, causing the valve not to be opened, and the whole valve will be damaged or scrapped.
2. The destruction of system security
Obviously, it is very dangerous when the pressure-bearing parts such as the shell and the bonnet are overpressured. Once overpressure occurs, the weak parts of the pressure element may be perforated first, causing medium leakage. The packing and the self-sealing ring are often washed away by high-pressure fluids, leading to a large amount of medium leakage. When the medium is high-temperature, toxic or harmful gas, it will cause more serious consequences, and even cause damage to the equipment or cause the worker injuries.
3. Huge losses to the production control process
The normal opening and closing of valves is the key to the control of various industrial processes. Once they can't be controlled, shut down maintenance should be done for the system, which will cause huge losses.
1. The damage to the valve itself
The strength of the valve shell, the bonnet and the valve stem is generally designed according to the nominal pressure of the valve. When the pressure rises abnormally, the opening pressure will increase manyfold. As a result, the service stress of related parts increases manyfold. When the actual stress of the material exceeds the allowable stress, the high stress parts will break and be damaged, causing the valve not to be opened, and the whole valve will be damaged or scrapped.
2. The destruction of system security
Obviously, it is very dangerous when the pressure-bearing parts such as the shell and the bonnet are overpressured. Once overpressure occurs, the weak parts of the pressure element may be perforated first, causing medium leakage. The packing and the self-sealing ring are often washed away by high-pressure fluids, leading to a large amount of medium leakage. When the medium is high-temperature, toxic or harmful gas, it will cause more serious consequences, and even cause damage to the equipment or cause the worker injuries.
3. Huge losses to the production control process
The normal opening and closing of valves is the key to the control of various industrial processes. Once they can't be controlled, shut down maintenance should be done for the system, which will cause huge losses.
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