Abnormal pressure rise of gate valves
may happen in many applications and the reason can be classified into this two aspects: the system media changed from cold into hot after the boot; the gate is off in the cold state and on in hot state. Therefore, if there is no action to be taken to protect the system, huge destruction from the abnormal pressure rise is almost inevitable and the following is the hazard:
(1) Damage to the valve itself
Normally, the strength of the valve housing, cover and other parts of the stem is decided by the nominal pressure. When the pressure is increased abnormally, the opening pressure will be double increased as well, resulting in the use stress of the related parts raised exponentially. When the actual stress of the material exceeds the allowable stress, a fracture failure will be occurred in high stress areas and cause the valve
can not be opened, or even damaged or scrapped.
(2) Damage to the system security
Obviously, it is very dangerous for the housing, cover and other pressure parts to over the pressure. Once overpressure, its weak part may be perforated, causing leaking problems; also its packing and seal sites are likely to be rushed out of the high-pressure fluid and make the media leak out. If the media were high temperature gases, toxic gases or harmful gases, the consequence would be more serious, even cause injury to the equipment and personnel.
(3) Huge losses to the production control process
Normal switch of a valve is the key to all types of industrial process control, once this control can not be achieved, the system will be paralyzed, which will result in huge director indirect losses.