Basic knowledge of safety valve

There will be some faults in the process of using the safety valve. The following is a summary of some faults that will occur in the safety valve and the solutions when these problems occur. Common failure causes and troubleshooting methods of safety valve: 1. Safety valve leakage 1) Scale, scale, sundries, etc. fall on the sealing surface, which can be purged or disassembled by manual exhaust (steam). 2) Mechanical damage or corrosion of the sealing surface. It can be repaired or replaced by grinding or grinding after turning. 3) When the spring fails due to excessive load or the spring is reduced due to corrosion, the spring should be replaced. 4) When the valve stem is bent and deformed or the valve core and the valve seat support surface are deflected, the cause should be found out, and the valve stem and other components should be reassembled or replaced. When the lever and fulcrum of the lever type safety valve are deflected, the center line of the lever should be corrected when the force on the valve core and the valve seat is uneven. 2. The safety valve does not act under the adjusted seating pressure 1) The safety valve is not adjusted properly, and the influence of the actual working medium characteristics and working temperature is ignored when adjusting the pressure, and needs to be re-adjusted. The continuous adjustment in the hot state shall not exceed three times. Otherwise, the error of the lifting pressure value is large, and it cannot operate under the normal debugging pressure. 2) The sealing surface is stuck and rusted due to medium pollution or crystallization; the safety valve needs to be purged, and the valve core and valve seat need to be researched in serious cases. 3) The gap between the valve stem and the bushing is too small, and it expands and gets stuck when heated; it is necessary to appropriately increase the gap between the valve stem and the bushing. 4) Improper adjustment or maintenance, the spring contraction of the spring-type safety valve is too tight or the tightness is not enough, the rusted plate of the lever-type safety valve is too heavy or too light, and the safety valve needs to be re-adjusted. 5) The valve passage is blocked by obstacles such as blind plates; the obstacles should be removed in time. 6) The spring is permanently deformed, and the spring should be replaced. 7) Improper selection of safety valve. For example, in the case of large fluctuation of back pressure, an unbalanced safety valve is selected, and the corresponding type of safety valve needs to be replaced. 3. The safety valve is not fully open 1) The nominal pressure selected for the safety valve is too large and the spring stiffness is too large, so the safety valve needs to be re-selected. 2) The adjustment ring is not properly adjusted and needs to be re-adjusted. 3) The friction force of the valve disc in the guide sleeve is too large, and it needs to be cleaned, repaired or replaced. 4) The exhaust pipe of the safety valve is improperly set, and the flow resistance of the gas (steam) body is large, so the exhaust pipe needs to be readjusted. 4. The disc oscillates 1) The gap between the adjusting ring and the disc is too large and needs to be re-adjusted. 2) The discharge volume of the safety valve is much larger than that required by the container, and should be re-selected to match. 3) The load area of ​​the safety valve inlet pipe is too small or the resistance is too large, so that the exhaust (steam) supply of the safety valve is insufficient, and the safety valve inlet pipe needs to be replaced or adjusted. 4) The resistance of the discharge pipe is too large, and the pipeline should be adjusted to reduce the resistance. 5. The valve disc cannot be seated in time 1) The frictional resistance of the valve disc in the guide sleeve is large, the gap is too small or the axis is different, and it needs to be cleaned, repaired or replaced. 2) The opening and seat return mechanism of the valve disc is not adjusted properly and should be readjusted. For the spring-type safety valve, its opening pressure can be adjusted by adjusting the spring pressing force; its return pressure can be adjusted by adjusting the position of the lower adjusting ring. 3) The verticality of the safety valve exceeds the standard, and it is necessary to find the verticality again. 4) Cracks on the sealing surface of the safety valve seat of the boiler and pressure vessel. When the safety valve has never been seated after debugging, it may be that the rainwater enters the safety valve body from the exhaust pipe and causes cold shock with the high temperature medium, resulting in cracks on the sealing surface of the valve seat. It is recommended to install a rain cover on the outlet of the exhaust pipe. At the same time, the cracked valve seat sealing surface is eliminated, and the safety valve is replaced if necessary. In a word, safety valve is an important part of boiler pressure vessel. It is also a fault-prone component. The control of the safety valve of the boiler and pressure vessel is the safety supervision and quality control of the whole process of safety valve selection, installation, commissioning, operation, maintenance and maintenance. If there is an error in a certain link, it may cause an accident in the boiler and pressure vessel. Therefore, for the safety valve of the boiler and pressure vessel, only when the selection, installation, commissioning, operation and maintenance and maintenance of each process are strictly checked, and the requirements of the standards and regulations are carefully implemented, the safety valve of the boiler and pressure vessel must be able to meet the overpressure state of the boiler and pressure vessel. Take off to relieve pressure and protect the safety of its equipment. Thereby ensuring the safe and economical operation of the boiler and pressure vessel. Are there any solutions to these failures?