How to select, repair and calibrate safety valves in coal chemical system - part one
Coal is chemically processed into gas, liquid and solid fuels and other chemical products. During the production process, the pressure of the medium in the equipment or pipeline rises due to operational errors, mechanical failures, and abnormal chemical reactions. As a safety protection valve, the safety valve is normally closed in the coal chemical system. When the medium exceeds a certain pressure, it is automatically opened. By discharging the medium outside the system to prevent the pressure of the medium in the pipeline or equipment from exceeding the specified value. A safety valve plays an important protective role for personal safety and equipment operation, and is closely related to energy conservation and environmental protection.
Safety valve selection
According to the pressure and medium diversity and complexity of the coal chemical system, the influence of temperature, pressure, medium and other factors in the equipment should be taken into consideration when selecting the safety valve. According to the design requirements, the appropriate safety valve type is configured according to the circulation diameter and diameter of the safety valve. When determining the safety valve, the nominal pressure must be greater than the setting pressure. When the full opening is reached, the pressure should not exceed the nominal pressure of the safety valve. The smaller the spring working pressure range is, the better the safety valve performance will be.
(1) When discharging non-toxic and non-polluting medium, use open-type safety valve with open bonnet if it is allowed to leak to the atmosphere; if it is required to perform regular opening test on safety valve, use safety valve with lifting wrench. When the medium pressure reaches more than 75% of the set pressure, the lift wrench is used to check the flexibility of the valve opening.
(2) Closed safety valves must be used for toxic or flammable media. The bonnet and protective cover gaskets should have a good seal to ensure that the discharged media does not leak. After the safety valve starts to jump, the medium should be discharged according to the specified outlet. At the same time, a gas tightness test is required.
(3) For high back pressure, back pressure balanced safety valve or pilot type safety valve should be used. If necessary, install two safety valves that are mutually standby. The inlet and outlet shut-off valves are preferably mechanical interlocking devices, which can meet the required amount of medium discharge during maintenance.
(4) Corrugated pipe safety valve should be used for medium with high toxicity, strong corrosion and extreme danger. Bellows safety valve uses bellows to isolate spring and guiding mechanism from the medium, and can eliminate the influence of back pressure fluctuation on valve performance. It also protects springs and other internals from media corrosion.
(5) Safety valves with radiators are often used in applications where the medium temperature is high. ① When the operating temperature of the enclosed safety valve exceeds 250 °C and the operating temperature of the open safety valve exceeds 350 °C, a safety valve with a radiator is used; ② When the pressure of the gas medium in the equipment is greater than 3.0 MP and the temperature exceeds 235 °C, a safety valve with a cooling fin is used.
Safety valve repair
When the coal chemical system is unstable, the medium in the equipment is affected by system pressure and temperature changes. Particles and impurities in the medium will rush into the valve body, and some solid impurities will fall on the sealing surface, causing leakage between the valve core and the valve seat, and forming an indentation on the sealing surface, and the medium stored in the sealing surface will corrode. The pit marks caused by corrosion cause continuous leakage or adhesion of the medium and cannot meet the production requirements. At this time, the safety valve should be repaired.
The repair of the safety valve is mainly for the repair of the sealing surface of the safety valve. Most of the safety valves in chemical equipment have residual pungent chemicals after use, so workers should pay attention to their own protection when disassembling. The valve body and the spring of some safety valve are adhered to the medium coagulation. After disintegration, high temperature steam or other non-corrosive cleaning agent should be used to remove the residue. Non-metallic sealing surfaces are generally replaced or turned after being damaged. The metal sealing surface is ground in the case of less severe damage. When grinding, the seat and spool must be ground separately with a flat abrasive. When the sealing surface is damaged seriously or there is obvious damage such as crushing, the grinding paste with a particle size of 300-400 is used for preliminary grinding, and then the grinding paste with a particle size of 600-800 for fine grinding, and finally abrasive paste with a particle size of 1000-1200 is used for polishing. Every time you change the paste, you must use acetone to scrub. When polishing, grind it with a small amount of abrasive paste until it is bright. After grinding, clean the paste on the valve core and sealing surface. Grind several times until the sealing requirements are met.
Safety valve selection
According to the pressure and medium diversity and complexity of the coal chemical system, the influence of temperature, pressure, medium and other factors in the equipment should be taken into consideration when selecting the safety valve. According to the design requirements, the appropriate safety valve type is configured according to the circulation diameter and diameter of the safety valve. When determining the safety valve, the nominal pressure must be greater than the setting pressure. When the full opening is reached, the pressure should not exceed the nominal pressure of the safety valve. The smaller the spring working pressure range is, the better the safety valve performance will be.
(1) When discharging non-toxic and non-polluting medium, use open-type safety valve with open bonnet if it is allowed to leak to the atmosphere; if it is required to perform regular opening test on safety valve, use safety valve with lifting wrench. When the medium pressure reaches more than 75% of the set pressure, the lift wrench is used to check the flexibility of the valve opening.
(2) Closed safety valves must be used for toxic or flammable media. The bonnet and protective cover gaskets should have a good seal to ensure that the discharged media does not leak. After the safety valve starts to jump, the medium should be discharged according to the specified outlet. At the same time, a gas tightness test is required.
(3) For high back pressure, back pressure balanced safety valve or pilot type safety valve should be used. If necessary, install two safety valves that are mutually standby. The inlet and outlet shut-off valves are preferably mechanical interlocking devices, which can meet the required amount of medium discharge during maintenance.
(4) Corrugated pipe safety valve should be used for medium with high toxicity, strong corrosion and extreme danger. Bellows safety valve uses bellows to isolate spring and guiding mechanism from the medium, and can eliminate the influence of back pressure fluctuation on valve performance. It also protects springs and other internals from media corrosion.
(5) Safety valves with radiators are often used in applications where the medium temperature is high. ① When the operating temperature of the enclosed safety valve exceeds 250 °C and the operating temperature of the open safety valve exceeds 350 °C, a safety valve with a radiator is used; ② When the pressure of the gas medium in the equipment is greater than 3.0 MP and the temperature exceeds 235 °C, a safety valve with a cooling fin is used.
Safety valve repair
When the coal chemical system is unstable, the medium in the equipment is affected by system pressure and temperature changes. Particles and impurities in the medium will rush into the valve body, and some solid impurities will fall on the sealing surface, causing leakage between the valve core and the valve seat, and forming an indentation on the sealing surface, and the medium stored in the sealing surface will corrode. The pit marks caused by corrosion cause continuous leakage or adhesion of the medium and cannot meet the production requirements. At this time, the safety valve should be repaired.
The repair of the safety valve is mainly for the repair of the sealing surface of the safety valve. Most of the safety valves in chemical equipment have residual pungent chemicals after use, so workers should pay attention to their own protection when disassembling. The valve body and the spring of some safety valve are adhered to the medium coagulation. After disintegration, high temperature steam or other non-corrosive cleaning agent should be used to remove the residue. Non-metallic sealing surfaces are generally replaced or turned after being damaged. The metal sealing surface is ground in the case of less severe damage. When grinding, the seat and spool must be ground separately with a flat abrasive. When the sealing surface is damaged seriously or there is obvious damage such as crushing, the grinding paste with a particle size of 300-400 is used for preliminary grinding, and then the grinding paste with a particle size of 600-800 for fine grinding, and finally abrasive paste with a particle size of 1000-1200 is used for polishing. Every time you change the paste, you must use acetone to scrub. When polishing, grind it with a small amount of abrasive paste until it is bright. After grinding, clean the paste on the valve core and sealing surface. Grind several times until the sealing requirements are met.
Related News
- Flexible Design of Industrial Pipeline
- Major Safety Facilities in Hazardous Chemical Storage Warehouses
- Intelligent Era: Predictive Maintenance of Valves
- Basic Knowledge of Diaphragm Couplings
- How to Deal with Poor Stability of Pneumatic Valves
- What to Do When the Electric Actuator of an Electric Valve is Overheating?
- Principle of Valve Temperature Controller
- Several operations to avoid during valve installation
- Landee Hosts Successful Visit from Al Prince Engineers, Pakistan
- Chemical Composition and Performance Characteristics of 2507 Stainless Steel Seamless Pipes
News
Newsletter
At XIAMEN LANDEE INDUSTRIES CO., LTD. you will find an extensive range of Industrial Steel Pipe, Steel Plate, Valve, Flange, Pipe Fitting, Fastener, Gasket and other spare parts for industrial use - more than 50 product types available in over 400 sizes and 20 materials, in fact. And our engineers work tirelessly to innovate and improve. We release one new model every month.
Latest News
- Flexible Design of Industrial Pipeline 04 22, 2024
- Major Safety Facilities in Hazardous Chemical Storage... 04 15, 2024
- Intelligent Era: Predictive Maintenance of Valves 04 08, 2024
Useful Links
Contact Us
Mr. Kevin Wang
Tel: 86-592-5204188
Fax: 86-592-5204189
Email: [email protected]
Website: www.landee.cn
Copyright © 1994 - 2024 Xiamen Landee Industries Co., Ltd. All Rights Reserved. Privacy Policy | Terms of Service | sitemap
Website Design & Support: jeawin.com