Pressure relief valve for boiler Setting points The following points should be paid attention to when setting safety valve: (1) When there are gas and liquid two-phase materials in the container, the safety valve should be installed in the gas phase part. (2) When the safety valve is used to…
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Pressure relief valve for boiler
Setting points
The following points should be paid attention to when setting safety valve:
(1) When there are gas and liquid two-phase materials in the container, the safety valve should be installed in the gas phase part.
(2) When the safety valve is used to discharge flammable liquid, the outlet of the safety valve should be connected with the accident tank. When the discharged material is high temperature combustible, the receiving container should have corresponding protective facilities.
(3) General safety valves can be vented in situ. The vent should be higher than 1 m (m) of the operator and should not be directed towards the open flame location, spark emission location and high temperature equipment within 15 m (m). The safety valve vent of indoor equipment and containers should lead out the roof and be over 2 meters (m) above the roof.
(4) When there is a partition valve at the entrance of the relief valve, the partition valve should be in a normal open state and be sealed with lead to avoid mistakes.
Import and Export Pipeline
(1) The cross-sectional area of the connecting pipe and the through-hole of the pipe fittings between the safety valve and the boiler or pressure vessel shall not be less than the import cross-sectional area of the safety valve; if several safety valves share an import pipe, the flow cross-sectional area of the import pipe shall not be less than the sum of the import cross-sectional area of the safety valve.
(2) No cut-off valve or steam outlet pipe shall be installed between the safety valve and the drum or header of the boiler. It is not suitable to install cut-off valves or other lead-out pipes between safety valves and pressure vessels. For pressure vessels with extremely high, high and moderate toxicity, inflammable, corrosive, viscous or precious media, the cut-off can be installed between safety valves and pressure vessels only with the approval of the technical person in charge of the pressure vessel of the user unit and the formulation of reliable preventive measures. Valves. During normal operation of pressure vessel, globe valve must be kept fully open, sealed or locked with lead. The structure and diameter of the stop valve shall not hinder the safe discharge of the safety valve.
(3) Spring safety valve with thread connection should be connected with short pipe with thread, and welding connection should be used between short pipe and simplified body and header.
(4) Safety valves must be equipped with discharge pipes. The discharge pipe should avoid twists and turns as far as possible to minimize resistance. The exhaust pipe should go straight to the safe place and have enough cross-section area to ensure smooth exhaust. For safety valves that can interact to produce chemical reactions, one discharge pipe cannot be shared; when safety valves are installed on equipment with corrosive and flammable gases, measures should be taken to prevent corrosion or fire and explosion; when the equipment equipped with safety valves is toxic medium and the steam density of the medium is greater than air density, the medium and steam discharged from safety valves should be introduced. To the closed system, and from the closed system recovery to production use.
(5) The relief valve discharge pipe should be fixed so as to avoid excessive additional stress or vibration of the relief valve.
(6) Safety valves installed in the open air shall be equipped with reliable measures to prevent the water content in the medium of the valve from freezing and affecting the discharge of the safety valve when the temperature is below 0 oC.
(7) When the medium crystallization temperature of the safety valve is higher than the lowest ambient temperature, the safety valve must be equipped with an insulating jacket and installed with insulating and purging steam to prevent the medium crystallization from clogging the safety valve and affect the normal operation performance of the safety valve. The inlet and outlet pipes of safety valves must also be designed with steam insulation jackets or with additional insulation steam accompanying pipes to prevent medium crystallization from clogging the pipes.
Maintain
1. Safety valve should have a device to prevent the weight from moving by itself and a guide to limit the deviation of lever. Spring safety valve should have a lifting handle and a device to prevent the screw from screwing randomly.
2. It should be installed vertically at the highest position of the cooker and header. Between the safety valve and the drum or header, there shall be no outlet pipe and valve for taking steam.
3. The cross-sectional area of the connecting pipe between the safety valve and the boiler shall be no less than the cross-sectional area of the inlet of the safety valve. If several safety valves are installed on a short tube directly connected to the pot drum, the cross-section area of the short tube should not be less than 1.25 times the exhaust area of all safety valves.
4. For boilers with rated steam pressure less than or equal to 3.82 MPa, the throat diameter of safety valve shall not be less than 25 mm; for boilers with rated steam pressure greater than 3.82 MPa, the throat diameter of safety valve shall not be less than 20 mm.
5. Safety valves should generally be equipped with exhaust pipes, which should go straight to the safe place and have enough cross-section area to ensure smooth exhaust. The bottom of the relief valve exhaust pipe should be equipped with a drain pipe connected to the safe place. Valves are not allowed to be installed on the exhaust pipe and the drain pipe.
6. The safety valve of pressure vessel should be installed directly at the highest position of pressure vessel body. Safety valves for liquefied gas tanks must be installed in the gas phase. Generally, the short pipe can be connected with the container, and the diameter of the short pipe of the safety valve should be no less than the diameter of the safety valve.
7. Valves should not be installed between safety valves and containers. For flammable, explosive or viscous media containers, globe valves can be installed in order to facilitate the cleaning or replacement of safety valves. The globe valves must be fully opened and sealed with lead during normal operation to avoid chaos.
8. Boilers with rated evaporation greater than 0.5 t/h shall be equipped with at least two safety valves; boilers with rated evaporation less than or equal to 0.5 t/h shall be equipped with at least one safety valve. Safety valves must be installed at the outlet of separable economizer and steam superheater.
9. For pressure vessels with flammable, explosive or toxic media, the medium discharged by the safety valve must have safety devices and recovery systems. The installation of lever relief valve must keep the vertical position, and spring relief valve should also be installed vertically to avoid affecting its action. When installing, attention should also be paid to coordination, coaxiality of parts and uniform stress of bolts.
10. The outlet of safety valve should be free of resistance to avoid back pressure, if installed in rows.