Valve sealing surface material applicable temperature medium comparison table valve pressure test should comply with the 16 principles and matters needing attention

Valve sealing surface material applicable temperature medium comparison table valve pressure test should comply with the 16 principles and matters needing attention

Valve sealing surface material applicable temperature medium comparison table
material
Suitable service temperature
Directions for use
Butyl rubber Buna-N
- 23 ℃ ~ 82 ℃
Short -23℃ ~ 120℃
Butadiene rubber has good self-malleability, wear resistance and hydrocarbon resistance properties, as a general material can be used in water, vacuum, acid, salt, alkali, lipid, oil, butter, hydraulic oil, glycol and other media, but can not be used in **, ketone, nitrate and fluorinated hydrocarbon places.
YiBing rubber
EPDM
- 40 ℃ ~ 135 ℃
Short -50℃ ~ 170℃
Ethylene propylene rubber is a good universal synthetic rubber, can be used in hot water systems, beverages, dairy products, methyl ketone, alcohol, nitrate and glycerol and other media, but can not be used in hydrocarbon based oil, inorganic matter or solvent.
Fluoroprene Neoprene
- 29 ℃ ~ 135 ℃
Short -35℃ ~ 113℃
Fluoroprene rubber can be used in acid, oil, fat, butter solvents and other media, has a good resistance to anhydrous ammonia and alcohol performance.
Fluorinated rubber
Viton
- 29 ℃ ~ 205 ℃
Fluorinated rubber is a good resistance to hydrocarbon based oil, oil gas and other petroleum products of the fluorinated rubber, suitable for water, oil, air, acid and other media, but can not be used for steam, over 82℃ hot water or concentrated alkali system.
Silicone rubber
Silicone
- 40 ℃ ~ 180 ℃
Silicone rubber resistance to high temperature, low temperature, chemical stability, widely used in strong acid, weak alkali and food industries.
PTFE PTFE
- 10 ℃ ~ 200 ℃
Polytetrafluoroethylene has stable chemical properties, outstanding surface non-viscosity, good lubricity and anti-aging properties, widely used in strong acids, weak bases, strong oxidants and other corrosive media.
Valve pressure testing shall comply with the principles and the matters needing attention in 16 valve production process is a complex and simple, ordinary production of valves such as gate valve, ball valve, globe valve, butterfly valve, check valve, the production cycle of generally in three days, good manufacturing valves must go through a variety of performance testing, including * * important a test is to test. Pressure test is to test whether the pressure value of the valve can bear meets the requirements of production regulations, the general valve pressure test must comply with the following principles and matters needing attention:
The production of valves is a complex and simple process. The production cycle of ordinary valves such as gate valves, ball valves, globe valves, butterfly valves and check valves is generally in three days. The production of valves must be tested by various performance tests, among which the most important test is pressure test. Pressure test is to test whether the pressure value of the valve can bear meets the requirements of production regulations, the general valve pressure test must comply with the following principles and matters needing attention:
(1) Under normal circumstances, the valve is not subjected to strength test, but the valve body and valve cover after repair or corrosion damage should be subjected to strength test. For the safety valve, the constant pressure and return pressure and other tests should comply with the specification and the provisions of the relevant procedures.
(2) The strength and tightness of the valve should be tested. Low-pressure valve spot check 20%, such as unqualified should be 100% inspection; Medium and high pressure valves should be 100% inspected.
(3) During the test, the valve should be installed in the direction of easy inspection.
(4) For valves in the form of welded connection, conical seal or O-ring seal can be used for pressure test when the pressure test with blind plate is not feasible.
(5) hydraulic test will try to eliminate the valve air.
(6) The pressure should be gradually increased during the test, and rapid and sudden pressurization is not allowed.
(7) Strength test and sealing test duration is generally 2-3 minutes, important and special valves should last 5 minutes. Small diameter valve test time can be correspondingly shorter, larger diameter valve test time can be correspondingly longer. During the test, if in doubt, the test time can be extended. During the strength test, do not allow the body and cover to sweat or leak. Sealing test, the general valve is only once, safety valve, high pressure valve and other raw valves need to be carried out twice. During the test, low pressure, large diameter unimportant valves and valves with provisions allowing leakage are allowed to have trace leakage phenomenon; Due to the different requirements of universal valves, power station valves, Marine valves and other valves, the leakage requirements should be carried out in accordance with the relevant regulations.
(8) The throttle valve is not closed for sealing test, but should be strength test and packing and gasket sealing test.
(9) In the pressure test, the valve closing force only allows a person’s normal physical strength to close; It is not allowed to apply force with levers or other tools (except torque wrenches). When the diameter of the handwheel is greater than 320mm, two people are allowed to close it together.
(10) The valve with the upper seal should be taken out of the packing for sealing test. After the upper seal is closed, check whether there is leakage. When testing with gas, fill the stuffing box with water for inspection. Do not allow the upper seal to be in a close position when packing tightness test.
(11) where the valve has a driving device, when testing its sealing, the driving device should be used to close the valve for sealing test. Manual drive device, should also be used to close the valve seal test.
(12) Strength test and sealing test installed on the main valve bypass valve, in the main valve strength and sealing test; When the main valve shutoff is opened, it should also be opened accordingly.
(13) During the strength test of cast iron valve, the copper hammer should be used to tap the valve body and valve cover to check whether there is leakage.
(14) When the valve is tested, the sealing surface of the valve is not allowed to be oiled except that the sealing surface of the plug valve is allowed to be oiled.
(15) During the pressure test of the valve, the pressure of the blind plate on the valve should not be too large, so as to avoid deformation of the valve and affect the test effect (if the cast iron valve is too tightly pressed, it will be damaged).
(16) After the valve pressure test is completed, the water in the valve should be removed in time and wiped clean, and the test record should be made.