Home > categories > Hydraulic & Pneumatic > Other Valves > How can the material be checked by valve approach? What experiments do you need?
Question:

How can the material be checked by valve approach? What experiments do you need?

How can the material be checked by valve approach? What experiments do you need?

Answer:

Under normal circumstances, in the selection of the valve has been considered the main components of the valve material, the use of the valve to determine (for example, media, temperature, pressure, etc.), the valve can not change the material used. For higher or special purpose valves, in addition to the normal valve strength, sealing test, the main material must be used for the inspection and confirmation. The chemical composition and mechanical properties of the valve body, valve cover, sealing surface, valve stem, packing and sealing parts shall be examined. Samples can be taken in bulk or tested with test sticks attached to the product.
(8) the throttle valve does not test the tightness of the closing parts, but the strength test and the tightness test of the stuffing and the gasket shall be carried out.(9) the pressure test, the valve closing force only allows a person's normal physical strength to close; not augmented with tools like leverage (except torque wrench), when the hand wheel diameter is greater than the wait at 320mm, allowing two common off.(10) with a sealed valve, should be taken out of packing for sealing test, sealed after the official closed, check whether leakage. When gas is used as a test, check the water in the stuffing box. When sealing test is carried out, the upper seal is not allowed to be in the tight position.(11) when the valve with drive device is tested and its tightness is tested, the sealing test shall be carried out by using the driving device to close the valve. For manual drive units, seal test shall also be done with the actuating closing valve.(12) the by-pass valve installed on the main valve after the strength test and the sealing test. The strength and tightness test of the main valve is carried out. The main valve should be opened when the closing member is opened.(13) iron valve strength test, the application of Pratia tapping valve and valve cover, check whether there is any leakage.(14) the valve test, in addition to the provisions of the plug valve to allow sealing surface oiling, other valves are not allowed in the sealing surface of the oil test.(15) when the valve pressure test, the blind plate on the valve pressure should not be too large, so as to avoid deformation of the valve, affecting the test results (cast iron valve if pressed too tight, will be damaged).(16) after the valve test pressure, should promptly remove the water and clean the valve, should also be prepared for the test record.
First of all, to check material certification, and secondly, the material appearance, shape and size of the initial test, again on the alloy material according to the standard spectrum analysis, the valve to do pressure test.
May refer to the valve pressure test principle and the pressure test matters needing attention.(1) in general, the valve shall not be subject to strength test, but the body and bonnet shall be subjected to strength tests after the repair of the valve body and bonnet or corrosion damage. For the relief valve, the constant pressure and seat return pressure and other tests shall be in accordance with the specifications and the relevant regulations.(2) the installation of the valve should be done for strength and tightness test. Low pressure valve sampling 20%, if not qualified should be 100% of the inspection; medium and high pressure valve should be 100% of the inspection.(3) the installation position of the valve shall be in the direction of easy inspection during the test.(4) welding connection valve, not with blind plate pressure test can be used when the cone seal or O ring seal pressure test.(5) when hydraulic test, the valve air will be excluded as much as possible.(6) the pressure should be increased gradually during the test, and the pressure will not be sudden and sudden.(7) strength test and sealed test duration is generally 2~3min, important and special valves should last 5min. Small caliber valve test time can be a little shorter, large caliber valve test time can be longer. During the test, the test time can be extended if in doubt. Strength test, does not allow the body and bonnet sweating or leakage. Sealing test, the general rotor valve only once, the safety valve, high pressure valve and other raw valve to be carried out two times. When testing for the low pressure, large diameter valve is not important and there are provisions to allow leakage of the valve, allowing a small amount of leakage; the common valve, power station valve, marine valves and other valve requirements vary on leakage requirements according to relevant regulations.

Share to: