Factory inspection of ball valves

Factory inspection of ball valves is an important part of ensuring that the quality of valves meets the standards and design requirements. The following is a detailed introduction to common inspection methods:

1. Appearance inspection Visual inspection: The inspector directly observes the appearance of the valve with the naked eye to check whether there are casting defects such as cracks, sand holes, and heavy skin; check whether the surface roughness meets the requirements, whether the coating is uniform, without flow marks, peeling and other defects. Dimension measurement: Use measuring tools (such as vernier calipers, micrometers, rulers, etc.) to measure the key dimensions of the valve, such as valve body diameter, height, inlet and outlet flange dimensions, connection bolt hole spacing, etc., to ensure that they meet the tolerance range specified in the design drawings.
2. Pressure test Strength test
Test medium: Generally, clean water is used as the test medium. For valves that are not allowed to contact water, compressed air or other suitable gases can be used.
Test pressure: Usually 1.5 times the nominal pressure of the valve, but not less than 0.3MPa. Test method: Install the valve on the test device, close the valve outlet, slowly increase the pressure to the specified test pressure, maintain for a certain time (usually 5-10 minutes), and check whether there is leakage or sweating in the valve housing, stuffing box and other parts. Sealing test test medium: For valves with liquid media, water is often used as the test medium; for valves with gas media, air or other gases are used.
Test pressure: Generally 1.1 times the nominal pressure of the valve. Test method: After the strength test is qualified, open the valve to a certain angle (generally 1/4-1/2 of the full opening), then slowly increase the pressure to the specified test pressure, maintain for a certain time (usually 15-30 minutes), and check whether the sealing surface of the valve is leaking. For valves with upper sealing structure, an upper sealing test is also required.
3. Functional test
Switch flexibility test: Manually operate the valve to check whether its opening and closing process is flexible and whether there is any jamming. For electric, pneumatic or hydraulic valves, remote operation tests are required through the corresponding actuators to check the accuracy and reliability of their actions.
Flow characteristic test: Use flow test equipment to measure the flow of the valve at different openings, draw the flow characteristic curve of the valve to verify whether its flow characteristics meet the design requirements.
4. Material analysis
Spectral analysis: Use a spectrometer to analyze the material of the valve to determine its main chemical composition and its content to verify whether it meets the material standards specified in the design.
Hardness test: Use a hardness tester to measure the hardness value of different parts of the valve to determine whether the hardness of the material meets the requirements and ensure that the valve has sufficient strength and wear resistance.