The quality of the valve needs to be measured from multiple aspects, covering dimensions such as appearance, materials, and performance to ensure that the valve can operate safely and reliably in actual use. Here are some common methods to detect valve quality:

Appearance inspection: Surface quality: Check whether the valve surface is smooth and whether there are any casting or processing defects such as sand holes, air holes, cracks, shrinkage marks, etc. These defects may affect the strength and sealing performance of the valve.

Dimensional accuracy: According to the specifications and design drawings of the valve, use calipers, micrometers and other measurement tools to check the dimensions of the valve, such as the valve body diameter, valve stem diameter, connection size, etc., to ensure that it meets the standard requirements.

Marking clarity : Check whether the marking on the valve is clear and complete, including the valve model, specifications, nominal pressure, medium flow direction, manufacturer and other information. Clear signs help to properly install and use the valve.

Material inspection: Material certification document review: Suppliers are required to provide valve material certification documents, such as quality assurance certificates, chemical composition analysis reports, mechanical performance test reports, etc., to verify whether the materials meet the design and use requirements.

Material hardness test: Through hardness testing instruments (such as Brinell hardness meter, Rockwell hardness meter, etc.), the main components of the valve (such as valve body, valve stem, sealing surface, etc.) are tested to determine whether the hardness of the material is within the specified range to ensure the strength and wear resistance of the material.

Metallographic analysis: When you have any doubts about the quality of the material, you can conduct metallographic analysis to observe whether the material's structure is uniform, whether there are abnormal tissues or defects, and evaluate the microscopic quality of the material.

Sealing performance test: Housing test: Install the valve on the test bench, close the valve sealing pair, fill the valve body with a test medium of the specified pressure (usually water), hold the pressure for a certain period of time (such as 5-15 minutes), and check whether there is leakage in the valve body, valve cover and other parts. The housing test mainly tests the strength and pressure resistance of the valve housing.

Sealing test: According to the type and use requirements of the valve, upper seal test, seal test and low-pressure seal test are carried out separately. The upper seal test is used to check the sealing performance between the valve stem and the valve cover; the seal test is used to check the sealing performance of the sealing pair when the valve is closed; the low-pressure seal test is used to check the sealing performance at a lower pressure. During the test, fill one side of the valve with test medium and check for leakage on the other side.

Operating performance test: Manual operation test: Manually open and close the valve to check whether the valve is flexible and light, and whether there are any phenomena such as jamming, abnormal sounds, etc. Record the torque required for the valve to open and close and ensure it is within the specified range.

Drive device test: For valves equipped with electric, pneumatic, hydraulic and other driving devices, test the performance of the drive device, including starting, stopping, speed regulation, reversing and other functions, and whether the output torque or thrust of the drive device meets the operating requirements of the valve.

Stroke and limit test : Check whether the opening and closing strokes of the valve meet the design requirements and whether the limiting device is accurate and reliable to prevent the valve from being over-opened or closed, damaging the valve and equipment.

Pressure test: Strength test: Based on the nominal pressure of the valve, increase the strength test for a certain proportion (such as 1.5 times the nominal pressure), and maintain the pressure for sufficient time to check whether the valve can withstand the specified pressure without deformation, rupture and other damage.

Fatigue test: For valves used under frequent opening and closing or fluctuating pressure conditions, fatigue tests can be performed to simulate pressure changes and opening and closing times under actual working conditions, and to verify the durability and reliability of the valve.

Other performance tests: Fire resistance test: For valves used in special occasions (such as petrochemicals, fire protection, etc.), fire resistance tests may be required to check the sealing performance and structural integrity of the valve in the event of fire.

Corrosion resistance test: If the valve is used in a corrosive medium environment, corrosion resistance tests can be carried out, such as salt spray tests, acid-base corrosion tests, etc., to evaluate the corrosion resistance of the valve material.

Valves of different types and uses may have different quality inspection standards and methods. During the actual inspection process, comprehensive and strict inspection should be carried out according to relevant national standards (such as GB/T 13927-2008 "Industrial Valve Pressure Test", etc.), industry standards and design requirements.