**Abstract:** This paper presents the commonly used standards in the manufacturing and inspection of valves for water supply and drainage systems, while also discussing the necessary test items and methods for different types of valves. Valves play a crucial role in controlling fluid flow within pipelines, serving functions such as shut-off, regulation, prevention of backflow, and air release. They are categorized into cut-off valves, regulating valves, check valves, and exhaust valves, each with specific design and performance requirements. Before leaving the factory, every valve must undergo rigorous testing to ensure it meets quality and safety standards. Some valves also require type testing to confirm their performance under various conditions.
**1. Overview**
Valves are essential components in piping systems, designed to control the flow, pressure, and direction of fluids. In water supply and drainage systems, they are classified based on their purpose: cut-off valves (e.g., gate, globe, butterfly, ball, and plug valves), which are used to open or close the flow; regulating valves (such as pressure-reducing and throttle valves), which manage flow and pressure; check valves, which prevent reverse flow; and exhaust valves, which release air from pipelines. Each type has its own set of testing requirements to ensure reliable operation and compliance with industry standards.
**2. Inspection and Test Items**
Valves must undergo both factory tests and type tests, as outlined in tables 1 through 4. These tests include shell testing, seal testing, and operational checks. The sealing structure of the valve must be tested to ensure no leakage occurs during operation. It is important to note that certain test items are mandatory, indicated by specific symbols in the documentation.
**3. Manufacturing and Testing Standards**
A comprehensive list of domestic and international standards for valve manufacturing and testing is provided. Domestic standards include GB/T series specifications for valve marking, dimensions, materials, and performance. International standards such as ISO, BS, ANSI, AWWA, and JIS cover various aspects of valve design, testing, and application. These standards guide manufacturers in ensuring product quality and consistency across global markets.
**4. Quality Requirements**
The quality of a valve is determined by several factors, including the chemical composition and mechanical properties of the materials used, the accuracy of casting dimensions, the absence of surface defects, and the integrity of internal connections. Valves must pass pressure and sealing tests, operate smoothly under nominal pressure, and maintain a long service life. Additionally, valves should have a high flow capacity with minimal pressure loss, contributing to energy efficiency and system performance.
**5. Testing Methods**
Casting quality is assessed through dimensional checks, material analysis, and visual inspections to ensure there are no cracks, voids, or surface imperfections. Pressure testing is a fundamental step, involving shell and seal tests according to GB/T 13927 and other relevant standards. Seal tests can be conducted using either liquid or gas, depending on the valve type. Operational torque and life tests are also performed, especially in foreign standards, to evaluate long-term reliability. Flow characteristics, such as flow coefficient and pressure drop, are measured to optimize system efficiency.
**6. Conclusion**
To ensure the safe and effective operation of water supply and drainage systems, valves must be manufactured and tested in strict accordance with established standards. Comprehensive testing at the factory level guarantees that valves meet all required performance criteria and contribute to the overall safety and reliability of the piping system. As technology and regulations evolve, continuous improvement in testing procedures will remain essential for maintaining high-quality valve production.
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