Introduction to Plastics International Standard and Discussion of Problems
**Abstract:**
This paper provides a comprehensive overview of the international standards governing plastic valve products, focusing on raw material specifications, design requirements, manufacturing processes, performance criteria, testing methods, and system application guidelines. It highlights the critical quality control aspects such as seal tests, torque tests, and fatigue strength tests, which are essential for ensuring the reliability and durability of plastic valves. A detailed table summarizes the key performance requirements, including seat sealing tests, body sealing tests, body strength tests, long-term performance tests, fatigue tests, and operating torque regulations. Through an analysis of several issues identified in international standards, this work emphasizes the importance of standardization for both manufacturers and users. The keywords include "plastic valve," "life," "seal test," "fatigue strength test," and "test conditions."
With the increasing use of plastic pipes in hot and cold water supply systems and industrial applications, the quality control of plastic valve systems has become increasingly significant. Plastic valves offer advantages such as lightweight, corrosion resistance, non-scaling properties, compatibility with plastic piping, and long service life, making them superior to other types of valves in water supply (especially hot water and heating) and industrial pipeline systems. However, in domestic production and application, the lack of reliable control methods has led to inconsistent product quality, resulting in leakage problems and reduced application efficiency. As China’s national standards for plastic valves are being developed, they are largely based on international standards.
The main types of plastic valves include ball valves, butterfly valves, check valves, diaphragm valves, gate valves, and globe valves, with structures ranging from two-way to multi-way configurations. Common materials used include PVC, PB, PE, PP, and PVDF. International standards specify strict requirements for raw materials, ensuring they meet creep resistance curves. Seal tests, body tests, long-term performance tests, fatigue strength tests, and operating torque measurements are all defined. The expected service life for industrial fluid transfer is 25 years.
Key technical requirements cover material selection, design considerations, manufacturing processes, short-term and long-term performance tests, fatigue strength, torque, and operational force limits. Standardized connection dimensions and temperature-pressure relationships are also outlined. The paper discusses challenges in current standards, such as inconsistencies in nominal size and pressure marking, insufficient torque specifications, and limitations in design stress values. These issues require further attention and refinement to ensure the safe and efficient use of plastic valves in various applications.
In conclusion, adherence to international standards ensures that plastic valves meet the necessary performance and safety requirements for modern piping systems. While some areas of the standards may need improvement, ongoing development and collaboration between manufacturers and users will enhance the reliability and acceptance of plastic valves globally.
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