RMI Plastic valve technical requirements

Preface: Through the international plastic valve products and test methods in the standard raw material requirements, design requirements, manufacturing requirements, performance requirements, test methods, system requirements and the use of pressure and temperature and other related content introduced, you can understand the requirements of plastic valves Seal test, torque test and fatigue strength test and other basic quality control requirements. Form the table summarizes the performance requirements of the plastic valve valve seat sealing test, the body seal test, body strength test, the valve long-term test, fatigue test and the provisions of operating torque. Through the discussion of several problems in international standards, producers and users of plastic valves have drawn much attention. As the proportion of plastic piping in hot and cold water supply and industrial piping engineering continues to increase, the quality control of plastic valves in plastic piping systems becomes more and more important. Due to the plastic valve has the advantages of light weight, corrosion resistance, non-adsorption scale, integration with the plastic pipe and long service life, etc., plastic valves in the water supply (especially hot water and heating) and other industrial plastics Pipeline system, the advantages of its application is that other valves can not be compared. Currently in the domestic production and application of plastic valves, there is no reliable method of its control, resulting in water supply and industrial use of other fluids plastic valve product quality is uneven, resulting in the closure of engineering applications and serious leakage phenomenon, The formation of a plastic valve can not use the remarks, affecting the overall development of plastic pipe applications. China's national standard plastic valve is being developed in the process, the product standards and method standards are based on international standards. The main types of plastic valves rmi plastic offer are ball valves, butterfly valves, check valves, diaphragm valves and globe valves. The main structural forms are two-way, three-way and multi-way valves. The main raw materials are ABS, PVC-U, PVC-C, PB, PE, PP and PVDF and so on. In the international standards for plastic valve products, the first is the production of raw materials used in valve requirements, the raw materials of the manufacturer must have a plastic pipe products meet the creep failure curve; at the same time on the plastic valve seal test, valve test, the overall Long-term performance tests of valves, fatigue strength tests and operating torques are all specified, giving the design service life of 25 years for plastic valves for industrial fluid transfer. The main technical requirements of international standards 1 raw material requirements Body, bonnet and bonnet material should be used in line with ISO 15493: 2003 "industrial plastic pipe systems - ABS, PVC-U and PVC-C - Pipe and Fitting System Specifications - Part: Metric Series "and ISO 15494: 2003" Industrial Plastic Piping Systems - PB, PE and PP - Pipe and Fitting Systems Specifications - Part 1: Metric Series ". 2 DESIGN REQUIREMENTS a) If the valve has only one direction of pressure bearing, it shall be marked with an arrow on the outside of the valve body. Symmetrically designed valves shall be suitable for the flow and isolation of fluids in both directions. b) The sealing member is driven by the valve stem to open and close the valve. It should be positioned at the end point or in the middle by friction or actuator, and the fluid pressure can not change its position. c) According to EN736-3, the valve cavity minimum through-hole shall comply with the following two points: - for any aperture through which the medium in the valve circulates, no less than 90% of the valve DN value; - for structurally reduced media flow Aperture valves, the manufacturer should explain the actual minimum through-hole. d) The seal between stem and body shall comply with EN736-3. e) In terms of valve wear resistance, the design of the valve should take into account the service life of the wearing parts or the manufacturer should indicate in the operating instructions that the entire valve be replaced. f) The flow rate applicable to all valve operators shall be 3 m / s. g) From the top of the valve, the valve handle or handwheel should close the valve in a clockwise direction. 3 manufacturing requirements a) The performance of purchased raw materials should be consistent with the manufacturer's instructions and meet the product standards. b) The body should be marked on the raw material code, diameter DN, nominal pressure PN. c) Body should be marked with the manufacturer's name or trademark. d) Body should be marked with the date of manufacture or code. e) The valve body shall be marked with the code of the manufacturer's different manufacturing locations. Short-term performance requirements Short-term performance in the product standard is the factory inspection items, mainly to do the seat seal test and body sealing test for checking the sealing performance of plastic valves require plastic valves that can not have internal leakage (valve Seat leakage) phenomenon, can not have external leakage (body leakage) phenomenon. Seat seal test is to verify the performance of the valve isolation pipe system; the body of the seal test is to verify the valve stem seals and valves at the junction of the seal leak. Plastic valves and piping systems are connected by butt welding connection: the outer diameter of the valve connecting parts and the outer diameter of the pipe is equal, the end face of the valve connecting parts and the pipe end face welding; Socket bonding connection: the valve connection parts for the socket form , Fused with the pipe connection; fused socket connection: the valve connecting parts for the laying of electric wire diameter socket form, and the pipe fused connection; socket hot melt connection: valve connection parts for the socket form, and the pipe Hot melt socket connection; socket adhesive connection: valve connection parts for the socket form, and the pipe bonding socket connection; socket rubber seal connection: valve connection parts for the rubber ring in the form of socket , And the pipe socket connection; flange connection: the valve connecting parts in the form of flanges, with the flange on the pipe connection; screw connection: the valve connection parts for the thread form, and pipe or pipe thread connections; live Connection: The valve connection is a live connection, with the pipe or pipe connections. A valve can have different connections at the same time. The relationship between the use of pressure and temperature With the use of temperature, the life of plastic valves to be shortened. In order to maintain the same life, you need to reduce the use of pressure.