It has the characteristics of pipes and pressure vessels. National standard "code for design of transmission pipeline engineering (hereinafter referred to as the" GB50251-2003 "design specification") will regard it as the pipeline accessories, and the combination of conditions working pressure, geometric dimensions and working medium with pressure vessels safety and technical regulations issued by the State Bureau of quality and technical supervision "(hereinafter referred to as the" content regulation "). Jurisdiction. Therefore, the manifold in the design, manufacture, use and maintenance, whether it is treated as a pipe attachment or by the pressure vessel, in the exchange of gas mains on the mouth is essential to the production process.