Large-caliber valve Large-caliber valve With the advancement of science and technology, the butterfly valve is not only simple in structure, small in size, light in weight, material consumption, small in installation size, but also in small driving torque, easy and fast to operate, and can also have good performance at the same time. With its flow decay function and closing and sealing characteristics, it is one of the fastest-growing valve varieties in the past ten years. Especially in developed countries such as the United States, Japan, Germany, France, and Italy, butterfly valves are widely used. The variety and number of its use continue to expand, and it is developing towards acid and alkali resistance, high temperature, high pressure, large diameter, high sealing performance, long life, excellent adjustment characteristics, and one valve with multiple functions. Its reliability and other performance indicators All have reached a high level, and have partially replaced the globe valve, gate valve and ball valve.

 

Installation points

 

1. The installation position, height, and direction of import and export must meet the design requirements, and the connection should be firm and tight.

 

2. The handles of all kinds of manual valves installed on the thermal insulation pipeline must not be downward.

 

3. The valve must be visually inspected before installation. The nameplate of the valve should comply with the current national standard "General Valve Marking" GB 12220. For valves with a working pressure greater than 1.0 MPa and a cut-off function on the main pipe, the strength and tightness performance test shall be carried out before installation, and the valve shall be used only after it is qualified. During the strength test, the test pressure is 1.5 times the nominal pressure and the duration is not less than 5min. The valve housing and packing should be qualified without leakage. During the tightness test, the test pressure is 1.1 times the nominal pressure; the test pressure should meet the requirements of the GB 50243 standard during the test duration, and no leakage on the ram sealing surface is qualified.

 

The sealing surface can be sealed only by the pressure of the medium, that is, relying on the pressure of the medium to press the sealing surface of the gate against the valve seat on the other side to ensure the sealing of the sealing surface, which is self-sealing. Most gate valves adopt forced sealing, that is, when the valve is closed, the gate must be forced against the seat by external force to ensure the sealing performance of the sealing surface.　The gate valve of the gate valve moves linearly with the valve stem, which is called the lifting stem gate valve (also called the rising stem gate valve). Usually there is a trapezoidal thread on the lifting rod, through the nut on the top of the valve and the guide groove on the valve body, the rotary motion is changed into linear motion, that is, the operating torque is changed into operating thrust. Large diameter valve