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The pipe valve only plays the role of sending and receiving the pig when pigging the pipe, and the pig is responsible for pigging and cleaning the pipe.

The structural characteristics of the pigging valve are a new type of valve innovatively designed according to the structural principle of T-type three-way fixed ball valve, which has been transformed and increased in function.

The pigging valve works by placing the pig into the inner cavity of the pig ball, rotating 90% through the ball in a three-way valve perpendicular to each other. When the spherical channel and the pipe channel are on the same axis, the pig is activated by the pig valve under the action of the fluid pressure in the pipeline.

Depending on the application, pigging valves can be divided into three categories:

1: Standard type (PC type)
The aperture of the sphere is approximately 25% larger than the inner diameter of the connecting pipe. One end of the aperture is equipped with a stop strip that allows the medium to pass through but prevents the pig. When the pig is removed and loaded, the liquid will be cut off for a short time.

2: Bypass type (Pb type)
When the conveying medium is not allowed to be cut off for a short time, a bypass pigging valve should be used. The ball is larger than the standard pigging valve, and the bore diameter and structure are the same as the standard pigging valve, but the total flow section of the two bypass channels in the vertical direction of the orifice axis is about 25% of the valve aperture section. The fluid flow is not interrupted throughout the pig transmission and reception.

3: Isolated type (PS type)
The aperture of the sphere is only about 3% larger than the inner diameter of the connecting tube. To minimize mixing of media upstream and downstream of the isolation ball, an additional seal is installed on the upstream side of the bore baffle.

The pigging valve is actually a T-shaped three-way fixed ball valve that is installed and used in long-distance oil and gas pipelines. Therefore, the design specifications of the pigging valve comply with the provisions of GB/T 19672-2005 "Technical Conditions for Pipeline Valves", GB/T 20173-2006 "Pipeline Inversion of Belt Conveyor System in Oil and Gas Industry" and API 6D-2008 "Pipeline Valves". Pigging valves are designed and calculated in the same way as conventional fixed ball valves.

Pigging valve is a new type of valve designed and innovative after improvement and addition of functions on the basis of the structural principle of fixed ball valve. It realizes the opening and closing of the valve by rotating 90° of the ball, uses the double piston effect to achieve sealing, and is designed with double locking and discharge functions according to the characteristics of the ball valve, so that when the valve is fully opened or completely closed, the medium in the body cavity can be discharged. It inherits all the advantages of fixed ball valves and has the same adaptability as fixed ball valves. The side of the valve body is provided with a branch pipe perpendicular to the center line of the runner, and the branch pipe is equipped with a quick opening blind plate and a discharge valve to facilitate the pig to enter and exit the pig valve. A stop strip is provided at one end of the spherical channel to block the channel of the pig and allow the medium to flow.