The Pigging Valve is a new type of device primarily used for pigging operations in pipelines transporting petroleum, natural gas, chemicals, and other liquids. It is used for launching and receiving pigs, performing mechanical cleaning of the pipeline inner wall (removing dirt, rust, and foreign objects), and separating different products. It has been widely applied in oil and gas fields, chemical plants, terminals, oil and gas storage and transportation depots, and offshore platforms.

The pigging valve comes in three types to meet different operational needs.

1. Type I Pigging Device:
 Type I is the standard pigging valve for pipeline cleaning. The bore is slightly larger than the pipeline inner diameter. It functions for both launching and receiving pigs and also has a shut-off capability.

2. Type II Pigging Device:
 Type II is a pigging valve with a bypass. The bore is slightly larger than the pipeline inner diameter. Two circular channels are opened on the hollow ball body perpendicular to the ball bore. This structure ensures no flow interruption occurs even during pig launching or receiving. The Type II pigging valve cannot be used as a shut-off valve.

3. Type III Pigging Device:
 Type III is primarily a pigging valve for isolating and sequentially transporting media to prevent mixing. The bore is slightly larger than the pipeline inner diameter, and there is an additional seal inside the ball bore of the receiving pigging valve to ensure a seal is formed when the isolation pig reaches the receiving pigging valve.

The sealing principle of this device is the same as that of a ball valve. Under the combined action of the spring and the medium, the two valve seats are pressed against the ball, isolating the sealing channel from the valve body chamber. The loading, launching, receiving, and unloading of the pig are accomplished by rotating the ball. When the ball bore is aligned with the quick-opening blind flange, the pig can be loaded or unloaded (see Figure 1); after the ball rotates 90 degrees, when the ball bore aligns with the pipeline, the pig can be launched or received under the action of the medium (see Figure 2).