Definition and use

The receiving barrel is a device used to send and receive the pig (also known as the pipe pig) in the pipeline, which is mainly used in the field of long-distance oil and gas pipelines, chemical pipelines, etc. Its main use is to carry out internal cleaning, detection and isolation of pipelines.

For example, in a long-haul natural gas pipeline, impurities such as dirt, rust, and paraffin may accumulate on the inner wall of the pipeline over time. The pipe is cleaned by using a receiving barrel to send a pig, which runs inside the pipe and scrapes these impurities and pushes them forward, eventually being collected by the receiving barrel. At the same time, the receiver can also be used to send detection instruments (such as smart pig) to detect the wall thickness of the pipe, corrosion, etc.

Structural composition

Barrel section

The receiving cylinder is usually composed of a cylinder, which is generally a cylindrical metal container. Its length and diameter are determined according to the specifications of the pipe and the size of the pig. The material of the cylinder is mostly carbon steel or alloy steel to ensure sufficient strength to withstand the pressure of the pipeline. For example, in high-pressure oil and gas pipelines, the cylinder of the receiving cylinder can withstand higher pressure to ensure safety and reliability.

The two ends of the cylinder are provided with quick-opening blind plates, which are for the convenience of putting and taking out the pig. The quick-opening blind plate uses a special mechanical structure, which can be quickly opened and closed, and can ensure a good seal. During operation, when the pig needs to be sent or received, open the blind plate, put the pig in or out, and then close the blind plate to maintain the tightness of the piping system.

Connecting part

The receiving cylinder is connected with the main pipe through a flange. The flange connection has the advantages of solid connection and good sealing performance. When connecting, ensure that the sealing surface of the flange is smooth, and the gasket is suitable to prevent the leakage of oil and gas and other media. At the same time, the receiving cylinder will also have some auxiliary connection ports, such as interfaces for connecting pressure sensors, blowdown valves and blowdown valves.

Accessory equipment

Blow-off valves and blowdown valves: Blow-off valves are used to discharge gas or liquid from the receiving cylinder before and after operation to ensure safe and easy operation. The blowdown valve is used to discharge the impurities and accumulated liquid in the receiving cylinder. For example, after cleaning the pipe, the blowdown valve can remove dirt collected in the ball collecting cylinder.

Pressure sensor: Used to monitor pressure changes in the receiving cylinder. In the process of sending and receiving the pig, the change of pressure can reflect the operating state of the pig. If there is an abnormal increase or decrease in pressure, it may indicate that the pig has encountered blockage, leakage, etc., in the pipeline.

Working principle

Serving process: At one end of the serving barrel, open the quick-opening blind plate to put the pig into the barrel, close the blind plate to ensure the seal. Then by injecting a medium (such as oil or gas) into the cylinder, the pressure of the medium pushes the pig into the main pipe. With the continuous injection of media, the pig moves forward in the pipe and begins to perform cleaning, inspection, and so on.
Ball collection process: After the pig runs in the pipe for a period of time, it reaches the ball collection cylinder. When the pig enters the ball receiving barrel, it will cause the change of the pressure and liquid level in the ball receiving barrel. Determine whether the pig has been received by observing changes in these parameters or by using a detection device such as an ultrasonic detector. After the ball collection, open the blind plate of the ball collection cylinder, take out the pig, and complete a working cycle.