I would like to ask the experts: in the design of natural gas receiving and sending cylinders, how is the equipment length determined? And what types of pipe connections should be available on them?

The firing cylinder is located at the starting point of the gas pipeline, and its internal pressure is zero when it is not in use. Valve 1# is a valve on the main gas pipeline and is usually open. Valve 2# is a ball valve located at the large end of the ball sending cylinder; it is closed when not in use. Valve 3# is a valve on the main gas pipeline leading to the ball sending cylinder, and it is closed when not in use. Valve 4# is a vent valve that is connected to the station’s venting pipeline; it is closed when not in use

Structural features: Pig receiving/sending cylinder; its material and pressure resistance must meet the design requirements as well as those of the medium. Quick-release blind flanges of various types such as clamp-type, lock-ring type, and bayonet-type are available; they feature a rational structure, good sealing performance, rapid opening and closing, easy operation, and reliability. At the same time, the snap-type quick-opening blind flange features easy opening, as well as safety self-locking functions (self-locking of the blind flange, vibration prevention, anti-loosening, and the ability to relieve pressure again after opening), which makes the operation simpler and safer ； In addition to its safety self-locking feature, the clamp-type quick-release blind flange ensures that there is no relative rotation between the sealing ring and the sealing surface when the blind flange is locked, which prevents the sealing ring from being damaged and thus provides better protection for the sealing system ； Like the clamp-type quick-release blind flanges, the lock-ring type also possesses a high pressure resistance and excellent performance.

The length is primarily determined with regard to the running distance L of the pig; this distance is calculated using a volumetric method, based on the amount of gas in the pipeline once the pig enters it. L = 4PoTVoZ / (πd2PTo) (3) Where: L is the distance from the pig to the starting point, in meters ； V0 is the cumulative volume of gas introduced after serving (under conditions of 0.1033 MPa and T = 293 K), in m3. By substituting the relevant values into equation (3), it can be determined that L = 0.743Vo/P (4)

Physical image 1: Main gas valve of the gas pipeline； 2 Gas pipeline vent valve ； 3 Ball valve for receiving cylinders ； 4 Balance valve ； 5 Ball collection cylinder vent valve ； 6 Inlet valve for the collection cylinder ； 7 Ball collection tube drain valve ； 8 Quick-Open Blind Flanges ； 9 Anti-loosening unloading block ； 10 Receiver cylinder pressure gauge ； 11 Water injection valve for upper water pipeline ；

Please have the original poster take a look at the QSHCG 11020-2017 Technical Specifications for the Purchase of Ball Receiving and Sending Tanks for Gas Transmission Pipelines