Polyethylene all-plastic ball valve formed by hot melt socket welding

Abstract

The invention relates to a pipeline cut-off valve, in particular to a polyethylene all-plastic ball valve formed by hot melt socket welding. The ball valve comprises a valve rod, a valve body, a valveball, a stub tube, a first valve ball sealing ring and a second valve ball sealing ring, wherein, the valve ball is arranged in the valve body, and the valve rod which rotates the valve ball is arranged thereon; the first valve ball sealing ring is fixed between the valve body and the valve ball, and the second valve ball sealing ring is fixed between the stub tube and the valve ball; the stub tube and the valve body are in hot melt socket-type connection, the inner surface of the insertion chamber of the valve body is provided with a melt glue surface of the valve body, and the outer surfaceof the stub tube is provided with a melt glue surface of the stub tube; and the valve body is matched with the stub tube and is provided with an axial positioning structure used for positioning the axial depth of the stub tube inserted into the valve body. The axial positioning structure of the invention guarantees the axial depth of the stub tube inserted into the valve body, thereby guaranteeing the axial spacing of sealing faces formed by the two valve ball sealing rings, and enabling the pretightening force of each sealing face to be consistent with the designed pretightening force.

Description

technical field [0001] The invention relates to a pipeline cut-off valve, in particular to a polyethylene all-plastic ball valve for hot-melt socket welding. Background technique [0002] Polyethylene (PE) all-plastic ball valves are free from corrosion and aging, with a service life of up to 50 years, while metal valves can last up to 25 years; PE valves can be hot-melt connected with PE pipes, and the joints have high strength and no leakage; and can be directly Buried, no need to build valve wells. Compared with metal ball valves, the construction period for connection with the pipe network is short, the valve is light in weight, easy to carry and weld, and the welding quality can be directly observed without complicated non-destructive testing. It has been widely used in developed countries such as Europe, America, Japan and South Korea. [0003] The small-diameter PE ball valves are integrated by hot-melt welding, and the large-diameter valves are welded by electrofus...

AI Technical Summary

Problems solved by technology

The disadvantage of this structure is that the socket depth directly affects the axial distance between the two sealing surfaces, and affects the pre-pressing force of the valve ball sealing surface.

The socket depth is large, the pre-tightening force is large, the torque to open and close the valve is large, and the wear on the sealing surface is large; the socket depth is small, the sealing surface pre-tightening force is small, and there is a hidden danger of internal leakage

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