Three-eccentric metal sealing butterfly valve structure capable of replacing sealing pair on line

Abstract

A three-eccentric metal sealing butterfly valve structure capable of replacing a sealing pair on line comprises a valve body, a limiting pin a, a three-open ring, a locking nut, a screw a, a valve seat sealing ring, a multilayer sealing ring, a limiting pin b, a butterfly plate, a pressing plate and a screw b. The valve seat sealing ring is arranged in the valve body. The valve seat sealing ring is fixed in the valve body through the three-opening ring, the locking nut and the screw a. The limiting pin a is arranged between the valve seat sealing ring and the valve body. The valve seat sealingring is limited through the limiting pin a. The multilayer sealing ring is arranged on the butterfly plate. The multilayer sealing ring is pressed by the pressing plate and fixed to the butterfly plate through the screw b, and the butterfly plate, the multi-layer sealing ring and the pressing plate are fixed in position through the limiting pin b; and an overhauling bin opening is formed in the valve body. The three-eccentric metal sealing butterfly valve structure has the beneficial effects that the defect that an original three-eccentric structure cannot replace the sealing pair on line issolved; and during online replacement, by arranging the limiting pins, the sealing pair position is determined, the leakage risk of a butterfly valve is reduced, and the safe and effective operation of an LNG receiving station is ensured.

Description

technical field [0001] The invention relates to a triple-eccentric metal-sealed butterfly valve, in particular to an ultra-low temperature butterfly valve used in LNG projects and other ultra-low temperature working conditions. Background technique [0002] At present, the commonly used butterfly valves with on-line replaceable sealing pairs are often double eccentric structures, and their sealing rings are made of copper alloys, but they are not suitable for ultra-low temperature conditions of sulfur-containing LNG. Sulfides will cause corrosion of copper and seriously affect the sealing performance of the valve. At the same time, the butterfly valve with double eccentric structure has many disadvantages and is not suitable for LNG working conditions. Its sealing principle is position sealing. The sealing surface of the butterfly plate and the valve seat is in line contact, which is realized by the elastic deformation caused by the extrusion of the butterfly plate on the val...

AI Technical Summary

Problems solved by technology

[0002] At present, the commonly used butterfly valves that can replace the sealing pair on-line are usually double eccentric structures, and the sealing rings are made of copper alloy, but they are not suitable for ultra-low temperature conditions of sulfur-containing LNG. The sulfide will cause corrosion of copper and seriously affect the sealing performance of the valve.

At the same time, the butterfly valve with double eccentric structure has many disadvantages and is not suitable for LNG working conditions. Its sealing principle is position sealing. The sealing surface of the butterfly plate and the valve seat is in line contact, which is realized by the elastic deformation caused by the extrusion of the butterfly plate on the valve seat. Sealing, high requirements on the closing position, especially the metal valve seat, often has the disadvantages of low pressure bearing capacity and large leakage

In the common triple eccentric structure, because the sealing surface of the sealing pair is oblique cone type, the sealing point cannot be directly aligned when the valve seat sealing ring is installed. The sealing pair is directly replaced

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