Maintaining method of internal leakage low-pressure bypass valve of valve body

Abstract

The invention provides a maintaining method of an internal leakage low-pressure bypass valve of a valve body. The method comprises the steps that welding properties of materials of a valve element anda valve base of the low-pressure bypass valve are determined; when it is judged that welding can be carried out, welding materials are selected; the unsmooth position of the repair welding surface ofthe valve seal face is ground; repair welding is carried out; welding stress is removed, and it is checked and guaranteed that no surface cracks or dense air holes exist; the valve base, the valve element and a valve rod are machined, it is ensured that coaxiality of the valve base, the valve rod and the valve element is within the preset range, the valve element and the valve base are ground, and roughness brought by machining is removed; a valve base seal ring is arranged on the side, facing the valve element, of the valve base, the valve element is mounted, the valve element is sleeved with a balance seal ring, the valve element is sleeved with a flow sleeve, and the flow sleeve is pressed on the valve base seal ring and is fixed; and a valve cover seal ring and the valve rod are mounted; the valve base does not need to be cut and dismounted, the phenomenon of coinciding of the mechanical zero-position and the thermotechnical zero position can be avoided, or the phenomenon that after the thermotechnical zero position is determined, the valve seal face is insufficient in tightening force, and the valve inner leakage is caused is avoided.

Description

technical field [0001] The invention relates to a maintenance method for a valve, in particular to a maintenance method for a valve internally leaking. Background technique [0002] The low-pressure bypass valve is a very important device in the steam turbine bypass system, which plays a very important role in improving the start-up performance of the unit and protecting the normal operation of the unit. The high-pressure bypass system device is composed of a low-pressure bypass valve, a water spray regulating valve, and a water spray isolation valve. During the start-up process of the unit, if the internal leakage of the low-pressure bypass valve is large, it will seriously affect the operation safety of the unit and the thermal efficiency of the unit. [0003] In many cases, the valve seat of the low-pressure bypass valve is welded on the valve body, which is not easy to disassemble and replace. This requires a maintenance method that does not require disassembly of the v...

AI Technical Summary

Problems solved by technology

During the start-up process of the unit, if the internal leakage of the low-pressure bypass valve is large, it will seriously affect the operation safety of the unit and the thermal efficiency of the unit

[0003] In many cases, the valve seat of the low-pressure bypass valve is welded on the valve body, which is not easy to disassemble and replace. This requires a maintenance method that does not require disassembly of the valve seat.

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