Torque reducer for high-pressure gate valves

Abstract

A torque reducer assembly including a ball screw assembly and a plunger gear assembly with a low torque allowing a single user to operate a hand wheel to open or close a valve under very high pressure without need of gear reduction and a Balance Stem. A gear shaft, ball screw, valve stem and gate are fixed from rotation with respect to each other but move axially together in response to rotation of a ball screw nut in the ball screw assembly. The plunger gear assembly rotates with the ball screw nut. In the engaged position, a plunger prevents rotation of the ball screw nut in the valve open direction but permits rotation of the ball screw nut in the valve close direction. In the disengaged position, the plunger permits rotation of the ball screw nut in the valve open direction and the valve close direction.

Description

[0001]This application claims benefit of U.S. provisional application 62 / 464,552 filed Feb. 28, 2017, U.S. provisional application 62 / 504,107 filed May 10, 2017, and U.S. provisional application 62 / 508,018 filed May 18, 2017, which are each incorporated herein in their entirety.BACKGROUND OF THE INVENTIONField of the Invention[0002]The present invention relates generally to torque reduction for high pressure rising stem gate valves and more specifically to a Torque Reducer with an improved ball screw assembly and a novel gear plunger assembly for an unbalanced rising stem gate valve that allows use of a hand wheel to operate a high pressure valve without need for the valve to include a gear box or a Balance Stem.Background of the Invention[0003]High pressure gate valves may include valves capable of handling high pressures including, for example, valves for 4 1 / 16 ″ bore size at 10000 PSI and 3″ bore size at 15000 PSI and above.[0004]Gate valves are used in a variety of industries t...

AI Technical Summary

Benefits of technology

The present invention aims to provide a high pressure rising stem gate valve that can be easily operated without the need for a Balance Stem. This valve is designed to open more easily and quickly as the high pressure increases, making it more reliable and longer-lasting compared to prior art gate valves.

Problems solved by technology

The disadvantages of Balance Stem gate valves includes increased cost, increased overall height, increased complexity and the creation of an additional potential leak path between the second stem and the corresponding stem packing.

Unfortunately, for many large or high pressure valves which require large actuating forces, this method requires more torque to be applied to the hand wheel than is practical to exert by hand.

This pressure differential results in very high forces which push the gate against the downstream seat.

One disadvantage of this device is that, in order to sufficiently reduce the required torque on the hand wheel, the gear ratio must be very high.

Consequently, a large number of turns are required to open or closed the valve, which adds fatigue to users rotating the hand wheel.

For example, to fully open a three inch 20000 PSI valve, a gear operated valve may require rotation of the hand wheel about 90 revolutions and results in the relatively slow movement of the gate valve for each revolution of the hand wheel.

Moreover the torque required to overcome the drag of the gates due to high differential pressure and the drag of the packing is considerable and becomes ever greater as the pressures increase.

The slow movement of the gate is especially troublesome when moving the gate from the closed position to the open position.

In many cases, the fluid may contain abrasive particles which tend to erode the valve components during high velocity flow.

Thus, the slower the gate moves to the open position it creates more wear and tear of gate and seats.

Otherwise, the back pressure developed in the valve cavity would act on an unbalanced stem and would try to push the gate upwards with a tendency to open the valve automatically due to low torque of the ball screw mechanism.

However, the drag forces discussed above still cause resistance to movement.

Moreover the drag forces increase with increasing high pressure.

There is also a chance of the valve opening automatically in partial open condition due to low torque of the ball screw mechanism, which is very dangerous and could even lead to a massive accident.

However, disadvantages of Balance Stem gate valves include increased cost and complexity.

Another disadvantage is a resulting height restriction.

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