US-12624764-B2 - Stem controlled valve for cryogenic conditions

US12624764B2US 12624764 B2US12624764 B2US 12624764B2US-12624764-B2

Abstract

A stem controlled valve uses a stack which includes a plurality of spacing discs and a plurality of sealing discs, where the spacing discs are interdigitated between the sealing discs, or uses a monolithic plug or inner wall of a valve seat with spaced apart extension areas. The sealing discs or extension areas are slightly larger in diameter than a valve seat they fit within or plug wall they fit against such that they elastically deform against the inner wall of the valve seat or the outer wall of the plug. For sealing in cryogenic applications, at least the outer portions of the sealing discs, or the extension areas in the case of a monolithic plug and inner seat wall are pre-stressed to generate void spaces that govern deformation and cryogenic pliability of the single or groups of sealing discs.

Inventors

Jacob W. LEACHMAN
Michael S. Wood

Assignees

WASHINGTON STATE UNIVERSITY

Dates

Publication Date: 20260512
Application Date: 20240119

Claims (16)

1 . A stem controlled valve, comprising: a plurality of sealing discs, a plurality of spacing discs, and a valve seat having an inner seat wall and/or a valve plug having an outer wall, wherein the plurality of sealing discs and the plurality of spacing discs are arranged as a stack with one or more spacing discs positioned between and directly adjacent single sealing discs or groups of the sealing discs of the plurality of sealing discs, wherein sealing is by either configuration a) or b) wherein in configuration a) the single or groups of sealing discs of the plurality of sealing discs in the stack have a larger diameter than both i) a diameter of the one more spacing discs that are positioned between and adjacent the single sealing discs or groups of sealing discs, and ii) an inner diameter which extends between opposing sides of the inner seat wall, such that under a compressive pressure on the stack, portions of the sealing discs in the plurality of sealing discs abut against and elastically deform on the inner seat wall of the valve seat beyond an outer diameter of a respective directly adjacent spacing disc, or wherein in configuration b) the single or groups of sealing discs of the plurality of sealing discs in the stack have openings that extend therethrough which have a smaller inner diameter than both i) an inner diameter of openings which extend through each of the one or more spacing discs that are positioned between and adjacent the single sealing discs or groups of sealing discs, and ii) a diameter of the outer wall of the valve plug such that under a compressive pressure on the stack, portions of the sealing discs in the plurality of sealing discs abut against and elastically deform on the outer wall of the valve plug beyond an inner diameter of a respective directly adjacent spacing disc.
2 . The stem controlled valve of claim 1 wherein each of the plurality of sealing discs have a same diameter and each of the plurality of spacing discs have a same diameter.
3 . The stem controlled valve of claim 1 wherein the diameter of the sealing discs and the diameter of the spacing discs each become progressively smaller from a bottom of the stack to the top of the stack.
4 . The stem controlled valve of claim 1 wherein the diameter of the sealing discs and the diameter of the spacing discs each become progressively larger from a bottom of the stack to the top of the stack.
5 . The stem controlled valve of claim 1 wherein the inner seat wall of the valve seat is cylindrical.
6 . The stem controlled valve of claim 1 wherein the inner seat wall of the valve seat is conical.
7 . The stem controlled valve of claim 1 wherein the inner seat wall is conically rounded.
8 . The stem controlled valve of claim 1 wherein the outer wall of the valve plug is cylindrical.
9 . The stem controlled valve of claim 1 wherein the outer wall of the valve plug is conical.
10 . The stem controlled valve of claim 1 wherein sealing is by configuration a).
11 . The stem controlled valve of claim 1 wherein sealing is by configuration b).
12 . The stem controlled valve of claim 1 wherein a single spacing disc of the plurality of spacing discs is positioned between each pair of sealing discs of the plurality of sealing discs in the stack.
13 . The stem controlled valve of claim 1 wherein the single or groups of sealing discs of the plurality of sealing discs are processed, at least at portions which extend beyond the spacing discs, to generate a plurality of void spaces in the at least portions which extend beyond the spacing discs sufficient for cryogenic pliability of the single or groups of sealing discs.
14 . The stem controlled valve of claim 13 wherein the plurality of void spaces is formed by pre-stressing the at least portions of the single or groups of sealing discs by deforming the at least portions of single or groups of sealing discs.
15 . The stem controlled valve of claim 14 wherein pre-stressing is performed in the stem controlled valve at a pressure which exceeds a valve set pressure.
16 . The stem controlled valve of claim 14 wherein deforming is performed at room temperature.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to U.S. Ser. No. 63/480,571 filed Jan. 19, 2023, and the complete contents thereof is herein incorporated by reference. FIELD OF THE INVENTION The embodiments herein are directed to a stem controlled valve utilizing a disc configuration with a plurality of sealing discs and spacer discs, in which each spacer disc allows the sealing disc below it and/or above it to elastically deform without fracturing. In particular, the stem control valve is applicable to structures such as, for example, a valve and a plug operating at cryogenic conditions. BACKGROUND OF THE INVENTION Pipes and valves can run in an above ground and/or underground network to supply fluids like water and gas to homes and businesses. Because of the nature of where pipes and valves exist, there is a risk of damage from the elements. If pipes and valves are left open and unsecured, dirt, debris, rain, snow, salt and more can settle into pipes and then corrode the pipes. As pipes corrode, major problems may result, such as a burst water main or a gas leak. Pipes and valves above ground can be exposed to dust particulates and other foreign object debris in the air which can enter the pipes through intake or exhaust vents, and can lead to similar problems with below ground pipes. Additional problems that arise include leakages such as valve leakage, internal leakage, and external leakage. Valve leakage refers to flow through a valve which is set in the ‘off’ state. The importance of valve leakage depends on what the valve is controlling. In the United States, the American National Standards Institute specifies six different leakage classes for control valves, with “leakage” defined in terms of the full open valve capacity: Class I, or ‘dust-tight’ valves, are intended to work without much leakage, but are not tested for leakage loss; Class II valves have no more than 0.5% leakage with 50 psi (or less if operating pressure is less) of air pressure at the operating temperature; Class III valves have no more than 0.1% leakage under these same conditions as specified for Class II valves (this may require soft valve seats, or lapped metal surfaces); Class IV valves have no more than 0.01% leakage under the same conditions specified for Class II valves (this type of performance tends to require multiple graphite piston rings or a single Teflon piston ring, and lapped metal seats); Class V valves leak less than 5*10−12 cubic meters, per second, per bar of pressure differential, per millimeter of port diameter, of water when tested at the service pressure; Class VI valves are slightly different from Class V valves in that they are required (at 50 psi or operating pressure, whichever is less) to have less than a specified leakage rate in milliliters of air per minute as shown in Table 1 below. TABLE 1Leakage Size mL/min Bubbles/Min1 inch 0.15 1 1.5 inch 0.3 2 2 inches 0.45 3 2.5 inch 0.6 4 3 inches 0.9 6 4 inches 1.7 11 6 inches 4 27 8 inches 6.75 45 10 inches 9 63 12 inches 11.5 81 Valve Leakage rate for a Pressure Relief Valve, (PRV) is determined by the size of the orifice diameter, and the size of the valve, according to the American Petroleum Institute standard API 527. ‘Soft Seated’ PRV's are to be tested on Air or nitrogen near ambient temperature and are to exhibit no leakage for 1 minute at either 90%, or 5 psig below, of lifting pressure. Table 2 gives the leakage rate values for PRV's for metal-to-metal seated PRV's. TABLE 2Manufacturer's orifice area Allowable (in2) Bubbles/min0.47 and smaller 40 0.71 and smaller 40 1.264 20 Cryogenic valves still have some problems remaining to be solved, including without limitation internal leakage and external leakage. There are several reasons for the internal leakage of cryogenic valves. One is the sealed auxiliary deforming at low temperature. The phase transition of valve materials, which is formed by the decrease of the medium temperature, changes the volume of the cryogenic valve, and causes the warping deformation of the sealing surface. Another is hysteresis in the subassemblies after initial testing where the seat or spring can become misaligned preventing a tight seal. Yet another reason is seal embrittlement and wear of the seal and seat contact area caused by low medium temperature and standard use. Thus, cryogenic valves tend to have poor sealing performance at low temperature. In a low-temperature test, the cryogenic valve DN250, whose media are liquid nitrogen (−196° C.) and whose disc material is 1Cr18Ni9Ti (without low-temperature treatment), it was found that the warping deformation of the valve's sealing surface can reach about 0.12 mm. This deformation is the main reason for the internal leakage for metal-to-metal seated valves. In external leakage of the cryogenic valves, the cryogenic valve can leak when they are connected to the pipeline with a flanged connection and a gasket, and where the connecting bolt and fi