WO2016016595A1

WO2016016595A1 - Pressure relief valve and pressure relief valve seating assembly

Info

Publication number: WO2016016595A1
Application number: PCT/GB2014/052357
Authority: WO
Inventors: Paul Campbell
Original assignee: Axon Energy Products Uk Ltd
Priority date: 2014-07-31
Filing date: 2014-07-31
Publication date: 2016-02-04

Abstract

A relief valve having a valve seat assembly with a valve member inserted in a bore. In a closed position, the valve member seals against a valve seat, preventing flow through the valve. In an open position, the valve member lifts from the seat permitting flow through the valve. The valve member partially abuts the bore in both the open and closed positions, maintaining alignment of the valve member within the bore. The non-abutting surface of the valve member and the inner surface of the bore define fluid pathways such that in the open position, fluid is permitted to flow around the valve member and through the relief valve.

Description

PRESSURE RELIEF VALVE AND PRESSURE RELIEF VALVE SEATING

ASSEMBLY

TECHNICAL FIELD

The present disclosure relates to relief valves for process equipment and piping, and specifically to seating assemblies within relief valves.

BACKGROUND

Relief valves are commonly installed in a hydraulic or pneumatic system to prevent over- pressurization of the system. System over-pressurization is undesirable as it may lead to improper process conditions, damage to process equipment, and danger to personnel and the environment.

In general, relief valves are spring-biased valves containing a plug or other sealing member at an inlet of the relief valve. When hydraulic or pneumatic pressure at the inlet exceeds the force of the spring, the plug or sealing member lifts from a valve seat into an open position, permitting flow through the valve and out of an outlet. When the pressure at the inlet returns to a normal range, the spring causes the plug to reseat in a closed position, sealing off flow through the valve.

Efficient flow through the relief valve is aided by minimal restriction of flow through the relief valve when in the open position. Typically, this is achieved by ensuring that the clearance between the valve seat and the plug in the open position is sufficiently large. However, relying on large clearance between the plug and the valve seat can lead to plug alignment issues, impeding quick and accurate reseating once system pressure returns to normal. As a result, a relief valve with low restriction on fluid flow in the open position and that maintains proper plug alignment is desirable.

SUMMARY

Embodiments of the present disclosure are directed to a pressure relief valve having a valve seat assembly. The valve seat assembly includes a valve plug having a leading surface that is biased against a valve seat when the valve plug is in a closed position. The valve plug is moveable away from the valve seat into an open position when fluid pressure at an inlet of the pressure relief valve reaches a predetermined value.

The valve plug is at least partially disposed inside a plug bore having an inner surface such that an outer profile of the valve plug partially abuts the inner surface of the plug bore. One or more flow paths are defined where the outer profile of the valve plug abuts the inner surface of the plug bore. When the valve plug is in the open position, fluid may flow through the flow paths, into a body of the relief valve, and through an outlet. In some embodiments, the outer profile of the valve plug and the inner surface of the plug bore are shaped such that the flow paths have a large enough cross-sectional area to minimize restrictions on fluid flow through the valve.

As the valve plug travels between an open and closed position, the outer profile of the valve plug continues to abut the inner surface of the plug bore. As a result, the plug maintains a consistent axial position relative to the valve seat and inefficiencies associated with misalignment during movement between the open and closed positions are minimized. These and various other features and advantages will be apparent from a reading of the following detailed description and drawings along with the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments and advantages of the present disclosure may be best understood by one of ordinary skill in the art by referring to the following description and accompanying drawings. In the drawings:

FIG. 1 is a cross-sectional view of a relief valve in accordance with embodiments of the present disclosure.

FIG. 2A and 2B are partial, enlarged views of the sealing assembly of the relief valve of FIG. 1 illustrating the relief valve in an open and closed position, respectively.

FIG. 3 is a partial cross-sectional view of the relief valve of FIG. 1 illustrating the flow paths of the relief valve defined by the valve plug and the plug bore.

FIG. 4A-F illustrate valve plugs of different profile shapes in accordance with embodiments of the present disclosure

DETAILED DESCRIPTION

FIG. 1 illustrates a relief valve 100 in accordance with one embodiment of the disclosure. The relief valve 100 has a hollow valve body 102 with an outlet 106. An inlet port member 104 is installed in the valve body 102. The inlet port member 104 has an inlet bore 108, an orifice 110, and a plug bore 112. While the plug bore 112 is depicted as having a diameter that is larger than the orifice 110, the orifice 110 and the inlet bore 108 may have equal diameters. The inlet bore 108 and the orifice 110 together form an inlet volume.

As depicted in FIG. 1, the inlet port member 104 is installed in the valve body 102. Installation of the inlet port member 104 into the valve body 102 may be by any suitable connection, including a weld or threads. The inlet port member may also include an O-ring 114 or other gaskets to create a seal between the inlet port member 104 and the valve body 102. Although the embodiment of FIG. 1 depicts the inlet port member 104 and the valve body 102 as separate pieces, the inlet port member 104 may be integral with the valve body 102. Similarly, the inlet port member 104 may be a single piece, as depicted in FIG. .1, or may comprise multiple pieces combined in a suitable manner, such as welding or threaded connections. For example, the plug bore 112 and the orifice 110 may be part of separate exchangeable components such that a single valve body may be used in multiple applications with differing plug and orifice requirements. The edge created by the transition between the orifice 110 and the plug bore 112 may be "broken" or chamfered, or filleted to avoid sharp edges.

As depicted in FIG. 1, the inlet member 104 has an inlet process connection 105. The inlet process connection 105 is depicted as a threaded connection. Similarly, the outlet 106 has an outlet process connection 107, depicted in FIG. 1 as a threaded connection. FIG. 1 depicts only one embodiment of the disclosure and the possible process connections that may be used. Under other embodiments, the inlet process connection 105 and the outlet process connection 107 may be threaded connections, butt welded connections, flanged connections, compression connections, or any other process connection type or combination of process connection types.

The valve body 102 has an adjustment screw bore 116 through which an adjustment screw 118 enters the valve body 102. Turning the adjustment screw 118 in a first direction causes the adjustment screw 118 to enter into the valve body 102 while turning the adjustment screw 118 in a direction opposite the first direction causes the adjustment screw 118 to move out of the valve body 102. A spring retainer 120 mounted on one end of a spring 122 is attached to or abuts the adjustment screw 118. The spring 122 may be a single spring, as depicted in FIG. 1, or may be a set of springs. Further, the spring 122 may be a coil spring, as depicted, or may be another suitable type of spring including a volute spring, a gas spring, or a Belleville washer. When installed, the spring 122 is maintained in compression. The spring 122 extends through the valve body 102 and is attached to or abuts a plug locator 124. The plug locator 124 holds a plug 126 having a leading surface 127. The spring 122, plug locator 124, and plug 126 are configured such that the plug 126 is partially disposed inside the plug bore 112. Because the spring 122 is in compression, the spring 122 biases the plug 126 against a valve seat 128 defined by the orifice 110 and the plug bore 112 with a force based on the degree to which the spring 122 is compressed. The leading surface 127 of the plug 126 is designed such that when the plug 126 is biased against the valve seat 128, the leading surface 127 and the valve seat 128 form a seal that prevents fluid flow into the valve body 102.

Turning the adjustment screw 118 changes the degree to which the adjustment screw 118 is displaced inside the valve body 102. As the adjustment screw 118 is turned, the spring retainer 120 also moves within the valve body 102 and changes the degree to which the spring 122 is compressed. Because the force at which the plug 126 is biased against the valve seat 128 is determined by the degree of compression of the spring 122, a set point of the valve at which the valve opens, may be changed by turning the adjustment screw 128. To prevent the adjustment screw 118 from loosening or otherwise moving during operation, a lock nut 123 may be installed on the adjustment screw 118.

FIGS. 2A and 2B depict the relief valve 100 during operation. FIG. 2A depicts the relief valve 100 in a closed position. The closed position occurs when fluid pressure in the inlet volume is insufficient to overcome the force applied by the spring 122 to the plug 126. As a result, the spring 122 maintains the leading surface 127 against the valve seat 128, sealing off flow.

FIG. 2B depicts the relief valve 100 in an open position. The open position occurs when fluid pressure in the inlet volume is sufficient to apply a force to the leading surface 127 that exceeds the force of the spring 122. The force on the leading surface 127 causes the spring 122 to compress and the leading surface 127 displaces from the valve seat 128. Although the leading surface 127 is depicted as rounded, the plug 126 may have any leading surface suitable for seating against the valve seat 128 and sealing flow from the orifice 110. For example, in one embodiment, the plug may be disc-shaped with a flat leading surface. In another embodiment, the plug may be tapered with a conical leading surface.

FIG. 3 is a cross-sectional view of the relief valve depicting the placement of the plug 126 inside the plug bore 112. To permit fluid flow when the relief valve is in the open position, the plug 126 is shaped so the plug 126 only partially contacts the plug bore 112. Where the plug 126 does not abut the plug bore 112, fluid pathways 130A-D are defined. As a result, when the plug 126 is in the open position, fluid is permitted to flow past the plug 126, through the plug bore 112, into the valve body 102, and through the outlet 106.

In some embodiments, the plug 126 and plug bore 112 are shaped such that the fluid pathways 130A-D have a combined cross-sectional area equal to or greater than the cross-sectional area of the orifice 110. Doing so minimizes any flow-restricting effect of the plug and plug bore. As a result, efficient flow through the relief valve may be achieved with minimal lift of the plug.

Additional valve inefficiencies caused by plug alignment issues are minimized in the present disclosure. Specifically, as the plug 126 moves between the open and closed positions during operation, contact between the plug 126 and the plug bore 112 maintains the plug 126 in alignment with the valve seat 128.

The plug of FIGS. 1-3 is depicted as having a square-shaped profile; however, the profile of the plug is not limited to a square, provided the plug partially abuts the plug bore to maintain alignment, and the plug and plug bore define fluid pathways to permit fluid flow through the relief valve. For example, FIGS. 4A-F depict alternative shapes for the plug including a square shape FIG. 4A-B; a triangular shape FIG. 4C-D, and a hexagonal shape FIG. 4E-F.

Although numerous characteristics and advantages of embodiments of the present disclosure have been set forth in the foregoing description and accompanying figures, this description is illustrative only. Changes to details regarding structure and arrangement that are not specifically included in this description may nevertheless be within the full extent indicated by the claims. For example, process conditions and fluid properties significantly vary for systems in which relief valves may be installed. As a result, various changes to the relief valve to accommodate these variables, such as selection of materials and changes related to sizing are within the scope of the claims.

Claims

1. A valve seat assembly comprising

a seat body having

a first bore;

a second bore; and

a valve seat disposed between the first and second bores;

a valve member at least partially disposed within the second bore,

the valve member having an outer surface partially abutting the second bore wherein a fluid pathway is defined between the nonabutting outer surface of the valve member and the second bore;

the valve member being movable between

a closed position, wherein the valve member is biased against the valve seat, and

an open position, wherein the first bore and the fluid pathway form a continuous volume.

The valve seat assembly of claim 1, wherein

the valve member is one of a disc, a rounded plug, or a tapered plug.

The valve seat assembly of claim 1, wherein

the outer surface of the valve member has a cross-sectional shape that is one of a triangle, square, or hexagon

The valve seat assembly of claim 1, wherein

in the closed position, the valve member is biased against the valve seat by at least one spring.

The valve seat assembly of claim 4, wherein

the at least one spring is one of a coil spring, a volute spring, a gas spring, or a Belleville washer.

The valve seat assembly of claim 13, wherein

the total cross-sectional area of the fluid pathway is greater than or equal to the cross- sectional area of the first bore.

A relief valve comprising

a valve body having an internal volume to accommodate a flow of fluid through the valve, the valve body further comprising,

an inlet, and

an outlet; and

a valve seat disposed within the valve body, between the inlet and the outlet, the valve seat comprising a seat body having

a first bore;

a second bore; and

a valve seat disposed between the first and second bores;

a valve member at least partially within the second bore,

the valve member having an outer surface partially abutting the second bore wherein a fluid pathway is defined between the nonabutting outer surface of the valve member and the second bore; and

the valve member being movable between

8. The relief valve of claim 6, wherein

the inlet further comprises a process connection for connecting the relief valve to a hydraulic or pneumatic system,

9. The relief valve of claim 7, wherein

the process connection is one of a butt weld, socket weld, flange, compression connection, or threaded connection.

10. The valve seat assembly of claim 6, wherein

the valve member is one of a disc, a rounded plug, or a tapered plug.

11. The valve seat assembly of claim 6, wherein

the outer surface of the valve member has a cross-sectional shape that is one of a triangle, square, or hexagon.

12. The valve seat assembly of claim 6, wherein

13. The valve seat assembly of claim 11, wherein

14. The valve seat assembly of claim 13, wherein

15. A relief valve comprising:

a first bore;

a second bore located above the first bore;

a valve seat disposed between the first and second bores; and a valve member at least partially disposed within the second bore, wherein a fluid pathway is defined between a portion of the outer surface of the valve member that is not in contact with a surface of the second bore; the valve member being movable between a closed position, wherein the valve member is in contact with the valve seat, and an open position, wherein the valve member is not in contact with the valve seat.

16. The valve seat assembly of claim 15, wherein

the valve member is one of a disc, a rounded plug, or a tapered plug.

17. The valve seat assembly of claim 15, wherein

18. The valve seat assembly of claim 15, wherein

19. The valve seat assembly of claim 16, wherein

20. The valve seat assembly of claim 15, wherein