Patent Application
20150267819
1. Field of the Invention
The present disclosure relates to hardware for the production of hydrocarbons, and in particular to a seal element for use in valves used in hydrocarbon production.
2. Brief Description of Related Art
Typical gate valves used in connection with oil and gas operations have a valve body with a flow passageway that extends therethrough. The flow passageway intersects a central cavity in which a gate is typically reciprocated. The gate has an opening, and moves between open and closed positions. When in the open position, the opening is aligned with the fluid path so that fluid can flow therethrough. Conversely, when the gate is in the closed position, the gate blocks the flow passageway. Annular valve seats are usually provided in the valve body on opposing sides of the gate, the valve seats circumscribe the passage and seal against the valve to prevent cross flow between the flow passageway and central cavity. Valve gates typically attached to a stem, which controls the position of the gate between the open and closed positions and inserts through an axial bore in the valve body. A gland packing is usually installed in an annular space between the stem and axial bore. Seal elements are often installed with the valve seats and gland packing that seal between the valve body, elements of the gland packing, and valve body.
Disclosed herein are examples of a valve assembly. In an example the valve assembly includes a valve body, where the valve body has a flow passageway, a cavity that is intersected by the flow passageway, and an axial bore in communication with the cavity. Also included with the valve assembly is a stem that inserts into the axial bore and a seal assembly disposed in the valve body. In this embodiment the seal assembly is made up of an annular elastomeric casing and an annular spring having a V-shaped cross section disposed in a recess in the casing and that has legs with free ends that are contoured towards one another so that a rounded surface is formed on inner and outer curved surfaces of the spring. The seal assembly can be disposed between the stem and a gland packing that is inserted in the axial bore and circumscribes the stem, and wherein the seal assembly defines a seal on the stem. The valve assembly can further have a plurality of seal assemblies in sealing contact around the stem, and wherein the gland packing has annular members that couple together in the annular space between the stem and the axial bore. Counterbores can be formed in the flow passageway and annular seat rings can be inserted into the counterbores, wherein a seal assembly is disposed in each of the counterbores, and the seat rings have a face that contacts opposing surfaces of a gate that is attached to the stem. Further included in this example are primary seal assemblies in annular spaces between the seat rings and the counterbores, wherein the seal assemblies are secondary seal assemblies, and wherein the primary seal assemblies are between the secondary seal assemblies and the faces. The valve body is optionally connected to a wellhead assembly that is used for producing hydrocarbons from a subterranean formation. In an example, the free ends angle from the legs of the spring at a value of from about 5° to about 25°.
In another example the valve assembly includes a valve body, where the valve body has a flow passageway, a cavity that is intersected by the flow passageway, and an axial bore in communication with the cavity a stem that inserts into the axial bore, a gland packing in the axial bore and that circumscribes the stem, an annular seal assembly that circumscribes and seals around the stem, and that comprises an annular elastomeric casing and an annular spring having a V-shaped cross section disposed in a recess in the casing and that has legs with free ends that are contoured towards one another at an angle from the legs so that a rounded surface is formed on inner and outer curved surfaces of the spring. The seal assembly may be a gland seal assembly and where the valve assembly further includes a valve seat seal assembly that is disposed between a seat ring and a counterbore in the valve body. This example can further include primary seal assemblies in annular spaces between the seat rings and the counterbores, wherein the seal assemblies are secondary seal assemblies, and wherein the primary seal assemblies are between the secondary seal assemblies and the faces. The angle can range from 5° to 25°. Optionally, the valve body couples to a wellhead assembly used for producing hydrocarbons. A lip can be included on the elastomeric case that depends radially inward and over a one of the free ends of the spring.
Another example of a valve assembly disclosed herein includes a valve body having a flow passageway, a cavity that is intersected by the flow passageway, and an axial bore in communication with the cavity. A counterbore is included in the valve body that circumscribes the passage and a seat ring in the counterbore. An annular seal assembly is between the counterbore and seat ring, and that is made up of an annular elastomeric casing and an annular spring having a V-shaped cross section disposed in a recess in the casing and that has legs with free ends that are contoured towards one another at an angle from the legs so that a rounded surface is formed on inner and outer curved surfaces of the spring. The valve assembly can further include a stem that inserts into the axial bore, and a gland packing around the stem, and wherein the seal assembly is a seat ring seal. A gland packing seal can be disposed between the gland packing and the stem and that defines a seal around the stem. The valve body can connect to a wellhead assembly that produces hydrocarbons. Optionally, the free ends depend from the legs at an angle of at least around 5°.
The present technology will be better understood on reading the following detailed description of nonlimiting embodiments thereof, and on examining the accompanying drawings, in which:
While the invention will be described in connection with the preferred embodiments, it will be understood that it is not intended to limit the invention to that embodiment. On the contrary, it is intended to cover all alternatives, modifications, and equivalents, as may be included within the spirit and scope of the invention as defined by the appended claims.
The method and system of the present disclosure will now be described more fully hereinafter with reference to the accompanying drawings in which embodiments are shown. The method and system of the present disclosure may be in many different forms and should not be construed as limited to the illustrated embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey its scope to those skilled in the art. Like numbers refer to like elements throughout. In an embodiment, usage of the term about includes +/−5% of the cited magnitude.
It is to be further understood that the scope of the present disclosure is not limited to the exact details of construction, operation, exact materials, or embodiments shown and described, as modifications and equivalents will be apparent to one skilled in the art. In the drawings and specification, there have been disclosed illustrative embodiments and, although specific terms are employed, they are used in a generic and descriptive sense only and not for the purpose of limitation.
The gate 16 and stem 20 are selectively moved between an open position and a closed position. To illustrate this functionality, in
Movement of the gate 16 between an open and a closed position may be accomplished by any appropriate means. For example, the embodiment of
An example of the gland packing assembly 12 from area 2 of
Referring back to
Referring back to
An annular spacer 66, positioned between the secondary stem seal 38 and the tertiary stem seal 40, and extending into a cavity behind the tertiary stem seal 40. The annular spacer 66 has a lower end 68 that fits into the annular space between the extended portion 44 of the primary stem seal 36 and the stem 20. One purpose of the annular spacer 66 is to restrain axial movement of the secondary stem seal 38 by providing a barrier to movement of the secondary stem seal 38 toward the tertiary stem seal 40. In alternate embodiments, the annular spacer 66 could be replaced with any mechanism capable of helping to maintain relative movement of the secondary stem seal 38 and the tertiary stem seal 40. For example, the annular spacer 66 could be replaced with a snap ring (not shown).
The gland packing assembly 12 is designed to provide a multi-fault system for retaining pressurized fluids below the gland packing assembly 12, and to prevent such fluids from passing between the stem seal gland packing assembly 12 and the stem 20. Each of the primary, secondary, and tertiary stem seals 36, 38, 40 has a different structure, as described in detail below, and each provides a secure seal against the stem 20 of the gate valve assembly 10. Each seal is structurally independent of the other seals, and is capable of sealing the space between the stem seal gland packing assembly 12 and the stem 20 independent of the other seals. Moreover, together these seals provide a redundancy that maintains the integrity of the interface between the gland packing assembly 12 and the stem 20, even if one or two of the seals fail.
Referring now to
As shown in side sectional view
By contouring the free ends 94 of the legs 90 so that the rounded surface 96 contacts the elastomeric casing 80 lowers stresses between the spring element 88 and casing 80. This in turn reduces damaging forces applied by the spring element 88 against the casing 80 and prolongs the useful life of the casing 80 and thus the seal assembly 78. To retain the spring element 88 in the recess 86, an optional lip 98 is provided on the casing 80 proximate the opening to the recess 86 and on an inner surface and terminal end of one of the legs 82. In an example, the free ends 94 contour at an angle θ from the legs 90 that ranges from about 5° to about 25°.
An advantage to utilizing the embodiments disclosed herein is that a seal made in accordance with the present disclosure seals better after many thermal and/or pressure cycles. Due to the different in thermal expansion of different materials in the seal assembly, the edge end of the spring protrudes into the seal jacket and has a ratcheting effect when the spring and jacket expand at different rate. The result is the jacket will be stretched and flattened after many thermal and pressure cycles until it can no longer seal.
The present invention described herein, therefore, is well adapted to carry out the objects and attain the ends and advantages mentioned, as well as others inherent therein. While a presently preferred embodiment of the invention has been given for purposes of disclosure, numerous changes exist in the details of procedures for accomplishing the desired results. For example, instead of elastomeric, the subject material can be a polymeric material, a polymeric/elastomeric material, and combinations thereof. This and other similar modifications will readily suggest themselves to those skilled in the art, and are intended to be encompassed within the spirit of the present invention disclosed herein and the scope of the appended claims.
