Check valve

A top entry check valve including a valve body with an access port. A compressible hanger body engages a portion of the valve body and is positioned in alignment with the access port of the valve body. A clapper is connected to the hanger body so that the clapper is movable between a closed position wherein the clapper engages a valve seat to occlude the passage of fluid through the fluid flow passage and an open position wherein the clapper is moved away from the valve seat to permit passage of fluid through the fluid flow passage. A closure member is connected to the valve body to close the access port of the valve body. The closure member has an abutment surface engaging the hanger body so that the hanger body is compressed between the closure member and the valve body.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates generally to valves and more particularly, but not by way of limitation, to a check valve particularly designed and constructed for facilitating repair and maintenance of the valve when worn or otherwise damaged.

2. Brief Description of Related Art

Check valves are old and well known for use in flow lines where it is desirable to permit fluid flow in one direction and preclude fluid flow in the opposite direction. A common structure for achieving one-way flow is by the use of a disk or clapper that is positioned so that it can pivot about an axis of a pivot shaft. The disk is loosely retained in position between a recess formed in the valve body and the lower edge of a bonnet used to close an access port.

In non-corrosive applications, such a structure generally allows for a reasonable service life. In most applications, however, in particular petroleum production, corrosive constituents generally exist within the flow media. Even when the flow media is only mildly corrosive, the combined action of the corrosion and the erosion created by vibration and the rubbing movement of the pivot shaft against the valve body and the bonnet often causes a loss of surrounding metal which may result in failure of the valve due to misalignment of the disk. One solution to this problem would be to make the entire valve from stainless steel or some other corrosion resistant material. While this would solve the corrosion problem, the cost of the valve would greatly increase and would not be economically viable.

To this end, a need exists for an improved check valve that is capable of being used in a corrosive environment yet is cost effective to manufacture and repair. It is to such an improved check valve that the present invention is directed.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the drawings, and more particularly toFIGS. 1 and 2, a valve10constructed in accordance with the present invention is shown. The valve10includes a valve body12, a clapper assembly14, and a closure member16. The clapper assembly14cooperates with the valve body12to permit fluid flow in one direction while preventing fluid flow in the opposite direction. As such, the valve10is of the type commonly known as a “swinging check valve.”

The valve body12has a first end17with an inlet port18and a second end19with an outlet port20which is generally opposing the inlet port18. The inlet port18extends into the valve body12and opens into a valve chamber22formed in a medial portion of the valve body12. An annular valve seat24is defined about the inlet port18. The valve seat24is shown to be formed as an integral part of the valve body12. However, it will be appreciated that the valve seat24may be formed on a module that is inserted into the valve body12. The outlet port20extends into the valve body12and opens into the valve chamber22generally opposite the inlet port18. The inlet port18and outlet port20are shown to be internally threaded to provide a means for connecting the valve10into a conduit utilized for transporting a fluid. However, it will be appreciated that the inlet port18and the outlet port20may be adapted to be interposed in a flow line in other ways, such as be formed with flanges.

The first end17of the valve body12includes a shelf portion26which extends into the valve chamber22and defines a portion of the inlet port18. The shelf portion26includes a generally flat bearing surface28for supporting the clapper assembly14in a manner to be discussed below. A pin receiving hole30is formed through the bearing surface28and into the shelf portion26along a center line of the valve body12.

The upper portion of the valve body12is provided with an access port32which is in communication with the valve chamber22. The access port32is threaded and sized to allow passage of the clapper assembly14to and from the valve chamber22via the access port32. The shelf portion26of the valve body12projects into alignment with the access port32such that the bearing surface28faces the access port32and thus is accessible via the access port32.

The closure member16functions to seal the access port32and thus has external threads to mate with threads or the access port32. The closure member16further has a flange34for compressing a seal member36, such as an elastomeric O-ring, disposed in a groove38of the valve body12. The seal member36is compressed to effect a fluid tight seal between the closure member16and the valve body12when the closure member16is threaded onto the valve body12with the flange34engaging the valve body12.

The closure member16further includes an abutment surface40defined by a lower end of the closure member16. The abutment surface40serves to engage a portion of the clapper assembly14and thus cooperate with the valve body12to fix the clapper assembly14within the valve chamber22. The size and position of the abutment surface40may varied so long as the abutment surface40engages the clapper assembly14when the closure member16is operably secured to the valve body12to effect a fluid tight seal. However, the abutment surface40is preferably annular in so far as the abutment surface40may slidingly engage the clapper assembly14as the closure member16is being secured to the valve body12.

Referring now toFIGS. 1–4, the clapper assembly14includes a hanger42and a clapper44pivotally mounted to the hanger42with a pivot shaft46. The hanger42is adapted to be firmly held between the bearing surface28of the valve body12and the abutment surface40of the closure member16and thereby support the clapper44in alignment with the inlet port18. With reference toFIGS. 3–4, the hanger42includes a body member48, an alignment pin50extending from one side of the body member48, and a compressible member52connected to an opposing side of the body member48.

The body member48is shown to be a generally cubicle member with a bore54extending therethrough from one side to an opposing side. However, it will be appreciated that the body member48may be formed of a variety of shapes so long as the body member48functions to pivotally support the clapper44and is securable between the bearing surface28of the valve body12and the abutment surface40of the closure member16in the manner to be described below. The alignment pin50extends from the body member48and is adapted to be matingly received in the pin receiving hole30of the valve body12. The alignment pin50is positioned so that the clapper assembly14may be supported within the valve chamber22with the clapper44aligned with the inlet port18prior to the closure member16being secured to the valve body12.

The compressible member52is connected to a side of the body member48opposite the alignment pin50such that the combination of the compressible member52and the body member48are capable of being held firmly between the bearing surface28of the valve body12and the abutment surface40of the closure member16when the closure member16is operably secured to the valve body12. The function of the compressible member52is to cause the clapper assembly14to be held firmly in position between the valve chamber22and the closure member16while compensating for differences in dimension to the various components of the valve10due to normal manufacturing tolerances. For example, if a non-compressible body member were sized to be positioned alone between the closure member16and the valve body12, in some instances the dimensions of the components of the valve10would result in the closure member16being properly sealed with the valve body12and the clapper assembly14being held in position without vibration or rubbing occurring between the clapper assembly14and the closure member16and/or the valve body12.

However, in other instances when the dimensions of the components of the valve cause the distance between the bearing surface28of the valve body12and the abutment surface40of the closure member16to be decreased, the body member48would interfere with the closure member16being properly sealed to the valve body12, thereby increasing the risk that the valve10wouldl leak. On the other hand, if the dimensions of the components of the valve are such that the distance between the bearing surface28of the valve body12and the abutment surface40of the closure member16are increased, the height of the body member would be less than the distance from the bearing surface28to the abutment surface40. As such, the closure member16would not engage the body member48before the closure member16is secured to the valve body12. Consequently, the combined action of corrosion and the erosion created by vibration and the rubbing movement of the body member against the valve body12and the closure member32would rapidly cause a loss of surrounding metal which may result in failure of the valve10due to misalignment of the clapper44.

The compressible member52is preferably some type of compression spring. The compressible member52is illustrated herein as being a “flat” spring formed from a strip material56to have a general U-shape with an intermediate portion58and two opposing end portions60. The compressible member52is oriented in a substantially parallel relationship to the bore54of the body member48whereby the strip material56is tangentially positioned relative to the abutment surface40of the closure member16. The end portions60of the strip material56are curved so that the end portions60of the strip material58curve away from the access port32to facilitate sliding engagement with the abutment surface40of the closure member16. The compressible member52is connected to the body member48in a suitable fashion, such as with a pin, rivet or weld, or alternatively, the body member48and the compressible member52may be formed as a single piece.

The hanger42, including the body member48, the alignment pin50, and the compressible member52are fabricated of a corrosion resistant material, such as stainless steel. The compressible member52is preferably resilient whereby the compressible member52is capable of recovering its shape after being deformed by the application of force caused by securing the closure member16to the valve body12. However, it should be appreciated that the compressible member52may be formed of a material that becomes permanently deformed upon being compressed by the application of force so long as the compressible member52maintains sufficient tension against the abutment surface40so that the hanger42is held firmly between the closure member16and the valve body12. It will also be appreciated that while the compressible member52has been described and illustrated as being engaged with the closure member16, the compressible member52may alternatively be positioned on the body member48so that the compressible member52engages the valve body12.

The clapper44is pivotally secured to the body member48with the pivot shaft46and cooperates with the valve seat24to provide alternate open and closed positions for the valve10. The clapper44includes a substantially circular disc member62adapted to engage the valve seat24in the closed position of the valve10. A suitable sealing member, such as an O-ring64, is disposed in an annular groove66for engaging the valve seat24to preclude leakage of fluid in the closed position of the valve10. Alternatively, the sealing member may be disposed in the valve seat24instead of on the disc member62.

A pair of arms68extend from the disc member62in a spaced apart, parallel relationship. The arms68are spaced a sufficient distance to receive the body member48therebetween. The distal end of the arms68is provided with a bore70(FIG. 4) extending transversely therethrough for receiving the pivot shaft46therein. The pivot shaft46may be secured within the bores70of the arms68and the bore54of the body member48in any suitable manner, such as securing a fastener on the ends, forming a head on the ends of the pivot shaft46by enlarging or flattening the ends of the pivot shaft46, or providing the pivot shaft46with a length where the ends of the pivot shaft46are positioned near the interior surface of the valve body12. The distal end of the arms68are offset relative to the center of gravity of the disc member62. As such, the pivot axis of the clapper assembly14is offset from the center of gravity of the disc member62, thus causing the disc member62to be constantly urged in a direction toward the valve seat24in a normally closed position.

FIGS. 3 and 4illustrate the bore54of the body member48being oversized relative to the pivot shaft46whereby the pivot shaft46is able to move laterally within the bore54to permit an amount of free play between the pivot shaft46and the body member48. Such free play allows the clapper44to properly align with the valve seat24upon the clapper44moving to the closed position, thereby compensating for any potential misalignment of the clapper44with the valve seat24due to wear or manufacturing tolerances.

As illustrated inFIGS. 5 and 6, the free play between the pivot shaft46and the body member48further permits the clapper44to move linearly along an axis72of the inlet port18in response to variances in line pressure. More specifically, the free play between the pivot shaft46and the body member48permits the clapper44to move along the axis72of the inlet port18whereby a uniform pressure is maintained on the seal member64in a low pressure condition (FIG. 5) and a high pressure condition (FIG. 6).

FIG. 7illustrates another embodiment of a clapper44ahaving arms68a. Each arm68ais provided with a bore70athat is elongated wherein the elongated bores70aallow axial movement of the clapper44ain a manner similar to that described above to effect a uniform compression seal.

The above described construction of the valve10permits rapid repair of the valve10without requiring the valve body12being removed from the flow line. In particular, access to the clapper assembly14is obtained by unscrewing the closure member16from the valve body12. With the closure member16removed from the valve body12, the clapper assembly14can be grasped and withdrawn from the valve body12via the access port32. A new clapper assembly14may then be inserted into the valve body12by inserting the alignment pin50in the pin receiving hole30. The closure member16is then threaded onto the valve body12so that the abutment surface40of the closure member16engages and compresses the compressible member52of the hanger42and forces the body member48firmly against bearing surface28of the valve body12.

Where fluid pressure is applied at the inlet port18, such pressure bears against the disc member62of the clapper44to force the clapper44out of engagement with the valve seat24to provide a flow passage through the valve chamber22from the inlet port18to the outlet port20so that fluid will flow through the valve10. When fluid pressure is applied at the outlet port20, the weight of the clapper44cause the clapper44to pivot to the closed position wherein the disc member62engages the valve seat24to occlude the passage of fluid through the valve10.

Referring now toFIGS. 8 and 9, a valve10aconstructed in accordance with the present invention is illustrated. The valve10ais similar in construction to the valve10described above, with the exception the valve10ais provided with a modified clapper assembly14a. The clapper assembly14ais similar to the clapper assembly14described above, but the clapper assembly14ais provided with features that may enhance the performance of the clapper assembly14aover that of the clapper assembly14. First, the clapper assembly14ais provided with a counterweight80on a clapper44bto facilitate movement to the closed position in both horizontal and vertical service. The clapper44bis further shown to have a pair of return springs82and84(FIGS. 8 and 9) to further facilitate rapid closure of the clapper44bby biasing the clapper44bin the closed position. The return springs82and84also reduce slamming of the clapper44bcaused by pressure reversal. Finally, the valve10ais shown to be provided with a cushion spring86positioned to receive the clapper44band thus absorb the impact of the clapper44bupon rapid opening of the clapper44b.

From the above description, it is clear that the present invention is well adapted to carry out the objects and to attain the advantages mentioned herein as well as those inherent in the invention. While presently preferred embodiments of the invention have been described for purposes of this disclosure, it will be understood that numerous changes may be made which will readily suggest themselves to those skilled in the art and which are accomplished within the spirit of the invention disclosed and as defined in the appended claims.