NO20151481A1 - A wafer type dual plate check valve assembly with rising stem override - Google Patents

Description

A WAFER TYPE DUAL PLATE CHECK VALVE ASSEMBLY WITH RISING STEM OVERRIDE

FIELD OF THE INVENTION

The present invention relates to the seat in a rising stem check valve assembly. Reference is made to the Norwegian patent application no. 20130357 and PCT application no. 53324XX01.

The above patent applications describes in detail the use of a rising stem and an outside yoke system incorporated on a dual plate check valve. This invention consists of the design of a wafer type dual plate check valve with a rising stem override function, with or without lugs.

BACKGROUND OF THE INVENTION

The seat in a dual plate check valve, typically defining two D - shaped flow paths in the valve bore, is described in the above mentioned patent applications as an integral part of the body.

On a wafer type or lugged type dual plate check valve with rising stem override, the extraction of the dise assembly might be limited due to the fact that the discs will dash with the body if flow is going through the valve from the upstream side to the downstream side during overriding. This is because the flange to flange dimension is so small that there is not space for a full extraction of the dise assembly when the discs are forced open by flow from the upstream side to the downstream side. Extraction of the discs in such case could possibly damage the valve as the discs would dash with the valve body. Therefore the wafer- or lugged design is best for cases where limited reverse flow is required during a shut down scenario, typically when draining the piping downstream the valve via a drain point upstream the check valve. When the stem and the dise assembly is operated to the lower position so that the typically D - shaped discs are engaged with the valve seat, the spring member will force the two discs towards the valve seat. In this position, the process media is prevented from passing from the downstream side of the valve to the upstream side of the valve according to criteria given in typically API 598. With the design described in this invention, the stem and dise assembly can be extracted radially from the sealing position by only a minor distance, in other words the discs are extracted only partially clear of the seat and thereby allowing a limited reverse flow. To allow the discs to be overrided to the "upper" position, the seat surface can be manufactured oval with a minor elevation so that the discs are tilted angular versus the seat surface when the dise assembly is extracted. Thereby it can be both a radial gap and an angular gap between the sealing surfaces on the discs and the seat. As shown on the attached figures, no separate bonnet is required with this invention, the yoke can be casted or forged as a part of the body as is normal on conventional double or triple offset butterfly valves. The valve can be provided with a handwheel and threads in the yoke bushing and on the stem for manual operation or it can be operated by the use of an electrical-, pneumatic- or hydraulic actuator. The valve can also be provided with a back seat in the body similar to what is described for a bonnet backseat in section 4.2.5 in API 603, Sixth Edition from May 2001.

OBJECT OF THE INVENTION

An object of the present invention is to provide a wafer type or lugged type dual plate check valve assembly with rising stem as described in detail in Norwegian patent application no. 20130357 and PCT application no. 53324XX01, but with a flange to flange dimension equal to conventional dual plate check valves for interchangeability and light weight and compact design.

SUMMARY OF THE INVENTION

Thus, the above described object are intended to be obtained in a first aspect of the invention by providing an wafer type dual plate check valve with rising stem override, with or without lugs of any kind and with an oval or oblong shaped valve seat. The valve seat can be provided with an elevation for the tilting of the discs in the overrided position.

The dual plate check valve with rising stem can in this way be provided as wafer type or lugged type with an integral yoke for guidance of the stem. No separate bonnet is required, though it can be implemented. This invention also allows for interchangeability between ordinary dual plate check valves as typically described in VDS CHAS50R in NORSOK L-001 and the invented dual plate check valve with rising stem in existing piping. This because the face to face dimensions can be equal.

The valve described in this invention can be provided completely lugged or with only two or four lugs, threaded or drilled through.

BRIEF DESCRIPTION OF THE FIGURES

The design according to the invention will now be described in more detail with regards to the accompanying figures. The figures shows one way of implementing the present invention and are not to be construed as being limiting to other possible embodiments falling within the scope of the attached claim set.

Figure 1 shows a wafer type rising stem dual plate check valve assembly 30 for mounting between piping flanges as typically described in ANSI B16.5. The valve on the figure is shown with four threaded bolt interfaces on the upstream side and four threaded bolt holes on the downstream side for machine bolts, but these holes can also be drilled through for through going piping stud bolts.

The valve is shown with the discs sealing towards the seat surface, hence no flow is going through the valve bore in any direction. Figure 2 shows same valve as in Figure 1, but discs in open position as when flow is going from the upstream side to the downstream side of the valve. Figure 3 shows the same valve as in Figure 1 and Figure 2, but with the stem and dise assembly in the "upper" overrided position.

DETAILED DESCRIPTION OF AN EMBODIMENT

The partially sectioned view in Figure 1 shows a dual plate check valve assembly 30 as described more in detail in Norwegian patent application no. 20130357 and PCT application no. 53324XX01, here as a wafer type valve for mounting between piping flanges with a yoke 16 as an integral part of the valve body 1 as on a high performance triple- or double offset butterfly valve.

Figure 1 is a partially sectioned view showing the valve from the downstream side with the dise members 12a, 12b engaged with the valve seat 50 when the rising stem 4 is in the lower position and there is no flow of process media through the valve. The spring 14 is forcing the dise members 12a,

12b towards the valve seat 50 thereby preventing process media from passing from the downstream side of the valve to the upstream side of the valve. Figure 2 is a partially sectioned view showing the dise members 12a, 12b in open position, not sealing against the valve seat 50, as when flow is passing through the valve from the upstream side to the downstream side. The forces from the spring legs towards the dise members 12a, 12b are less than the forces from the process media on the upstream side, thereby the discs are forced open. Figure 3 is a sectioned view showing the dual plate check valve assembly 30 with the rising stem 4 in the upper position where the stem seat surface 60 on the stem is engaged with the back seat 2 in the valve body 1.

Although the present invention has been described in connection with the specified embodiments, it should not be construed as being in any way limited to the presented examples. The scope of the present invention is set out by the accompanying claim set. In the context of the claims, the terms "comprising" or "comprises" do not exclude other possible elements or steps. Also, the mentioning of references such as "a" or "an" etc. should not be construed as excluding a plurality. The use of reference signs in the claims with respect to elements indicated in the figures shall also not be construed as limiting the scope of the invention. Furthermore, individual features mentioned in different claims, may possibly be advantageously combined, and the mentioning of these features in different claims does not exclude that a combination of features is not possible and advantageous.

Valve body 1

Backseat 2

Valve bore 3

Rising stem 4

Seat elevation 5

Gland follower 6

Gland flange 7

Gland Packings 8

End flange primary seal 13

End flange secondary seal 15

Yoke 16

Hinge Bearing 17

End flange bolt 23

Yoke bolt 20

Yoke nut 21

Hinge lock pin 22

Stem bearing 24

Hinge pin 9

Rotation stopper pin 10

Lower hinge pin retainer 11

Hinged dise members 12a, 12b

Spring member 14

Valve seat surface 50

Gland flange bolts 18

Yoke bushing 19

Check valve assembly 30

D-shaped flow paths 115a, 115b

Dise assembly 120

Stem seat surface 60

End Flange 61

Claims (8)

1. A wafer type dual plate check valve assembly 30 with rising stem 4 override for limited extraction of the dise members 12a, 12b in the radial direction versus the valve bore 3 and the valve seat surface 50.

2. A wafer type dual plate check valve assembly 30 as described in claim 1. With a partially or fully lugged valve body 1.

3. A wafer type dual plate check valve assembly 30 as described in any of the above claims with lugs either threaded or drilled through.

4. A wafer type dual plate check valve assembly 30 as described in any of the above claims with an oval or oblong shaped seat surface 50 giving room for the dise members 12a, 12b to be extracted from the seat in the radial direetion.

5. A wafer type dual plate check valve assembly 30 as described in any of the above claims with an elevation on the seat surface 50 for angular tilting of the dise members 12a, 12b when the dise assembly is in the overrided position.

6. A wafer type dual plate check valve assembly 30 as described in any of the above claims with a yoke 16 provided as an integral part of the valve body

7. A wafer type dual plate check valve assembly 30 as described in any of the above claims provided as a manually operated valve or as an actuated valve with actuator interface.

8. A dual plate check valve assembly 30 with rising stem 4 in any form with a backseat 2 in the body 1 or a bonnet as described in API 603, sixth edition, section 4.2.5.