GB2513641A

GB2513641A - Gate valve friction collar

Info

Publication number: GB2513641A
Application number: GB1307981.9A
Authority: GB
Inventors: Erling Arnum Freudendahl
Original assignee: AVK Holding AS
Current assignee: AVK Holding AS
Priority date: 2013-05-02
Filing date: 2013-05-02
Publication date: 2014-11-05
Also published as: GB201307981D0; CN105143744A; WO2014177681A1; HK1215727A1

Abstract

A gate valve 1 comprises a valve body having a passageway 3, a valve housing 4 and a valve assembly comprising a valve stem 6 carrying a gate 7. The valve stem 6 has threads 9 engaging a spindle nut 10. The upper part 11 of the valve stem 6 has circumferential grooves (13, Fig. 2) engaging complementary surfaces on an encircling collar 12.

Description

I

Title: Gate Valve Friction Collar

Technical Field

The invention relates to a gate valve comprising a valve body comprising a pipe section and a valve housing, and a valve top comprising an outer surface and an oppositely placed inner surface, said gate valve further comprising a valve assembly comprising a valve stem carrying an obturator adapted to be moved axisparallel with the centre line CL of the valve stem (and the movement thereof), whereby the pipe section Es opened and closed for passage through said pipe section, a lower part of said valve stem com-prising threads engaging a spindle nut and an upper part of the valve stem comprising at least one circumferential recess/groove, a collar comprising a radial surface facing the inner surface of the valve top and an oppositely placed surface facing the circum- ferential recess(es)/groove(s) of the valve stem, said collar comprising at least two col-ar parts adapted to encircle the recess(es)/groove(s).

Background

Gate valves are known to comprise a collar for supporting a stem in a valve housing.

The collar comprises two separate semi-circular parts placed around an upper part of the stem of the gate valve. The purpose of the collar is to absorb the axial forces during opening and closing of the gate valve. However, the force absorption requires the spin-dle nuts, the stem and the obturator to be powerfully constructed in order to withstand the considerable forces arising during operation. This makes the gate valve unneces-sarily expensive and requires large dimensions or expensEve materials for at least the obturator, the stem and the spindle nut. Further, this requires more energy for manu-facturing the gate valve in question.

EP2020543 discloses a gate valve comprising toothed bushing parts placed in the up-per part of a valve housing constructed to limit the torque. The construction is quite complicated due to the different components and the interaction thereof.

Disclosure of the Invention

An aspect of the invention is to provide a new gate valve overcoming at least one of the disadvantages of the prior art or at least providing a useful alternative.

According to a first aspect of the invention, a gate valve as described in the introduction is provided and the collar comprises at least one protruding part engaging the re- cess(es)/groove(s), said protruding part comprising a first surface and a second sur- face, said first and second surfaces converging and ending in a top part, said re-cess(es)/groove(s) being annular recess(es) comprising a bottom part and a third and a fourth surface diverging from said bottom part, said protruding part(s) being adapted to engage the recess(es)fgroove(s).

By this construction, the absorption of the axial forces is remarkably increased com- pared to the known gate valves. This is due to the inclined surfaces of the collar abut-ting the inclined surfaces of the grooves/recesses of the upper stem part. Thereby, a friction collar is provided. The inclined cone-shaped surfaces of the protruding parts of the collar ensure that a high friction takes place between the protruding parts and the recess(es) of the stem. Thereby, the axial forces transferred through the stern, obtura- tar and spindle nut are reduced making it possible to construct the parts in smaller di-mensions compared to the known or using a material with less strength properties and thereby also being less energy-consuming to produce. Thereby, the valve is cheaper to produce. Further, the valve housing, the valve top and the bolts for joining the construc-tion may also be formed in smaller dimensions than is the case with the known gate valves.

Due to the collar comprising at least two collar parts, the friction occurring during the rotation of the valve stem will take place between the valve stem and the abutting collar parts and further between the radially pointing surfaces of the collar parts and the valve top. Thereby, the friction effect is double-acting.

Further, it should be mentioned that the first, second third and fourth surfaces may also be curve-shaped. Then, the converging direction is measured between tangents to the curved surfaces in question (when the surface is convex) or to the chords of the curved surfaces (when the surface is concave).

According to another aspect of the invention, the gate valve comprises several annular recesses/grooves, each annular recess/groove being separated from the neighbouring annular recess/groove.

According to another aspect of the invention, the number of protruding parts and annu- ar recesses/grooves are equal and each protruding part is adapted to engage an an-nular recess.

By bavLng several protruding parts, each engaging in a recess, the friction absorption may be increased. This is important during closing for and opening to fluid flow of gate valves operating under great pressure. Each protruding part and each recess have an annular course and each recess is not connected to the neighbouring recess in any way. The same applies to the protruding parts; they are not thread-shaped.

According to another aspect of the invention, the top angle between the first surface and the second surface is 80-100°, preferably 85-95°, more preferably around 9Q0* According to another aspect of the invention, the top angle between the third and fourth surfaces converging towards the bottom part is 80-1 000, preferably 85-95°, more pref-erably around 90°.

By using the intervals mentioned; it has been shown that the friction properties are in-creased and optimised in relation to the purpose of the construction.

According to another aspect of the invention, the collar comprises several physically separated disc-shaped parts, said disc-shaped parts being vertically separated, each comprising at least one protruding part engaging the annular recess and each disc-shaped part comprising at Feast two separate half disc-shaped collar parts.

According to another aspect of the invention, the collar comprises a bushing-shaped part comprising several protruding parts, said bushing-shaped part comprising at least two separate half or pad-cylindrical collar pads forming the cylindrical bushing-shaped part when they are placed around the valve stem.

In a vertical direction (the axial direction of the valve stem) the collar may be one part.

However, the collar always comprises at least two collar parts in horizontal direction encircling the stem. A collar may comprise several protruding pads, and/or it may be formed by several physically separated disc-shaped parts each comprising at least one protruding part.

According to another aspect of the invention, the valve stem is manufactured in a first S material and the collar is manufactured in a second material different from the first ma-terial.

Advantageously, the first material may be a stainless steel and advantageously, the second material may be bronze. By having two different materials, it is avoided that the two parts are welded together when rotation occurs and a friction effect takes place According to another aspect of the invention, the collar is adapted to press the radial surface towards the inner surface of the valve top and the oppositely placed surface towards the recesses/grooves of the valve stem.

Thereby, the double-acting friction effect is optimised.

Further, the radial surface may also be curve-shaped and comprise protrusions engag-ing recesses in the inner surface of the valve top n the same way as the oppositely placed surface comprises protrusions engaging recesses of the valve stem According to another aspect of the invention, the collar comprises several coElar parts, said collar parts encircling the valve stem.

The collar comprises at least two half-shaped parts surrounding the stem when the col-lar is in place. However, during the manufacturing and assembling of the gate valve, it may be an advantage that the collar comprises more than the two parts.

According to another aspect of the invention, the diameter of the collar measured be-tween the top parts pointing towards each other is less than the largest diameter of the valve stem.

According to another aspect of the invention, the collar comprises several protruding parts, each protruding part being separated from the neighbouring protruding part by a collar groove.

Brief Description of the Drawing(s

The invention is explained in detail below with reference to the drawing(s), in which Fig. 1 shows a vertical sectional view through a gate valve according to the invention, Fig. 2 shows a detailed drawing of a collar and a valve stem part according to the in-vention, Fig. 3 shows a horizontal sectional view through the collar and the valve stem, Fig. 4 shows a vertical sectional view through a gate valve according to the invention and comprising a rotation lock.

Detailed description of the Invention

Fig. 1 shows a vertical sectional view through a gate valve I according to the invention.

The gate valve I comprises a valve body. The valve body comprises a pipe section 3, through which a fluid flows, a valve housing 4 and a valve top 5. The valve top 5 com-prises an outer surface 22 and an oppositely placed inner surface 23. Further, the gate valve I comprises a valve assembly comprising a valve stem 6 which carries an obtu-rator 7. The obturator 7 moves axis-parallel with the centre line CL of the valve stem 6.

By vertical movement of the obturator, the pipe section 3 is opened or closed for pas- sage of fluid. A lower part 8 of the valve stem 6 comprises threads 9 engaging a spin- dle nut 10. The spindle nut 10 engages the threads 9 of the valve stem 6, and the obtu- rator 7 is connected to said spindle nut 10. An upper part 11 of the valve stem 6 com-prises a collar 12. The collar 12, which is explained with reference to Figs. 1, 2and 3, comprises a first radial surface 24 Yacing the inner surface 23 of the valve housing 4 and further comprises an oppositely placed surface 25 facing circumferential re-cess(es)/groove(s) 13 made in the valve stem 6. The collar 12 is formed by at least two collar parts 26 placed in the same horizontal level and which, when in place, encircle the valve stem 6 making a closed circumferential collar around the recess/groove 13 of the valve stem.

The collar 12 engages the recess 13 of the upper part 11 of the valve stem 6. This construction is shown in detail in Fig. 2. The radial surface 24 of the collar 12 is an even and plane surface. The radial surface 24 is oriented substantially parallel to the centre line CL of the valve stem 6. The collar 12 comprises two collar parts 26 forming a substantially closed ring/bushing/cylinder when they are placed around the valve stem 6. The collar parts 26 are mirror images of each other. However, there may also be several collar parts 26, e.g. more than two. The important thing is that when the col-lar parts 26 are placed around the valve stem 6: they form a dosed ring/bushing/cylinder.

The collar 12 comprises at least one protruding pad 14. The protruding pads 14 are circumferential protrusions separated from each other by a circumferential collar groove 28. In Fig. 3, the collar 12 comprises three protruding parts 14 and three re-cesses/grooves 13 provided in the valve stem 6. Each protruding part 14 is constructed by a first surface 15 and a second surface 16 converging and forming a top angle V.A top part 20 is the top element of the protruding pads 14. When several protruding pads 14 are present, the collar grooves 28 are formed by the first surface 15 of one protru-sion part and the second surface 16 of the neighbouring protrusion pad 14. The top angle V between the first surface 15 and the second surface 16 is 80A00°, preferably 85-95° and most preferably around 90°. In the area where the collar 12 is placed, the valve stem 6 is provided with one or several recess(es)/groove(s) 13. The number of recesses/grooves 13 corresponds to the number of protruding pads 14. The re- cess/groove 13 is formed by a third surface 17 and a fourth surface 18 converging to-wards a bottom part 19 making the bottom of the recess/groove 13. The angle between the third surface 17 and the fourth surface 18 is substantially the same as the angle be-tween the first surface 15 and the second surface 16. The top angLe between the third 17 and fourth 18 surfaces converging towards the bottom parts 19 is 80-100°, prefera-bly 85-95°, more preferably around 90°. By this arrangement, the friction component between the engaging surfaces is optimised. Sealing rings 27 are placed at each side of the collar 12 and optionally between the inner surface 23 of the valve top 5 and the outer surface of the valve stem 6.

Fig. 3 shows a horizontal sectional view through the colLar 12 and the valve stem 6.

The collar 12 comprises two collar parts 26 encircling the valve stem 6. The top part 20 of the protruding parts 14 engages the bottom part 19 of the recesses 13 of the valve stem 6. The collar groove 28 is shown with a dotted line and comprises a circle when the two parts are placed around the valve stem 6. The two collar parts 26 are semi-circular each having two flat ends 29, said one flat end abutting the flat end of the other collar part 26.

Fig. 4 shows a specific embodiment of a collar 12 comprising a rotation lock 21. The collar 12 is the same as the one shown in Figs. 1-3 and therefore only differs from that by further comprising a bore 30 placed in the radial surface. In the valve housing 4 matching the placement of the bore 30, a through-going bore 31 is provided engaging the bore 30 of the collar 12. A pointed screw/bolt is placed in the bores. Thereby, the collar 12 is locked and any rotation of the collar is prevented.

The gate valve shown in the figures comprises several annular recesses/grooves 13 and each recess 13 is spaced from the neighbouring annular recess 13. The number of protruding parts 14 and the number of annular recesses/grooves 13 are equal, and each protruding part 14 is adapted to engage an annular recess/groove 13. The collar 12 may be formed as several disc-shaped parts each comprising at least one protrud-ing part 14 and the disc-shaped parts being physically separated from each other.

However, the collar may also comprise a single bushing/cylindrical part which corn-prises several protruding parts as shown in Fig. 2.

It is also important that the collar 12 does not friction weld to the valve stem 6 during the rotation. This is avoided by manufacturing the valve stem in a first material, for in-stance in stainless steel, and the collar 12 in a second material different from the first material, e.g. bronze. Further, the diameter of the collar 12 measured between the sur-faces pointing towards each other is less than the largest diameter of the valve stem 6 when the collar 12 is placed around the valve stem 6.

The gate valve 1 operates by rotating the valve stem 6. Thereby, the obturator 7 is moved upwards or downwards opening to or closing for fluid stream passing through the pipe section 3. The valve stem 6 is supported by the spindle nut 10 engaging the lower part 8 of the valve stem 6 and by the collar 12 engaging the upper part 11 of the valve stem 6. The obturator 7 is connected to the spindle nut 10. When the valve stem 6 rotates, the spindle nut 10 moves up and down, whereby the obturator 7 connected to the spindle nut 10 also moves up and down.

Due to the collar 12 comprising at least two collar parts 26, the friction occurring during the rotation of the valve stem 6 will take place between the valve stem 6 and the abut-ting collar parts 26 and further between the radially pointing surfaces of the collar parts 26 and the valve top 5. Thereby, the friction effect is double-acting.

List of references 1. Gate valve 2.

3. Pipe section 4. Valve housing 5. Valve top 6. Valve stem 7. Obturator 8. Lower part of valve stem 9. Threads 10. Spindle nut 11. Upper part 12. Collar 13. Recess/groove 14. Protruding pads 15. First surface 16. Second surface 17. Third surface 18. Fourth surface 19. Bottom part 20. Top part 21. Rotation lock 22 Outer surface valve top 23 Inner surface valve top 24 Radial surface Oppositely placed surface 26 Collar parts 27 Seal member 28 Collar groove 29 Flat ends Bore 31 Through-going bore CL Centre line

Claims

Claims 1. A gate valve (1) comprising a valve body comprising a pipe section (3) and a valve housing (4), and a valve top (5) comprising an outer surface (22) and an oppo-sitely placed inner surface (23), said gate valve (1) further comprising a valve assembly comprising a valve stem (6) carrying an obturator (7) adapted to be moved axis-parallel with the centre line CL of the valve stem (6) (and the movement thereof), whereby the pipe section (3) is opened and closed for passage through said pipe section (3), a lower part (8) of said valve stem comprising threads (9) engaging a spindle nut (10) and an upper part (11) of the vaLve stem (6) comprising at least one circumferential re-cess/groove (13). a collar (12) comprising a radial surface (24) facing the inner surface (23) of the valve top (5) and an oppositely placed surface (25) facing the circumferen tial recess(es)lgroove(s) (13) of the valve stem (6), said collar (12) comprising at least two collar parts (26) adapted to encircle the recess(es)/groove(s) (13), characterised in that the collar (12) comprises at least one protruding part (14) engaging the re- cess(es)/groove(s), said protruding part (14) comprising a first surface (15) and a sec-ond surface (16). said first (15) and second (16) surfaces converging and ending in a top part (20), said recess(es)/groove(s) (13) being annular recess(es) comprising a bottom part (19) and a third and a fourth surface (17, 18) diverging from said bottom part (19), said protruding part(s) (14) being adapted to engage the re-cess(es)/groove(s).
2. A gate valve according to claim 1, characterised in that the gate valve (1) corn-prises several annular recesses/grooves (13), each annular recess/groove (13) being separated from the neighbouring annular recess/groove (13).
3. A gate valve according to claim 1 or 2, characterised in that the number of pro- truding parts (14) and annular recesses/grooves (13) are equal, and that each protrud-ing part (14) is adapted to engage an annular recess (13).
4. A gate valve according to any of the preceding claims, characterised In that the top angle between the first surface (15) and the second surface (16) is 80-100, pref-erably 85-95°, more preferably around 90w.
5. A gate valve according to any of the preceding claims, characterised in that the top angle between the third (17) and fourth (18) surfaces converging towards the bot-tom part (19)is 80-100°, preferably 85-95°, more preferably around 90°.
6. A gate valve according to any of the preceding claims, characterised in that the collar (12) comprises several physically separated disc-shaped parts, said disc-shaped parts being vertically separated each comprising at least one protruding part (14) en-gaging the annular recess (13) and each disc-shaped part comprising at Least two separate half disc-shaped collar parts (26).
7. A gate valve according to claims 1-5, characterised in that the collar (12) com- prises a bushing-shaped part comprising several protruding parts (14), said bushing-shaped part comprising at least two separate half or part-cylindrical collar parts (26) forming the cylindrical bushing-shaped part when they are placed around the valve stem(6).
8. A gate valve according to any of the preceding claims, characterised in that the valve stem (6) is manufactured in a first material, and that the collar (12) is manufac-tured in a second material different from the first material.
9. A gate valve according to any of the preceding claims, characterised in that the collar (12) Es adapted to press the radial surface (24) towards the inner surface (23) of the valve top (5) and the oppositely placed surface (25) towards the recesses/grooves (13) of the valve stem (6).
10. A gate valve according to any of the preceding claims, characterised in that the collar (12) comprises several collar parts (26), said collar parts (26) encircling the valve stem (6).
11. A gate valve according to any of the preceding claims, characterised in that the diameter of the collar (12) measured between the top parts (20) pointing towards each other is less than the largest diameter of the valve stem (6).
12. A gate valve according to any of the preceding claims, characterised in that the collar (12) comprises several protruding parts (14), each protruding part being sepa-rated from the neighbouring protruding part (14) by a collar groove (28).