Safety Flap-valve

Abstract

A straightway safety flap-valve to be mounted on a tube conveying a pressure fluid and comprising: a collar secured to one open end of said tube and provided with a valve seat; a clack pivoted to said collar about a first axis extending outside of the surface of said tube and rotatable through 90.degree. for engagement with and disengagement from said seat; a yoke pivoted to said collar about a second axis parallel to the first one and intersecting the surface of said tube; a third axis passing through the free ends of said yoke in parallel relation to the two first axes and also extending through said clack adjacent to its first pivot axis; control means for rocking the yoke about said second axis and acting on the closed end of said yoke; and a vertically slidable counterweight surrounding at least partially said tube end and supported through links pivoted to said counterweight and to the free ends of said yoke adjacent to said third axis.

Description

The present invention relates essentially to a safety straight-way flap-valve or clack-valve or like hanging valve adapted to be mounted on a pipe-line or duct or on a tube through which a pressure fluid is flowing. The valves designed according to the present invention are adapted in particular to fit heads of wells producing combustible gases such as natural gases; their use may also be contemplated in oil producing wells.

The safety valves known heretofore are not entirely satisfactory either because they do not allow direct passage of the fluids or because they are of a too complicated structure and of a too expensive manufacture.

The known safety valves allowing to fully clear the cross-sectional area of the fluid passageway are indeed of a very costly and complicated construction. Under such circumstances one often is reluctant to use same. The use of simpler valves however wherein the fluid passage is not direct or straightway exhibits many inconveniences. In particular it becomes impossible or at least very difficult to have a tool being moved into the tube thereby limiting the working or producing capabilities.

The invention relates to a safety straightway flap-valve of a simple and not very expensive design and construction, having a very small size or bulk and the operation of which is perfectly reliable. For this purpose it comprises, mounted, for instance screw threaded, on an open end of said tube, a collar provided with a valve seat, a clack or like flap-valve member pivotally mounted on said collar about a first axis located outside of the surface of said tube so as to be movable to close the open end of said tube by bearing upon said seat in the closing position of the valve and to completely clear the open end of the tube after a rotation of about 90.degree. of said clack about the first axis, a yoke or like clevis pivotally mounted on said collar about a second axis parallel to the first one and intersecting the surface of said tube, a third axis passing through the free ends of said yoke in parallel relation to the two first axes and also extending through said clack adjacent to its first aforesaid pivot axis, control means for rocking, tilting or tipping the yoke about said second axis which act upon the closed yoke end opposite to those through which said third axis extends, and a counterweight mounted for vertical sliding motion and surrounding at least partially said end portion of the tube, said counterweight being supported through links pivoted to said counterweight and to the free ends of said yoke adjacent to said third axis.

With such a design of embodiment is achieved a valve of compact construction the closing of which may be very easily controlled for example by a hydraulic actuator of low power or output.

The invention will appear more clearly as the following description proceeds with reference to the accompanying drawings given by way of example only illustrating a form of embodiment of a flap-valve designed according to the invention.

In these drawings :

FIG. 1 shows in cross-section with parts broken away a general assembly view of a valve designed according to the invention and mounted at the end of a tube ;

FIG. 2 is an exploded perspective view drawn at a smaller scale and showing the main parts composing the structure of the valve shown in FIG. 1 ;

FIG. 3 shows at a larger scale and in longitudinal cross-section the essential parts of the valve illustrated in FIG. 1 and corresponding substantially to the central portion of this Figure ;

FIG. 4 is a view in horizontal section taken substantially upon the line IV--IV of FIG. 3 ;

FIG. 5 is a sectional view of a detail, this view being taken upon the line V--V of FIG. 4 ;

FIG. 6 shows a clack-disk dsigned according to a modification ;

FIG. 7 is a view in section taken upon the line VII--VII of FIG. 6 and illustrating a detail of this Figure ;

FIGS. 8, 9 and 10 show an alternative form of embodiment of the clack and of its operating means for open same ; and

FIG. 11 is an exploded perspective view showing some structural details of FIGS. 8 to 10.

Referring first to FIGS. 1 to 5, a flap-valve 10 designed according to the invention is mounted at the free end of a tube, pipe or duct 11' for the passage or conveyance of the fluid. This tube or pipe may be for example one of the elements of a drill pipe string for the head of a well producing a natural gas. The involved end of tube 11' may be located for instance under the surface of the ground at a depth of the order of 30 m. The valve assembly 10 is mounted within a casing or housing 12 which is mounted, for example screw threaded at 13 by means of a fitting connector 91 onto the free end 11'a of pipe 11'. The casing 12 has an extension in the shape of a frusto-conical portion 14 which connects with or merges into a tubular portion 15 substantially in extension of a tubular element or tube 11 which is in extension of the pipe 11'. The tubular element 11 is secured, for instance screw threaded at 90 onto the coupling or fitting 91 connecting the valve with the pipe 11'. At the free end of the portion 15 will be connected another tube (not shown) that will be located in extension of the tubes 11' and 11 and will have a similar diameter. Desirably for ease of mounting, that portion of tube 11 about which the valve 10 is mounted is screw threaded at both of its ends. This facilitates the connection with the tube 11' and the mounting of the collar 16 which carries the pivot mechanism of the clack or flap-valve member 17.

The valve essentially comprises : the collar 16 made fast at the lower open end 11a of tube 11 for instance through screw threading ; this collar 16 comprises as seen on FIG. 3 a desirably spherical seat 18 co-operating with the working or bearing surface of the closure disk 19 of the clack 17 ; the working surface 20 of disk 19 bearing onto the seat 18 is also of spherical shape ; the clack 17 which consists of the closure disk 19 and of a holder 21 for this disk having a surface 22 for fastening the disk and a pair of lugs 23 extending at right angles to the surface 22, said lugs being provided each one with two bores 24, 25 ; the clack 17 is pivoted about a first axis materialized by a pivot pin 26 which extends through the bores 25 of lugs 23 and through a bore 28 formed in a lug 29 of the collar 16 ; a yoke or clevis 30 formed from a flat sectional strip bent in U-shape and pivotally mounted on the collar 16 about a second axis materialized by bolts 31 screw threaded into the collar 16 and extending through the bores 32 formed in the central portion of the lugs 33, 34 of the yoke 30; notches 35 formed in each one of the free ends of lugs 33, 34 of the yoke 30 and which receive each one a loose roller 36 mounted for free rotation about a pivot pin 37 which extends through the bores 24 provided in the lugs 23 of the clack holder ; a counterweight 40 mounted for vertical sliding motion and encompassing for a major part the portion of tube 11, said counterweight being supported through the medium of links or connecting rods 41 pivoted onto said counterweight and onto the free ends of the yoke 30 ; the links 41 are pivotally connected onto the counterweight through pivot pins 43 and onto the yoke 30 by pins 44 which extend through the bores 46 of the yoke ; the counterweight 40 comprises moreover guide rollers 45 in its upper portion ; operating means for rocking or tilting the yoke 30 about the axis of pivots 31 (second aforesaid axis) and acting upon the base of the U of the yoke 30 ; to this end the yoke 30 is formed with a tab 47 upon which is acting the end 48 of an operating actuator 49 ; the end 48 comprises a pair of rollers 79 mounted on a fork 50 secured to a rod 51 integral or rigidly connected with the piston 52 of the actuator 49 the cylinder 53 of which is connected to a duct 54 for pressurizing for example with oil.

In addition to these essential parts the valve comprises accessory devices or like attachments. Thus as seen more clearly in FIGS. 4 and 5 there is provided a pressure equalizing or balancing device 56 which comprises a valve 57 mounted on a resilient blade or strip 58 adapted to close an aperture 59 provided in the wall of tube 11. In the normal working position, the biasing blade 58 keeps the valve 57 applied or urged within the aperture 59 against the outer wall of tube 11.

In the closure disk 19 of the clack there is provided a recess or like housing 60 with a substantially frusto-conical portion which terminates in a hole 61 opening inwards of tube 11 (in the closing position of the clack). Holes 62 for example three in number are provided in the surface 22 supporting the disk 19 and communicate with the recess 60. Moreover within the recess 60 is mounted a ball 63 which is captive or retained and the diameter of which enables to close the orifice 61.

In an alternative form of embodiment illustrated on FIGS. 6 and 7, the closure disk 19 of the clack is mounted on the disk supporting surface 22 for example by means of a screw 65 while leaving some clearance between the surface 22 and the disk 19. Resilient means such as springs for instance or resilient washers diagrammatically shown by the dashes 66 may be fitted between the disk 19 and its carrier 22. In this manner an outstanding bearing engagement of the disk 19 with its seat in the closing position of the clack is achieved.

The safety straightway flap-valve described opeates in the following manner. In the normal working position a fluid pressure maintained in the chamber 53 of the operating actuator 49 of the valve keeps the clack 17 positively in the open position as shown in solid lines on FIG. 3. In this position it is seen that the end 11a of tube 11 is entirely cleared or freed so that it is possible to run any tool whatever through the pipe string 11 without being hindered by the mounting of the flap-valve.

If the pressure happens to decrease or to lack within the chamber 53 of the actuator, the counterweight 40 pushes through the medium of the pivotally connected links 41 the pin 44 downwards thereby urging the yoke 30 to swing about the pivots 31 in the direction of the arrow F thereby causing simultaneously, through the notches 35 wherein the rollers 36 are riding, the clack 17 to swing about its pivot pin 26 until the closing of the clack as shown in dash-dotted lines in FIG. 3.

If the internal leakage flow rate that flows through the clack while passing through the orifices 62, the recess 60 and the orifice 61, remains low enough, the pressure differential between either side of the clack is not very significant and it is usually possible to re-open same through a simple action of the actuator 49 when the control pressure within the cylinder 53 of the actuator is brought back to a normal operating value.

When on the contrary the internal leakage flow rate reaches a previously determined limiting value, the ball 63 is pressed against the opening 61 and the effective pressure under the clack may become very large. Under such circumstances it is not usually possible to re-open the clack through mere action of the actuator 49 the operating rod 51 and fork 48 of which are not powerful enough. When it is desired to re-open the valve it would be sufficient to operate the pressure equalizing or balancing device 56 previously described. To do this it would be sufficient to move a tool into and down the tube 11 to push that portion of the valve 57 which projects into the tube 11. The fluid pressure under the clack may thus be equalized or balanced on either side of the clack by flowing through the bore 59. When the pressures are substantially equalized or balanced it will then be possible to operate the actuator 49 to re-open the clack.

The nature of the materials forming part of the composition of the valve will of course be selected so as to withstand the operating conditions or working requirements of the valve that is essentially the physical and chemical conditions to which it will be subjected inside of the fluid which circulates within the tube 11.

According to the alternative form of embodiment shown on FIGS. 8 to 11, wherein like parts which are shown in the preceding Figures have been denoted by the same reference numerals whereas similar parts but of differing configuration have been designated by the same reference numerals increased by hundred units, there is provided, under the clack-hodling surface 122, a lever 70 pivoted about a pivot pin 71 which extends through the bores 72 of lever 70 and 73 of the clack-holder 122, respectively. The lever 70 comprises a needle or conical pin 74 which under the action of a spring 75 made fast with the lever 70 and bearing under the clack-holder 122 is caused to normally close an opening 76 provided in the clack 117.

The lever is moreover so shaped that the fork 50 of the opening arrangement for opening the clack is caused to bear with its end 50a against the end 70a of lever 70 at the beginning of the opening of the clack (FIGS. 8 and 9). Under these circumstances at the beginning of the opening when the piston 52 tends to lower the fork 50, the end 50a of the latter is caused to engage the end 70a of lever 70 thereby swinging the latter about its pivot pin 71 before the roller 79 has acted upon the tab 47 of the yoke 30. In acting so, the opening 76 is cleared by the needle or conical pin 74 whereby an automatical equalizing or balance of the pressures on either side of the clack 117 is achieved before the opening operation proper.

When the pressure equalizing is substantially obtained, the piston 52 continuing its stroke operates the yoke 30 through the roller 79 of the fork 50 as previously described thereby resulting in the opening of the clack 117.

At 80 is shown a spring leaf which acting upon spigots 81 or like projections of the fork 50 moves or urges this latter back to the upper position (FIG. 8) when the operating pressure in the actuator 49 is small.

In a form of embodiment contemplated the tube 11 having an inner diameter of 60 mm a valve of the kind described has been designed to meet or comply with the following requirements :

1.degree. Automatic closure through exhaust or venting to the atmosphere of the end of the control line 54, i.e. the valve being generally located at 30 m below ground level, when the pressure in the actuating cylinder 53 decreases to an effective value of about 2.5 bar.

2.degree. Balance, with the clack closed, of the upstream and downstream pressures by means of the flow rate limiting device having a ball incorporated into the clack and allowing a limit flow rate of 50 Nm.sup.3 /h under a pressure of 150 bar.

3.degree. Opening pressure of between 60 and 80 bar at the head end of the line 54 after pressure equalization ; thus a good disengagement of the clack from its seat or initial motion of the clack off its seat is obtained.

4.degree. An internal leakage flow rate of 5 Nm.sup.3 /h under a pressure differential of 100 bar after closing of the limiting ball device.

5.degree. A maximum working pressure of 150 bar.

It should be understood that the invention is not at all limited to the forms of embodiment described and shown which have been given by way of example only. In particular the invention may apply to many fields of use every time it is desired to obtain an automatic closing of a tube, duct or like pipe-line while retaining a straightway of direct passage of the fluid, each time abnormal operating conditions occur in use. The invention therefore comprises all the technical equivalents to the means described as well as their combinations if same are carried out in accordance with its gist and are put into practice within the scope of the appended claims.

Claims

What is claimed is:

1. A safety straightway flap-valve adapted to be mounted on a tube conveying a pressure fluid comprising, mounted on the open end of said tube : a collar provided with a valve seat ; a clack pivoted to said collar for swinging about a first axis located outside of the surface of said tube so as to be able to close the open end of said pipe when bearing against said seat in the closing position of the valve and to fully clear the open end of said tube after a rotation of about 90.degree. of said clack about said first axis ; a yoke pivoted to said collar for rocking about a second axis coextensive in parallel relationship with the first one and intersecting the surface of said tube ; a third axis passing through the free ends of said yoke in parallel relation to the two first axes and also extending through said clack adjacent to its first pivot axis ; control means for tilting said yoke about said second axis and acting upon the closed end of said yoke which is opposite to those through which said third axis extends ; and a counterweight mounted for vertical sliding motion and surrounding at least in part said end of said tube, said counterweight being supported through links pivotally connected to said counterweight and to the free ends of said yoke, respectively, adjacent to said third axis.

2. A valve according to claim 1, wherein said clack comprises a closure disk of a shape conforming to that of said valve seat and a holder for said disk comprising a disk fastening surface and a pair of parallel lugs extending at right angles to said surface, said lugs being provided each one with two mutually confronting bores for the passage of pivot pins materializing said first and third axes.

3. A valve according to claim 2, wherein said yoke is made from a bent U-shaped sectional flat strip and is mounted on said collar by means of a pair of pins extending substantially through the centres of each lug of said U-shaped yoke thereby materializing said second axis and there is provided a notch in each one of the free ends of said sectional yoke, which notches receive each one a loose roller mounted for free rotation about a pivot pin materializing said third axis and extending through two of said mutually confronting bores formed in said lugs of said clack for operating the rotation of the clack about its first axis.

4. A valve according to claim 1, wherein said tube is directed vertically, said collar is secured to the bottom end of said tube, said clack being located below said yoke and the latter being located below said counterweight ; said first and second axes for pivotal connection with said collar of said clack and said yoke being substantially on a same level ; said first axis extending outside of said tube and said second axis passing substantially through a centre plane of said tube.

5. A valve according to claim 3, wherein the operating means for rocking said yoke comprise a hydraulic actuator which acts upon the base of the U-shaped yoke in a direction substantially parallel with the axis of said tube adjacent to the portion involved.

6. A valve according to claim 2, wherein there is provided in said closure disk of said clack a substantially frusto-conical recess with a hole opening towards the inside of said tube and a plurality of holes in the disk fastening surface providing an internal leakage flow through said clack as well as a ball mounted in said frusto-conical recess and captive between said disk and its fastening surface, said ball being adapted to close the hole formed through said disk when the leakage through said clack becomes too large.

7. A valve according to claim 2, wherein said disk is mounted with clearance onto said fastening surface.

8. A valve according to claim 1, wherein there is provided, in said tube downstream of said clack with respect to the stream of fluid flowing through the tube, an opening which is closed by a valve member which is kept applied by resilient means against the outer wall of said tube, said valve member projecting slightly into said tube so that it may be moved mechanically off its seat by running a suitable tool through said tube.

9. A valve according to claim 1, wherein the assembly of the parts composing said valve is mounted within a casing which is mounted in turn so as to encompass said tube near the free end thereof and said casing is formed with a frusto-conical extension connecting with a tubular portion substantially in extension of said free end of said tube.

10. A valve according to claim 2, wherein said closure disk of said clack is formed with an orifice and there is provided a lever pivoted under said disk about a pivot pin extending in parallel relation to said three axes and carrying a needle which closes said orifice in the position of said lever applied against said disk, resilient means being provided to normally press said lever against said disk and said operating means for tilting said yoke being adapted to swing said lever away from said closure disk before bearing against said yoke so as to cause the rocking of the clack and to operate the opening thereof.