Field of the Invention

This invention relates to a drilling apparatus.

The drilling apparatus according to the invention is concerned particularly, although not necessarily solely, with clearing of blockages in tapping points installed on vessels and pipework. The invention has been devised particularly for tapping points which provide a connection when the vessel or pipework is under pressure; such a connection is commonly known as a hot tap.

The drilling apparatus according to the invention may, however, also be utilised in installation of tapping points on vessels and pipework.

Background Art

The following discussion of the background art is intended to facilitate an understanding of the present invention only. The discussion is not an acknowledgement or admission that any of the material referred to is or was part of the common general knowledge as at the priority date of the application.

Tapping points of the type known as hot taps are used to provide internal access to vessels and pipework operating under pressurised conditions. The tapping points provide selective access to the interior of a pipeline or vessel for sampling of the contents or measurement of a characteristic (such as the pressure or flow) of the contents.

In certain circumstances, there may be a need to install the tapping point, or clear a blockage, within the tapping point, in a pressurised vessel or pipeline while a production facility incorporating the vessel or pipeline is in operation. Accordingly, penetration of the vessel or pipeline needs to be made while the vessel or pipeline is pressurised. A tapping point drilling apparatus can be used for this purpose. The tapping point drilling apparatus incorporates a drill bit which penetrates a wall of the pipeline or vessel, or alternatively clears a blockage in an existing tapping point. In either case, there is the potential of exposing a person operating the drilling apparatus to the risk of injury. The risk can arise for various reasons, including ergonomic issues associated with the manner in which the drilling apparatus is held to perform the tapping operation, and also exposure to contents of the pipeline or vessel escaping under pressure through the tapping point. It is against this background, and problems and difficulties associated therewith, that the present invention has been developed.

Disclosure of the Invention

According to a first aspect of the invention there is provided a drilling apparatus comprising a first drive means for rotating a drill shaft to perform a drilling operation, the first drive means being mounted on a guide structure for linear movement therealong to cause axial movement of the drill shaft, and a second drive means for moving the first drive means along the guide structure.

Preferably, the first drive means comprises a first drive motor. ,

Preferably, the guide structure comprises a guide track along which the first drive means is movable.

The guide track may comprise at least one guide rod.

The guide structure may further comprise a guide block slidingly engageable with the guide rod for guided movement axial therealong, wherein the first drive means is fixed to the guide block for movement therewith.

Preferably, the guide track comprises at least two guide rods and at least two guide blocks each in sliding engagement with respective one of the guide rods.

The, or each, guide block may incorporate a linear slide bearing in engagement with the respective guide rod.

Preferably, the second drive means comprises a rotatable drive shaft and a drive block in threaded engagement with the drive shaft, whereby rotation of the drive shaft causes axial movement of the drive block therealong, the direction of movement varying according to the direction of rotation of the drive shaft, and wherein the drive block is operably connected to the first drive means whereby the first drive means is caused to undergo linear movement along the guide structure upon axial movement of the drive block along the drive shaft.

Preferable, the second drive means further comprises a second drive motor for rotatably driving the drive shaft.

Preferably, the drilling apparatus further comprises a control means operable to selectively control operation of the first drive means and the second drive means remotely therefrom.

The control means may comprise a control unit operably connected to the first drive motor and the second drive motor.

In one arrangement, the connection between the control unit and the two drive motors may comprise an umbilical connection permitting an operator to control operation of the drilling apparatus by way of the control unit from a location remotely of the drilling apparatus. Because the operator is able to control the drilling apparatus remotely, the likelihood of the operator sustaining injury during the drilling operation is minimised or at least reduced. Preferably, the umbilical connection is a flexible connection to thereby permit the operator to select a variety of available positions remotely of the drilling apparatus to occupy while performing the drilling operation.

In another arrangement, the connection between the control unit and the two drive motors may comprise a wireless connection.

Preferably, the drilling apparatus further comprises a body adapted for connection to a tapping point outlet, the body defining an internal passage to receive the drill shaft for insertion into the tapping point outlet, the internal passage having an insertion end for receiving the drill shaft and a delivery end from which the drill shaft can extend for penetrating the tapping point outlet, an outlet communicating with the internal passage, and a first valve for selectively opening and closing the outlet.

Preferably, the internal passage comprises two passage sections of circular cross-section and of different diameters, the two passage sections comprising a larger passage section communicating with the delivery end and smaller passage section communicating with the insertion end, the outlet communicating with the larger passage section.

With this arrangement, an annular clearance space is established between the drill shaft and the larger passage section when the drill shaft is within the internal passage, the annular clearance space providing a flow path from the delivery end to the outlet.

Preferably, the drilling apparatus further comprises a second valve for selectively opening and closing the internal passage with respect to fluid flow from the tapping point outlet, the second valve permitting the drill shaft to pass therethrough when in an open condition.

Preferably, the drilling apparatus further comprises a third valve having a closed condition for blocking the passage against fluid flow, the third valve being biased into the closed condition and being adapted to open in response to insertion of the drill shaft into the internal passage.

Preferably, the third valve comprises a valve element adapted to locate in the internal passage of the body to block fluid flow, the valve element being biased into the closed condition by a biasing means.

The valve element may be configured as a valve ball. The biasing means may comprise a valve spring.

The third valve may further comprise a lateral valve recess into which the valve element can move away from the internal passage against the influence of the biasing means.

The lateral valve recess may be incorporated in the outlet. -The body may comprise a body portion defining the internal passage and a lateral passage extending from the internal passage, a nipple having an inner end configured for engagement in the lateral passage and an outer end configured for engagement with the first valve, the lateral passage and the nipple cooperating to define the outlet.

According to a second aspect of the invention there is provided apparatus adapted for connection to an tapping point outlet, the apparatus comprising a body defining a passage to receive a probθ for insertion into the tapping point outlet, the passage having an insertion end for receiving the probe and a delivery end from which the probe can extend for penetrating the tapping point outlet, an outlet communicating with the passage, a first valve for selectively opening and closing the outlet, a second valve for selectively opening and closing the passage with respect to fluid flow from the tapping point outlet, the second valve permitting the probe to pass therethrough when in an open condition, and a third valve having a closed condition for blocking the passage against fluid flow, the third valve being biased into the closed condition and being adapted to open in response to insertion of the probe into the passage. The probe may comprise a drill shaft.

According to a third aspect of the invention there is provided a method of clearing a blockage in a tapping point, the method comprising use of a drilling apparatus according to the first aspect of the invention.

According to a fourth aspect of the invention there is provided a method of clearing a blockage in a tapping point, the method comprising use of a apparatus according to the second aspect of the invention.

Brief Description of the Drawings

The invention will be better understood by reference to the following description of several specific embodiments thereof as shown in the accompanying drawings in which:

Figure 1 as a perspective view of drilling apparatus according to a first embodiment of the invention, with a drill shaft forming part of the apparatus depicted in a retracted condition; Figure 2 is a side view of the drilling apparatus of Figure 1 , with the exception that the drill shaft is depicted in an operating condition;

Figure 3 is a view similar to Figure 2 but in section to show certain internal features of the drilling apparatus;

Figure 4 is a view similar to Figure 3 except that a drill shaft forming part of the apparatus is depicted in the retracted condition;

Figure 5 is a side view of the drilling apparatus according to a second embodiment;

Figure β is a view similar to Figure 5 but in section to show certain internal features of the drilling apparatus according to the second embodiment;

Figure 7 is a side view of a portion of the drilling apparatus according to the second embodiment, illustrating in particular a body portion and a connection mechanism, with the drill shaft being depicted in the operating condition;

Figure 8 Is a sectional view of the arrangement shown in Figure 7;

Figure 9 is a sectional side view of the portion of the drilling apparatus shown in Figure 7, with the drill shaft being depicted in the retracted condition and a valve forming part of the connection mechanism shown in a closed condition;

Figure 10 is a view similar to Figure θ with the exception that the valve is shown in an open condition; and

Figure 11 is a schematic side view of the connection mechanism forming part of the drilling apparatus according to the second embodiment.

Best Mode(s) for Carrying Out the Invention

The first embodiment, which is shown in Figures 1 to 4, is directed to a drilling apparatus 10 for clearing of a blockage in a tapping point on a pipeline or vessel under pressure. The drilling apparatus may also be used for installation of a tapping point on a pipeline or vessel under pressure. The tapping point, which is not shown, comprises an access fitting such as a nipple installed on the exterior surface of the pipeline or vessel. A service valve (also not shown) is fitted onto the nipple. To establish the tapping point, a hole is drilled through the wall of the pipeline or vessel to communicate with the interior thereof. The service valve is used to isolate the contents of the pipeline or vessel from atmosphere. When the tapping hole is to be cleared of a blockage or drilled, the drilling apparatus 10 is coupled to the service valve, as will be described in detail later.

The drilling apparatus 10 according to the first embodiment comprises a body 11 which includes a body portion 13 having one end 14 configured for connection to the service valve. In the arrangement shown, the end 14 is configured as a male threaded coupling 15. In this embodiment, the body portion 13 is connected directly to the service valve. In other embodiments, such as for example a second embodiment which will be described later, the body portion 13 is connected to the service valve through an intermediate connection mechanism. The other end 16 of the body portion 13 is mounted on an end plate 17.

The body 11 also includes an internal passage 18 extending between the ends 14, 16 of the body portion 13. In particular, the internal passage 18 has an outer end 19 opening onto the threaded coupling 15 and an inner end 20 opening onto the end plate 17.

The internal passage 18 comprises two passage sections of circular cross-section and of different diameters. The two passage sections comprise a passage section 21 of larger diameter (hereinafter referred to as the larger passage section) communicating with end 14 of the body portion 13 and a passage section 22 of smaller diameter (hereinafter referred to as the smaller passage section) communicating with end 16 of the body portion 13.

The two passage sections 21, 22 merge at junction 23 to define a shoulder 24 therebetween.

The body portion 13 also incorporates a lateral passage 25 extending between the internal passage 18 and the outer periphery of the body portion 13. The lateral passage 25 communicates at its Inner end with the larger passage section 21 adjacent the shoulder 24.

The body 11 also includes a lateral portion 27 configured as a nipple 29 which is connected to the body portion 13 and which is adapted to receive a first valve 30. The nipple 29 has an inner end 31 configured for threaded engagement in the lateral passage 25 and an outer end 33 configured for threaded engagement with the valve 30. The nipple 29 defines a lateral passage 35 which extends between the inner end 31 and the outer end 33. The lateral passage 35 provides fluid communication between the internal passage 18 within the body portion 13 and the valve 30, the purpose of which will be explained later.

In the arrangement shown, the valve 30 comprises a manually operable ball valve 37 incorporating a valve handle 39 for manually opening and closing the valve 37.

The drilling apparatus 10 further comprises a drill shaft 41 which can extend through the body 11 Specifically, the drill shaft 41 passes through the passage 18 within the body 11, as shown in Figure 3. A guide 43 incorporating sealing means 45 at the end of the body 11 is provided for guiding axial movement of the drill shaft 41.

The drill shaft 41 is of a diameter which is a close but free fit within the smaller passage section 22 of the internal passage 18. Because the larger passage section 21 is of a larger diameter, an annular clearance space 47 exists between the drill shaft 41 and the outer passage section 21 when the drill shaft is within the internal passage 18. The annular clearance space 47 provides a flow path 49 about the drill shaft 41 from the end 19 to the lateral passage 35.

The drilling apparatus 10 further comprises a first drive means 51 for rotating the drill shaft 41 to perform a drilling operation and a second drive means 52 for moving the first drive means 51 to cause axial movement of the drill shaft 41.

The first drive means 51 comprises a first drive motor 53 and a drive boss 54 adapted to drivingly engage the end of the drill shaft 41. The drive boss 54 incorporates a mechanism 55 for delivering a hammering action to the drill shaft 41 as well as rotational torque thereto. The first drive motor 53 is drivingly connected to the drive boss 54 through a gearbox 56. In this embodiment, the gearbox 56 comprises a planetary gearbox. The first drive motor 53 is an electrical DC motor typically operating at 24 volts. Other motor arrangements are, of course, possible. The first drive motor 53 and the gearbox 56 are accommodated within a sealed housing 57 which is attached to a guide structure 61 for linear movement therealong to cause axial movement of the drill shaft 41. The guide structure 61 comprises a guide track 63 along which the first drive means 51 is movable. In this embodiment, the guide track 63 comprises three guide rods 65 arranged in a delta configuration, only one of which is shown in Figures 2, 3 and 4 of the drawings. The guide structure 61 further comprises a guide block 67 slidingly engageable with two of the guide rods 65a, 65b for guided movement axial therealong. Each guide block 67 incorporates a linear slide bearing 69 in engagement with the respective guide rod 65. The first drive means 51 is fixed to the guide blocks 67 for movement therewith. More particularly, in the arrangement shown, the guide blocks 67 are connected to the sealed housing 57 which accommodates the first drive motor 53 and which forms part of the first drive means 51.

The second drive means 52 comprises a rotatable drive shaft 71 and a drive block 73 in threaded engagement with the drive shaft, whereby rotation of the drive shaft 71 causes axial movement of the drive block 73 therealong. In the arrangement shown, the drive shaft 71 also functions as the third guide rod 65c. The direction of movement of the drive block 73 axially along the drive shaft 71 depends upon the direction of rotation of the drive shaft 71. The drive block 73 is operably connected to the first drive means 51 whereby the first drive means 51 is caused to undergo linear movement along the guide structure 61 upon axial movement of the drive block 73 along the drive shaft 71. More particularly, in the arrangement shown, the drive block 73 is connected to the guide structure 61.

The second drive means 52 further comprises a second drive motor 75 and a drive boss 77 drivingly connected to the drive shaft 71. The second drive motor

75 is drivingly connected to the drive boss 77 through a gearbox 79. In this embodiment, the gear box 79 comprises a planetary gearbox. The second drive motor 75 is an electrical DC motor typically operating at 24 volts. Other motor arrangements are, of course, possible.

The second drive motor 75 and gearbox 79 are accommodated within a sealed housing 81. The drive boss 77 is disposed at one end of the sealed housing 81. The drilling apparatus 10 further comprises a control means (not shown) operable remotely to selectively control operation of the first drive means 51 and the second drive means 52.

The control means comprise a control unit operably connected to the first drive motor 53 and the second drive motor 75. The connection between the control unit and the two drive motors 53, 75 comprises a flexible umbilical connection permitting an operator to control operation of the drilling apparatus 10 by way of the control unit from a location remotely of the drilling apparatus. With this arrangement, an operator can be positioned away from the location of the tapping point on the pipeline or vessel while the drilling apparatus 10 is in operation.

Because of this, the likelihood of the operator sustaining injury during the drilling operation is minimised or at least reduced.

Because the umbilical connection is flexible, the operator is able to elect to occupy any one of a variety of available positions remotely of the drilling apparatus 10 while performing the drilling operation.

A cable 82 forming part of the umbilical connection accesses the first drive motor 53 through a bulkhead connector 83 on the sealed housing 57. Similarly, a cable forming part of the umbilical connection accesses the second drive motor 75 through a bulkhead connector 85 on the sealed housing 81.

When there is a need to clear a blockage within an existing tapping point, or to install a tapping point, in a pressurised vessel or pipeline, the drilling apparatus 10 is mounted in position for use by connecting the threaded coupling 15 on the body 11 to the service valve installed onto the nipple provided at the tapping point on the pipeline or vessel. The two drive motors 53, 75 are then operated as necessary in order to cause the drill shaft 41 to perform the requisite drilling operation.

During the drilling operation, the drill shaft 41 is advanced and presented to the blockage in the tapping point. The drill shaft 41 subjects the blockage to a drilling and hammering action, thereby clearing it.

Once the blockage has been cleared, fluid under pressure can flow from the vessel or pipework out through the tapping point and along the flow path 49 provided by the annular clearance space 47 about the drill shaft 41 to the lateral passage 35. The operator is able to assess when the blockage has been cleared by the presence of fluid released upon manually opening of valve 30. The presence of the fluid flowing from valve 30 when opened provides an indication to the operator that the drilling operation can be terminated.

In the first embodiment, body portion 13 of the drilling apparatus 10 was connected directly to the service valve. In other embodiments, the body portion 13 is adapted for connection to the service valve of the tapping point through an intermediate connection mechanism. Such an arrangement is the subject of the second embodiment

Referring now to Figures 5 to 11, there is shown a drilling apparatus 100 according to the second embodiment. The drilling apparatus 100 according to the second embodiment is similar in many respects to the drilling apparatus 10 according to the first embodiment and similar reference numerals are used to identify similar parts.

The drilling apparatus 100 incorporates additional features which provide enhanced functionality and safety in certain circumstances. The drilling apparatus 100 includes a connection mechanism 101 for connecting the body portion 13 to the service valve of the tapping point. The connection mechanism 101 is depicted separately from the remainder of the drilling apparatus 100 in Figure 11. The connection mechanism 101 comprises a second valve 102 configured as a ball valve 103 of known kind. The ball valve 103 is operable to control fluid flow to the body 11 , as will be explained later.

The ball valve 103 comprises a valve body 105, a valve member 107 configured as a spherical member 108 having a port 109 extending through it, and a handle 111 for turning the valve member 107. The valve body 105 has two opposed open ends 113, 115 between which a flow path 117 extends. The valve member 107 is accommodated in the flow path 117 and is movable between an open condition in which the port 109 is aligned with the flow path 117 to permit fluid flow (as shown in Figures 8 and 10), and a closed condition in which the port 109 is transverse to the flow path such that the valve member 107 functions to block fluid flow (as shown in Figures 6 and 9). As will become apparent later, the drill shaft 41 can pass through the ball valve 103 when the valve member 107 is in the open condition, as best seen in Figure 8.

Valve body end 113 is configured as an internally threaded coupling 118 for connection to the coupling portion 15 on the body portion 13. Valve body end 115 is configured as an internally threaded coupling 119 for connection to a nipple 121. The nipple 121 has two opposed male threaded ends 123, 125. Nipple end 123 is threadingly engaged in valve body end 115 and nipple end 125 defines a coupling 126 for connection to the service valve of the tapping point.

The connection mechanism 101 also comprises a splash guard 127. In the arrangement shown, the splash guard 125 comprises a shroud 128 having an inner portion 129 and an outer portion 130. The inner portion 129 incorporates a central hole 131 through which the nipple end 123 extends such that the shroud 128 is clamped between the valve body 105 and the nipple 121. The outer portion 130 surrounds the coupling 126 which provides the connection to the service valve of the tapping point. With this arrangement, the shroud 128 provides protection against any fluid issuing from the connection to the service valve. The drilling apparatus 100 according to the second embodiment also Includes a third valve 141 which provides a safety feature in the event of breakage of the drill shaft 41 during operation of the drilling apparatus 100.

The third valve 141 comprises a valve element 143 configured as a valve ball 145 adapted to locate in the internal passage 18 of the body 11 to block fluid flow therealong from end 15 to end 16 of the body portion 13. This provides a closed condition for the valve 141. The valve ball 145 is biased into the closed condition by a valve spring 147.

The third valve 141 further comprises a lateral valve recess 149 into which the valve ball 145 can move away from the internal passage 18 against the influence of the valve spring 147. The valve recess 149 comprises an enlarged passage section 151 adjacent the inner end 31 of nipple 29. The passage section 151 confronts the larger passage section 21 of the internal passage 18 adjacent the shoulder 24 and is adapted to receive the valve ball 145 such that it is clear of, or at least does not obstruct, the internal passage 18.

The valve spring 147 acts between the valve ball 145 and a shoulder 153 at the inner end of the valve recess 149.

Before entry of the drill shaft 41 into the central passage 18 within the body 11 , the third valve 141 is in the closed condition; that is, the valve ball 145 is located within the central passage 18 to block fluid flow from end 15 to end 16, as previously explained and as depicted in Figure 9. When the drill shaft 41 first enters the central passage 18, its leading end contacts the valve ball 145 and causes it to deflect laterally into the valve recess 149, thereby permitting the drill shaft 41 to advance beyond the valve 141. As the valve ball 145 moves into the valve recess 149, the valve spring 147 is compressed. The compressed valve spring 147 exerts a spring force on the valve ball 145, causing the valve ball 145 to maintain contact with the drill shaft 41. This is a safety feature in the event of breakage of the drill shaft 41 drilling operation of the drilling apparatus 10, as will be explained later. In this second embodiment, the body 11 includes both the body portion 13 and the connection mechanism 101, the arrangement providing a passage 160 having an insertion end 1β1 for receiving the drill shaft 41 and a delivery end 163 from which the drill shaft 41.

Operation of the drilling apparatus 100 will now be described. When there is a need to clear a blockage within an existing tapping point, or to install a tapping point, in a pressurised vessel or pipeline, the drilling apparatus 100 is mounted in position for use by connecting the threaded coupling 123 to the service valve installed onto the nipple provided at the tapping point on the pipeline or vessel. At this stage, the service valve is closed, as is the first valve 30 and the ball valve 103. Additionally, the drill shaft 41 is within the central passage 18 at a location beyond the third valve 141 but not yet at the ball valve 103.

Prior to commencement of the drilling operation, the service valve and the ball valve 103 are both opened.

The two drive motors 53, 75 are then operated as necessary In order to cause the drill shaft 41 to advance and perform the requisite drilling operation. As the drill shaft 41 advances, it passes through the opened ball valve 103 and is presented to the blockage in the tapping point. The drill shaft 41 subjects the blockage to a drilling and hammering action, thereby clearing it.

Once the blockage has been cleared, fluid can flow under pressure out through the tapping point and along the flow path 49 provided by the annular clearance space 47 about the drill shaft 41 to the lateral passage 35. The operator is able to assess when the blockage has been cleared by the presence of fluid released upon manually opening of the first valve 30. The presence of the fluid flowing from first valve 30 when opened provides an indication to the operator that the drilling operation can be terminated. The drill shaft 41 can then be retracted, allowing the service valve to be closed. The ball valve 103 can also be closed once the drill shaft 41 has been retracted sufficiently to clear it. First valve 30 can then also be opened to allow trapped fluid to drain from within the body 11 , and the drilling apparatus 100 removed from the tapping point. If the drill shaft 41 happens to break during operation, the fractured part of the drill shaft 41 may remain in place and provide an obstruction which prevents the ball valve 103 from being closed. In such circumstances, withdrawal of the intact portion of the broken drill shaft might ordinarily allow fluid to issue under pressure from the open end 20 of the internal passage 18. However, the presence of the third valve 141 provides a safety feature to prevent or inhibit such an occurrence. In particular, as the intact portion of the broken drill shaft 41 is withdrawn past the third valve 141 , the valve ball 145 is caused to move under the influence of the valve spring 147 from the retracted condition in the valve recess 149 into the position within the central passage 18, thereby blocking fluid flow therealong and preventing, or at least inhibiting, discharge of fluid under pressure from the end 16 of the body portion 13 of the drilling apparatus 100. Remedial action as necessary can then be taken.

From the foregoing, it is evident that the present embodiments each provides a simple yet highly effective arrangement for clearing a blockage in a tapping point, or drilling a tapping point, in a pipeline or vessel under pressure without requiring an operator to be holding and operating a drilling apparatus at the site of the tapping point. Further, the second embodiment, in particular, has provision to allow the drill shaft to penetrate the tapping point while isolating the fluid contents under pressure within the pipeline or vessel.

It should be appreciated that the scope of the invention is not limited to the scope of the embodiments described. By way of example, the body 11 comprising both the body portion 13 and the connection mechanism 101 may in Itself constitute apparatus which can be used to deliver a probe into tapping point on a vessel or pipework under pressure. The apparatus has provision to allow the probe to penetrate the tapping point while isolating the fluid contents under pressure within the pipeline or vessel. The probe may be of any appropriate type. For example, the probe may be a sensor probe for sensing a characteristic of fluid contained under pressure within the vessel or pipework.- The probe may also be a drill shaft driven by a power drill or other drilling apparatus held manually by an operator. Throughout the specification and claims, unless the context requires otherwise, the word "comprise ¹¹ or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers.