GB2482671A

GB2482671A - A hot-tapping unit having pressure equalising means to balance the drill rod

Info

Publication number: GB2482671A
Application number: GB1013299.1A
Authority: GB
Inventors: Mark Edward Klinck; Timothy Klinck
Original assignee: Individual
Current assignee: Individual
Priority date: 2010-08-09
Filing date: 2010-08-09
Publication date: 2012-02-15
Also published as: GB201013299D0

Abstract

A hot-tapping unit for drilling holes into pressurised pipe work / valves, the unit having a balanced drill rod 9 contained within a high pressure lubricator 17. Preferably, the equal balanced pressure within the unit is provided by a lubricator 17 and a closed loop system 1, 7, 10, 13. Self-energising seals may be provided on a seal adaptor flange 1, which helps contain the drill rod. Preferably, the back end of the milling / drill rod is enclosed within the pressure lubricating section 17. The hot-tapping unit preferably comprises a collet chuck 2 to grip the drill rod, the chuck being mounted on a translating carriage 5 slidable on guide rods 3. Sliding of the carriage is preferably by piston 14, while an air motor 6 preferably drives the drill. The length of the drill rod may be extendable, preferably by connecting additional lengths of drill rod (and lubricators). Neutralising the pressure differential prevents the drill rod from being pushed back.

Description

High Pressure Hot Tap Drilling Unit Conventional Hot Tap equipment is of a low to medium pressure rating used mainly for tapping into low and medium pressure pipe and typically hand operated. Conventional Hot Tap equipment has a limited pressure rating and stroke of the drill rod, limiting depths to be drilled to the total length limitations of the unit and pressure rating of the whole component. This invention is a high pressure, high temperature design used for severe service conditions for the oil and gas industry but not limited to such. The unit utilises a high pressure lubricator to fully enclose the drill rod and contain the system pressure applied to balance the drill rod to a neutral state. Pressures acting on both ends of the drill rod area effectively cancel each other out eliminating the need for additional clamping arrangements to be employed to avoid the drill rod being forcibly ejected from the unit.

The construction of the high pressure Hot Tap drilling unit uses an alloy steel suitable for sour service within the oil and gas industry where by it can be used in extremely corrosive environments without damage. This is especially important for operator and facility safety. The unit is powered by compressed air and remotely operated from a small console consisting of an air driven hydraulic pump with reservoir, air filter dryer, two air regulators, oil fog lubricator a ball valve and a four way valve for control for the hydraulic piston. It is small and compact and ensures operator safety by removing them from any potential hazardous zones of operation while the unit is energised and under pressure. The High Pressure Hot Tap drilling Unit is used for drilling into tubular's, pipe work and valves while containing very high pressures and or corrosive gasses or fluids. When assembled and operational the unit has a closed loop pressurised system.

The new inventive key features of the unit are a closed loop pressurised system consisting of high pressure needle valves and tubing connected to both sealing adaptor flanges below the packing seals. A lubricator section of high pressure pipe contains the drill rod which is hard chromed and ground to ensure effective sealing on the high pressure packing. The new inventive use of additional lubricator sections to fully enclose the drill rod also allows additional lengths of drill rod to be used in sections screwed together to extend the overall drill rod length allowing deep or longer assemblies to be drilled through overcoming the limitations of existing equipment. High pressure self energising packing seals around the drill rod preventing release of any pressurised fluid or gas. When pressurised, force acting equally on both ends of the drill rod prevents the drill rod from being ejected from the unit. One air motor drives a simple gear train attached to a drive hub which in turn is attached to a collet chuck which clamps the drill rod and transmits rotation and torque when operational. The drive hub is supported by thrust and roller bearings in the traverse carriage allowing force to be applied to the drill rod while rotating at the required speed. Two tension rods join both sealing adaptor flange end assemblies together which also act as a guide for the traverse carriage. The tension rods also counteract any rotational torque encountered while the unit is operational. A through rod hydraulic cylinder mounted to the traverse carriage advances or retracts the drill rod by the clamping arrangement of the collet chuck over its length and also acts as an additional guide to the two tension rods.

The following drawings show in detail the new and inventive construction and design principle of the unit with explanations and reference to individual part numbers for clarification allowing an understanding of the basic operation of the Hot Tap unit.

Figure 1 shows the unit fully assembled with the high pressure lubricator not connected and set off to one side for clarity.

Figure 2 shows a partial cross section of the sealing adaptor flange.

Figure 3 shows a partial cross section of the traverse carriage and tension rod guide arrangement.

Figure 4 shows a partial cross section of the drive motor and hydraulic piston mounting arrangement.

In Figure 1 a hard chromed drill rod 9 passes through the centre of two sets of sealing adaptor flanges 1 and the traverse carriage assembly 5. The hard chromed drill rod 9 is enclosed within a lubricator 17 attached to the sealing adaptor flanges 1 by means of a hammer lug nut 16 complete with an integral seal. On the end of the hard chromed drill rod 9 a standard mill or drill bit 15 which is screwed on and torque up to the correct value is installed. A seal pack off screw 2 acts as a gland nut for the high pressure packing 19 shown in Fig 2 holding it in place against the system pressure once energised. A traverse carriage 5 acts as the main attachment point for a single hydraulic through rod piston 14, an air motor 6 and a collet chuck 4. The traverse carriage 5 slides on two tension rods 3 that also join the two sealing adaptor flanges 1 together, both tension rods 3 are secured by locking nuts 11. In addition to acting as the main anchor points for both end assemblies the sealing adaptor flanges 1 also act as a securing point for the hydraulic through rod piston 14 also by means of locking nuts 12. The sealing adaptor flanges 1 have high pressure ports machined into the side to allow fitment of needle valves 8. On one side gauges 7 are installed to monitor pressures in both sealing adaptor flanges 1. On the opposite side elbows 10 and tubing 13 form a conduit route for the high pressure medium to equalise the pressure in the closed loop system within the high pressure lubricator 17 and at the opposite end against the pipe work being drilled into.

In Figure 2 a partial cross section of the sealing adaptor flange 1 shows the hard chromed drill rod 9 complete with drill bit 15 passing through the high pressure packing 19 held in place by the seal pack off screw 2. High pressure ports 18 below the high pressure packing 19 connect to the needle valves 8 shown in Fig 1 machined into the sides of the sealing adaptor flange 1. The hammer lug nut 16 connects to the high pressure lubricator 17 shown in Fig 1 at the one end and the valve arrangement pipe work being drilled into (not shown) at the opposite end of the unit.

In Figure 3 a partial cross section of the traverse carriage 5 shows the tension rods 3 passing through guide bushes 24 to reduce friction, eliminate binding and ensure smooth operation while under load. A drive hub 21 acts as the main attachment for the gear 26 and the collet chuck 4 by socket headed cap screws 27 and 28. Supporting the drive hub 21 are a taper thrust bearing 23 to allow loads to be applied and a sealed for life deep groove roller bearing 22 for rotational support. Locking the drive hub 21 assembly into the traverse carriage 5 is a drive hub bearing nut 20. To ensure lubrication to the bearings 22 and 23 an oil sump 29 complete with an oil lip seal 25 is installed.

In Figure 4 a partial cross section of the traverse carriage 5 shows an alternative view 90 degrees from Fig 3 showing the mounting arrangement of the air motor 6 onto an adaptor plate 34 by means of socket headed cap screws 30. The adaptor plate 34 complete with air motor 6 is also mounted onto the traverse carriage 5 by socket headed cap screws 30. The shaft of the air motor 6 passes through the adaptor plate 34 and through the traverse carriage 5 where a spur gear is attached and secured by means of a grub screw 33 onto the standard key way on the air motor shaft. The spur gear meshes with the main gear 26 to transmit rotation and torque to the hard chromed drill rod 9 (not shown) securely clamped by the collet chuck 4 which in turn is secured to the drive hub 21. Supporting the drive hub 21 is a taper thrust bearing 23 to allow loads to be applied and a sealed for life deep groove roller bearing 22 for rotational support. Locking the drive hub 21 assembly into the traverse carriage 5 is a drive hub bearing nut 20. A cut away section of the traverse carriage 5 allows a hydraulic through rod piston 14 to be securely clamped to it by means of a clamp 31 and socket headed cap screws 30. Advancement and retraction of the whole assembly is accomplished by the hydraulic through rod piston 14 operated by a remote console in a safe area. The gears 26 and 32 and the taper thrust bearing 23 are oil lubricated by centrifugal force of the gears spinning while operational. Oil is contained in the oil sump 29 complete with an oil lip seal 25 to prevent leakage and contamination of the gears and bearings.

Claims

Claims 1. A High Pressure Hot Tap drilling unit used to drill holes into pressurised pipe work or through valves while under high pressure and or sever service conditions with a balanced drill rod contained within a high pressure lubricator.
2. A High Pressure Hot Tap drilling unit according to claim 1, in which equal balanced pressure within the tool is provided by a lubricator and closed loop system.
3. A High Pressure Hot Tap drilling unit according to claim 2, in which the drill rod is pressure compensated by means of a closed loop system and lubricator allowing the rod to be neutral with equal amounts of force being exerted on both ends.
4. A High Pressure Hot Tap drilling unit according to claim 1, in which self energising seals are installed within a seal adaptor flange, the sealing arrangement is self energizing against applied system pressure.
5. A High Pressure Hot Tap drilling unit according to claim 1, in which advancement and retraction of the drill rod is achieved by means of a through rod hydraulic piston attached to a traverse carriage.
6. A High Pressure Hot Tap drilling unit according to claim 1, in which the torque required to rotate the drill bit while under high pressure is achieved by an air motor coupled to a simple gear train attached to a collet chuck mounted on a drive hub which in turn is housed within the traverse carriage by means of bearings.
7. A High Pressure Hot Tap drilling unit according to claim 1, in which the drill rod length can be extended to extend the overall length of the drill rod.
8. A High Pressure Hot Tap drilling unit according to claim 7, in which the additional lengths of drill rod are fully contained within additional lengths of high pressure lubricator.
9. A High Pressure Hot Tap drilling unit according to claim 1, in which the traverse carriage is guided by tension rods that connect both sealing adaptor flanges together and counteract the rotational torque imparted while the drill rod is being rotated.
10. A High Pressure Hot Tap drilling unit according to claim 1, where the chuck is mounted on a drive hub supported by a taper thrust and deep grove roller ball bearing.