Abstract:
An apparatus for handling pipes, the apparatus, in certain aspects, having a body having a tapered surface and at least a first slip and a second slip slidable on the tapered surface, a slip actuator for setting said at least first slip and said second slip, said first slip and said second slip having interengaging elements such that upon actuation of said slip actuator, said first slip is set and said second slip is set by the interengaging elements transferring setting force from the slip actuator through said first slip to said second slip; and methods for using such an apparatus.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This is a nationalization of PCT application Serial No. PCT/GB 2004/050001 filed 16 Aug. 2004 (Int&#39;l Publication No. WO 2005/106185, published 10 Nov. 2005) which claims priority from U.S. Application 60/567,235 filed 1 May 2004—both of which applications are incorporated fully herein for all purposes and from both of which the present invention and application claim priority under the Patent Laws. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to an apparatus and method for facilitating handling pipe and handling pipe strings particularly, but not exclusively, to an elevator for handling pipe on drilling rigs. The pipe may be a single section, stand or string of drill pipe, a single section, stand or string of casing, tubular, premium tubular, drill collars or pipe incorporating a well tool. 
         [0004]    2. Description of Related Art 
         [0005]    In the drilling, completion and workover of a borehole in the oil, gas, water and geothermal industries pipes are run into and out of a borehole. Such an operation is sometimes referred to as “tripping in” for moving pipes down into a borehole and “tripping out” for moving pipes up and out of a borehole. Each of these operations requires pipes to be moved around a drilling rig. Accordingly, there are many problems associated with the handling and logistics of pipe handling of a drilling rig especially in the interconnecting, disconnecting, and storing of pipes on an oil drilling platform without interrupting the drilling process. 
         [0006]    The types of pipes which need to be moved around a drilling rig comprise drill pipes, drill collars, casings, tubing, perforated tubing, liners, liner hanger tools, packers, well cleaning tools etc. 
         [0007]    During a drilling operation on a conventional oil drilling platform, when the drill bit has penetrated such a distance into a borehole that only a small part of the drill string extends upwards from the upper surface of the drill floor, the drilling operation is stopped, and a new tubular drill string section is moved from a storage site or rack positioned outside the drill floor and connected to the upper end of the drill string. Once the new section is connected, the drilling operation may be continued. Normally, the length of the drill string sections is 30 feet or about 9 m (or a double or triple multiple thereof). Each time the drill bit has penetrated further into the underground, the drilling operation is usually stopped and a further drill string section (or stand) is added. 
         [0008]    Many prior art drilling systems have a rotary drive, and/or a top drive, a supportive rig floor, a derrick extending vertically above said rig floor, and a travelling block which can be raised and lowered within the derrick. During drilling operations, such rig equipment is often used to insert and, in some cases remove, tubular goods from a well. Drill bits and/or other equipment are frequently lowered into a well and manipulated within a tubular drill pipe. Once a well has been drilled to a desired depth, large diameter pipe called casing is often installed in the wellbore and cemented in place in order to provide structural integrity to the well and to isolate downhole formations from one another. 
         [0009]    Current systems for moving pipes on and around a drilling rig incorporate an elevator arranged on the end of a line hanging over a pulley wheel or travelling block hung from a derrick of the drilling rig or from bails of a top drive. The other end of the line is wound round a winch. The elevator generally comprises a pair of hinged semicircular segments, a latch and a safety mechanism to ensure the latch is closed properly. Such an elevator is sold by BJVarco under the trade name “BX Elevator”™. 
         [0010]    The pipe lies horizontally on a “catwalk” or on an inclined ramp or conveyor and is lifted manually clear of the surface on which it lies or the end of the pipe is exposed over a ledge. The segments of the elevator are closed about the body of the drill pipe and the latch is closed and the safety mechanism, usually a split pin is pushed into position to ensure the latch is properly closed and will not allow the latch to be opened until the split pin is removed. The elevator loosely fits around the body of the pipe such that the elevator can slide therealong until the elevator abuts an upset in the pipe or a collar threaded to an end of the pipe. Drill pipe comprises an upset known as a “box” in which a female threaded end is located, alternatively an end of the pipe is threaded on to which is threaded a collar of larger outer diameter, which form a shoulder. The winch is activated to lift the elevator and the pipe hanging therefrom clear of the rig floor to facilitate movement of the pipe on and around the drilling rig. A roughneck is then able to swing the pipe to another location, usually for stabbing into a string of pipe already in the well or located in a mousehole. One particular use is to facilitate movement of the drill pipe from the pipe storage areas to the well centre and the storage area close to the well centre known as the “fingerboard”. This method is used in tripping-in operations. The elevator is then used to hold the entire weight of the pipe string whilst the slips in the platform, known as a spider, are released. The pipe string is rotated and lowered into the well and then the slips in the spider are engaged with the pipe and the elevator released. 
         [0011]    The BJ Varco “BX hydraulically actuated elevator” is able to orient the throat of the elevator between a position to engage a vertical pipe to a position to engage a horizontal pipe and engaging a pipe lying at any angle therebetween. The elevator comprises segment in the form of hinged doors. The doors on a large elevator, which must be closed around the pipe, may weigh several hundred pounds. An elevator with doors needs clearance for the doors to swing in an arc under the pipe being engaged. The pipe has to be elevated, or clearance otherwise provided, for swinging doors. 
         [0012]    Many prior art elevators are of a “non-slip” variety. The non-slip variety are especially suited to handle pipe which does not have an upset, although may also be used with pipes which have upsets. These pipes are known as “flush”, “near flush” or “smooth walled” pipes. The non-slip elevator is provided with jaws with non-slip teeth move into engagement with the pipe, which prevents the pipe from slipping. Thus smooth walled pipe may be moved with such an elevator. The non-slip elevators have generally been constructed with doors (generally, one or two) which open to allow the insertion or removal of the pipe; doors which traditionally are heavy, slow in operation, difficult to handle and can present a considerable safety hazard to the operator. The balance point of such an elevator can change when the doors are open, thus creating handling problems and adding danger to the operator. Especially with very heavy pipes, for example, large casing, the pipe is initially in a horizontal position, laying in place on or near the floor beneath a derrick, and the hinged door elevator is lowered near the point of attachment to the pipe. The derrick personnel then are required to open the heavy door or doors, which may weigh several hundred pounds, to allow the elevator to be placed over the tubular. Because the door or doors must close around the tubular, the tubular end around which the elevator is located is often above the derrick floor. 
         [0013]    Often there is idle time in which no actual drilling takes place. In view of the fact that the investment made in a drilling rig is very high even a relatively small reduction of the idle time is significant. 
         [0014]    One solution commonly used to reduce the idle time on drilling rigs is to assemble two drill pipe sections, known as “singles”, each having a length of about 10 m into a 20 m stand, known as a “double”, placing the singles in a mousehole adjacent to the drilling opening and connecting the singles by using air tuggers and spinning wrenches while the drilling operations proceeds. 
         [0015]    One exemplary system and apparatus for such offline standbuilding is described in U.S. Pat. No. 4,850,439, the disclosure of which is incorporated herein by reference. However, although these conventional offline standbuilding systems do create significant efficiencies in the drilling process, they generally utilize many complex pieces of equipment, such as, hoists and multi-purpose pipehandling machines that result in a system which is complicated, costly, and requires significant ongoing maintenance. 
         [0016]    Tubulars such as casing, drill pipe or other pipe are typically installed in a number of sections of roughly equal length. These pipe sections are typically installed one at a time, and screwed together or otherwise joined end-to-end to make a continuous length of pipe. In order to start the process of inserting pipe in a well, a first joint of pipe is lowered into the wellbore at the rig floor, and suspended in place using a set of “lower slips.” Such lower slips are often wedge-shaped dies which can be inserted between the outer surface of said pie and the bowl-like inner profile of the rotary table. Such lower slips hold the weight of the pipe and suspend the pipe in the well. Although such lower slips can be automated, in many applications such lower slips are manually inserted and removed by rig personnel. 
         [0017]    To install pipe into a well, a first joint of pipe is generally inserted into a well and positioned so that the top of said joint of pipe is located a few feet above the rig floor. A rig crew or a pipe handling machine grabs a second joint of pipe, lifts the second joint of pipe vertically into the derrick, positions the second joint above the first joint which was previously run into the well, and “stabs” a male threaded end, known as a “pin-end” at the bottom of said second joint into a female threaded end known as a “box-end” at the top of the first joint. The second joint is then rotated in order to mate the threaded connections of the two joints together. Then an elevator attached to the travelling block in the rig derrick is typically lowered over the top of the second (i.e., upper) joint of pipe. Such elevators have a central bore which is aligned with the uppermost end of the joint of pipe. The pipe is received within the central bore of the elevator. Once the elevator has been lowered over the pipe a desired distance, slips within such elevators can be activated to latch or grip around the outer surface of said joint pipe. Depending on the length of the second joint of pipe, this can often occur 12 m (40 feet) or more above the rig floor. 
         [0018]    Upon proper latching and engagement of the elevator slips around the body of the pipe, the travelling block and elevator is raised to take weight off of the lower slips. The lower slips can then be removed. Once the lower slips are removed, the entire weight of the pipe string is suspended from the elevator slips. The pipe can then be lowered into the well by lowering the traveling block. After the second or upper joint of pipe is lowered a sufficient distance into the well, the lower slips are again inserted in place near the rig floor. 
         [0019]    The process is repeated until the desired length of pipe (i.e., the desired number of joints of pips) is inserted into the wellbore. This same process can be utilized for many different types and sizes of pipe whether small diameter drill pipe or large diameter casing. The entire weight of the pipe can be held or suspended by the elevators and by the elevator slips. This pipe can be very heavy, especially when many joints of large diameter and/or heavy-wall casing are being run into a well. 
         [0020]    Accordingly, it is important that the elevator slips be properly latched around the uppermost section of pipe in the derrick to ensure that the pipe remains securely positioned within the elevators. If the pipe is not properly secured within the elevators, it is possible that the pipe drop or fall out of the elevators, causing damage to the rig or the well, or injury to rig personnel. Incorporated fully herein by reference are U.S. Pat. Nos. 6,626,238 B2; 6,073,699; 5,909,768; 5,84,647; 5,791,410; 4,676,312; 4,604,724; 4,269,554; 3,882,377; 6,494,273; 6,568,479; 6,536,520 B1; and 6,679,333 B2. 
         [0021]    U.S. Pat. No. 6,073,699 discloses an elevator for lifting wellbore tubulars, the elevator having a pair of hinged doors, the doors interlocking with the use of a locking pin to prevent the elevator from opening. 
       BRIEF SUMMARY OF THE INVENTION 
       [0022]    The inventors have recognised that it is advantageous to have a remotely operated slip type elevator; that hydraulic circuits are very controllable and reliable; that the elevator has to work with top drive systems; to be able to handle flush and near flush pipe safely; for a single elevator which, by replacing the slips with one of six sets of sips can handle pipes which range between 2.3/8″-2.7/8″ for the first size set of slips, 2.7/8″-3.1/2″ for the second size set of slips, 3.1/2″-4.1/2″ for the third size set of slips, 4.1/2″-5.1/2″ for the fourth size set of slips, 5.5/8″-6.5/8″ for the fifth size set of slips and 6.5/8″-7.5/8″ for the sixth size set of slips. 
         [0023]    According to the present invention, there is provided an apparatus for handling pipes, the apparatus comprising a body having a tapered surface and at least a first slip and a second slip slidable on the tapered surface, the apparatus further comprising a slip actuator for setting the at least first slip and the second slip characterised in that the first slip and the second slip have interengaging elements therebetween such that upon actuation of the slip actuator, the first slip is set and the second slip is set by the interengaging elements transferring the setting force from the slip actuator through the first slip to the second slip. 
         [0024]    A slip is any item which can be used to prevent or inhibit a pipe from falling through an aperture, such as the throat of an elevator. A slip is traditionally a wedge inserted between an outer body provided with a tapering surface and the outer wall of a pipe. 
         [0025]    Traditionally the slip tapers, although a tapering outer surface is not essential, any arms or feet which provide a tapered interface would suffice. The taper allows easy removal of the slip, which would otherwise be very difficult. The taper allows the pipe engaging surface to move radially away from the pipe, as the pipe engaging surface is designed to resist longitudinal movement, mainly to inhibit downward slippage of a pipe or string of pipe, but also to inhibit a small amount of upward force. The slip may have a substantially planar pipe engaging surface or have concave and convex surfaces or have inserts with pipe engaging surfaces which are of varying depths which preferably conform to the outer wall of a pipe which will be held therein or the pipe engaging surface may be concave and provided with a plurality of inserts with pipe engaging surfaces. Preferably, the inserts are provided with gaps therebetween. By having a pipe engaging surface with a large contact area, the pipe engaging surface may be provided with smaller teeth or a less rough, less invasive surface, thus the outer wall of the pipe is less likely to be damaged. This is particularly important for pipes such as premium tubulars and pipes made from brittle alloys, carbon fibre and plastics pipes. However, a planar pipe engaging surfaces may suffice, particularly, but not exclusively, if the planar pipe engaging surface is provided with teeth which bite into the outer wall of the pipe. 
         [0026]    Preferably, the interengaging elements comprise an upstand and a recess and most preferably the upstand of the first slip is freely slideable into and out of the recess so that the when the slips are removed from the elevator, the slips are free to part from one another. 
         [0027]    Advantageously, the interengaging element of the first slip is in fixed relation to the first slip and the interengaging element of the second slip is in fixed relation to the second slip. Preferably, there are a plurality of interengaging upstands and recesses; the recess may be correspondingly shaped with the upstand, preferably to form an interference fit. The pin may be tapered and the recess may have a corresponding taper. 
         [0028]    Preferably, the interengaging element of the first slip is integral with the first slip and the interengaging element of the second slip is integral with the second slip. The interengaging elements may comprise a series of interengaging teeth on each side of the slip. 
         [0029]    Advantageously, the slip has a pipe engaging surface. The pipe engaging surface may be arranged on inserts which form part of the slip. The inserts may be arranged in grooves in the body of the slip. 
         [0030]    Preferably, the first and second slips each has a pipe engaging surface, a top, a bottom, a rear face and two sides. Advantageously, the interengaging elements are located on or in at least one of the sides. Preferably, the rear face slides along the tapered surface of the body. 
         [0031]    Advantageously, the slip actuator sets the at least first and second slips by moving the at least first and second slips down the tapered surface, wherein the interengaging elements allow lateral movement between the first and second slip. Preferably, the tapered surface takes the form of a frusto-conical surface. Thus by allowing freedom to move transverse to the direction of actuation of the slip along the frusto-conical tapered surface the slips can move apart on unsetting the slips and move together on setting the slips. Preferably, the body comprises a main body and at least one door, the tapered surface located on preferably both. 
         [0032]    Advantageously, the frusto-conical surface is located on a main body and two doors. The body comprises the main-body and the doors. Thus the weight of the pipe string is carried through the doors as well as the main body. 
         [0033]    Preferably, one of the doors comprises a latch and the other of the doors comprises a catch. Preferably, to ensure that the doors are not inadvertently opened or opened by mechanical shock. Advantageously, the main body subtends substantially one hundred and eighty degrees and each of the doors subtends between seventy-five and ninety degrees. Although the main body may subtend any angle, such as thirty degrees and the doors one hundred and sixty-five degrees each. Preferably, the first slip is located on the tapered surface of the main body and the second slip is located on the tapered surface of one of the doors. 
         [0034]    The frusto-conical surface may taper from top to bottom along a straight path, or may have a slight convex or concave curvature. The complete frusto-conical surface is commonly referred to as a bowl. 
         [0035]    Preferably, a third slip and a fourth slip slidable on the tapered surface, the apparatus further comprising a further slip actuator for setting the at least third slip and the fourth slip, wherein the third slip and the fourth slip have interengaging elements therebetween such that upon actuation of the slip actuator, the third slip is set and the fourth slip is set by the interengaging elements transferring the setting force from the slip actuator through the third slip to the fourth slip. 
         [0036]    Alternatively, the first actuating mechanism acts solely on the first slip and sets three or four or more slips simultaneously by transferring the setting force from the first slip through interengaging means on the second third and fourth slips to set all of the slips simultaneously. 
         [0037]    Advantageously, the slip actuator is hydraulically actuable. Most advantageously, the slip actuator and further slip actuator are actuable by a common hydraulic circuit, with a common supply of hydraulic fluid, and second preferably, the slip actuator may be, or may include a pneumatic, electrical, or mechanical means such as springs. The present invention also provides in or for use in the apparatus of the invention, a slip having interengaging elements. Preferably, the slip comprises a plurality of grooves, an insert arranged in each of the plurality of grooves. Advantageously, each insert has a pipe engaging surface. Preferably, the pipe engaging surface comprises at least one of the following: tungsten carbide particles, diamond particles, metallic teeth. Preferably, the slip has a pipe engaging surface, a top, a bottom, a rear face and two sides, the interengaging elements located on at least one of the sides. 
         [0038]    The invention also provides a method for setting slips in an apparatus for handling pipes of the invention, the method comprising the steps of operating the slips actuating mechanism to apply a setting force to the first slip, whereupon the interengagement means transfers the setting force to the second slip, setting the first and second slips simultaneously. 
         [0039]    According to a second aspect of the invention, there is provided an apparatus for handling pipes, the apparatus comprising a body with a tapered surface, a recess in the tapered surface and a pin arranged therein, the apparatus further comprising a slip slideable on the tapered surface, wherein the slip has a lug slideable on the pin, the slip biased by resilient means between the body and the lug to bias the slip into an unset position. Preferably, this allows easy replacement of the slip by withdrawing the pin. Preferably, apparatus further comprises a shoulder arranged in the path of action of the resilient means to inhibit clamping of the lug between the resilient means and the body and preferably defining an opening between the resilient means and the body which is slightly larger than the lug to facilitate easy replacement of the slip. 
         [0040]    Once the pin is removed, and upon removal of the slip, the lug of the slip being removed does not cause the resilient means to uncoil or decompress or to lose stored energy. Advantageously, the apparatus further comprises a sleeve about a portion of the pin close to the lug, wherein the resilient means surrounds the sleeve. Advantageously, the sleeve is fixed to the shoulder. Preferably, the shoulder comprises a plate to lie above the resilient means and a leg upstanding from the plate. Advantageously, the body of the elevator further comprises a lug, the resilient means biased between the lug of the slip and the lug of the body of the elevator. 
         [0041]    This preferably stabilises the pin. Preferably, the slip comprises a further lug arranged below the further lug of the body of the elevator. Preferably, the body comprises a ledge against which the lug of the slip is biased. Advantageously, the resilient means comprises at least one of the following: pneumatic piston and cylinder, hydraulic piston and cylinder and an accumulator, a coiled spring, Belville washers, and resilient material such as a foam, but most preferably a compression spring. 
         [0042]    The second aspect of the invention also provides a method of changing a slip in an apparatus for handling pipes using the apparatus of the second aspect of the invention, the method comprising the steps of removing the pin from the body  2  and moving the slip to slide the lug thereof out of the recess in the body of the apparatus. 
         [0043]    According to a third aspect of the invention, there is provided a method for indicating slips of an elevator have engaged a pipe, the elevator having a slip actuator for actuating slips to engage a pipe, the slip actuator comprising a hydraulically operated piston and cylinder, the method comprising the steps of applying pressurised hydraulic fluid to the piston in the piston and cylinder to move the piston to move the slips into engagement with a pipe, the piston passing a signal port, upon which pressurized hydraulic fluid communicates with hydraulic fluid in a line connected to the signal port, which indicates to the controller that the slips are actuated. Preferably, the line returns to a console from which the controller can observe the increase in pressure using a display of a pressure gauge. Advantageously, the apparatus further comprises a pressure limiting valve, the method further comprising the step of passing the pressurized fluid in line through the pressure limiting valve. Preferably, the increase in pressure is in the order of between 20 bar to 200 bar, most preferably 60 to 150. 
         [0044]    Advantageously, the elevator further comprises a door and a latch, the door operated by a hydraulic piston and cylinder, the piston and cylinder having a signal port, the method further comprising the step of applying hydraulic fluid under pressure to the piston and cylinder to move the piston to close the door, whereupon the piston passes the signal port, whereupon hydraulic fluid in a line connected to the signal port is pressurised to initiate activation of the latch. Preferably, the elevator further comprises a hydraulic switch, actuable upon the latch assuming a closed position, which switch allows hydraulic fluid under pressure to flow therethrough to initiate activation of the slips actuator. 
         [0045]    According to a fourth aspect of the present invention, there is provided a method for handling pipe using an elevator having a hydraulic slip actuator for activating slips for engaging a pipe, wherein the elevator further comprises a pilot line, the method comprising the steps of applying pressurized hydraulic fluid to the pilot line to activate the slips actuator to disengage the slips. Preferably, operating the slips actuator to disengage the slips doesn&#39;t necessarily mean that the slips themselves will be disengaged. If the pipe is unsupported when the slips actuator is disengaged from the pipe, the weight of the pipe will continue to energise the slips and maintain the slips in the down position with the pipe engaged in the elevator. 
         [0046]    The fourth aspect of the present invention also provides an apparatus for handling pipes, the apparatus comprising a body, at least one door and a hydraulic slip actuator for activating at least one slip characterised in that the apparatus further comprises a pilot line and a valve for directing flow of hydraulic fluid into the slip actuator to activate the slips actuator to disengage the slips. This allows the slips to be disengaged whilst the doors and latch remain engaged. 
         [0047]    According to a fifth aspect of the present invention, there is provided an apparatus for handling pipes, the apparatus comprising an elevator having a body, at least one ear, and a slip actuator for engaging slips with a pipe said apparatus further comprising a stator attachable to bails of a top drive, the apparatus further comprising a rotor attached to said at least one ear and drive means for rotating said rotor for tilting said elevator with respect to the stator. Preferably, the elevator further comprises at least one door. 
         [0048]    The fifth aspect of the present invention also provides a method for handling flush or near flush pipe using an elevator depending from bails of a top drive, the elevator having body and at least one door defining a throat, slips located in the throat and a slip actuator, the method comprising the steps of opening the at least one door of the elevator, tilting the elevator with respect to the bails, placing pipe in a throat of the elevator, closing the doors and activating slips to engage the pipe and hoisting the elevator which allows the elevator to assume its initial position with a pipe depending therefrom. 
         [0049]    By near flush pipes is meant any pipe which does not have an upstand or collar of sufficiently larger diameter than the diameter of the body of the pipe to form an upset from which the pipe can hang when arranged in an elevator having a shoulder on which the upset rests, such as the elevator shown in U.S. Pat. No. 6,494,273. 
         [0050]    Preferably, the elevator further comprises a hydraulically actuable piston and cylinder for facilitating opening the door, wherein the method further comprises the steps of opening the doors by raising hydraulic pressure in the actuator, the piston passing a signal port, whereupon a signal is sent which initiates a safety valve which allows the elevator to be tilted. Preferably, the piston and cylinders are double acting, the method further comprising the step of applying pressurized hydraulic fluid to the otherside of the piston to disengage the slip actuator. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         [0051]    For a better understanding of the present invention, reference will now be made, by way of example, to the accompanying drawings, in which: 
           [0052]      FIG. 1  is a perspective view of an apparatus in accordance with the present invention; 
           [0053]      FIG. 2  is a top plan view of the apparatus shown in  FIG. 1 , with a cover plate removed; 
           [0054]      FIG. 3  is a front view of the apparatus shown in  FIG. 1 ; 
           [0055]      FIG. 4  is a back view of the apparatus shown in  FIG. 1 ; 
           [0056]      FIG. 5  is a fragmentary perspective view showing part of the top and centre of the apparatus shown in  FIG. 1 ; 
           [0057]      FIG. 6  is a fragmentary perspective view showing parts of the underside and front of the apparatus shown in  FIG. 1 ; 
           [0058]      FIG. 7  is a cross-sectional view of the apparatus shown in  FIG. 1 , taken along the line VII-VII of  FIG. 3 , with the slips removed; 
           [0059]      FIG. 8  is a fragmentary cross-sectional view of the apparatus shown in  FIG. 1  taken along line VIII-VIII of  FIG. 3 ; 
           [0060]      FIG. 9  is a cross-sectional view of the apparatus shown in  FIG. 1  taken along the line IX-IX of  FIG. 2 ; 
           [0061]      FIG. 10  is a simplified view, similar to the view shown in  FIG. 9 , with the slips removed. 
           [0062]      FIG. 11  is a cross-sectional view of the apparatus shown in  FIG. 1  taken along the line IX-IX of  FIG. 2 ; 
           [0063]      FIG. 12  is a fragmentary cross-sectional view of the apparatus shown in  FIG. 1  taken along the line XII-XII of  FIG. 2 ; 
           [0064]      FIG. 13  is a fragmentary cross-sectional view of the apparatus shown in  FIG. 1  taken along the line XIII-XIII of  FIG. 2 ; 
           [0065]      FIG. 14  is a schematic representation of part of a drilling rig, including the apparatus shown in  FIG. 1  depending from bails; 
           [0066]      FIG. 15  is a schematic diagram showing a hydraulic circuit used in the apparatus shown in  FIG. 1 ; 
           [0067]      FIG. 16  is a graphical representation of steps in the operation of the hydraulic control circuit used to control the elevator shown in  FIG. 1 ; and 
           [0068]      FIG. 17  is a schematic representation of an apparatus shown in  FIG. 1  depending from a pair of bails, the apparatus provided with a device for adjusting the orientation of the apparatus. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0069]    Referring to  FIGS. 1 to 13 , there is shown an apparatus of the present invention generally identified by the reference numeral  1 . In the art of handling pipes on a drilling rig, the apparatus  1  is often referred to as an “elevator”. The elevator  1  comprises a part cylindrical body  2  having lifting ears  3  and  4  arranged on opposing sides of the housing  2  for connection to a pair of bails  5 , as shown in  FIG. 14 . Doors  6  and  7  are hinged to the body  2  on hinge pins  8  and  9 . A latch  10  is provided to latch the two doors  6  and  7  together to inhibit the doors  6  and  7  from inadvertent opening due to operational mechanical shocks. 
         [0070]    The body  2  has a part frusto-conical inner surface  11  which tapers inwardly from the top to the bottom of the body  2  at an angle of approximately ten degrees from vertical to define an open throat  12 , see  FIGS. 1 and 10 . From  FIG. 7  it can be seen that the part frusto-conical inner surface  11  subtends approximately one hundred and eighty degrees. The doors  6  and  7  each have a part frusto-conical inner surface  13  and  14  which taper inwardly from the top to the bottom at an angle of approximately ten degrees from vertical. The part frusto-conical inner surface  13  and  14  each subtend slightly less than quarter of a circle, approximately eighty-four degrees. When the doors  6  and  7  are closed, a substantially complete frusto-conical surface is defined. 
         [0071]    The complete frusto-conical surface may taper from top to bottom along a straight path, or may have a slight convex or concave curvature. The complete frusto-conical surface  11 , 13  and  14  is commonly referred to as a “bowl”. 
         [0072]    As can be seen from  FIG. 2 , four slips  15 , 16 ,  17  and  18  are provided in and line the frusto-conical surfaces  11 , 13  and  14 . Each slip subtends slightly less than ninety degrees in their operating positions. Two of the slips  15  and  17  are arranged on the part frusto-conical inner-surface  11  of the body  2  and each of the other two slips  16  and  17  is arranged on each part of frusto-conical inner surfaces  13  and  14  of each door  6  and  7 . Each slip  15  to  18  has a part frusto-conical outer surface  19  to  22 , which substantially corresponds with the frusto-conical inner surfaces  11 , 13  and  14 , when the slips  15  to  18  are located in a set position. The slips  15  are moveable along the part frusto-conical inner surface  11  to selectively engage (set) and disengage (unset) a pipe (not shown) in the throat  12  of the elevator  1 . The slips  15  to  18  are each provided with a mechanism A, B, C, D for maintaining the slips  15  to  18  in an unset position. Mechanism A will be described for slip  15 , although it will be understood that the slips  16 , 17  and  18  and the mechanisms therefor are generally similar. Referring to  FIG. 9 , in which slip  15  is shown in an unset position and  FIG. 10  in which the slips  15  and  16  are removed, slip  15  has an upper lug  23  and a lower lug  24  located on a frusto-conical outer surface  19 . The upper lug  23  and lower lug  24  are in vertical alignment and have holes, the centres of which align with a line parallel to the part frusto-conical outer wall  19 . The upper lug  23  and lower lug  24  are slidably arranged on a pin  25 . The pin  25  is arranged in a recess  26  in the part frusto-conical inner surface  11  and lies substantially parallel therewith and is retained in a hole in a lower projection  27  and in a hole in an upper projection  28  of the body  2 . The lower lug  24  of the slip  15  is arranged on the pin  25  beneath the projection  27  and the upper lug  23  of the slip  15  is arranged between the lower and upper projections  27  and  28 . A spring  29  is arranged about the pin  25  and a sleeve  30  between the lower projection  27  and a lip  31  on the upper end of the sleeve  30  on which upper lug  23  seats. 
         [0073]    The sleeve  30  has a back portion  32 , the top of which sits against the bottom of a small groove  32   a . The spring  29  biases the back portion  32  of the sleeve  30  against the bottom of the small groove  32 . The back portion  32 , the upper projection  27  and the lip  31  define an opening and the distance between the upper projection  27  and the lip  31  is slightly larger than the upper lug  23 ′, such that the upper lug can slide into and out of the opening. 
         [0074]    The spring force in the coiled spring  29  is greater than the weight of the slip, thus the spring  29  maintains the slip  15  in a raised, unset, disengaged position. 
         [0075]    The pin  25  is slideably removable from the hole in the lower projection  27 , through the spring  29 , sleeve  30  and upper projection  28 . By removing the pin  25 , the slip  15  can be removed and changed for a different slip of the same type or size, or a slip of a different size suitable for handling pipe of a different diameter or a pipe of a different kind, such as premium tubular, which might require pipe engaging teeth of a different kind to reduce the possibility of damage to the surface of the tubular. 
         [0076]    The pin  25  is then slid back through upper projection  28 , sleeve  30 , spring  29  and lower projection  27 . The pin  25  may be threaded to threadedly engage the upper or lower lugs  27  and  28 , or may have a smooth interference fit surface or may be a loose fit and may be prevent from falling out lugs  27  and  28  by a member lying over the top of the pin  25 . Each slip  15  to  18  is provided with a top projection  15   a ,  17   a  and (not shown) with a hole therein to facilitate removal and replacement. 
         [0077]    For an elevator  1  as described herein, the slips  15  to  18  can be exchanged for one of six different sizes for handling pipe sizes between 2.3/8″-2.7/8″. For the first size set of slips, 2.7/8″-3.1/2″ for the second size set of slips, 3.1/2″-4.1/2″ for the third size set of slips, 4.1/2″-5.1/2″ for the fourth size set of slips, 5.5/8″-6.5/8″ for the fifth size set of slips and 6.5/8″-7.5/8″ for the sixth size set of slips. The elevator  1  is preferably suitable for holding pipe string loads of 227 tonnes (250 short tons) and in other embodiments  454  tonnes (500 short tons), 681 tonnes (750 short tons) 907 tonnes (1000 short tons). 
         [0078]    The slip  15  has a solid body, which may be made of any material suitable for resisting compression forces of in excess of 227 Tonnes (250 short tons) and in other embodiments  454  tonnes (500 short tons), 681 tonnes (750 short tons) 907 tonnes (1000 short tons) or more. The solid body has three grooves  33 , 34 ,  35  therein running from top to bottom, as shown in  FIG. 5 . The grooves  33 ,  34 , 35  converge towards the lower end. Inserts  36 , 37 ,  38  which correspondingly converge towards a lower end, are slid into corresponding grooves  33 , 34 ,  35 . The inserts have a pipe engaging surface  39 , which may be any suitable finish or material, such as tungsten carbide particles, diamond particles, metallic teeth, or any material which resists slippage. 
         [0079]    The slip  15  also has a recess  37   a  in one side of the slip for receiving a corresponding upstand  38   a  on adjacent slip  16 . Slip  17  has a corresponding upstand (not shown) on the opposing side of the slip  17  to fit into a corresponding recess (not shown) in slip  18 . The upstand  38   a  is tapered and the recess  37   a  is correspondingly tapered, although in another embodiment, both the upstand  38   a  and the recess  37  may not be provided with tapers. Each slip  15  to  18  may thus be provided with an upstand and a corresponding recess, such that when fitted together, downward force can be transmitted through the upstand and recesses to adjacent slips, so that a setting force can be applied to one slip to transmit the setting force through the upstand and recesses to set one further or all the slips  15  to  18  simultaneously on a pipe. The upstand  38   a  and recess  37   a  allow a radial movement therebetween such that the slips can move apart when being moved up into an unset position along the part frusto-conical inner surfaces  11 , 13  and  14  and move together when the slips are moved down the part frusto-conical inner surfaces  11 , 13  and  14  into the set position, whilst still able to transmit the downward forces between the slips required to set the slips on a pipe. Preferably, the upstand  38   a  and corresponding recess  37   a  have an interference fit. Thus the slips interengage to transmit longitudinal force, whilst retaining the ability to radially contract and expand between one another. 
         [0080]    The slips  15  to  18  are set using a slip activation mechanism. The slip activation mechanism comprises two slips actuating mechanisms  40  and  41  which are generally similar to one another, one located on the left side of the body  2  and the other on the right side of body  2 . 
         [0081]    Slips actuating mechanism  40  will be described for activating slips  15  and  16 , although it will be understood that the slips actuating mechanism  41  is generally similar for activating slips  17  and  18 . Slips actuating mechanism  40  comprises piston  42  and a cylinder  43  defining a chamber  44  and an annulus  45 . The hydraulic fluid contact area on the piston provided by the annulus  45  is approximately the same as the hydraulic fluid contact area on the piston provided by the chamber  44 . A recess  46  is located in the top of the piston  42  for slideably receiving a pin  47 . The pin  47  has a hole  48  therein transverse to the length of the pin  47  for receiving a lever  49 . The lever  49  is rotatably arranged on a substantially horizontally disposed pin  50  on a lug  51  fixed to the body  2 . The lever  49  is shaped so that there is a defined distance between the lever  49  and the body  2  to limit the vertical travel of the lever  49 . The lever  49  has an integral finger portion  52  which lies above part frusto-conical inner surface  11  and above top projection  15   a  of the slip  15 , when there is a slip  15  in the elevator  1 . Upon activation of the slips actuating mechanism  40 , hydraulic pressure is increased in chamber  44  causing hydraulic fluid to flow into chamber  44  and inducing upward movement of the piston  42  and hydraulic fluid to flow out of annulus  45 . The pin  47  is pushed up with the piston  42 , which moves lever  49  upwardly about the pin  50  and thus finger  52  downwardly on to the top of the slip  15  to provide a setting force which compresses the spring  29  of mechanism A and the spring (not shown) of mechanism B by transfer of the setting force through the projection  38   a  and recess  37   a  to engage a pipe (not shown). The hydraulic actuating mechanism  41  is actuated in a similar way to set slips  17  and  18 . All slips  15  to  18  are set simultaneously on the pipe. The hydraulic force provided by the slips actuating mechanisms  40  and  41  is preferably sufficient to cause the pipe engaging surface  39  of the slip  15  to bite into the wall of the pipe. The elevator  1  is lifted on the bails  5  and the weight of the pipe causes the pipe further engage surfaces  39  of the slips  15  to bite into the surface of the pipe. The hydraulic actuating mechanism transfers approximately 4.5 tonnes (five short tons) of setting force to the slips  15  to  18 . The hydraulic pressure is maintained during the handling of the pipe to inhibit the pipe from disengaging, even if there is an upward force of about 4.5 tonnes (five short tons) of upward force applied to the pipe. 
         [0082]    The spring force on each spring  29  is approximately 300N to 500N sufficient to hold a slip in the raised, unset condition. The slips  15  to  18  weigh in one embodiment between ICON and 300N each, i.e. the spring force of each spring is greater than the weight of each slip  15  to  18 , so that the spring  29  will maintain the slip is a raised, unset, disengaged position. 
         [0083]    Hydraulic pressure may be increased in the annulus  45  and/or decreased in the chamber  44  to retract the piston  42 . This allows the pin  47  to fall back into the recess  46  and the lever to rotate about pin  50  to lift the finger  52  out of engagement with the top projection  15   a  of the slip  15 . Due to the weight of the pipe being greater than the spring force provided by the springs  29  and the corresponding springs in mechanisms B, C and D, the slips  15  to  18  will maintain a grip on the pipe until a upward force is exerted to sufficiently reduce the effective weight of the pipe, which will disengage the pipe engaging surface  39  of the slips  15  to  18  which will allow the spring  29  and the springs of the mechanism B, C and D to expand to return the slips  15  and  18  to a raised, unset, disengaged position. Such an upward force on the pipe may be provided by the pipe having been stabbed and connected to a pipe string, the pipe string being held in a spider, thus the weight of the pipe is taken by the drill string which allows the springs  29  to lift the slips out of engagement with the pipe. Further lowering of the elevator  1  would help disengage the slips  15  to  18 , but this would only be required occasionally or in exceptional circumstances. 
         [0084]    Referring back to  FIG. 1 , a cover  53  is provided to protect the slips actuating mechanisms  40  and  41  from being knocked or clogged with dirt, drilling mud and debris. The cover is hinged on a hinge  54  and a handle  55  is provided for lifting the cover to gain access to the actuating mechanisms  40  and  41  and to mechanisms A and C. 
         [0085]    The cover  53  also has a U-shaped cut out  56  and a plastics material or metal buffer, preferably a soft ductile metal buffer  57 , which acts as a pipe guide to facilitate locating a pipe in the throat  12  of the elevator  1 . 
         [0086]    A pipe to be handled is offered up to the elevator  1  when the doors  6  and  7  of the elevator  1  are open. 
         [0087]    Referring to  FIGS. 3 and 7 , to open the doors  6  and  7 , the latch  10  is released. The latch  10  comprises a locking bar  58  on upper and lower arms  59  and  60  which are hinged with a hinge pin  61  to door  6 . A curved linkage arm  62  is located in a recess  63  in the door  6 . 
         [0088]    The curved linkage arm  62  has two opposed ends, one end linked to the lower arm  60 , off-centre from the hinge pin  61  and the other end to a bearing  64  freely rotatable around hinge pin  8  of door  6 . A further linkage arm  65  is located in an opening  66  in the body  2  of the elevator  1  extending from the front of the elevator  1  to the back of the elevator  1  past the lifting ear  3 . The further linkage arm  65  has two opposed ends one linked to the bearing  64  and the other to an elbow linkage  67  which is linked to a piston  68  of a double acting piston and cylinder  69 , as shown in  FIG. 4 . Upon hydraulic fluid pressure increasing in an annulus  68   a  behind the piston  68  in the cylinder  68  and/or decreasing in a chamber  68   b  in front of the piston  68 , the piston  68  retracts pulling elbow linkage  67  and linkage arm  65  to rotate bearing  64  and pull the curved linkage arm  62  to rotate the latch  10  about the hinge pin  61  to unlatch the latching locking bar  58  from engagement with a catch  71  on the door  7 . 
         [0089]    The doors  6  and  7  are then opened. Linkage arms  72  and  73  each have two opposed ends and are arranged in openings which pass from the front to the back of elevator  1 . One end of the linkage arm  72  and  73  is located in a recess  74  and  75  and attached to their respective doors  6  and  7  at a point which is offset from the hinge pins  8  and  9 . The other end of each linkage arms  72  and  73  is attached to an elbow linkage  76  and  77  respectively, which are rotatable about pins  78  and  79 . 
         [0090]    The other end of elbow linkages  76  and  77  are attached to piston and cylinder  80 . An upstand  81  is slideably arranged in fingers  82  to allow the piton and cylinder  80  to move longitudinally. Upon hydraulic fluid pressure increasing in an annulus  83  behind the piston head, the piston  84  retracts into the cylinder  85  which pulls the ends of elbow linkages  76  and  77  to rotate the elbow linkages about pins  78  and  79 , which transfer a the pulling force into a pushing force on linkage arms  72  and  73  to open the doors  6  and  7 . 
         [0091]    A pipe is swung into or offered up to, or the elevator  1  is offered up to the pipe, through the open doors  6  and  7  into the throat  12  of the elevator  1  and abuts the buffer  57  of the pipe guide arranged in the U-shaped cut-out  56  in the cover  53 . The doors  6  and  7  are closed by raising the pressure in a chamber  86  and/or lowering the pressure of the hydraulic fluid in the annulus  83  of piston and cylinder  80 , which extends the piston  84  and moves the piston  84  to the left when referring to  FIG. 4  and the cylinder  85  moves to the right, both the piston  84  and cylinder  85  moving longitudinally, which pushes the ends of elbow linkages  76  and  77  to rotate the elbow linkages about pins  78  and  79 , which transfers the pushing force into a pulling force on linkage arms  72  and  73  to close the doors  6  and  7  about the pipe. As shown in  FIG. 5 , plastics material or metal, preferably a soft ductile metal, buffers  86  and  87  is provided on the edge of a curved cut-out  88  and  89  on cover plates  90  and  91  located on the top surface of the doors  6  and  7 . The buffers  86  and  87  act as a pipe guide to facilitate the locating a pipe into the throat  12  of the elevator  1  upon closing the doors  6  and  7 . The buffers  86  and  87  are bolted to cover plates  90  and  91 . 
         [0092]    Buffers  92 , 93  and  94  are provided on the underside of the elevator  1  in cover plates  95 , 96  and  97 , as shown in  FIG. 6 . 
         [0093]    The doors  6  and  7  take a substantial portion of the weight of the pipe and are thus built to withstand 227 tonnes (250 short tons) of force and in other embodiments  454  tonnes (500 short tons), 681 tonnes (750 short tons) and 907 tonnes (1000 short tons). The latch maintains the doors  6  and  7  closed, and thus must be substantial and withstand the spreading force of the slips as they engage the pipe. The latch  10  is built to withstand 227 tonnes (250 short tons) of force and in other embodiments  454  tonnes (500 short tons), 681 tonnes (750 short tons) and 907 tonnes (1000 short tons) in tension between the doors  6  and  7 . 
         [0094]    Referring to  FIG. 3 , the lifting ears  3  and  4  comprise lower lugs  98  and  99  and upper shoulder  98   a  and  99   a  integral with or welded to the body  2 . Curved locking arms  98   b  and  99   b  are attached at either ends with pins, so that the curved locking arms  98   b  and  99   b  can be removed. Curved locking arm  98   b  has an integral lug  98   c  and a slot  99   d  therein for receiving a mechanism for tilting the elevator whilst attached to the bails  5  of a top drive (not shown). The tilting mechanism is sold by BJVarco and is used in conjunction with the state of art BX elevator currently available. Such an arrangement is shown in  FIG. 17 . 
         [0095]    A hydraulic system is provided for controlling the operation of the elevator  1 . The hydraulic system is shown schematically in  FIG. 15 , which shows the system in a state in which the slips are retracted, disengaged, unset and the latch and doors are open. An operator controls the hydraulic system from a control console  100  in an operator&#39;s cabin (not shown). Hydraulic fluid flows through the system at between 7.5 and 20 litres per minute (2 to 5 gallons per minute) and is supplied whilst the elevator  1  is being operated. 
         [0096]    To close the doors  6  and  7 , latch  10  and set the slips  15  to  18 , the following steps are taken. Using the control panel  100 , an operator operates a system valve (not shown) to set the hydraulic pressure in line P to a high pressure of between 124 to 159 bars (1800 to 2300 psi) and leaves the hydraulic pressure in line XP at atmospheric pressure. The hydraulic fluid passes in line P through a filter  101 . The increase in pressure in the hydraulic fluid passes through line  102  and into control line  103  which shifts slide valve  104  to allow the increase in hydraulic pressure to pass from line  102  to line  105  and into line  106 . Chamber  86  of door piston and cylinder  80  shifts the piston  84  into an extended position, closing the doors  6  and  7 . Fluid is forced out of the annulus  83  into line  107  through check valve  108  into line  109  and into line  110  and through slide valve  104  and into line  111  and into line T. When the piston head of piston  84  passes a signal port  112 , high pressure from line  106  communicates therewith and applies high pressure hydraulic fluid in signal line  113 , which opens check valve  113   a  and allows hydraulic fluid at a high pressure to pass from line  106  across the check valve  113   a  to line  114  into the chamber  68   b  of the latch piston and cylinder  69 . The build up of high pressure hydraulic fluid in chamber  68   b  pushes on piston head of piston  68  to move the piston  68  into an extended position closing the latch  10 . 
         [0097]    A latch detection valve  116  is located between the latch  10  and the door  7 , such that upon closing of the latch  10 , the latch detection valve  116  shifts to allow high pressure hydraulic fluid to pass thereacross between line  117 , which is in fluid communication with line  105 , and signal line  118 . High pressure hydraulic fluid in signal line  118  passes into signal line  119  opening the check valve  120 , allowing high pressure hydraulic fluid to pass across check valve  120  between line  121 , which is in fluid communication with line  114 , and line  122 . High pressure hydraulic fluid flows on from line  122  through slide valve  123  into line  124  into lines  125  and  126  and into chambers  44  and  44   a  of slip actuating mechanism, piston and cylinders  40  and  41 , which shift the pistons  42  and  42   a  into extended positions moving fingers  52  and  52   a  downwardly on to the slips  15  and  17  against springs  29  and  29   a  to set the slips  15  to  18  on a pipe (not shown). The slips  15  to  18  are set with a hydraulic power down force of approximately 4.5 tonnes (5 short tons), which is enough to create an initial penetration of the teeth of a standard set of inserts located on the slips  15  to  18  into a wall of the pipe, inhibiting the pipe from slipping through the slips  15  to  18  and allowing the buildup of the downward hoist load. The hydraulic fluid in the annuli  45  and  45   a  is squeezed into lines  127 , 128  and into line  129 , through slide valve  123  into line  130  into line  131 , through slide valve  104 , through line  111  and out into line T. When the piston  41  is in an extended position, which indicates the slips  15  to  18  are set, high pressure hydraulic fluid passes through signal line  132  to a slips down detection valve  133 , which high pressure hydraulic fluid shifts the slips down detection valve  133  allowing high pressure 124 to 159 bars (1800 to 2300 psi) pneumatic fluid to communicate between signal line  118  and signal line  134 . The slips down detection valve  132  will shift to be in fluid communication between signal lines  118  and  134  upon a pressure greater than 103 bars (1500 psi). The high pressure in the hydraulic fluid from line  118  passes into line  134  and through a pressure limiting valve  135 , which limits the pressure flowing onwards to check valve  136  to approximately 69 bars (1000 psi), and into line XP with a pressure of approximately 69 bars (1000 psi) to indicate to the operator that the doors  6  and  7  are closed, the latch  10  is closed and the slips  15  to  18  are set. This is a step increase in pressure at XP from atmospheric to approximately 69 bars (1000 psi) which is easily noticeable by an operator. The slips down detection valve  133  will then return to its initial state by high pressure hydraulic fluid flowing through control line  133   b  through a restrictor  133   a , which delays the onset of high pressure on the opposing side of the slips down detection valve  133 . The spring force on the slips down detection valve returns the valve to its initial state in which it blocks fluid communication between signal lines  118  and  134 . 
         [0098]    Once the slips  15  to  18  are set, the elevator  1  is lifted and the weight of the pipe self-energises the slips  15  to  18 , and thus are firmly held by the slips  15  to  18 . If, for any reason, an upward force on the pipe occurs of up to 4.5 tonnes (5 short tons), the slips  15  to  18  will remain engaged due to the pistons  42  and  42   a  remaining in the extended position, which are held set by a force of at least 4.5 tonnes (5 short tons) of hydraulic force to the top of the slips. The high pressure hydraulic fluid is maintained at high pressure whilst the elevator  1  is in use. High pressure through line P is maintained throughout use of the elevator  1 . 
         [0099]    The slips  15  to  18  may be released whilst maintaining the doors  6  and  7  and latch  10  closed. This is accomplished using a slips activation system  200 . The first step is to activate a PILOT valve (not shown) on the control panel  100  to allow, preferably 138 to 172 bars (2000 to 2500 psi) to flow through line  201  which activates slide valve  202 , which requires a minimum of 103 bars (1500 psi) to operate to allow fluid communication between signal line  118  and line  203 , which applies a high pressure to slide valve  123 , shifting the valve to allow line  122  to communicate with line  129 . The high pressure hydraulic fluid flows through lines  127  and  128  applying high pressure hydraulic fluid to annuli  45  and  45   a , which retracts pistons  42  and  42   a  which allows the fingers  52  and  52   a  free to hinge about hinge points  50  and  50   a . Hydraulic fluid in chambers  44  and  44   a  flows through lines  125 , 126 , through sliding valve  123  into line  130 , through the line  131 , through slide valve  104  into line  111  and into line T. The freely hinged fingers  52  and  52   a  allow the slips  15  to  18  to move to a retracted, disengaged, unset position on springs  29 , 29   a  and (not shown), unless the weight of the pipe being held therein is not supported, in which case the slips  15  to  18  will remain engaged with the pipe due to the self-energising nature of the slips  15  to  18 . 
         [0100]    The latch  10  is opened and the doors  6  and  7  are then opened by maintaining the hydraulic pressure in line P at a high pressure of between 124 to 159 bars (1800 to 2300 psi) and operating XP valve (not shown) from the control panel  100  to allow hydraulic pressure of a greater pressure, preferably 14 bars (200 psi greater) i.e. between 138 to 172 bars (2000 to 2500 psi) to flow through line XP. The hydraulic fluid passes through the filter  101 . The increase in pressure in the hydraulic fluid passes through line  102  and into control line  103 , which pushes the valve  104 , but is resisted and overcome by the pressure in line  137  applied by the pressure in line XP. The greater pressure in line XP flows through a filter  138  into a control line  139  which overcomes 103 bars (1500 psi) required to shift valve  140  to allow fluid communication between line XP and line  137 . Hydraulic fluid at high pressure is allowed to flow from line  102  into line  131 , line  110  and into the annulus  68   a  of the latch piston and cylinder  69  at a pressure of between 124 to 159 bar (1800-2300 psi), which causes the piston  68  to retract, unlatching the latch  10 . The hydraulic fluid in chamber  68   b  is now at atmospheric pressure and flows through line  114  past check valve  113   a  into line  106 , through slide valve  104 , into line  111   a  and into line T. 
         [0101]    Once the piston has retracted fully and thus unlatched the latch  10 , the piston head passes a signal port  141 . 
         [0102]    High pressure hydraulic fluid is allowed to pass through signal port  141  and through signal line  142  to activate check valve  108  to allow high pressure hydraulic fluid to flow through from line  110 , through line  109  across check valve  108  into line  107  and into annulus  83  of: the piston and cylinder  69  to retract the piston  84  to open the doors  6  and  7 . Hydraulic fluid squeezed out of chamber  86  flows through line  106  through slide valve  104  into line  127  and out of line T. 
         [0103]    It should be noted that slips activation system  200  can be activated at any time to release the fingers  52  and  52   a  from engagement with slips  15  and  17 . This is particularly important for applications where it is needed to allow the pipe to be released and re-gripped. 
         [0104]    The slips activation system  200  may be replaced by or complemented by a hydraulic circuit which activates the pistons  42  and  42   a  of slips piston and cylinders  40  and  41  to automatically retract upon applying the greater pressure to line XP for opening the latch  10  and the doors  6  and  7 . This can be accomplished by having a link between the XP valve and the PILOT valve, so that on activating the XP valve, the PILOT valve is activates, but when the PILOT valve is activated, the XP isn&#39;t activated. The slips activation system  200  is an optional system and may not be required in certain applications. 
         [0105]    The hydraulic control circuit is housed in a box  145  located on the rear of the elevator  1 , as shown in  FIG. 4 . A hydraulic control manifold  146 , shown in  FIG. 11  is provided on the elevator  1  for connecting the P line, T line, XP line, PILOT line and a FLOAT line  147  from the control panel  100  to the elevator  1 . The hydraulic lines  144  connected to the manifold  146  may hang free or be bound into one umbilical and lead to a part of the derrick DR or to a top drive from which the elevator  1  may depend and onward to the control console  100  and to a source of hydraulic fluid and means for pressurizing the hydraulic fluid, which are commonly available on drilling rigs and platforms. 
         [0106]      FIG. 16  shows a graphical representation of steps in the operation of the hydraulic control circuit against time, starting with the elevator  1  in an open position with a pipe in the throat  12  ready to be engaged and hoisted. The first step shown is the doors closing  301 , when the doors are sufficiently closed, a signal  302  is sent to start the latch closing step  303 . Once the latch is sufficiently closed, a signal  304  is sent to allow operation of the slips. The slips pistons  42  and  42   a  are extended  305  to set the slips. The slips are now set  306 , and a signal  307  of 69 bar (1000 psi) is sent to the XP port to indicate to the operator that the slips  15  to  18  are set. A pressure  308  is applied to the PILOT line  201  to retract the pistons  42  and  42   a  for disengaging the slips  15  to  18 . Pressure  308  of between 138 to 172 bars (2000 to 2500 psi) in the pilot line is moved to atmospheric  309 , whereupon slips pistons  42  and  42   a  are extended  310  to set  311  the slips  15  to  18 , and a signal  313  of 69 bar (1000 psi) is sent to the XP port to indicate to the operator that the slips  15  to  18  are set. 
         [0107]    A greater pressure of 138 to 172 bars (2000 to 2500 psi) is applied  314  to port XP and a pressure of 138 to 172 bars (2000 to 2500 psi) is applied  315  to the PILOT line to retract  316  the slips and the opening sequence commences with latch  10  opening  317 , whereupon a latch open signal  318  initiates door  6  and  7  opening  319 . It should be noted that the pressure  320  in line P of between 124 to 159 bar (1800-2300 psi) is maintained throughout the operation. 
         [0108]    Optionally, the elevator  1  can be tilted by a device  400 , as shown in  FIG. 17 . The elevator  1  depends from bails  5 . The device  400  comprises plates  401  rigidly secured to bails  5 . The plates  401  each have a hydraulic motor  402  having a stator  403  fixed to the plates  401  and a rotor  404  attached to the ears  3  and  4  the elevator  1 , so that upon activation of the rotors  404 , the elevator  1  is tilted for receiving a pipe lying at an angle between horizontal and vertical through the doors  6  and  7  into the throat  12  of the elevator  1 . This allows picking up pipe from or laying pipe down on the ramp leading to the opening in the derrick known as the V-door. Such a mechanism is used on the state of the art BX elevator sold by BJVarco. Preferably, the FLOAT line  147  is used in conjunction with a hydraulic system (not shown) for operating the device  400 , for providing a signal to allow the hydraulic system for the device  400  to rotate only when the slips are down, latch  10  is unlatched and the doors  6  and  7  are open, to prevent the device  400  from being operated when the elevator has a pipe therein. 
         [0109]    In conclusion, therefore, it is seen that the present invention and the embodiments disclosed herein and those covered by the appended claims are well adapted to carry out the objectives and obtain the ends set forth. Certain changes can be made in the subject matter without departing from the spirit and the scope of this invention. It is realized that changes are possible within the scope of this invention and it is further intended that each element or step recited in any of the following claims is to be understood as referring to the step literally and/or to all equivalent elements or steps. The following claims are intended to cover the invention as broadly as legally possible in whatever form it may be utilized. The invention claimed herein is new and novel in accordance with 35 U.S.C. 102 and satisfies the conditions for patentability in 102. The invention claimed herein is not obvious in accordance with 35 U.S.C. 103 and satisfies the conditions for patentability in 103. This specification and the claims that follow are in accordance with all of the requirements of 35 U.S.C. 112. The inventors may rely on the Doctrine of Equivalents to determine and assess the scope of their invention and of the claims that follow as they may pertain to apparatus not materially departing from, but outside of, the literal scope of the invention as set forth in the following claims. All patents and applications identified herein are incorporated fully herein for all purposes