CA1077918A - Finger latch actuation sensor - Google Patents

Abstract

LATCH ACTUATION SENSOR
ABSTRACT OF THE DISCLOSURE
In a hydraulically operated pipe handling system, there is a finger board for restraining substantial movement of drill pipe when in its storage position adjacent the side of a well drilling derrick. The finger board will typically have an array of spaced-apart locations for containing the individual drill pipe lengths. Forming the individual locations may be latch mechanisms, which are selectively controllable, each latch mechanism having two positions, either opened or closed. There is provided a sensing mechanism for determining the actuation of an individual finger latch, the sensor comprising a fluid actuated switch and may have associated therewith fluid pressure maintaining devices.

Description

1~77918 FIN OE R LATCH ACTUATION SENSOR

BRIEF DESCRIPTION OF THE DRAWIN~S
-Fig. 1 is a top view of a portion of the finger board assembly.
Fig. 2 is a view of a well drilling derrick.
Fig. 3 is a piping schematic of the hydraulic conduits associated with the finger latch control apparatus.
Fig. 4 is an enlarged view of a portion of the finger board assembly shown in Fig. 1.
Fig. 5 illustrates a latch and the manifold assembly of the finger board assembly.
Fig. 6 is a side view of the manifold assembly of Fig. 5, illustrating also the mechanical components of the fluid pressure sensor switch.
Fig. 7 is a block diagram illustrating a portion of the automated sequence for removing a drill string from a well, appearing with Figure 3.

I BACKGROUND OF THE INVENTION
This invention is directed generally to the field of equipment for storing pipe lengths on or adjacent a drilling platform during the drilling operation, and ~ specifically to a fluid pressure sensor for determining ;~ the actuation of finger latches holding pipe lengths in a finger board.
In the drilling operation as pipe lengths are ` withdrawn from the well, as, for example, when removing the drill string to change a drill bit, the successively removed pipe lengths are moved to the storage location adjacent the side of the well drilling derrick. The pipe rackers which accomplish this movement of the successive pipe lengths as each is removed from the drill string, may be, . .

~(~77918 for example, similar to tho~e described i:n co-pending Canadian patent application, Serial No. 243,613 for "Automated Drill Pipe Handling System". With the pipe length in its storage position, a latch mechanism associated with the various fingers of the finger board closes and prevents the pipe length from moving with respect to the finger board and adjacent pipe lengths.
Actuation of the respective latch may be manually or automatically controlled, however, it is essential that the proper functioning of the latch be determined, preferably by a remote signal available for display to a floor-level drilling operator. Of course, it is desirable to provide -' as many storage locations as practicable for the available ~ space within the well drilling derrick, and it is not uncommon ;i.
to have as many as 184 storage locations. Associated with each storage location is the latch mechanism, which may be selectively opened or closed.
' Heretofore the individual actuation of each latch associated with the fingers may have been determined by a ;` limit switch coupled to each latch. One can readily appreciate ~,. . .
that the installation of 184 limit switches is a formidable $,~
task, the proper operation of all 184 at any one given time being doubtful due to mechanical or electrical failures.
~ Another means of sensing actuation of the individual latches i- is to use a set of limit switches which extend from the upper racker head of the pipe racker apparatus to sense actuation of the individual latches. Due to the proximity of the ; racker head, being about seven feet from the finger latch, ; this system would be quite cumbersome.
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~(~i77~18 SU~iARY OF THE INVENTION
The present invention provides sensing apparatus for determining the individual actuation of a latch associated with the various fingers of a pipe racking finger board. The finger board may be one such as described in ~lam, U.S.
Patent No. 3,615,027. The sensor of the present invention provides a feedback signal to a control or visual display device by sensing the change in fluid flow or pressure associated with the individual actuation of the res~ective latches. Since the finger board is commonly a substantial distance above the derrick floor, and therefore from the fluid power source, it may be convenient to have associated with the pressure sensing apparatus a fill valve for maint-aining fluid pressure in the drain lines adjacent the pressure sensor.

In its broadest aspect, the invention contemplates a finger latch actuation sensor which comprises a fluid inlet manifold, a valve for receivina a pressurized fluid from the fluid inlet manifold and for controlling the actuation of a hydraulic cylinder, and a latch mechanism actuated by the hydraul~ic cylinder which forms a quadri-lateral opening in a pipe racking apparatus and thereby restrains a pipe within the quadrilateral opening from substantial movement. A fluid outlet manifold receives fluid from the hydraulic cylinder and a pressure switch senses a fluid pressure pulse in a condult in fluid communication with the outlet manifold.

~l077918 DESCRIPTION OF THE PREFERRED EMBODIMENTS
-Referring to ~ig. 1, there is shown a portion ofa typical finger board assembly 20, and as shown is in two sections; one, 21, located on the left-hand side and the other, 22, located on the right-hand side of a central opening 23. It is noted that this finger board assembly 20 may be positioned at a considerable height in a well drilling derrick, for example, approximately ~0 feet above a derric platform located at or near ground level.
~`he finger board assembly may be constructed as described in Ham, U.S. Patent No. 3,615,027. Generally, '! however, the finger board assembly 20 may have a rear rail ~ . .
24 extendi.ng across the rear of the combined finger board : assembly 20. Extending across the right-hand finger board ' ';

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. ' 1~)77918 section 22 is what may be termed the end rail 25. Extending inwardly from the end rail 25 is front rail 26. The rails 24, 25, 26 and their respective counterparts in the left-hand side of the finger board assembly 20, comprise the framework for supporting the finger board sections, and are commonly referred to as'a walk-around. The front rail 26 may have braces 27 and 28 for supporting the assem,bly.
Mounted on the end rail 25 are the drill pipe fingers 31, 32, 33, 34, 35 and 36, and one or more drill collar fingers 37. These finge~rs are mounted on their right-hand ends to extend horizontally toward the center line across the derrick horizontally, and are spaced laterally from the front rail 26 to the drill collar finger 37 a distance sufficient to accommodate the size of drill pipe to be racked therein. The finger 37 is spaced from the rear rail 24 a distance to accommodate the diameter of the drill collar to be racked therein. The space between the front rail 26 and the finger 31 is here shown at 38.
This space extends from the outer end of the finger to the base of the finger near the rail 25 and has sufficient horizontal depth to accommodate a selected number of stands of pipe, in the illustration shown as 12. The same holds true with respect to the remainder of the spaces between the fingers 32-36. The right-hand end of the space 45 is shown as being closed by a gusset 39 which is preferably attached between the rear rail 24 and the drill collar finger 37 and .
extends horizontally outward a distance to provide a support '' and reinforcement ,for the~assembly and a stop for the first drill collar stand racked therein.

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1(~77918 Each of the fingers 31-37 has a series of latches 41 spaced apart a sufficient distance to accommodate the diameter of a drill pipe, and extending from end to end on the fingers, there being shown in the illustration twelve such latches for each finger. The latches are indicated in their opened or raised position at 42, for example, and in the closed position at 43. In the opened position, pipe may be moved freely into and out of the openings between the fingers.

Drill collar finger 37 has a number of drill collar latches 44 extending for the length of the opening 45 at spaced intervals. The drill collar latches are indicated closed at 46 and opened at ~7 for a purpose similar to the opened and closed latches of the racking fingers above described. Similarly, the left-hand racking board section 21 is provided with drill pipe fingers to accommodate drill pipe and a drill collar finger to accommoda-te drill collars.
In general, these fingers are identical with the fingers 31-37 above described, and function the same way.
Preferably mounted on end rail 25, and on the corresponding end rail (not shown) associated with the left-hand end of fi~ger board assembly 20, are hydraulic manifolds 48, there being in the illustration shown one manifold for each racking finger. Details of this manifold will be described hereinafter, but each manifold contains , ~ . .
` twelve four-way valves and solenoids for actuating the valves :
~`~ for each latch on the racking finger served thereby, together with hydraulic lines leading to the latch-actuating mechanism and electrical connections ~eading to a console switch ` ' `~

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10779~8 under control of a derrick man in the manual mode of operation.
and in the automated mode of operation, under the control of a general purpose digital computer and associated electrical apparatus collectively referred to as a system controller.
There is provided meaas for moving the respective pipe lengths and drill collars into or out of the finger board assembly 20. This apparatus is as described in co-pending Canadian Serial No. 243,613, entitled "Automated ~rill"
pipe Handling System" and includes a racker arm 49 having a racker head 50 with pipe-gripping means 51~ also referred to as a claw 51. Racker arm 49 is under either automatic control of a system controller such as that described in Canadian Serial No. 243,613 or manual control and may be extended or retracted longitudinally. In addition, carriage 52, being mounted in a horizontal track 53 extend-ing horizontally along the side of the derrick, has means under either automated or manual control for moving the carriage laterally in the track from side to side of the derrick. The details of the carriage, racker arm, racker head and claw means are not a part of this application and are shown in Fig. 1 only for purposes of indicating the general arrangement.
Although the precise details of the finger board apparatus may be constructed as disclosed in U. S. Patent 3,501,017, a brief explanation of the principal details of the finger board apparatus and hydraulic piping associated therewith will be given in order that the importance associated with determining the proper actuation of the respective finger latches will be more fully appreciated ,~,.
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1C~779~8 Turning to Fig. 4, there is illustrated a portion of the right-hand racker section 22 above referred to in Fig. 1.
As will be noted, the fingers 35 and 36 and the drill collar finger 37 are attached by means of bolts 54 to a vertical flange 55 on the inside of the end rail 25 and extend above and below the top and bottom of the end rail.
Both the drill pipe fingers 35 and 36 and the drill collar finger 37 have a base plate 56 attached by welding or other means to the inner end of the fingers, and likewise have a reinforcing angle iron 57 attached between the body of the fingers and the base plate 56.
As is clearly evident from Fig. 5, the latches 41 are mounted in trunnions 58 for rotary movement between a horizontal and vertical position. For example, the latch 41 on the left is shown in horizontal or latched position and the latch on the right in opened position at 42, in which latter position it will be vertical with respect to the top of the finger 36. The latches are all ; equipped with suitable means for coupling them to the rod -of a hydraulic cylinder 60, which hydraulic cylinder provldes the motive force for operating each latch-. As illustrated in Fig. 5, -this coupling means may be, for example, a clevis 59, which couples to the rod oE hydraulic cylinder 60 through an appropriate bolt. Retraction or extension of the rod into or out of the cylinder by providing hydraulic pressure to cylinder 60 will result in ; movement of latch 41 to a vertical or horizontal position.
The latch is held in its positions so long as the fluid pressure in the cyiinder ~cts to maintain the plunger in ., .

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'. , : ' 1~77918 - its extended or retracted position. ~ounted in the finger 36 as in the case of all the fingers, is a series of hydraulic cylinders 60 extending vertically and mounted for rotary movement on a bracket 61 in the well-known manner.
Referring brlefly to Fig. l, there is indicated as visible between the fingers of the racking board, up-standing base-pipe rackers 64 which comprise a hemispherical seat located on the derrick base or set back 102 as shown in Fig. 2, on which the lower end of the stand of drill pipe lengths is placed to rack a stand properly aligned. As shown in Fig. 2, these are directly below racker sections and the stand of pipe would be positioned as vertical in such arrange-ment. However, as a practical matter, these base rackers may be offset from the vertical toward the adjacent side of the derrlck, so that the bottom of the stand of drill pipe or drill collar will be moved back from the center line of the derrick to allow more room around -the well hole. Thus, the stands of pipe and the stands of drill collar will slant inwardly at their tops toward both center lines of the derrick, placing additional weight on the fingers and increasing the necessity of having an accura-te indication of latch actuation. Were an indication of latch actuation received by the system controller when in fact the latch had not closed, the next step in the automated sequence, that being the opening of the racker claws holding the drill pipe, would result in the pipe falling from the Çinger board assembly and possibly causing damage to the well - drilling derrick apparatus or injury to personnel working ,, . ~ ~.
thereon.

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Further, the derrick 101 may be utilized in an environment, such as on a well drilling ship, where the mo~ion of the ship causes the drill pipe lengths 62 and drill collars 63 to continually exert a force on the fingers and latches and may, i~ there were a limit switch for sensing latch actuation, cause enough movement of the latch to slightly open the contacts of the limit switch and thereby generate a faulty signal. In both events, when opera-ting the pipe racking apparatus in an automated mode, as described in co-pending Canadian Serial No. 243,613, an accurate and reliable feedback signal from the finger board assembly 20 indicatinc3 to the system controller that a finger latch has closed and the racker may tllen be instructed to release the individual pipe stand and proceed to the well center line for the racking of an additional pipe stand is necessary.
` As previously mentioned, actuation of the latches associated with each finger is controlled by an electrically operated solenoid. As noted in Fig. 5, the manifold 48 is f : i ' ' shown as mounted on the top of the end rail 25. Valve and .
, solenoid assembly 65 are shown as beincJ mounted adjacent ~ to and on top of the manifold ~8. The manifolds may be any :.
commonly available type, and do no-t per se Eorm a part of this invention. It may be noted, however, that there is ,- shown a valve with two solenoids as available for each latch, ~ and each latch is independently connected to a four-way valve .,, ~` with solenoid actuating means. A manifold is available : for eaeh finger assembly and for each section of the racking . " ;~
~ board for both drill pipe a~d drill collar fingers. Referring .~ ,. . .
; ~ 30 to Fig. 6, as will be apparent, the manifold has fluid inlet , ~r . - 1 0 ~'''' ' :: . . : , ,.
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1~779~3 .

conduit 66 and fluid ou-tlet conduit 67, conduit 66 being attached to a source of fluid pressure and conduit 67 leading to the sump. These conduits are in communication with the valves through appropriate piping.
Conduit 91 adjacent manifold 48, is provided through which electrical leads are brought from the system controller into a terminal box 90. From there the individual electrical connections are made to the solenoids for each valve.
The hydraulic piping associated with the various solenoids, valves and latch assemblies is diagrammatically shown in Fig. 3. Referring~to Fig. 3, each of the valves 65 has two hydraulic lines 92 and 93 connected to the hydraulic cylinders 60, as above described, for each of the latch means. Thus, fluid pressure is always maintained on each manifold valve from a common conduit, and actuation of the valve to open the circuit to hydraulic line 93 will divert the pressure into the line and into the rod end of the cylinder 60. At the same time, the valve will open ~;20 the fluid circuit in line 68 to dump fluid pressure therein to the fluid outlet conduit 67 and return the excess fluid to the sump. Reversal of the valve by the solenoid arrange-ment will place the hydraulic fluid pressure in the hydraulic line 92 and relieve the pressure in the line 68, forcing `the piston therein toward the rod end and ex-tending the rod, thus, lowering the latch 41. Each drill collar latch may be similarly operated by reversing the flow of operating fluid in the conduit serving the respective dxill collar latches. ~

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1~77918 As notecl in Fig. 3, the drain conduit associated with each valve 65 always serves to receive fluid for transmitting it to the fluid outlet conduit 67, which conduit, that is fluid outlet conduit 67, communicates direc~ly with conduit 72. Conduit 72 serves as a fluid communi-cating conduit to transmit changes in flow or pressure in fluid outlet conduit 67 to a flow sensing apparatus 7~.
Forminy a part of flow sensing apparatus 74 is orifice valve 75, pressure switch 73 which may be adjustable over a range of pressure, fill conduit 79, back pressure check valve 77 and sump 78.
As fluid is directed to fluid outlet conduit 67, it thereby is communicated to the flow sensing apparatus 74 thro~gh conduit 72 with orifice 75 being appropriately sized to provide a momentary pressure increase in conduit ~; 72, wllicll pressure increase is thereby communicated to pressure switch 73 through conduit 80, with the hydraulic fluid then draining through conduit 76 and check valve 77 into sump 78. Associated with fill conduit 79 is adjustably ' 20 controllable orificed fill valve 94. As illustrated in !"
Fig. 3, fill valve 94 is supplied with pressurized fluid ~; from fluid inlet conduit 66. As previously mentioned, ' the finger board assembly may be located at some distance, ?`~ approximating 80 feet, above the base of the drilling derrick.
Or, in some applications, the finger board may be located at a lesser distance from the base of the derrick. In those applications where the finger board is at a considerable ;, ,~' height in the well drilling derrick, and consequently the fluid conduits are of considërable length, it may be 30 necessary to provide the fill valve 94 connectincJ fluid inlet conduit 66 to conduit 72 so as to maintain a supply of .,.

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1~779~8 fluid in the conduits and prevent air or other contaminants from entering therein and interfering w~th the operation of pressure switch 73. For example, if t~e hydraulic fluid were to leak from conduit 80, actuation of a finger latch and channeling of fluid into fluid outlet conduit 67 would cause the air in conduit 80 to be compressed as opposed to the fluid actuating pressure switch 73, thereby resulting in no signal being generated to the control system.
The operation of the pipe handling sequence in the semi-automated mode of operation is as disclosed in U. S. Patent 3,501,017 and in the automated mode by co-pending Canadian Serial No. 243,613. With respect to the flow sensing apparatus if it is desired to move finger latch 41 to the open position for receiving a pipe stand or drill collar, the spool of hydraulic valve 65 will move in a direction to align conduit 93 with conduit 66, thereby causing rod 82 of hydraulic cylinder 60 to move in a downward direction so as to direct latch 41 to the open position. Of course, conduit 92 will be aligned with valve drain conduit 68 and thereby communicate an increase in fluid pressure to fluid outlet conduit 72.
So as to further understand the complete operat-ing sequence associated with moving pipe in and out of the finger board assembly, reference is made to Fig. 7 wherein the typical sequence of removing pipe from a well is shown in block diagram form. Fig. 7 illustrates the typical sequence of steps required in the automated removal of pipe from a well for changing a bit or other maintenance require-. . .
ment. The sequence illustrated is not intended to be .'. ' .
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1(~7q9~8 complete, but is a portion of that complete sequence illustrated in co-pending Canadian Serial No. 243,613.
As indicated at block 83, the rackers associated with one or more pipe moving means move to the well center line, where the claws, such as that illustrated in Fig. 2 at 51, grip the pipe stand, also illustrated in Fig. 2 at 69.
After lifting the stand out of the box (or the next lower pipe stand 95) the rackers are synchronously driven to the proper position within finger board assembly 20. A lifting mechanism then lowers the stand onto the base or set back 102, and the appropriate finger latch locks the stand in place. It is at this point that the importance of the feedback signal is realized. For example, after the stand is lowered onto the base, as indicated at block 87, a signal is generated to the appropriate finger latch to lock the stand in place, as indicated at block 88. By noting block - 89 to be the next step in the programmed sequence, that is, ,, where the claws open and release the pipe, one can readily appreciate the inherent danger to workmen and other mechanical apparatus if there is not received an accurate feedback signal by the controller positively indicating operation of the ~` finger latch and consequent locking of the stand in its ' proper position, prior to the claws opening and releasing 3 the pipe stand.

!,1 OPERATION OF THE FEEDBACK SENSOR
Referring to Fig. 3, the apparatus associated with generating the feedback signal is illustrated. It is under-, stood that one or more finger latches may be actuated at any .t .- .
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'' ' , ' , " ' ~077918 given time. The following explanation will be with reference to but one finger latch, although the feedback signal will operate similarly no matter how many latches are actuated at a given command from the automatic controller apparatus.
Now turning to Fig. 7, in the automated mode of operation a signal is generated to the rackers indicating the pipe is to be withdrawn from the well. As indicated at 83, the rackers move to well center line and the claws grip the pipe. After the lower tool joint is broken (block 84) lift head 96 (Fig. 2~ lifts pipe stand 69 away from next lower pipe stand 95 (as indicated at block 85) for removal to the storage location adjacent the side of well drilling derrick 101. As indicated at block 86, the rackers are ,.
automatically driven to the selected row and column position within finger board assembly 20 (Fig. 1). After the stand 89 is lowered onto set back 102 (block 87), the proper finger latch will be actuated (block 88) by the system ; controller for closure, thereby forming a quadrilateral open--~ 20 ing for containing the pipe within. Referring to Fig. 5, pipe 62a is positioned within the finger board assembly, and ready for closure of latch 41. Latch 41, being in the open position as indicated at 42, upon command (block 88, ;- Fig. 7) closes, thereby preventing pipe 62a from further ~r,;' movement.

^~ Referring now to Figs. 3, 5 and 6, closure of -~ latch 41 is accomplished, first, as previously mentioned, by generating an appropriate electrical signal to the desired finger and latch through terminal box 90. The signal is then transmitted to the corresponding valve and .'' ~

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~779~8 - solenoid assembly 65. Since there is, during tlle period of operation of the rackers, always pressurized fluid appearing at the inlet to valve 65, that is in conduit 66, movement of the spool of valve 65 to the desired position directs pressurized fluid to hydraulic eylinder 60 through conduit 92 thereby closiny latch 41. Concurrently with movement of plunger 82 of hydraulic cylinder 60, fluid is directed from cylinder 60 through conduit 93 and thence into fluid outlet conduit 67. Conduit 72 communicates the pressure rise in conduit 80 to pressure switch 73, thereby causing switch 73 to actuate, the electrical signal beillg thence directed to the system controller confirming latch actuation. In the preferred embodiment of this invention, a pressure switch which functions upon sensing both a pressure increase and decrease`is employed. In operation, the fluid pressure in conduit 67 will rise approximately 100-150 psi above ambient UpOIl actuation of latch 41, thell after movemellt of the latch ceases, decrease slowly to -the ambient system pressure. Only upon the switch sensing this pressure decrease will the appropriate signal be generated indicating ?; latch actuation. ~t will be readily appreciated that latch movement could be impeded by an improperly placed drill pipe length such tllat only sensing a pressure rise would generate a signal indicating latch actuation when in fact , the latch had only partially moved leaving fluid pressure on the hydraulic cylinder and an improperly functioninc3 latch. 'rhe most apt description of sensing the pressure change would be tlle sensin~ of a fluid-pressure pulse, tha~ is, both an increase and a decrease. As a part of flow sensing apparatus 74, there is provicled orifice . .

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valve 75 which is sized somewhat smaller than conduit 72, and therefore impedes the flow of pressurized fluid through conduit 72, resulting in the pressure increase and decrease in conduit 72 being of a somewhat longer duration than other-wise, for proper switch 73 actuation. Back pressure check valve 77 is provided to maintain a certain minimum fluid pressure in conduit 72 and to prevent the introduction of air into the conduit system. Conduit 79 is provided as indicated to be in fluid communication with fluid inlet conduit 66 and flow sensing apparatus 74. Fill valve 94, which may be an adjustable orificed valve, is provided in those applications where the flow sensing apparatus 74 may be spaced a substantial vertical distance from the source of fluid pressure. There being a distance between the flow sensing apparatus and drain sump 78, it is probable that fluid will leak from the conduits, increasing the likelihood of air contaminating the fluid system and decreasing the efficiency of the pressure sensor. For example, if conduit 72 were to become contaminated with air pressure switch 73 may not be actuated by latch movement, resulting in no feed-back signal being generated to the sys-tem controller, when in fact the latch has properly func-tioned.
In describing the invention, reference has been ; made to a-preferred embodiment. However, -those skilled in the art and familiar with the disclosure of the invention may recoynize additions, deletions, substitu-tions or other mod-ifications which would fall within the purview of the invention as defined in the claims.

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Claims (5)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A finger latch actuation sensor, comprising:
a fluid inlet manifold;
a valve for receiving a pressurized fluid from said fluid inlet manifold and controlling the actuation of a hydraulic cylinder;
a latch mechanism actuated by said hydraulic cylinder for forming a quadrilateral opening in a pipe racking apparatus and thereby restraining a pipe within said quadri-lateral opening from substantial movement;
a fluid outlet manifold for receiving fluid from said hydraulic cylinder; and a pressure switch for sensing a fluid pressure pulse in a conduit in fluid communication with said outlet manifold.

2. The finger latch actuation sensor of Claim 1, further including an orifice valve in said conduit in fluid communication with said outlet manifold, said orifice valve for delaying the effects of an increase and decrease in the fluid pressure in said conduit to insure actuation of said pressure switch.

3. The finger latch actuation sensor of Claim 2, including a check valve downstream of said orifice valve for maintaining fluid pressure in said inlet and outlet manifolds.

4. The finger latch actuation sensor of Claim 3, including a fill valve maintaining pressurized fluid in said conduit in fluid communication with said fluid outlet manifold.

5. The finger latch actuation sensor of Claim 3, further including a fluid outlet manifold for receiving fluid from said check valve.