Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 02664978 2009-05-06
TONG
BACKGROUND OF THE INVENTION
Field of the Invention
The invention generally relates to methods and apparatus for use in making
or breaking tubular connections. More particularly, the invention relates to a
tong
assembly for use in making or breaking tubular connections within a tubular
string
of an oil or gas well.
Description of the Related Art
Construction of oil or gas wells usually requires making long tubular strings
that make up casing, risers, drill pipe or other tubing. Due to the length of
these
strings, sections or stands of tubulars are progressively added to the tubular
string
as it is lowered from a drilling platform. In particular, applying slips of a
spider
located in the floor of the drilling platform usually restrains the tubular
string from
falling when it is desired to add a section or stand of tubular. The new
section or
stand of tubular is then moved from a rack to above the spider. The threaded
pin
of the section or stand of tubular to be connected is then located over the
threaded
box of the tubular string and a connection is made up by rotation
therebetween.
Thereafter, the spider releases the newly extended tubular string, and the
whole
tubular string lowers until the top of the tubular string is adjacent the
spider
whereupon the slips of the spider reapply to maintain the position of the
tubular
string for repeating the process.
It is common practice to use a tong assembly to apply a predetermined
torque to the connection in order to make this connection. The tong assembly
is
typically located on the platform, either on rails, or hung from a derrick on
a chain.
In order to make up or break out a threaded connection, the tong assembly
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includes a two tong arrangement. An active (or power) tong supplies torque to
the
section of tubular above the threaded connection, while a passive (or back up)
tong supplies a reaction torque to a lower tubular below the threaded
connection.
Particularly, the back up tong clamps the lower tubular below the threaded
connection and prevents it from rotating. The clamping of the tubulars may be
performed mechanically, hydraulically, or pneumatically. The power tong clamps
the upper part of the connection and is driven so that it supplies torque for
at least
a limited angle.
In order to make up or break out a connection between tubulars in a tubular
string, torque must be supplied over a large angle without having to take time
to
release and clamp the tubular again. Large diameter and heavy tubulars such as
risers have threaded connections requiring a high torque that prior tong
assemblies fail to provide. For example, the prior tong assemblies having one
or
two drives fail to provide a sufficient rotation force to a rotary of the
power tong.
Further, a jaw assembly of the prior tong assemblies tends to tilt and provide
a
non-uniform load on the tubular surfaces when used at the high torques. When
the jaw assembly tilts, only a portion of the jaw assembly contacts the
tubular,
thereby causing damage to the tubular, limiting the torque that can be applied
and
causing failure of the jaw assembly itself.
In use, the reaction force on the power tong transmits through the
connection and the back up tong to the lower tubular. This torsional force
creates
a side force tending to move the back up tong and power tong out of axial
alignment, thereby bending the tubular string at the connection. Thus, torque
transmitting devices used with power tongs and back up tongs inhibit them from
moving out of axial alignment. However, prior torque transmitting devices
limit
how close that the power tong and back up tong may be spaced.
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The possibility of a premature rotation of the rotary gear such as prior to
closing gates of the tong assembly presents a serious potential danger to an
operator. While the gates are open, the rotary gear may become misaligned with
the power tong. Further, premature rotation can cause costly and time
consuming
damage to the tong assembly.
Therefore, there exists a need for an improved method and apparatus for
making or breaking a tubular connection. There exists a further need for a
tong
assembly that includes an improved jaw assembly, rotor, torque transmitting
device, and/or safety features.
SUMMARY OF THE INVENTION
The invention generally relates to methods and apparatus for making and
breaking tubular connections within a tubular string. In certain aspects, a
tong
assembly includes gated power and back up tongs coupled to a torque bar. Jaws
of the tongs may be arranged circumferentially with support members disposed
between adjacent jaws to substantially complete a 3600 closed circle. A
hydraulic
circuit may equally distribute fluid and pressure to actuate the jaws. The
power
tong may include a gated rotor driven by at least three drive motors. The
rotor
may be selectively physically locked from rotation or movement by one or more
rotor locks. Further, the tong assembly may include an interlock that prevents
activation of the drive motors until the rotor locks actuate to unlock the
rotor.
Additionally, gate locks may secure the tongs and rotor when closed, and a
releasable coupling arrangement may aid engagement of a motor to a rotor pump.
BRIEF DESCRIPTION OF THE DRAWINGS
So that the manner in which the above recited features of the present
invention can be understood in detail, a more particular description of the
invention, briefly summarized above, may be had by reference to embodiments,
some of which are illustrated in the appended drawings. It is to be noted,
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however, that the appended drawings illustrate only typical embodiments of
this
invention and are therefore not to be considered limiting of its scope, for
the
invention may admit to other equally effective embodiments.
Figure 1 is a view of an embodiment of a tong assembly in operation with a
tubular string positioned therein.
Figure 2 is a side view of the tong assembly showing a detail of gate locks
on a power tong and a back up tong and a detail of a rotor lock on the power
tong.
Figure 3 is a section view of the power tong illustrating a rotor with jaws
according to aspects of the invention.
Figure 4 is a top view of the power tong.
Figure 5 is a side view of a motor disposed on a housing of the power tong
that operates a pump on the rotor in order to actuate the jaws.
Figure 5A is a view of an end of the motor along line 5A-5A in Figure 5.
Figure 5B is a view of an end of the pump along line 5B-5B in Figure 5.
Figure 6 is a schematic of a back up tong hydraulic circuit used to actuate
jaws of the back up tong.
Figure 7 is a schematic illustrating engagement of the motor and the pump
used in a rotor hydraulic circuit that actuates the jaws of the power tong.
Figure 8 is a schematic of a portion of a tong assembly hydraulic circuit that
provides a safety interlock between the rotor lock and fluid supplied to
operate
drive motors.
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DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
The invention generally relates to a tong assembly for making up and
breaking out a tubular connection such as between two tubulars in a tubular
string.
The tubular string may be made of tubulars that form a riser, casing, drill
pipe or
other tubing. In operation, the tong assembly grips the tubulars and applies
torque
to the connection. For example, the tong assembly may apply 300,000 foot
pounds of torque to a riser thread connection in a riser string that is about
twenty
inches in diameter.
Figure 1 illustrates an embodiment of a tong assembly 100 according to
aspects of the invention. The tong assembly 100 includes a power tong 101
disposed above a back up tong 102. In operation, the tong assembly 100
suspends from a handling tool 104 that positions the tong assembly 100 around
a
tubular of a tubular string such as a lower tubular 108 held by a spider 106
and a
stand or upper tubular 110. As described in more detail below, the power tong
101 grips the upper tubular 110, the back up tong 102 grips the lower tubular
108,
and the power tong 101 rotates the upper tubular 110 in order to make up or
break
out a connection between the tubulars 108, 110. Three drive motors 111 operate
to rotate the upper tubular 110.
Each of the tongs 101, 102 are segmented into three segments such that
the front two segments pivotally attach to the back segment and enable
movement
of the tongs 101, 102 between an open and a closed position. In the open
position, the front sections pivot outward enabling the tubulars 108, 110 to
pass
between the front sections so that the handling tool 104 can align the
tubulars 108,
110 within the tongs 101, 102. The tongs 101, 102 move to the closed position
as
shown in Figure 1 prior to make up or break out operations. Pistons 128 (only
one
piston is visible) on each side of the power tong 101 operate to pivot the
front
segments relative to the back segment in order to open and close a gate
between
the front segments that is formed where an extension 132 on one of the front
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segments mates with a corresponding grooved portion 134 of the other front
section. Similarly, pistons 130 (again only one piston is visible) on each
side of
the back up tong 102 operate to pivot the front segments relative to the back
segment in order move the back up tong between the open and closed position.
The pistons 128, 130 may be operated by a tong assembly hydraulic circuit that
supplies fluid pressure to various components of the tong assembly 100 through
a
common pressure source. As with all other components of the tong assembly 100
operated by the tong assembly hydraulic circuit, automated or manually
operated
valves (not shown) may be used to separately or in combination open and close
fluid supply to each component (e.g. the pistons 128, 130) at the desired
time.
A torque bar assembly 112 located adjacent a counterweight 120 connects
the power tong 101 to the back up tong 102. The torque bar assembly 112
includes two arms 114 extending downward from each end of a horizontal top bar
or suspension 116. A back end of the power tong 101 connects to a horizontal
shaft 118 that extends between the arms 114 below the suspension 116. The
shaft 118 may fit within bearings (not shown) in the arms 114 to permit
pivoting of
the power tong 101 relative to the torque bar assembly 112. Damping cylinders
400 (shown in Figure 4) connect between a top of the power tong 101 and the
suspension 116 to prevent free swinging of the power tong 101 about the shaft
118. Clamps 122 on the back up tong 102 grip a longitudinal recess 124 in the
arms 114, thereby securing the back up tong 102 to the torque bar assembly
112.
The clamps 122 slide along the recess 124 to permit movement of the back up
tong 102 relative to the power tong 101 during make up or break out
operations.
The torque bar assembly 112 provides a connection between the tongs 101, 102
that permits the back up tong 102 to rise into near contact with the power
tong
101.
The torque bar assembly 112 keeps side forces out of the connection
between the tubulars 108, 110 by eliminating or at least substantially
eliminating
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shear and bending forces. As the power tong 101 applies torque to the upper
tubular 110, reaction forces transfer to the torque bar assembly 112 in the
form of
a pair of opposing forces transmitted to each arm 114. The forces on the arms
114 place the suspension 116 in torsion while keeping side forces out of the
connection. A load cell and compression link 126 may be positioned between the
clamp 122 and back up tong 102 in order to measure the torque between the
power tong 101 and back up tong 102 during make up and break out operations.
Figure 2 shows a side of the tong assembly 100 and a detail of a power
tong gate lock 200, a back up gate lock 201 and a rotor lock 202. The gate
locks
200, 201 lock the tongs 101, 102 in the closed position. The rotor lock 202
prevents rotation of a rotor 300 when in the open position and prevents any
possible misalignment of parts of the rotor 300 caused by moving the power
tong
101 to the open position since the rotor may be forced outward in the open
position. Thus, the rotor lock 202 maintains the rotor 300 in position and
prevents
rotation of the rotor 300 until the rotor lock 202 is actuated.
The power tong gate lock 200 includes an outer shroud 204 mounted on a
housing 207 of the power tong 101. The outer shroud 204 supports a gear
profiled
bolt 206 having a lifting member 208 connected thereto. Rotation of a gear 216
mated with the gear profiled bolt 206 lowers and raises the gear profiled bolt
206
between a power tong gate locked position and a power tong gate unlocked
position. In the power tong gate locked position shown in Figure 2, the gear
profiled bolt 206 inserts downward into an aperture within the extension 132
and
an aperture in the corresponding grooved portion 134 that form the gate in the
housing 207 of the power tong 101. Thus, the gear profiled bolt 206 maintains
the
power tong 101 in the closed position by preventing movement between the
extension 132 and the corresponding grooved portion 134 when in the power tong
gate locked position. The gear may be actuated by a hydraulic or electric
motor
(not shown) controlled by the tong assembly hydraulic circuit.
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At the end of the lifting member 208, a slotted lip 210 receives a recessed
profile 212 at the top of a rotor bolt 214. Due to the slotted lip 210 fitting
in the
recessed profile 212, the lifting member 208 which raises and lowers with the
gear
profiled bolt 206 acts to raise and lower the rotor bolt 214 when the rotor
bolt 214
is aligned below the lifting member 208. Similar to the housing of the power
tong
101, a rotor 300 is gated so that the rotor 300 opens and closes as the power
tong
101 moves between the open and closed positions. Thus, the rotor 300 includes
a
rotor extension 232 and a corresponding rotor grooved portion 234 that each
have
an aperture therein for receiving the rotor bolt 214 which prevents movement
between the rotor extension 232 and the corresponding rotor grooved portion
234
while in the power tong gate locked position. As the rotor 300 rotates during
make
up and break out operations, the recessed profile 212 of the rotor bolt 214
slides
out of engagement with the slotted lip 210 and may pass through the slotted
lip
210 with each revolution of the rotor 300. The rotor bolt 214 realigns with
the
lifting member 208 when the rotor returns to a start position such that the
rotor bolt
214 may be raised to the power tong gate unlocked position. Only when the
rotor
300 is in the start position with segments of the rotor 300 properly aligned
may the
power tong 101 be moved to the open position. Figure 3 further illustrates the
power tong 101 in the start position with the rotor bolt 214 and the gear
profiled
bolt 206 maintaining the power tong 101 in the closed position.
The back up gate lock 201 locks the gate on the back up tong 102 in the
closed position similar to the power tong gate lock 200 for the power tong
101. A
single back up bolt 218 operated by a gear 220 moves between a back up gate
locked position and a back up gate unlocked position. Since the back up tong
102
does not have a front housing or a rotor that rotates, a back up jaw assembly
may
include a gated section therein with mating features such as the gate of the
power
tong 101. Thus, the bolt 218 in the back up gate locked position prevents
movement between members in the gated section of the back up jaw assembly
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similar to the gear profiled bolt 206 and rotor bolt 214 used in the power
tong gate
lock 200 on the power tong 101.
Referring still to Figure 2, the rotor lock 202 mounts to the housing 207 of
the power tong 101 and includes a body 222, a female end 224, a piston 225 and
a spring 228. The rotor lock 202 moves between a rotor locked position and a
rotor unlocked position. The rotor lock 202 normally biases to the rotor
locked
position and must be actuated by fluid pressure from the tong assembly
hydraulic
circuit to the rotor unlocked position. In the rotor locked position shown,
the
female end 224 coupled to the piston 225 receives a male member 226 protruding
from the rotor 300. The male member 226 aligns below the female end 224 when
the rotor 300 is in the start position. The engagement between the female end
224 and the male member 226 prevents rotation and movement of the portion of
the rotor having the male member 226 thereon. As shown in the top view of the
power tong 101 in Figure 4, the power tong 101 may include two rotor locks 202
on each side which may be aligned with pivot points 304 (shown in Figure 3)
where the front segments of both the housing 207 and rotor 300 open. Thus, the
rotor locks 202 may engage both front opening segments of the rotor 300 to
secure the segments relative to the housing 207 of the power tong 101 when the
power tong 101 is in the open position. Prior to make up or break out
operations,
the female end 224 retracts to the rotor unlocked position by fluid pressure
applied
to the piston 225 in order to urge the piston 225 upward against the bias of
the
spring 228. Thus, the rotor lock 202 permits rotation of the rotor 300 only
when in
the rotor unlocked position since the female end 224 and male member 226
disengage.
Figure 3 illustrates the rotor 300 within the power tong 101. The rotor 300
includes a segmented rotary gear 302, three active jaws 306, and support
members 308 disposed between the jaws 306. The support members 308 are
fixed within the inner diameter of the rotary gear 302 such that the jaws 306
and
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the support members 308 rotate with the rotary gear 302. Prior to rotating the
rotor 300, the jaws 306 move inward in a radial direction from a release
position
shown to a gripping position with the jaws 306 in gripping contact with the
tubular
110. A spring (not shown) biases the jaws 306 to the release position. Each of
the jaws 306 include two pistons 312 hydraulically operated by a separate
rotor
hydraulic circuit to push a jaw pad 314 against the tubular 110 in the
gripping
position. Three pinions 310 driven by the three motors 111 (shown in Figure 1)
mesh with an outer circumference of the rotary gear 302 in order to rotate the
rotor
300 during make up and break out operations. Since the pivot points 304 for
both
the housing 207 and rotor 300 are the same, there is no relative movement
between the rotor 300 and housing 207 as the power tong 101 moves between the
open and closed positions. Consequently, the two motors 111 on the front
segments of the housing 207 do not move relative to the rotary gear 302 such
that
it is not necessary to actuate the two motors 111 as the power tong 101 opens
and
closes.
The rotary gear 302 may be tensioned prior to assembly such that the
rotary gear 302 is initially deformed. Thus, when the rotary gear 302 is
assembled
in the power tong 101 and when the tubular 110 is gripped by the jaws 306, the
deformed rotary gear reworks to obtain a circular outer circumference.
Support rollers 316 hold the rotary gear 302 in order to axially position the
rotor 300 within the power tong 101. Each of the pinions 310 creates a force
on
the rotary gear 302 that is perpendicular to the tangential. Due to the 120
spacing of the pinions 310, these forces are all directed to the center of the
rotor
300 and cancel one another, thereby centrally aligning the rotor 300.
Therefore,
the rotor 300 does not require radial guiding since the rotary gear 302
centrally
aligns itself when a load is placed on the pinions 310 arranged at 120 around
the
rotary gear 302.
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The jaws 306 and support members 308 laterally support one another
throughout a 3600 closed circle such that corresponding torque from the rotor
300
only transmits to the tubular 110 in a tangential direction without resulting
in any
tilting of the jaws 306. During make up and break out operations, a side face
of
one jaw 306 having a close contact with a side face of an adjacent support
member 308 transmits force to the adjacent support member 308 which is in
close
contact with another jaw 306. The closed 360 arrangement effectively locks
the
jaws 306 and support members 308 in place and helps the jaws 306 and support
members 308 to laterally support one another, thereby inhibiting tilting of
the jaws
306. Thus, load on the tubular 110 equally distributes at contact points on
either
side of the jaw pads 314. Adapters (not shown) for both the support members
308
and jaws 306 may be added in order to allow the power tong 101 the ability to
grip
tubulars having different diameters.
The jaw assembly (not shown) in the back up tong 102 may be identical to
the rotor 300. However, the jaw assembly in the back up tong 102 does not
rotate
such that an outer ring surrounding jaws in the back up tong may not be geared
with motors providing rotation.
The top view of the power tong 101 in Figure 4 shows a motor 402 used to
operate a pump 404 that supplies hydraulic pressure to the rotor hydraulic
circuit
that actuates the jaws 306. The motor 402 may be actuated by the tong assembly
hydraulic circuit. The motor 402 mounts on the housing 207 while the pump
mounts on the rotor 300. Therefore, the motor 402 must disengage from the pump
404 after the pump 404 actuates the jaws 306 in order to allow the pump 404 to
rotate with the rotor 300 during make up and break out operations.
Figures 5, 5A and 5B illustrate a releasable coupling arrangement between
the motor 402 secured to the housing 207 and the pump 404 secured to the rotor
300. The motor 402 slides along a guide shaft 500 between an engaged position
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toward the pump 404 and a disengaged position away from the pump 404. As
shown, a spring 502 biases the motor 402 to the disengaged position. Hydraulic
fluid supplied from the tong assembly hydraulic circuit moves the motor 402
against the bias of the spring 502 toward the pump 404. As the motor 402 moves
toward the pump 404, a coupling such as a claw 504 of the motor 402 engages a
mating coupling such as an elongated S-shaped bar 506 of the pump 404. The
claw 504 and the S-shaped bar 506 provide a wide angle for possible engagement
with each other. However, the claw 504 and S-shaped bar 506 may interferingly
hit one another without engaging. To simplify the next engagement of the claw
504 with the S-shaped bar 506 due to a missed engagement or for subsequent
operations of the pump 404, the motor 402 rotates the claw 504 a small amount
as
the motor 402 slides on the guide shaft 500 back to the disengaged position.
As
shown in further detail in Figure 7, pressurized fluid used to fill a piston
chamber in
order to move the motor 402 on the guide shaft 500 toward the pump 404 flows
to
the motor 402 to turn the claw 504. Since the volume of the piston chamber
remains the same, the claw 504 of the motor 402 rotates a fixed amount with
every movement of the motor 402 between the engaged and disengaged
positions.
Figure 6 illustrates a schematic of a back up tong hydraulic circuit 600 used
to actuate jaws 602 of the back up tong 102 in order to grip the lower tubular
108
as shown in Figure 1. A grip line 601 from the tong assembly hydraulic circuit
selectively supplies fluid pressure to a back up tong motor 603 that operates
a
single back up tong pump 604. The jaws 602 of the back up tong 102 connect to
the back up tong pump 604 which supplies an equal volume and pressure of fluid
to each of the jaws 602 through three equal flow outlets 606. To prevent a
stop of
the motor/pump 603, 604 with only one of the jaws 602 in gripping contact, the
hydraulic circuit 600 provides a cascade circuit with flow from all three jaws
602
passing to a single common adjustable pressure limiter 608, a single common
preset safety valve 610 and a single common release check valve 612. Due to
the
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arrangement of the two check valves 614, the pump 604 continues to supply
pressurized fluid even if one of the jaws 602 grips prior to the other jaws
602.
Pressurized fluid supplied to the jaw gripping prematurely flows to the tank
616
while the other jaws continue to receive fluid pressure for proper actuation.
Therefore, there is no volumetric influence of one of the jaws 602 with
respect to
the other jaws. After completing the make up or break out operation, a
hydraulic
signal through a release line 618 of the tong assembly hydraulic circuit opens
the
release check valve 612 and permits fluid pressure acting on the jaws 602 to
dump to the tank 616. The back up tong hydraulic circuit 600 with the pump 604
may supply high pressures such as greater than 6000 pounds per square inch or
500 bar.
Figure 7 shows a schematic illustrating engagement of the motor 402 and
the pump 404 used in a rotor hydraulic circuit 700 that actuates the jaws 306
of the
power tong 101. The jaws 306 actuate through a similar manner as described
above with respect to the back up tong hydraulic circuit 600 in Figure 6.
However,
a release valve 702 is opened upon completing the make up or break out
operation. The schematic in Figure 7 also illustrates the motor 402 that is
moveable between the engaged and disengaged positions. To move the motor
402 from the disengaged position to the engaged position, fluid selectively
supplied from the tong assembly hydraulic circuit to an engage pump line 704
passes through check valve 708 and enters piston chamber 710 in order to move
the motor 402 toward the pump 404. The fluid pressure in the engage pump line
704 closes check valve 706. However, release of fluid pressure from the engage
pump line 704 permits pressurized fluid from the piston chamber 710 to pass
through check valve 706 into a motor drive line 712 in order to rotate a claw
504 of
the motor 402 as described above when the motor returns from the engaged
position to the disengaged position.
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Figure 8 illustrates an interlock portion 800 of the tong assembly hydraulic
circuit that provides a safety interlock that includes the rotor locks 202 and
a motor
lockout that selectively blocks fluid supplied to operate the drive motors
111. The
interlock portion 800 includes a normally open pilot valve 802 having an input
from
a dump line 803 and an output to a tank 816, a first check valve 804 having an
input from a break out supply line 805 and an output to a reverse drive line
810,
and a second check valve 806 having an input from a make up supply line 807
and an output to a forward drive line 812. An automated or manually operated
drive valve 818 selectively supplies fluid pressure to one of the supply lines
805,
807 at the appropriate time. Fluid supplied through the reverse drive line 810
operates the motors 111 for break out, and fluid supplied through the forward
drive
line 812 operates the motors 111 in an opposite direction for make up. Thus,
the
drive motors 111 only operate when the check valves 804, 806 can open to
permit
fluid flow between one of the supply lines 805, 807 and a corresponding one of
the
drive lines 810, 812. A first pilot port line 809 connects a pilot port of the
first
check valve 804 with the break out line 805, and a second pilot port line 811
connects a pilot port of the second check valve 804 with the make up line 807.
The check valves 804, 806 only open when the pilot port lines 809, 811 supply
fluid pressure to the pilot ports. However, the pilot port lines 809, 811 do
not
supply an opening pressure to the pilot ports of the check valves 804, 806
when
the pilot valve 802 is open since the pilot port lines 809, 811 connect
through
check valve 813 to the dump line 803 that passes fluid to the tank 816 when
the
pilot valve 802 is open.
As described above, the rotor locks 202 physically block rotation of the rotor
300 until a fluid pressure is applied to the rotor locks 202 in order to place
the rotor
locks 202 in the rotor unlocked position. Thus, the fluid pressure for placing
the
rotor locks 202 in the rotor unlocked position is supplied from the tong
assembly
hydraulic circuit through a disengage locks line 808 that may be controlled
independently from the supply lines 805, 807 by a lock valve 820. A portion of
the
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fluid from the disengage locks line 808 is supplied to a pilot port of the
pilot valve
802 in order to close the pilot valve 802 only when both the rotor locks 202
are in
the rotor unlocked position. Once the pilot valve 802 closes, fluid pressure
from
either of the supply lines 805, 807 can pressurize a corresponding one of the
pilot
port lines 809, 811 that are no longer open to the tank 816, thereby
permitting
opening of a corresponding one of the check valves 804, 806. Thus, opening the
drive valve 818 supplies fluid selectively to one of the supply lines 805,
807, which
are blocked from operating the drive motors 111 until actuation of the rotor
locks
202 unlocks the interlock that provides the motor lockout. Once both the rotor
locks 202 actuate and the drive valve 818 is opened to permit fluid flow to
the
appropriate supply line 805, 807, a pressurized fluid is simultaneously
supplied to
all of the motors 111 through a corresponding one of the drive lines 810, 812
during make up or break out. Further, each motor 111 produces the same torque
and any mechanical parts for "locking" such torque are not necessary as all
the
motors 111 simultaneously stop hydraulically due to the check valves 804, 806.
A
gear change 814 may be used to adjust the suction volume of the motors 111 in
order to adjust the speed of the motors 111. Additionally, a solenoid valve
(not
shown) can be activated such that the drive motors 111 are also immediately
stopped, and a pressure limiter 822 may protect the interlock portion 800.
In alternative embodiments, the pilot valve 802 is closed by a signal other
than the hydraulic signal from the disengage locks line 808. For example, the
pilot
valve 802 may be controlled to close by an electric signal supplied thereto or
may
be manually closed. Further, the hydraulic circuit shown for the interlock
portion
800 may be used in applications and methods other than tong assembly 100
where there is a desire to block actuation of motors prior to receiving a
signal from
an interlock.
The tong assembly 100 described herein may be used in a method of
making up a tubular connection between a first tubular 110 and a second
tubular
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108. For clarity, the method is described using the reference characters of
the
figures described herein when possible. The method includes opening a power
tong 101 and back up tong 102 of the tong assembly 100 and positioning the
tubulars 108, 110 therein. The method further includes, closing the tongs 101,
102
around the tubulars 108, 110, locking gate locks 200, 201 to maintain the
tongs
101, 102 and a rotor 300 in the closed position, actuating jaws 306 of the
tongs
101, 102 such that the power tong 101 grips the first tubular 110 and the back
up
tong 102 grips the second tubular 108, unlocking a rotor lock 202 to permit
rotation
of the rotor 300, and unlocking an interlock including a rotor motor lockout.
Additional, the method includes rotating the rotor 300 by distributing a drive
force
on the rotor 300 such as by simultaneous rotation of at least three motors
111,
wherein rotating the rotor 300 rotates the first tubular 110 relative to the
second
tubular 108 and forms the connection. The method may be used with connections
in tubulars having diameters greater than fifteen inches such as risers.
While the foregoing is directed to embodiments of the present invention,
other and further embodiments of the invention may be devised without
departing
from the basic scope thereof, and the scope thereof is determined by the
claims
that follow.
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