Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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TONG
CROSS-REFERENCE TO RELATED APPLICATIONS
~0001~ This application claims benefit of United States provisional patent
application
serial number 60/452,270, filed March 5, 2003. This application is a
continuation-in-part
of co-pending U.S. Patent Application Serial No. 10/048,353, filed July 14,
2000, which
is herein incorporated by reference. This application is a continuation-in-
part of co-
pending U.S. Patent Application Serial No. 10/146,599, filed May 15, 2002,
which is a
continuation-in-part of U.S. Patent Application Serial No. 10/074,947, filed
February 12,
2002, all of which are herein incorporated by reference.
BACI(GROUND OF THE INVENTION
Field of the Invention
~0002~ 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. ~ue 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.
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[0004 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
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.
[0005 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.
[ooos~ 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.
[ooo~~ 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.
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Further, premature rotation can cause costly and time consuming damage to the
tong
assembly.
~0008~ 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
~ooos~ 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 360° 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 ofi 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.
EI~IEF ~ES~RIhTI~N ~F THE ~I~A~If~OS
Cooio] 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, 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.
~001~) Figure 1 is a view of an embodiment of a tong assembly in operation
with a
tubular string positioned therein.
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~00~2~ 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.
~ooys~ Figure 3 is a section view of the power tong illustrating a rotor with
jaws
according to aspects of the invention.
(0014 Figure 4 is a top view of the power tong.
~ools~ 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.
~oo~s~ Figure 5A is a view of an end of the motor along line 5A-5A in Figure
5.
~oo~~f Figure 5B is a view of an end of the pump along line 5B-5B in Figure 5.
~oo~s~ Figure 6 is a schematic of a back up tong hydraulic circuit used to
actuate
jaws of the back up tong.
[oo>~, 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.
[0020] Figure 0 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.
~E'f~B~E~ ~E~~~I~TI~i~ ~F TAE PBEFERRB~ E~I~iB~~~i~iBi~9T
Coo21] 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.
~0022~ 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
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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.
~oo2s~ 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 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.
~0024~ 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
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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.
[0025 The torque bar assembly 112 keeps side forces out of the connection
between the tubulars 108, 110 by eliminating or at least substantially
eliminating 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 t~ measure the torque between the power tong 101 and back up tong 102
during make up and break out operations.
[002] 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 misalignrnent 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.
[002] 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 supporfis 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
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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.
[oo2a~ 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. ~nly 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.
[0029 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
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members in the gated section of the back up jaw assembly similar to the gear
profiled
bolt 206 and rotor bolt 214 used in the power tong gate lock 200 on the power
tong
101.
[0030 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.
[0031) 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 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
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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.
~0032~ 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.
~0033~ 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.
~oo~a.f The jaws 306 and support members 308 laterally support one another
throughout a 380° 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.
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[ooss~ 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.
[oo3s] 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.
[0037 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
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. ~s 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 B-shaped bar 506 provide
a
wide angle for possible engagement with each other. However, the claw 504. and
B-
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.
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~ooss~ 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 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
fihe 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.
[oos~> Figure 7 shows a schematic illustrating engagement of the motor 402 and
the
p~arnp 404 used in a rotor hydraulic circuit 700 that acfiuates 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
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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.
~ooao~ 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.
~00~1~ 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 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
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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.
Coo~.z> 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.
X0043) 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 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
13
CA 02517892 2005-09-O1
WO 2004/079148 PCT/US2004/006753
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.
~oo4a~ 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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