Note: Descriptions are shown in the official language in which they were submitted.
This invention relates to the field of tapered threaded
pipe joints. It particularly concerns a method and apparatus
- for use in the gaying and joining of tapered, threaded pins and
boxes.
Pipe sections used in oil fields (for e~ample, long
sections of well casing or tubing) usually have tapered, exteriorly-
threaded male ends, called "pins." Such ends are threaded into
collars (which are short female pipe section~ the threadsd portions
of which are often called "boxes"), there being an interiorly-
threaded tapered box region at each end of each collar. The
~; tapered, threaded joints are very difficult to make up (form)
properly.
For example, because the male and female threaded
regions are tapered (fru~toconical), there can only be a certain
amount of penetration of the pin into the box before permanent
deformation of the threads occurs. Such permanent deformation is
not desired for reasons including the fact that the pins and
boxes are then not reusable. In extreme cases, the box may ~plit.
Conversely, however, there must be a sufficient penetration to
; 20 achieve good sealing against gas or oil leakage, to achieve adequate
resistance to axial tensile stre~ses, etc.
There are two major ~actors that determine whether or not
a joint between two tapered pipe regions (namely, between a pin and
a box~ is correctly made. The first factor is the degree of
penetration, or amount of engagement, as stated above. The second
factor i~ the makeup torque, namely the torque which exists at the
very last increment of the makeup procedure. Makeup torque values
have been e~tablished by the American Petroleum Institute ("API")
for each size, weight, and grade oE casing and tubing.
Although it has long been known that there must be both
(a) proper engagement (namel~, proper degree of penetration) and
(b) proper torque, in order to have a correctly m~de up taper ~ .
699
joint, workers in oil fields do not now achieve these factors
conjointly with any degree of regularity. Instead of knowing
~hen there is proper engagement (degree of penetration) in each
joint, at the proper torque, it is conventional practice to rely
upon approximations, estimates, and surmises. It is not conven-
tional to gage the pin ancl/or box at each and every joint and
then use the results of the gaginc3 to achieve good connections.
The present invention makes it practical to gage the pin and
box for each joint, even in the field, and employs the results of
the extensive gaging to assure that there is proper engagement
(penetration) at each joint.
The gaging effected by the present apparatus and
method produces, as one of its major benefits, the correct location
of the actual "hand tight plane." The hand tight planes of tapered
pipe and collar members are planes normal to the axes of each,
which planes are coplanar when the two mert~ers are in so-called
hand tight engagement~ When in such hand tight engagement, the
threads have been interengaged to a point where they are in
intimate contact but without deformation. Thi5 normally will occur
at a torque of from ten to eighty foot pounds for seven inch long
thread (8-round) casing, for example.
From another point of vlew, the hand tight planes of the
collar and pipe are coplanar when the two have been threaded to-
gether to such an extent that any ~urther threading of the male
member into the female men~er will commence to deform the thread~.
(Thi~ hand tight engagement of tapered threaded elements is
analo~ous to an interengagement of male and female smooth-~urfaced
frustoconical member~, which are axially interenc3ayed to a point of
intimate contact in which no significant deormation -~akes place.
With such smooth frustoconical members, further interengagement
from this analogou~ hand tiyht engagement would require deEormation
of the two parts, namely a decrease in diameter of the male and/or
,, . , ~ ,
an increase in diameter of the female.
The hand tight plane is defined by the American
Petroleum Institute in the API Specification for Threading, Gaging,
and Thread Inspection of Casing, Tubing, and Line Pipe Threads,
API Standard 5B, Ninth Edition, March, 197~. Page 6 of this
Specification shows (Figure 2.1) that the plane of hand tight en-
gagement of the collar is at a distance M from the end of the
coupling, and that the plane of hand tight engagement of the pipe
is at a distance Ll from the end of the pipe. These two planes
are coincident in the condition of hand tight makeup of the two
elements. (Reference is also made to Figure 1 of the present
- patent application.)
Values of M and Ll are given in this API Specification
` for different sizes and thread types of casing, line pipe and -
tubing. It is emphasized, however, that the API data concerning
M and Ll are not used by applicants to locate the hand tight plane.
The reason M and Ll data are not used by applicants for hand tight
plane locations is that the API permits substantial tolerances
which applicants desire to eliminate.
Unless the actual (not theoretical) hand tight plane or
planes are known, you can't be sure whether or not there is proper
engagement (degree of penetration of the pin into the box) in the
completed joint. Furthermore, as stated above, unless there is
., .
proper engagement at the proper torque you can't be assured of a
correctly made up joint.
It might be thought that since the pipes ~and collars)
are mass produced in pipe mills, the hand tight planes thereof
are the same and could be known by (for example) a mark made a
certain distance from the end. This is not so, since there are
manu~acturing tolerances which make the pipes (and collars) far from
perfectly uniform. The only practical way to be sure of locating
,
69~
the hand tight planes correctly is to use a standard thread gage
on each pipe and collar element.
It is an important advantage of the present apparatus
and method that they work properly on tubular sections (tubing and
casing sections and collars) having "standard" API thxeads, such
as those referred to in the above-cited API Specification. ~n
most of these standard API threads, the cross-sectional shape of
each thread is substantially triangular. (The word "substantially"
;~ is used because, for casing and tubing threads, the apex is often
rounded-the threads being therefore conventionally termed "round.")
Other API threads include buttress, etc.
The present apparatus and method not only locate, and
make extensive use of, the true hand tight planes, but they also
achieve other important benefits of extensive field gaging. Thus,
for example, the gaging informs the user whether or not there has
been any thread damage. Such damage may result from various factors
existing after the pipes and collars leave the factory.
Very importantly the present gage apparatus can be
employed while the pipe sections are horizontally positioned in
racks near the wellhead. It is thus known, before the actual well-
head is reached, whether or not each pin and hox meets API require-
ments. The gage apparatus can also be employed at pipe manufacturing
plants, threading plants, and along pipelines. ~t i~ preferred that
gaging occur in the ield, since changes subsequent to leaving the
fac~ory, etc., will then be detected.
Pipe gages Iring gage~ and pluy gages) for tapered pins
and boxes have, of course, long been used. They are often heavy,
and thus difficult to "start" (commence threading~ without false
starts and/or cro~s-threading. There i3 thus a major need for
plug gages and r~ng gages which-even when heavy and cumbersome-can
be used quickly and easily. The present invention not only
provides such gage apparatus but further achieves the great added
... .
.
6'3~
benefits of simple, practical and economical pipe-maxking means
- adapted to mark the pipes and collars in accordance with the
actual locations of the hand tight planes. The marks and suitable
tclrque gages are then used at the wellhead, in a very simple
manner requiring almost no wellhead time, to conjointly achieve
both (1) proper penetration (engagement) and (2) the proper,
measured makeup torque.
The pipe and collar memhers are each gaged, and a mark
is made on each at a predetermined axial position relative ~o the
hand tight plane of each gage when the latter is in hand tlght
engagement with the member. The axial distance between the marks
is then used, at the wellhead, to inform the operator whether or
not each joint, which has been made up to a desired torque value
which is measured as by a torque gage, is good. More specifically,
a mark-distance measuring (and tolerance) means in the form of a
gage card is used at the wellhead as soon as torquing ceases.
In accordance with another embodiment, the thus-marked
pipe and collar members are made up until the marks have pre-
determined axial positions relative to each other, and the measured
makeup torque is noted to see whether or not it is in a desired
range.
The apparatus and method for gaging and marking
(preferably at racks spaced from the wellhead) employ centering means
to line up the plug or ring gage with the pipe axis, so that the
plug or ring may ~e power-threaded with no false starts. Such
centering means incorporate fluid-operated "packers." As soon as
the gage has been driven to the hand tight position, the apparatus
and method ef~ect precision marking o~ the pipe and collar in a very
short time. The marks extend circumferentially, for at least half
the pipe circumference, being thu~ readily viewed without walking
around the string.
Certain aspects of the apparatus and method may be used
- --6~
3L084G99
to effect gaging only, or to effect gaging or marking of only the
pipes or only the collars. For example, a mark may be made on the
pipe by the gaging and marking means. This mark is then correlated
to the position of the end of the collar after the predetermined,
measured makeup torque is reached. In accordance with the other
embodiment, torquing is continued until the mark is in predetermined
relationship to the collar end, and then the measured makeup
torque is noted.
These and other features and advantages of the present
invention may be und~rstood more fully and clearly upon considera-
tion of the following specification and drawings in which:
Figure 1 illustrates, in section, one side of a tapered
~ threaded joint;
Figure 2 is a perspective view showing the overall gaging
. and marking apparatus adjacent a rack of horizontal pipe sections; .
Figure 2a is a perspective view of the particular appara- .-
tus for gaging and marking a pipe, namely a tubing or casing
section;
Figure 3 is a longitudinal section of the apparatus of
Figure 2a, taken on line 3-3;
Figures 4, 5, and 6 are transverse sections taken on
lines 4-4, 5-5, and 6-6 o.f Figure 3;
Figure 7 is an enlarged fragmentary sectional view
showing more clearly the relationships between certain parts of
~ the apparatus;
: Figure ~ is a perspective view of parts of the marker
head assembly;
Figure 9 shows the underside of the rocket arm;
Figure 10 is a sectional view of part~ of the apparatus
of Figures 2-9, but modified for gaging and marking a collar; and
Figure 11 is a perspective view of a joint gage applied
to inspect, at the wellhead, makeup of a vertically-or.iented
--7--
69~
.,
coupled joint~
When the collar and pipe are threadedly engaged past the
hand tight plane, and the number of turns increases, stress on the
threads increases because of the taper. As stress increases,
greater resistance is exerted to further turning. There~ore,
torque required for further turning increases as the interengage-
ment proceeds. By the time that the desired torque has been
attained, the two parts have relatively rotated a number of turns
and thus, ~or a theoretically good pipe and collar of each type,
size, etc., there exists a predetermined correct number o~ turns
past the hand tight plane at the desired ~orque.
Such predetermined correct number of ~urns past the hand
tight pl~ne can be determined empirically for each type, size, etc.,
of pipe. It is emphasized, however, that if the actual (not
theoretical or "nominal") hand tight plane is not correctly knowll,
the "predetermined correct number of turns past the hand tight
plane" cannot be regularly achieved. This is true even though
there is a certain tolerance in the predetermined correct number of -
tuxns (that is to say, there is a predetermined maximum number of
turns and a predetermined minimum number thereof, all referenced
to the actual hand tight plane).
Should the pipe and/or collar components depart from
the ideal, having misshaped or damaged threads, wrong taper, dirt
on the thread~, etc., the very same desired torque will not provide
the same number of turns past the hand tight plane. Thus, if the ~`
number of turns past the hand tight plane is not within the pre-
determined tolerance limits, at the desired torque, it is known
that the joint is defective.
The present inventiGn nol- only provides a method and
means for accurately and quickly locating the actual hand tight
plane, and for gaging the pipe, bu-t it also provides a practical
method and means whereby the operator can easily and quickly
.,
99
determine whether or not there has been more or less than the
correct num~er (or range) of turns past the hand tight plane at
-the desired toxque. (When the operator thus determines that
there has been either (a) more than or (b) less than the pre-
determined number or range of turns, he can use his own judgment
regarding whether or not to discard the joint. In any event, he
k.eeps a log or record of the joint for future reference.)
Each of the pipe and collar elements is marked at a
known axial distance from its actual hand tight plane and, after
makeup ~at the wellhead) of the join~ to the desired torque, the
axial distance between the two marks is compared to the axial
distance hetween such marks on ideal pipe and collar members that
have been made up to the desired torque. In this manner manufactur-
ing tolerances and other deviations of the threads from nominal
are compensated for, since each mark is placed while actually
gaging the particular pipe and/or collar, being positioned
relative to the actual (rather than the nominal or estimated) hand
tight plane of the member.
Referring now to Figure 1, there are shown tapered
20 (frustoconical) threaded parts 10 and 12 (10 being the pin, 12 being
the box). The two parts are illustrated in solid lines in a
condition of hand tight interengagement, wherein the tapered pin
is inserted into the tapered collar until the thread suxEaces of
the two are in firm engAgement but no noticeable deformation o
either occurs. The hand tight plan~ of the collar is indicated by
dashed line 14, and the hand tight plane of the pin 10 is indicated
by the same dashed line since the two are (as above stated) co-
planar in this condition. The hand tight plane of the collar is
located at a distance M from the e;nd of the collar 1~, and the
hand tight plane of the pipe is located at a distance Ll from the
end of the pipe. Values (data) of M and Ll for various pipe types
and sizes are stated in the American Petroleum Institute Standard
_g_
~84~69~
5B, identified above, but it is again emphasized that these API
~alues of M and I,l involve tolerances which applicants do not use
for location of the hand tight planes.
When threaded elements of the type shown in Figure 1 are
made up into a typical joint, the pipe 10 is advanced into the
collar 12 beyond the hand tight position, illustrated in solid lines,
to the po~ition illu~trated in dashed lines. Such advance is
through an axial distance indicated on the drawings as NP, where N
i5 the number of turns past the hand tight plane and P is the pitch
10 of the thread. Thus, axial advance i9 the mathematical product -
of turns (N) times pitch (P). It is emphasized that the
illustrated dashed-line position is exemplary only, being for
purposes of discussion.
Both pipe and collar are marked at a predetermined, fixed
di~tance (axial) from the actual hand tight plane. Thus, with
reference to Figures 1 and 11, a fine but readily visible marker
line, extending circumferentially, is placed on the pipe and on
the collar, at points 11 and 13 respectively, by apparatus to be
described below. These lines are placed at known axial distances
Kl and K2 frM the trus hand tight planes 14 of the pipe and collar,
and therefore are at a known di~tance K1 and K2 from each other
when the pipe and collar are in hand tight enyagement (solid lines,
Figure 1~.
When the joint i5 made up to the selected (desired)
torque, the marker lines move relative to each other by the
distance NP, to the position shown in Figure 11 and to the dashed-
line position of Figure 1. Thus, for a good pipe and collar, made
up to the selected (desired) torque, the two marker line~ are at a
known distance S = Kl ~ K~ - NP from each other. It is not necessary
to determine any hand tight or other reference position during
makeup. The pipe and collar are merely threaded upon one another in
the usual manner until the selected makeup torque has been attained
--10--
' ~ ~
99
by the conventional tooling used ~or this purpose. Such tooling is
caused to include a torque gage, or torque sensing means.
To inspect the made up joint it is only necessary to
measure the distance S (Figure 1) between lines 11 and 13. This
measurement can be made in many ways. At present it is preferred
to employ a joint gage card C which is used as illustrated in
Figure 11. The gage card is formed of a thin rigid sheet such as
aluminum or plastic or the like, of a substantially rectangular
configuration and having a transverse step or shoulder 19 to enable
first and second gage card sections 21, 23 to lie substantially flat
upon the surfaces of pipe and collar, respectively, bridging the
joint and the collar end.
One end of the gage card, such as end 25, extends trans-
versely to the length of the gage card and, in use, is placed upon
the marker line 13 of the collar. The other section of the gage card
has an elongated -transverse window 27 formed therein. The window
has a width (measured in the axial direction, parallel to the pipe
and collar axes when the gage card is in use) equal to the
tolerance in the empirically-determined values of NP. The distance
between edge 25 and the center of window 27 is precisely fixed, for a
given type of pipe, to be equal to the distance between the marker
lines of a good pipe and collar when made up -to the selected
(desired) torque. Stated otherwise, the center of the gage card
window 27 is at the correct distance S tFigure 1) from the edge 25.
With the card edge 25 on the collar marker line 13 of a
made up joint, the line 11 of the pipe is visible through the
window ~Figure 1) if the proper number o~ turns has been achieved
at the selected torque. If the line 11 is not visible through the
gage card window, the joint is not correct since the desired
makeup position has not been attained at the selected torque. Line
11 is spaced from the end of the pipe by a distance gxeater than
the length of pipe that is coverecl by the collar, to insure its
i,9~
visibility after makeup.
With the above-defined method, and with the apparatus
described below, it is a simple task to gage each pipe and collar,
place the marks thereon at the predetermined locations, and torque
the collar to the predetermined torque. This procedure enables
inspection of the validity of the joint simply by placing the
joint gage card and viewing the marker line through the gage card
window. No complex equipment is needed at the wellhead. No tools
or inspection devices are necessary at the wellhead, other than
the conventional joint torquing equipment, the torque maynitude
indicating instruments, and the gage card.
; There will next be described the apparatus of the
invention, following which methods will be further described.
Proceeding first to the apparatus for (1) gaging the
pine, (2) locating the actual hand tight plane thereof, and (3)
marking the pipe in reference to such actual hand tight plane,
reference is made to Figures 2 through 9, inclusive. Figure 2
shows the actual preferred orientation of the apparatus, adjacent
horizontal pipe sections in a rack. Figures 2a through 9 are
rotated ninety degrees, from the preferred operating position of
Figure 2, to aid in visualiæation of the various ro~ational move-
ments.
Referring to Figure 2, pipe sections 18 are shown as
they are usually oriented, horizontally, in a rack. A truck "T"
incorporating a boom "B" suspends the appara~us next to be
described, for example by means of a spring or chain. The
apparatus may either be moved to each pipe section, or vice versa~
During gaging and marking, each pipe section may be moved axially
in order to increase clearance relative to adjacent pipe sections.
As seen in Figures 2a and 3, the apparatus generally
comprises a support shaft 20 rotatably carrying a ring gage assembly
22 which is adapted to be rotated by means of an air motor assembly
-12-
!39
24 and geax box 26, all o~ which are carried by an L shaped
mcsunting bar 28~ ~ marker standard 30 is mounted for rotation
about the axis o support shaft 20. It carries a marking
mechanism 32 which is keyed to the ring gage and can move both
(1) circ~ferentially about the ring gage and the gaged pipe 18,
and (2) radially inwardl.y and outwardly with respect to the ring
gage and pipe.
Referring to Figures 3-7, shaft 20 carries first and
second expandable packers 34, 36 which are identical to each other
and axially spaced along the shaft. Each of the packers is fixed
to support shaft 20, and includes a hub 38 and a circumferential
resiliently expandable outer casing 40. Such casing is spaced from
the hub to define therewith an air chamber 4~. Casing 40 is formed
of rubber or other elastomeric or plastic material.
Chamber 42 communicates with a source of air pressure
~ (not shown) via a radial air passage 44 and an axial passage 46
: that extends from an air hose 48 to the central hubs of both of the
packers 34, 36.
Shaft 20, with both of the packers 34, 36 thereon, is
inserted into the male threaded end of a pipe 18 that i5 to be
gaged and marked. The casing 40 of each packer i~ relatively
unpressurized during such insertion. Air pressure i9 then trans-
mitted through the several passages to pre~surize chambers 42
and expand the casings 40, thus locking shaft 20 against axial and
rotational motion with respect to the pipe.
Very importantly, expansion of the packers_into pressure ~:
engagement with the interior pipe surface-achieves immedia~e,
automatic alignment of the yage with the pipe (the axes of the gage
and pipe becoming coincident when the packers are thus fluid~ .... :
energized). Therefore, it becomes possible and practical to power-
drive the gage onto the pipe as stated below.
A sleeve 50 i5 fixed to .shaft 20, being secuxed to a sup-
-13-
.
69~
port plate 52 which forms one side of a sprocket housing 54.
Rotatably mounted upon sleeve 50, by means of axially spaced
bearings 56, 58, is a gage drive sleeve 60. A driven sprocket
62 is fixed to sleeve 60 and engaged with a chain 64. Chain 64,
in turn, is driven by a driving sprocket 66 that is fixed to the
output shaft 68 of an air motor 70 (and its gear bo~). The air
motor is provided with fittings 71, 72 for connection to a source
of pressurized air (not sho~m). Sprocket housing support plate
52 is bolted to the mo~mting bar 28 which thereby carries the
entire mechanism. Bar 28 is what is connected to the boom B,
Figure 2, to facilitate positioning of the apparatus with respect
to a pipe or collar member to be gaged and marked.
A gage driving collar 74 is slidably mounted on driving
sleeve 60 by means of circumferentially extending slide bearings
B 75~ 76 preferably ~ormed of ~Teflon.'~ It fixedly carries a roller
77 that rides in an axially extending slot 78 formed in an outer
surface of the sleeve 60. Gage driving collar 74 is bolted to the
gage assembly 22. Such assembly comprises a gage carrying cap 80
~ which in turn is bolted to a ring gage 82.
A circumPerentially extending window 84 is provided as an
aperture in the gage and gage cap to enable viewing of the extreme
end of the pipe 18, for gaging purposes stated hereinafter. The
ring gage 82, and the plug gage 82a described below, meet standard
~PI 6pecifi~ations. They are, however, modified to incorporate
the window 84 and also annular grooves or guideways (tracks) set
forth subsequently.
Disreyarding, at this time, the marking apparatus and its
support, the operation of the gage is as follows. Assume that the
gage 82 is initially at a rearward axial positlon with respect to
the packers 34, 36, the gage being relatively close ~o the gear
hou~ing 54. The keying roller 77 .1s thus in an "upper" portion of
slot 78 (as viewed in Figure 3).
~ o~s r~ c ~ 14-
39L69~
The entire apparatus is so moved that (1) -the packers
34, 36, and part of shaft 20, enter the end of the pipe, and (2) a
part of the gage shifts (laps) over the narrow end of the pipe
(pin). Thereafter, packers 34, 36 are pressurized to create the
above-stated alignment whereby the pipe axis and the axis of shaft
20 are made coincident.
The air motor is then started and turns the gage upon
the pipe threads until the stalling torque of the air motor
(and associated gearing) is reached. The air motor (and gearing~
is set to have a maximum torque of between 10 and 80 foot pounds,
preferably about 25 to 50 foot pounds, so that when the torque
reaches the stall value no further turning of the gage upon the
pipe occurs. The gage is then in the hand tight position. Figure
3 shows the gage in the thus-achieved full forward position, in
hand tight engagement with the pipe. Figure 7 shows the gage in an
intermediate position, partly threaded on the pipe, but not in
hand tight engagement. ~;
During threading of the gage upon the pipe, the gage and
its driving collar 74 advance axially relative to the support
shaft 20 around which they are mounted. Sleeve 60 is rotated by
the motor-driven sprockets and chain 62, 64, 66, but has no axial
travel. Because of the keyway or slot 7a, and the keying roller
77, rotation of sleeve 60 rotates the gage collar 74. Such collar
is caused to move axially of the shaft 20 as the gage is threaded
upon, and advances axially along, the pipe 18.
If the pipe thread is within tolerance, the extreme end
of the pipe may be viewed (in a radial direction) through the
window 84 to thus complete the gag:ing of the pipe. Stated other-
wise, if the extreme end of the pipe is vis:ible ~hrough the
window, the pipe thread is known to be good (within gage)~ If not,
the pipe thread is not satisfactory. The axial dimension and
positioning of the gage window 84, and of the plug gage window 84a
-15-
~8~6~
described belo~, are in accordance with API specifications and
tolerances as taught (for example~ by the above-cited API
Specification.
Proceeding ne~t to a description of the pipe markiny
apparatus, there is rotatably mounted upon collar 74 the marker
standard 30 which is inserted into and bolted to a rotatable marker
standard sleeve 86. The latter is mounted upon collar 74 by means
of bearings 88. Bearings 88 and sleeve 86 are retained in axial
position relative to collar 74 by means of snap rings 87, 89
(Figure 7) engaged in grooves in collar 74.
Marker standard 30 -thus mOV2S axially with the gage but
is rotatable relat~ve to the gage about the gage axis (and about
the coincident axis of support shaft 20).
; Standard 30 carries a marker support sleeve 90 that is .
. axially slidable along the standard (radially with respect to the
gage and pipe), but is locked against rotation with respect to the
standard by means of a fixed pin 92 that rides in a slot 94 formed
~: in standard 30. A handle 96 extends radially of the standa.rd 30
and is fixed thereto to provide for manual control and manipulation
of the marker standard and the marking apparatus.
Marker support sleeve 90 may be kemporarily locked, in
any position of axial adjustment with respect to standard 30, by
a brake mechanism 98. The brake comprlses a handle 100 pivoted to
a link 102 that i8, in turn, pivoted to sleeve 90 at 104. Handle
100 is also pivoted at 106 to a bell crank 108 which is itself
pivoted to sleeve 90 at 110. The bell crank carries an adjustable
brake shoe 112 arranged to bear against the sur~ace of standard
30.
When the brake elements are moved to the positions
illustrated in Figure 3, leeve 90 i8 locked against axial motion
relative to standard 30.
When handle 100 iB pivoted in a clockwise direction about
-16-
its pi~otal connection to link 102, bell crank 108 is pivoted
about point 110 in a counterclockwise direction. This retracts
the brake shoe 112 and frees sleeve 90 for sliding motion along
standard 30 under control of the handle 96.
The marker mechanism itself is adjustably carried by the
sleeve 90 by means of a pair of telescoping tubes 114, 116. These
are axially adjustable with respect to one another, there beiny a
lock bolt 118 (Figures 2a and 3) rotatably mounted in the wall of
tube 114 and extending into an axially elongated slot 120 in tube
116. Lock bolt 118 is associated with suitable nut means, not shown,
in such manner that when the bolt is rotated to a tightened condi- -
tion the telescoped tubes 114, 116 are prevented from moving relative
to each other. The described adjus~ment permits marker line 128
to be shifted axially relative to guide groove 1~2~ to compensate
for any variations in the locations of the guide grooves of
different gage elements relative to the hand tight planes.
The marker mechanism includes a marker support plate 122
(Figures 4, 5, 8) which i~ fixed to the outer end of tube 116.
Plate 122 carries a marker wheel 124 which is rotatably mounted
upon a shaft 126. An ink or paint-applying narrow marker line
(a peripheral flange, formed of rubber) 128 is fixed upon the
periphery of the marker wheel. It is provided with ink or paint
~ from a reservoir in the form o a sponge roller 130.
- Roller 130 is carried by a shaft 132, and is held in a
desired position of adjustment by a bolt 134 (Figure 4) that is
threaded edgewise into plate 122 and bears against a hub 136 for
: the roller. Hub 136 is-rotatably mounted in plate 122, and shaft
132 is eccentric to the hub. Thus, when hub 136 is turned (after
release from bolt 136) the degree of pressure of sponge roller 130
on the marker wheel is varied.
Marker roller shaft 126 has an enlarged shank 131 (Fiyure
3) extending through a ~langed hub 133 which rotatably mounts a
~8~6~5~
guide wheel 135. Hub 133 is recessed at the side thereof facing
the marker wheel 124, and receives one end of a spacer sleeve 138
which bears at i~s other end upon a bearing plate 139 interposed
; between the sleeve and the marker support plate 122. ~ nut 140 is
threaded on the shank 131 and presses the hub 133 agalnst the
spacer sleeve 138 to axially position the guide wheel with respect
to the marker wheel.
Guide wheel 135 rides in a circumfer~ntial groove,
track or guideway 142 extending around the entire periphery of
the ring gage 82. Such groove (and a corresponding groove in the
below-described plug gage) is provided by applicants and has a
fixed, certain positional relationship to the hand tight plane of
the gage.
To maintain precise alignment of the marker head assembly,
support plate 122 extends behind marker wheel 124 (as viewed in
Figure 3) and also toward the ring gage to form a projecting
alignment section 146. Alignment section 146 (Figures 4, 5, 8)
is provided with a slot 147 that terminates in an aperture 149.
The aperture receives a shaft or pin 148 which carries an align-
ment arm 150. Pin 148 and arm 150 are adjustably locked by a .
clamping bolt 152 which extends across the slot in support plate
; section 146, being threaded into the support plate at the far side
of the slot to provide the clamping action that retains pin 148.
Arm 150 carries a shaft 154 at the free end thereof, upon
which is rotatably mounted an alignment wheel 156 which rides in
the gage groove 142 (in circumferential alignment with the guide
or positioning wheel 135). Alignment wheel 156 is thus adjustable
with respect to the marker wheel 124, both axially and radially
of the ring gage, permitting wse with different sizes of pipe and
different lengths of sleeves 138.
Groove 1~2 in the gage is, as above stated, the reference
with respect to which the mark i8 placed upon the pipe 18 by the
-18-
6~5~
marker wheel 124. Thus, the axial distance between the marker
wheel 124 and the guide wheel 135, which rides in the reference
groove 142 of the ring gage, is precisely controlled in accordance
with the predetermined distan~e between the hand tight plane and
the marker line that is placed on the pipe. In the manufacture of
the gage, ~he groove 142 is formed and its position precisely
located relative to the hand tight plane of the gage.
The length of the spacer sleeve 138 determines the
distance of the marker line from the hand tight plane. The
axial distance between the guide wheel 135 and the marker line 128
is not necessarily the distance between the hand tight plane and
the marker, since the ring gage groove 142 is not necessarily
; positioned precisely at the hand tight plane of the gage, although
its location with respect to the hand tight plane is precisely
known.
Mounting bar 28 has an angulated portion 160 (Figure 2a)
that pivotally carries a rocker arm (double arm) 162. Such arm is
urged to a neutral position by means of a leaf spring 164 which is
fixed to a collar 166 that fixedly carries arm 162. Spring 164
has its opposite ends captured between pins 168 on opposite sides
of the arm 160 (Figure 9).
Standard 30 carries at its free end a cap 170 having an
arcuately grooved bracket 178 that is adapted to receive one or
the other of a pair of rods lao, 182 fixed to the oppos:ite ends of
arm 162. The rods 180, 182 are sufficiently long to be engaged by
the standard, regardless of the axial position of the lat-ter~ There
are thus created detent or holding effects as stated below.
Shown in Figure 10 is a fragmentary sectional view of
the apparatus for gaglng and marking the collar. This apparatus
is the same as the above-described apparatus for gaginq and marking
the pipe sections, differing only in that a plug gaye 82a is b~lted
to the gage-carrying cap 80 instead of the ring gage 82 of the
~19-
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, ".,, ',, " ,,, , j , ,, , , , ,: .:
previous figures. (It is emphasized t.ha-t the packer 34, not
shown in Figuxe 10, is present at the end of shaft 20, and that
packers 34 and 36 provide the above-described centering and
aligning functions.)
The plug gage includes an externally threaded portion
83 having precision (API standard) threads adapted to engage the
internal threads of collar 18b which has been previously threaded
(for example, at ~he factory) upon one end of a pipe 18a. Fixed
to the threaded portion 83 of plug gage 82a is a gage sleeve 85
having a circumferential flange 87. Such flange circumscribes
portion 83 and is radially spaced therefrom to provide an annular
; channel for reception of the end of the collar to be gaged.
Flange 87 has a gage window 84a therein through which
the extreme end of collar 18b may be viewed when the plug gage is
turned into the collar and is in hand tight engagement therewith.
As above stated, the window is 50 sized and located that, when the
end of the collar may be viewed therethrough, the collar meets
API standards.
All other components, and the operation, of the apparatus
for gaging and marking collars are identical to corresponding
components and operat on o~ the previously-described apparatus
for gaging and maxking pipe sections.
With respect to both the ring-gage form and the plug-gage
orm (all of Figures 2a and 10), the entire marker mechanism is
slidably moved along the marker standard 30 toward the ga~e just as
soon as gage rotation ceases. To permit such movement, brake
mechanism 98 (Figure 3) is first released, being relocked when
wheels 135 and 156 are in groove 142 (or 142a). Such wheels are
automatically registered with the groove, because the marker means
moves axially with the qage.
The marker line 128 is then in marking engagement with
the exterior surface of the tubular element, at a predetermined
-20-
. " . . ..
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16~
axial di.stance rom the hand tight plane.
By manipulating the handle 96, the standard 30 and
marker wheel 124 are then caused to revolve around the pipe
section 18 or collar 18b (with the marker wheel rotati.ng about
its own axis as it revolves), so that marker line 128 marks the
surface of the pipe section or collar. Thus, a nearly continuous
circumferential mark is placed upon the surface of the pipe (or
collar) at a predetermined distance from the gage groove 142
(or 142a) and, therefore, at a predetermined distance (as
determined by the length of sleeve 138 or a similar sleeve 138a
shown in Figure 10) from the hand tight plane of the gage and
from the hand tight plane of the gaged pipe 18 or collar 18b.
In order to permit ~he above-described rotation of
standard 30, in response to manipulation of handle 96, rocker arm
162 is first manually pivoted in such direction as to release
bracket 178 (Figure 2a) for movement away from the position shown
in Figures 2a and 9. The rotation of the standard 30 (and marker)
continues for somewhat less than 360 degrees, until brac]cet 178
:~ contacts and receives the second la~ching rod 182 of arm 162.
Standard 30 is then mainta:inecl in a second position.
After completion of marking, brake 98 i5 released.
The marker head assembly is then radially withdrawn from the
gage, moving axially outwardly on the standard 30. The assembly is
then locked in this inoperative position by a second operation of
brake 98. Air motor 70 is now started in a reverse direction to
withdraw the ring gage 82 (or plug gage) from its hand tight position
on the pipe. The apparatuY is then ready for gaging and marking
another pipe, since the reverse driving of the gage cau~es axial
motion which bring collar 74, etc., back to the original position
(with the gage relatively near sprocket housin~ 54).
In the next marking, the marker assembly is rotated abou-t
the p.ipe in the opposite direction, 3ince it starts from the second
-21-
of its two latched rotational positions. Thus, much movement is
prevented - the marker standard only rotates when there is
actually marking.
In another form of the apparatus, presently preferred,
there is only one detent or locking means for the marker standard
30. Such standard therefore rotates the full 360 degrees for each
pipe or collar section. For-the next pipe or collar section, the
standard rotates 360 degrees in either the same direction or the
reverse direction. In no case is it necessary to rotate the
~ 10 standard on a dry run - when no marking is occurring.
; The marking is effected for at least 180 degrees (one-
half the circumference of the tubular element), and should be
close to 360 degrees. This greatly facilitates the measuring
step ~Figure 11) which occurs at the wellhead, there always being
two line regions axially opposite each other. Furthermore, it is
then unnecessary for the operator to keep walking around the pipe
joint.
Described above, with reference to apparatus descrip-
tions, are several methods. These will not be redescribed here,
but further description will now be given of the methods described
above under the subhead "Preliminary Discussion, and General
Description of the Method."
The present method is preferably practiced by using
standard API makeup torques to form the joints at the wellhead.
Such torques, for various types, sizes, etc., of casing and tubing
` are specified in API RP 5Cl, Tenth Edition, March, 1973, entitled
: API Recommended Practice for Care and Use of Casin~ and TubinF~
rr ,,
It is pointed out that the referencedAPI material gives "maximum,"
"minimum," and "optimum" torques. One of such three ~maximum,
minimum, and optirnum) torques is selected and used as the pre-
determined makeup torque for each string of tubing or casing, in
accordance ~Jith the desires of the operator.
- 22 -
. .
.. . . .
When the API -torques are used, and when the engagement
is proper (corr~ct amount of penetration of the pin into the box,
in reference to the actual -not "nominal" -hand tight plane), it is
known that both (a) torque and (b) engagement are correct. Thus,
it is known that the joint is correctly made.
The correct number of turns (N) past the actual hand
tight plane is (as above noted) determined empirically. Such
empirical determinatiolls are used in gaging and evaluating (with
card C) the locations of marks 11 and 13 (Figures 1 and 11), for
example. The empirical determination are the results of making up
numerous joints of each type, grade, size, etc.
For example, to make the empirical determination relative
to a particular type, size~ and grade of casing, at the "optimum"
API torque, a substantial number of such joints are first made up
in the oil field, using such "optimum" torque. Before thus making
up each joint, each pipe and collar section is gaged and marked as
set forth in detail above. It will be found that, or the great
majority of the joints thus made up, the distance "S" (Figure 1)
will fall within a certain narrow range. However, for some of the
thus-made joints, distance S will be outside such range (thereby
indicating bad joints). The joints wherein distance S falls within
the narrow range are good joints, closely approaching ideal.
To learn when the predetermined desired makeup torque is
reached, for example, "optimum," torquing equipment, including
torque-measuxing means (~uch as a torque gage), is employed.
The gage card C (Figure 11) is constructed so that the
center of window 27 is at the middle of the above-indicated narrow
range. The upper edge (Figure 11) defining window 27 is at one end
of the narrow range, while the lower edge of the window 27 is at the
other end of such range.
Once ~he gage card C has been thus constructed, lt i~ used
to gage and evaluate a large numbex of other join-ts between pipe and
-23-
.
~6[313~699
collar sections of the same type, size, and grade, and using the
same API torque (such as "optimum"). Therefore, if the line 11
(Figure 11) is not within the window 27 it is known that the joint
is bad. Stated otherwise, the marks 11 and 13 on those made up
~oints having incorrect penetration are out-of-tolerance on the
thus-constructed gage card C.
The marks 11 and 13 being located relative to the true
hand tight planes, it will be immediately known, during running of
the actual string of tubing or casing, whether or not a certain
joint is "bad." This is because, as described, the predetermined
torque (such as, for example, the "optimum" API torque) will then
produce a penetration lengagement) not within the tolerance per-
mitted by gage card C.
To be sure that the present gage (ring and plug) seat
properly in hand tight positions, the pipe and collar threads are
cleaned before gaging. This may be done by means of solvents,
a wire brush, and a blast of compressed air.
As stated in the early part of this specification, the
present invention has the very important advantage of being
performable on standard API threads, including those having a
triangular section (see Figure 1) but termed "round." No special
thread type or shape is re~uired. The threads may~ as stated, also
be buttress (or square).
It is emphasized that use of only portions of the present
overall invention produces important, beneficial results. For
example, the described apparatus and method may be used only in - -
- gaging (not marking) pipes and/or collars.
As another such example, only the pipe and/or collar is
marked-in refer~nce to the true hand tight plane. Assuming,~ for
example, that such mark is on the pipe, the mark is used (a-t the
wellhead) to indicate ~relative to a part, such as the end, of the
collar--whether the penetration is as desired. The length of
-2~-
',: , . ' ' . '. . , ' ' :
, : , - . .
.sleeve 138 of the marker mechanism is changed, when desired, to
vary the mark positions, thus facilitatinq reference to the collar
end. The painted-on line is preferably wide, not narrow, with
the width indicating an empirically-determined tolerance. The
location of the mark is also determined empirically. The marking
of pipe or collar only is greatly inferior to the double-marking
(both pipe and collar) method described above, but is still superior
to the prior art.
In accordance with the method as stated in the preceding
paragraph, the pipe and collar (or other tapered, threaded members)
are threaded together at the wellhead until the predetermined
desired torque (for example, the "optimum" API torque) is achieved
as measured by ~e torque gage. It is then noted whether or not the
end of the collar is in registry with the painted-on line. If it is,
the joint is "good," whereas if there is no registry the joint is
regarded as bad. Instead of the end of the pipe being in actual
registry with the line when the joint is good, the relationships
may be made such that (after a predetermined makeup torque has
been applied to the pipe and collar) the end of the collar is at a
20 predetermined distance from the line when the joint is good. Such
predetermined distance is achieved (and known) by altering the
position of the pipe-marking means relative to the hand tight plane
of the gage.
A further method, related to the one described in the
preceding two paragraphs, is to thread the collar upon the pipe in
the field, with suitable makeup tooling, and to monitor the makeup
torque (by suitable torque gage mean~). Torquing of the collar upon
the pipe is caused to continue until the measured torque reaches a
preselected value. If (as above ~;tated) the collar end is then in
registry with the painted-on line, the joint is known to be good as
set forth. However, if the collar end has then not reached the
line, the torque is increased to the upper limit of a desired
; -25-
torque range, such upper limit being (for example) 1.25 times the
optimum torque. If the collar end has still not- despite applica-
tion of the increased -torque -reached the painted-on line it is
known that the joint is bad.
Conversely, if the collar end passes completely over
the painted-on line prior to a time when the measured torque achieves
a lower limit, so that no part of the line is visible, it is also
known that the joint is bad. Such lower torque limit may be, for
example, 0.75 times the optimum torque. --
It will thus be seen that, in accordance with the two
preceding paragraphs, the measured torque is monitored in
accordance with (in relation to) the degree o~ penetration (engage-
ment). Such degree of engagement is determined in re~erence to
the painted-on line which, in turn, is applied by reference to the
gage (the hand tight plane). Both torque and degree of engagement
are monitored, torque by means of a torque gage and position by
means of the gage-referenced mark. A certain range of torques, and
a certain range of positions (degrees of engagement or penetration)
are regarded as acceptable. Thus, so long a~ both the torque and
the engagement are within predetermined li.mits Ithe latter being
deterrnined by the gage-re~érenced lina) the joint is good.
Furthermore, the degree-of engagement may be made
substantially precise, in relation to the gage-referenced line, and
the torque monitored (measured) to ~ee whether or not it is within
a aesired range (such as between 0.75 times optimum, and 1.25 -times
optimum). This may be done, for example, by making the line on the
pipe relatively narrow and then stopping torquing when the collar
end registers with the line. The measured torque i5 then noted to
see whether or not it is within the range (e.g., 0.75 optimum to
1.25 optimum).
When both the pipe and collar are gaged and marked, as is
greatly preferred and a~ is set forth at length in major portions of
-26-
6~
this specification, the precise degree of engagement (in reference
to the gage-referenced lines on both pipe and collar) is achieved
by continuing torquing only until the two lines are a predetermined
axial distance from each other. Such axial distance is the one
selected to achieve the optimum degree of thread contact. It is
then noted whether or not the torque is within the desired range,
for example between 0.75 optimum and 1.25 optimum. If the torque
; i~ in the desired range, at the stated degree of engagement, it is
known that the joint is good.
The speed of driving of the gage, by the motor and gear
means, may be (for example) one revolution per second.
In the latest (and presently perferred) form of the
apparatus, the arm 28 is replaced by a strong plate from which a
stub shaft extends. Such stub shaft is perpendicular to the plate
and parallel to shaft 20, being disposed in the same general
location as arm portion 160. The supporting element from boom B
(Figure 2) is preferably a helical tension spring, and is connected
to the stub shaft at such location that the tool, when suspended,
will balance properly with shaft 20 substantially hoxizontal. Also,
in such latest form of the apparatus, the second follower roller 156 ~ ;
(and its associated apparatus) i9 eliminated. To insure that there
will be sufficient friction to cause rotation of marker wheel 124
about its own axis, a drive roller (not inked) is provided and is
adapted to engage the pipe surface.
The words "mark," "marker," etc., as used in the appended
claims, include not only painting or inking onto the pipe, but
also other types of indicia. Thus, for example, a strip of tape -
when adhesively applied to a pipe ~is a "mark" in the present
sense. Also, scratches, etc., axe "marks." The "mark" need not be
visible to the eye, so lony as it may be sensed at the wellhead by
appropriate apparatus. The "mark" may be magnetic, radioactive, or
whatever else is desirable. It is to be understood tha-t the mark
-27-
: ~ :
. . .
, ;' " '' ' , . ' ~
69~3
need not be continuous but may be (for example) a dashed line.
When the coupllng is previously jointed with one end of
a pipe section, as is frequently the case, the combination pipe
s~ction and coupling may be regarded as a single pipe section
(tubular element) having a female threaded end.
The above-stated equation S = Kl + K2 ~ NP was discussed
on the basis of the line 13 (Figure 1) being on the side of hand
tight plane 14 remote from the unthreaded body of the pipe (that is
to say, on the right side of plane 14 as viewed in Figure 1). If
line 13 were at plane 14 when the threads are i~ the hand tight
condition, K2 would be zero. If line 13 were then on the left side
of plane 14 (Figure 1), K2 would be a negative number.
One of the numerous advantages of the present invention
is that pipe and collar sections may be made economically (for
example, without external or internal shoulders, or special threads
or seals) yet yood, strong sealed joints will result.
The foregoing detailed description is to be clearly under- -
stood as given by way of illustration and example only, the spirit
and scope of this invention being limited solely by the appended
claims .
-28-
.
