CA1254032A - Thread measurement tool - Google Patents

Abstract

ABSTRACT

A portable, automatic thread inspection tool for measuring a plurality of parameters on a pipe thread and the like in situ irrespective of whether the thread is internal or external to the pipe. The tool comprises a frame adapted to be readily installed over the wall of a pipe from the pipe end. A first signal is generated and is representative of the thread height error. A second signal is generated and is representative of the thread lead error. A third signal is also generated and is related to the average taper of the thread. The first, second and third signals are received and treated to generate a display of the thread height error, thread lead error and average thread taper relating to the thread being measured.

Description

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Case IS/16176 ~J~83-0072) T~~P_~Ea~ E~ ÇQ~

S ~A~ D ~F ~E ~JF~ImT~O~

-~~ This invention relates to devices ror inspection and measurement or pipe threads and, more particularly, to the inspection of pipe threads utilized in oil-drilling eaui?ment to determine that such threads are wit~in tolerances.
Threaded couplings and the threaded end-por.ions of pipes are used for joining pipes together in numerous situations ranging from ~5 applications in the home to industrial applications.
In certain situations, particularly in the c~se of oil-drilling equipment, pipes naving 2 relatively large diameter and long lengths are employed. Such pipes re~uire a correspondingly large area of thread to ensure adequate strength to a threaded joint. To ensure ease or joining such pipes, and to insure that tbe resulting joints will h2ve adeauate strength and *

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will not leak, it is essential that t~e thr~ads be made with su~ricient precision to allow t:he threaded enc-portion of a pipe to be pro~erly threaded into a cou~ling.
A problem arises with res~ect to the ins~ection ~rocess for determining that ad`equate precision is ?resent in the pipe thread, namely, that the process is not accomplished as readily zs wculd be desired and that, furthermore, not all measurement parameters can be inspected by existing ins~ection equipment. mhe parameters of a thread w~ich are useful in deter~ining the accuracy of fit in a joint are ciscussed - in the American Petroleum Institute Specification 5B. These lnclude lead error, thread ; helght error, pitch line non-lineari,y, 2verase taper znd in,erval taper. Reference is made to p~ 2 & 14 o the API Specirication for a discussion of the latter two parameters. The problem is compounded in that, heretorore, more than one article of measuring equipment needed to be employed in the measurement of these par2meters while no commercially available equipment ~ppears to be available for measurement of ~59~3 ~

the pitch line non-linearitv The follcwing U S Patents are exemplzr~ of the s.ate of the art~ A portable thread measuring device for mezsuring the distance of a pipe thread to t~e end o the pipe is taught in the ~orton 4,184,265 Devices for measuring taper are shown in Dietrich ~` 3,961,047, Mittenbergs 3,047,960 and ~ossztl 4,139,9~7 A device for measurement of pitch or a thread is taught in Raifesh 3,827,154, Peterson 2,937,458, Schasteen a,202,109 and Heslin 3,271,872 A device for gauaing tle shape of threads is taught in Johnson 3,318,011 Devices for measuring thread diame~er are taught in Reish 3,~32,935 ,5 S~MMA~V OF T~E I~E~TTON

The foregoing problem is overcome by measuring inspection apparatus wnich incor?orates the invention so as to provide for the measurement and tolerance inspection of all or the foregoins ~arameters of pipe .hread This is accomplished bv a sincle measuring device, or tool, comprising an assembly of ` 125~3~

probes and transducers It is thus an object of the lnvention to provide a measurement tool which is readily a~ached to a ?ipe thread to provide a set of readin~s of the foregoing parameters arter which the tool is readily deiached from the pipe to permit use of the pipe Such readings can be taken simultaneousl~ T~e tool is able to take a ~ultiplicity of thread measurenents within the confines of one instrument The tool also has the advantage or taking a wide range of pipe sizes and measuring both internal and external t;~eads The tool is capable of very accurate readings without 2 good - ceal or operator experience since it is an automatlc system once properly set on the threads and ac.ivated -~5 and is a ~hands off n sys~em This is because the o~erator is not reauired to have direct interac'ion with the sensor assembly during the takins of measurements In fact, the operator need not have any direct interaction with the tool as a whole, once ins.alled and activated, during the measurenent phase~
Fur.hermore, the pipe being measured does not need to be in a horizontal position for reliable readin~s since ~5~3~

it can be measured in situ, or in its existing position.
In accordance with the invention, the neasurement tool comprises a palr of ar~s configured ; as jaws or gripping the pipe or coupling, each arm having a handle on its end. One of the jaws contacts - ~ the outside surface of the threaded portion of a pipe . ., or coupling while the other jaw contacts the inner surface of the pipe or coupling. The tool is readily held Dy its handle and tne jaws are reacily opened and closed to facilitate manual attachment and detachment or the tool from the thread being inspected.
In one embodiment, the tool incl~des an assembly of sensors and probes 'or cetectins the "t.5 positions of portions of the pipe thread. The sensor assembly is mounted on one of the jaws which also serves as a base ror an inclinometer. The second jaw pivotably connects with the first jaw and terminates in a pair of contacts or legs which are placed against the ~o other surface of the pipe wall to secure tne tool rrom wobbling. The first jaw includes a pair of contacts or legs which are spaced apart in a direction parallel to ~54~3~

the axis or the pipe being measured so as to secure the tool from any rocking motion relat~ve to the pipe or coupling. The two legs on the first ja~ and the two legs on the second jaw work in collaDoration to assure s stable support of the tool on the plpe.
Average tnread taper is me2sured bv the use - of an inclinometer that is mounted on the first jaw.
Ta~er measurement requires that ~-~o measurements be taken on the pipe thread; a first in the vicinity of the top of the pipe thread and a second in the vicinity of the bottom of the pipe thread. These two readings of the inclinometer are then subtracted .^rom one another to provide the true taper of the thread. As is well kno~n, such ta~er facilitates the insertion or the ,~lS threaded end~portion of a pipe into a threaded coupling. Proper tolerznces of such taper alas in the fitting of the pipe to the couplins.
Thread height error is obtained by a set or probes which comprise rod-shaped members slidably mounted within a cvlindrical housing for movement perpendicular to the longitudinal axis of the pipe.
The probes are pointed for lnsertion into the troughs ~25~

of the threads. The probes are connect~d with trznsducers which measure such motion. In addition, each probe is moun~ed by a slide to the base of the rirst jaw so as to permit lateral, or transverse, motion in a direction generally parallel to the axis of tne pipe îor alignment of the terminus or tip of 2 probe with the low point of a trough. 3y use of more than one of the heisht measuring probes, it is possible to obtain a plurality of such measurements simultaneously for 2 more accurate determination of the thread helght at various s~aced intervals along the thr aced length.
Additional probes are mounted by slides to the base of the first jaw for bo~h longitudinal motion . .
in a direction normal to the axis of the pipe as well as transverse motion in a direction parallel to the axis of the pipe. These additional probes are employed with transducers for measuring the transverse motion so as to obtain the value of t~e lead error of the thread. The probes utilized in tne lead error measurement are terminated in ball (spherical) contacts which set within the troughs of the thread. The legs ~2S~

which support the first jaw along the thread are provided with ball contacts for inser~ion within the thread troughs. To this end, one oî these legs is ~ounted in a sliding fashion to the first ~aw so as to accommodate and lead error that misht exist between these threads.
The non-llnearity of pitch line of the thre2d is obtained by the use of probes displaceable in a direction normal (or radial) to the axis of the pipe which are terminated in ball-type contacts~ For this purpose, it is advantageous to employ the two end legs for providing reEerence values of height at the ends of the base of the .irst jaw with the probes Ibeing utilized to provide intermediary values of ~adial displacement. Transducers are used to sense the . .
displacement of the probes in the rzdial direction to provide a set OL electrical sisnals representing the deviation of the pitch line from a straight line drawn between the two end legs. Such deviation is most useful in determining whether the thread of the pipe and the thread of the coupling will mate properly, or whether there will be high spots ca~sing binding or low ~ll;25~g~3~

spots causing too loose a fitting with the ensuing loss of integrity and leakage.
A further eature in the cons.ruction of the assembly of the probes is the ln.erleaving of the positions or the height error measurement probes with the lead error measurement probes within a plane containing the axis of the pipe so as to provide fo- a better distribution of the measure~ent sites for each of the roregoing measurements.
~o facilitate the ensuing disclosure of the invention, the invention wi;1 be described with reference to taking measurements principally or the external thread of a pipe. However, it should be understood that the tool is not limited to external ~'5 thread application. The tool is equally applica~le to taking the same measurements on internally threaded pipe. Indeed, it is considered an important aspect of the tool that it can be used randomly ror measuring internally or externally threaded pipes without any change whatsoever to the tool.

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- 9a -According to a broad aspect of -the present inven-tion there is provided a portabl.e, automatic thread inspec-tion tool for measuring a plurality of parame-ters on a pipe thread and the like in situ irrespective of whether the thread is internal or external to the pipe. The tool comprises frame means adapted to be readily installed over the wall of a pipe from the pipe end~ Means is l.ocated on the frame means for generating a first signal representative of the thread height error. Means is also located on the frame means for generating a second signal reresentative of the thread lead error. Means is located on the frame means for generating a third signal relating to the average taper of the thread. Means is associated with the frame means for receiving the first, second and third signals and generating a displ.ay of the thread height error, thread lead error, and average thread -taper rela-ting -to the thread being measured.

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~ F pESC~I TIO~ ~F T~E D~

The aforementioned zspects and other eatures of the invention are explained in the followlng description taken in connection with the accompanying drawing wherein:
Figure 1 is a stylized view of the measuring tool of t~e invention shown attached to the threaded portion of a pipe, and being connected to electrlcal circuitry for processing the signals received from the tool;
Figure 2 is an enlarged frac~entary view of the tool of Figure 1, ~i~ure 2 showing a detailed arrancement of the components of a sensor assem~ly of ~-i Figure l;
Figure 3 is a sectional view of ~ointed probes 28C and 28E used in the thread height measurement including a transducer, the probe also being shown in Figure 2;
~igure 4 is a schematic illustration of the ball probes, such as probe 28D, used to measure the lead error, cumulative lead, and non-linearity of the .. . . . .. . . . ..

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pitch line.
~igure 5a is a schematic lllustr2tion of the probes on the thread area of a pipe similar to Flgure

2, but in simpler form.
s Flgure 5b is a chart showing the various LVDTs used in the tool shown in ~igure 2.
Figure 6 is a sche~atic illustration of the average taper measurement.
Figure 7 is a graphical lllustration of an example of a theoretical pipe thre~d profile depicting various as?ects of the thread.
Figure 8 is a graphical illustration of the same thread profile show in Figure 7, but also de~icting z ball type probe seated in tbe trough of t~e thread.
, ~igure 9 is a graphical illustration or a theoretical pipe thread profile showing four intervals of measurement used to aetermine if non-lineari'y of pitch line exists.
Figure 10 is a graphical illustration, (without the thread being shown) of the same four intervals of measurement as in l~igure 9, but in an , . .. ~

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actual pipe wherein there exists pitch line non-linearity~
Figure ll i5 a chart showing sample calculations of average taper, interval. taper, lead error, non-linearity of pitch line and thread height error.
Figure l~ is a schematic illustration of an instrument to assure proper placement of the tool in th e pipe.
Figure 13 is a schematic illustration of rragmentary portions of the pipe and tool showing the support arrangement of the tool when installed on an externally threaded pipe.
Figure 14a is a schematic illustration of the ~5 tool and pipe in Figure 13, but viewing it from the end of the pi pe .
Figure 14b is a schematic illustration of the same tool as in Figure 14a, but installed on an internally threaded pipe.
Figures 14c and d are side by side views.
similar to Figures 14a and b, respectively, showing that there is no change of distance bet-~een the 1st jaw ~ 3~

and prohes in using the tool for external and internal threads.
Figure 15 is a schematic illustration of three styles of tool that will cover practically all 8 S round casing pipe sizes.
Fisure 16 is an abbreviated block diasram of the signal processor sbown in Figure l.
Figure 17a shows the standoff system of the tool when the stando~f ball probe falls within the established range of the standoff mechanism.
Figures 17b and c show the standoff system o the tool when the standoff ball probe falls outside the established range of the standoff mechanism.
Figure 18 shows a sample printout from the thread measurement system.

Figure l shows a stylized view of a thread measurement system 20 for measurement of th~
characteris~ics o~ the thread 22 of a pipe 24. The system 20 includes a measurement tool 26 which

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incorporates the inventlon and co~prises a set or probes 28 which contac~ the thread 22 ror measuring tbe thread characteristics. Also included in the sys~em 20 is a cor.sole 30 comprising a display 32 which ~resents s inrormation such as the characteristic being measured and the value of the measurement under control of push buttons of a keyboard 34 on the console 30. Also included in the console 30 is a signal processor 36 which is electrically connected via cables 37-~8 to the tool 26 for extracting data from the sisnals detected by the probes 28. The aata is coupled from the processor 36 to the display 32 for presentation to an operator of the system 20. A printer can lalso be coupled with the console to create a hard copv record of the mezsurements. A sample record produced by such a prin.er ln conformanc~ with the measurements or the various parame.ers as described hereinarter is shown in Figure 18.
The tool 26 measures the following characteristics of the thread 22; the taper, the lead error, the height error, and 'he non-lineari.y of the pitch line. Taper is the increase in the pitch diameter 33~

of the thread, in inches per foot, me2sured within an axial plzne of the pipe 24. Lead is the distance r^rom a point on a thread turn to a corres?onding ~oint on the ne~t t:-~read turn measured in an axial ~lane of the S pipe 24 parallel to ~he longitudinal axis or the pipe.
Height is the distance between the crest and the root, - or trough, measured in an axial plane of Lhe pipe 24 normal or ~erpendicular to the longitudinal a~is of the pipe. These measurements and others may be taken simultaneously and, furthermore, mav be taken while the Dipe is in situ; that ls, in its existins posi'ion such as being stacked for storase. As mentloned above, this description of the construction and operation of the tool 26 is being presented principally with respect to ! `'5 the me surement of the ext~rnal thread o~ a pipe, it being unders.ood that this description applies in an analogous rashion to the internal thread of a coupling (as shown in Figure l~d).
he tool 26 is formed as a set of two arms which are hinged about a pivot 40 whereby the two arms can grip the thread 22 in the manner or a pair of jaws.
The upper arm or jaw is formed as a base 42 which ~5~

supports 2 sensor assembly 44 and ~n incli~ometer 46, a.nd terminates in a handle 48. The lower arm or jaw 50 terminates a' its back end in a handle 52 opposite the handle 48. -~he front end of the jaw 50, as may be seen in a cut away.portion of t;ne pipe 24, supports 2 ~zir of contacts 53-54 which, in this e~bodiment, have a rounded ror~ and are spaced apart along a transverse plane or the pipe 24 for contacting the inner surrace of the threaded portion of the pipe 24~ A spring 56 is disposed bet~een the base 42 and the lower j2W 50 ~or urging these two together for gripping .he thread 22.
Figure 13 shows oné manner in which the tool is supported for taking measurements on an externally ~l~ threaded pipe. Probes 28 are supported by base 42 and are aligned in a plane on one side of the pipe wallr the thread side, while contacts 53 and 54 (or loading balls) are supported by lower ar~ or jaw 50 of the tool on the other side of the pipe wall, the non~threaded side~ Contacts 53 and 54 are located so as to substantially equalize the load on probe 28A and 28G.
Located between probes 28A and 28G to eliminate any .

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possibility of the tool rocking ~hile measurements are being taken is eliminated.
Figures 14a and b a~e view~ of the tool installed on external and internal pipe threads 24 and 24', respectively. It is seen that such an arrangement of contacts 53 and 54 with the probes has advantages when both internal and externa~ threads are to be measured by the same tool. As seen in Figures 14c and d, the distance D and D' are nearly identical due to the motion of locating support and probes 28A and 28G
in the plane of measuring probes 2aB, C, D, E, and ~.
Referrins again to Figure 1, the overall size of the tool 26 is sufficiently small so as to -be readily carried about by a person measuring the pipe 24. The console 30 can be fabricated as a relatively large, stand-alone console, or, preferably can be fabricated as a miniaturized portable console tnat may be carried about with the tool 26 in a carrying case ~not shown). The system 20 requires only that the person manually attach the tool 26 to the thread 22, and that he sianiry, via the keyboard 34, the values of ; relevant parameters and what measurements are to be presented on the display 32. Such automa'ic opexation of the measurins steps er.ables very accurate readings to be taken each time the tool is used and operator ex?erience does not enter as a factor into such accuracy. In this respect, the tool is a ~hands off n system O
-?; In accordance with the invention, the set of probes 28 extend downwardly from the sensor assembly 44 within an axial plane of the pipe 24 to contact the 1~ thread 22. ~he end ones of the probes (28A and 28G) serve as legs for support of the base 42 and the assembly 44 upon the thread 22 to counteract the force of the spring 56. -A horizontal bumFer probe 58 extends from a transducer 60 supported beneath the base 42 and ~15 abuts the end of the pipe 24 for designating the position of the tool 26 relative to the end of the pipe. Probe sa, which can be similar to probes 28B, D
and F, provides standoff for the tool when being located on the pipe by the operator. The standoff probe determines how far from the end of the pipe the first probe; for example, probe 28A in FigurQ 2, is located.

A de~cription of haw the stand of system oFerat. 5 as the operator places the tool onto a pipe is no~ descrioed~ The operator grasps handles 48 and 52 (Figure 1) and saueezes t~em toaet:~er so as to open jaws 42 and 5Q. The operator then places the open jaws onto the area of the pipe carryin~ the thread to be - .~easured. ~he jaw portion or the tool is placed around the pipe wall, the base 42 of the first jaw adjacent 'he threaded or outside ~ortion of the pipe and the contacts 53-54 of the jaw adjacent the inside wall of the pipe in this e~bodiment. The jaw portion is slipped over the end or the pipe wall by the o~erator until stand off pin 250 contacts the end of the pipe.
Stand off pin 250, which can be a ~air o~
~15 pins as shown in partial cutaway fzshion in Fisures ~, 17a-c, is fixedly mounted to base 42. The stand off transducer 60 and bumper probes 58 shown in a general fashion in Figure 1 can be of any suitable type such as that depicted in Figures 17a-c. For instance, transducer 258 can be an L~DT type similar to transducer 78 shown in Figure 2 which has a corP
attached to probe tip 260, or ball 260, by rod 262.

The transducer 258 is rigidly mounted onto bracket Z56 which in turn is rigidly mounted onto base 420 It is noted that the mechanism and pipe are not necessarily drawn to scale in Figures 17a-c.
In addition to LVDT 258, the stand off mechanism shown in Figures 17a-c also includes a stand off member 252 which is slideable relative to stand off pin 250 as depicted by the arrows. Stand off ~ember 25Z has a pipe contact portion 251 which can be biased by LVDT probe ball 260 generally located on the right side o standoff pin 250 (Fiyures 17a and 17b) as the tool is being placed on the pipe. Stand off membèr 252 is adapted to be translatable through slide 254 which is rigidly mounted on base 42. Slide 254 can be any suitable type such as the slide 215 depicted in Fiaure

4.
As stand off pin 250 approaches the end o the pipe, portion 251 of stand off member 252 is located in a position just ahead, or to the right in 20 Figures 17a-c, of stand off pin 250, being maintained in this position by probe ball 260. Thus, stand off member 252 first contacts the end of the pipe as the .

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operator installs the tool. Then, 2S the o~erator places the tool farther onto the pipe, stand off pln 250 will come into contact with the end of the pipe thereby preventing any f urhter move~ent of the tocl in such direction. Durlns this time, portlon 2~1 of stand of^ member 250 is pushed to the left rela.-ve to the stand off pin and base by the pipe end enabling ~ortion 251 of member 252 to reach the position shown in Figure 17b.
After the stand o~r pin contacts the end of the pipe, the operator releases his grip on handles 48 and 52 allowing the jaws to come together and sfat themselves on the pipe~ As this occurs, the tool's fixed probe, such as pro~e 2~a, seats itsel~ into an ,~
~_j adjacent trough of the thread. If the position or the ball probe 26C falls outside of an established range when probe 28a seats itself in the troush of the tnread, then the operator receives a sign21 to reposition the tool. In this c2se, transduceer lnput data is void and the progr2m stops until the tool is properly repositioned within the measurlng range.
Figure 17a represents the position o, the ~54~3~

standoff mechanism when the tool ls positioned properly. Flgures 17b and 17c represent out of r~nge conditions. The ~z n dimension shown in Figure 17a is the distance Lrom the nose o~ the pipe to the fixed probe 28a resting or seated in a good thread trough.
In the case where out or range conditions exist (17~ &
17c), when the operator repositions the tool, the fixed probe 28a moves accordingly~
As an example of the three conditions shown ]0 in Figures 17a-c, it is assumed that the "Lixed dlmenslon" is 0.500 inches; In Figure 17a, Z is equal to or greater than 0.320 inches and equal to or less than O.S00 inches. In Figure 17b, the standoff mechanism is out of range since Z is greater than 0.500 inches. In Figure 17c, the standor~ mechanis~ is also out of range slnce Z is less than 0.320 inches. All dimensions recited above are approximate.
Upon receiving the signal to reposition the tool, the operator must move the tool either left or right relative to the pipe ~Flgures 17a-c). Assumins the condition shown in Figure 17b exists, the operator must move the tool to the left relative to the pipe.

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As the o~erator repositions the tool, the fixed ~robe will move to the left towards the end of the pipe to seat itself, such as in the next trough. In so doing, the tool, base 42 and stand off pin 250 move to tr.e lert from the position shown in Figure 17b to the position shown in Figuxe 17a.
As stand off pln 250 moves to the left, the LVDT which biases ball tip 260 to the right keeps stancl off me~ber 252, particularly portion 251, in contact with tne end of the pipe~ There is surficient stroke in the LVDT to accommodate probe 28a moving one full thread spacing. The position that ball tip 260 reaches 25 the tool is shifted to the left to seat th-e fixed ~robe in the trough is measured by the core of the LVDT
258. This determines how far from the end of the pipe the fixed probe, such 25 probe 28a, is located.
As the fixed probe seats itself in the trough, the other probes also seat the~selves in adjacent troughs and contacts 53-54 (Figure 1) come into contact with the other side of the pipe w211. At this time, the tool is fully installed on the pipe in a proper manne~ and the operator activates the electronic ~;~5~3~

control unit to take the thread measurements which may be printed out of a printer in the hard copy form, e.g., paper, shown in Figure 18.
Figure 2 shows an enl2rs2d view or one embodiment or the sensor assembly 4~' previously described with reference to ~lgure 1. In this embodiment, there are seven probes which are further identified by the legends A-G~ The probe 28A is the end probe fixed in position on base 42 and the probe 28G is an a~ially movable end probe (moves senerally in the direction of the pipe a~is), these t~o pro~es serving as supporting legs as was noted with res?ect to Figure 1. Probes 28A and 28G co~tact the threads and, although shown as end probes in Fisure 2, can be i~ located in any convenient position relative to each other and relative to the other probes on the tool as long as they can provice their intended sup~ort function. The probe 28G is secured to the base 42 bv means of a slide 64 which permits a~ial displacement in a general direction noted by the arrow. The displacement is cenerally in the axial plane o~ the pipe 24 and slides suitable for use as the slide 64 are 3~

available commerci211y The probes 28A and 28G are provided with ball points 66 to facilitate location of the probes 28A and 28G within the troughs of the thread The slide 64 permits the probe 28G to be displaced sideways permi.ting alignme~t of the prooes -~- 28A and 28G with the precise spacing actuallv existlng between troughs of the thread 22. Thereby, the probes 28A and 28G can serve as less for securely supocrting the base 42 and the assembly 44 upon .he thread 22 The assembly 44 further comprises an ~?oer deck 68 supported by posts 70 upon the base 42 T~e probes 28B-F pass through enlarged apertures 62 in both the base 42 and the deck 68. The probes 28~-F are `1S supported by slldes 64 disoosed in alternating fzshion upon the base 42 and the deck 68, this alternating arrangement providing space for impl2cement of the slides 64 among the probes 28B-F. Each of the slides 64 permits sideways movement of their resoective probes 28 while holding the housings 72 of the respective probes 28 against ver.ical motion rel~tive to the base 42. Each of the probes 28~-F include an extensible rod . . .. . , . ..... . . . . ; ... ~ .... , . .... ,.. ,,, .. .. . .~,, ,. ~

~5 whicn can move vertically within the respective housing 72 for enc2aement of the probes wi th ~he thread 22.
The tips of all the probes shown in the embodiment of Flgure 2, with the exception of prooe 23A, can move in the X direction. The tips of all the probes of Fisure 2, with the exception of probes 28A and 28G, can also move in the Y direction. The amount o~ tip movement in the X direction is measured for probes 28B, 28D, 28F
and 28G~ The amount of tip movement in the Y direction is measured ror probes 28B-E'.
The probes 28B, 28D and 28F are each provided with the ball points 66 so a5 to be centered within the troughs of t~e thread 22 at the pitch line. mhe probes 28C and 28E are provided with retractable points 76 (to be descri~ed further hereinafter) for contacting the root, or ~ase, of the respective troughs upon making contact with the thread 22. The sli~es 64 permit the points 76 to be displaced sideways or parallel to the axis of the pipe so as to find the roots of the thread 2C 22.
The assem~ly 44 further comprises a set of tran.ducers 79, individual ones o~ which are connected ~5~3;~

to respective ones of ,he probes 28~, 28D, 28F and 28G
for de.ecting the amou~t o. sidewavs displace~ent and, tnerefore, providing data as to the precise locatlon or^
each or these probes. The transducers 78 and 79 can be of any suitable type, such as an LVDT or Linear Variable Differential Transformer which is a standarcl - device used in measurement applications. The AG Series transducer sold by Sangamo Transducers of Grand Island, N.Y. is one type suita~le for this application. They provide electric signals via lines 7aa and 79a to the processor 36, these signals being linearly related to the displacement of the respective probes 28 aenerally in or perpendicular to the axial plane of the pipe 24. I
The transducers 78 and 79 are shown schematically in Fisure 2. Transducers 79 may be mounted in stagcered rashion upon the base 42 and the ceck 68 so as to provide space for all the transducers among the probes 28 and the slides 64.
All of the probes 28 are disposed along a common axial plane wnich preferably bisec.s the distance between the two contacts 53-5~ (Figures 1, 13, and 14) to provide for a stable mountlng of the ... . . . . .. . .. .

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assembly 44 upon the thread 22, the contacts 53-54 preventing a lateral rocking while the leas (probes 28A
and 28G) preventing a longitudinal rocking. Each of the probes 28B-F contain electric leads which fan into s the cable 38 for connection of the signals of these probes to the signal ~rocessor 36.
~ lith reference now to FiSures 3, 4, and S, there is provided a more detailed description of the configuration of the linear displacement transducers employed in the transducers 78 and 79 as well as in the probes 28B-F. The construction of probes 2aC and 28~, which measure thread heiaht is shown in detail in I Figure 3. The probe assembly has a floating tip 202 which seats into the root troush of the thread :5 assembly. As the tool is placed on the pipe thread, reference surface 204 rests or seats itself on the top or crest OL the thread. Surface 204 is on floating thread crest standoff collar 206.
Collar 206 is mounted on LVDT case 208, such as by ~he screw shown, which contains LVDT core 210 which generates a sisnal indicative of the thread height error. Tip 202 is connected to the LVDT core S~ 3~

210 so that after collar 206 is positioned on the thread top, the tip seats itself in the t:hrea~ trough.
The tip's position locates the LVDT core relative to i.s case and generates the thread heisht error signal, a zero sisnal indicating that the thr~ad height h2s no error therein.
The LVDT case 208 is slideaDly mounted on an LVDT suide 21~, such as bv a slip fit, so that as the tool is placed on the pipe, collar 206 adjusts itself r~lative to guide 212 to come to res. on top o~ the threads. Guide 212, which is mounted on the frz~e of the tool, such as to base 42 or upper dec~ 68, has a hollow housing 211. The guide does not mbve in the vertical direc.ion relative to the base 42. The LVDT
oase 208 is securely mounted to bearing 209 which is a~le to ride up and down inside the hollow of the guide. Gulde 212 also contains a spring 207 which biases the LVDT case 208 downward towards the pi?e, the 2Q upoer and lower limits of the case's movement, or its stroke, being limited by dog 205 in slot 203 of the guide. S?ring 207 is held in the guice by aajus.able s~rinS bushing 201.

. . . . .. .. . .

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-Figure 4 is an illustration of the probe confisuxation that is used for probes 28 B, D, &
which are ball probes as opposed to pointed probes~
Here, the LVDT case 211 is securely mounted against movement in the vertical direction to the frame of the tool, such as on base 42 or deck 68.- The probe ball is attached to the LVDT core 21Q so that the position of LVD~ core 210 relative to LVDT case 211 is dete~mined by the position at which the ball comes to rest on the pipe. This position generates a signal, as in Eisure 3, which indicates the pitch ].ine error, a zero signal meaning that the pitch ~ine has no error~ The connecting member above the ball has a protective cover 214. ~ .
Figure 4 also illustrates the manner in which the probe is mounted for sideways mo-~ement, if needed, to locate ball 213 into the trough of the thread. Ball slide or positioning assemblies 215 are fixedly mounted on the frame of the tool, such as on deck 42 or deck 68, so that such motion can be accomplished.
Any suitable ball slide or positioning slide assemblies can be used for this purpose such as those :~S~

supplied by Del-Tron Precision, Inc., of BrookLield, CT. In the configuration shown in ~isure 4, the slide assemblies 215 are mounted onto the frame of the tool to provide sideways (horizontal) motion t:o the probes while LVDT case 211 is fixed to a member 42a which is mounted on the slide assemblies 215. In this manner, - the LVDT case 211 is restrained from vertical movement relative to tne frame of the tool, but can adjust itself horizontally or seneral~y sideways of the frame to enable the probe tip or ball to seat itself in the trough of the thread. A similar arrangement for sideways movement can be used for probes 28B-G.
Ball pro~e ~8A is fix~d to~the frame of the tool, such as to base 42 25 shown in Figure 2, and its :`'5 ball 66 is not permitted to move up or down or sideways relati~e to the tool since, i~ addition to being a support leg, it provides a fixed reference position ~or the tool when it seats itself into the trougA of a thread. Ball probe 58, which acts as a bum~per probe, as described earlier, is connected to an LVDT unit which is also tied into the sianal processor 36.
The standoff pin places probe 28A into the ~5 vicinity of a full thread such 2S the first full thread on the pipe as the tool is placed on the pipe by the o-perator. The ball of probe 28A will sl.ide down into the actual location of the trough of the first full th~read as the operator releases his grip on the handles 48 and ;2. Since probe 28A is fixed to the tool ~ithout any movement permitted theresetween, as ball 66 o~ probe 28A is shifted sideways to seat itself in tbe t~ough of the first full thread, it alsc shifts the entire tool with it.
Once probe 28A is properly seate~, LVDT 60 ls relied upon to provide an accurate reading of standoff;
that is, the distance beltween the end of the pipe and first full thread. Also, as the operator releases his ( grip on handles 48 and 52, the other probes 28B-G seat themselves in the troughs of threads, each being able to move sideways as needed to seat properly in the adjacent thread trough: by virtue or its slide positioning assembly Referring again to Figures 1 and 2, it is .seen that the tool also has an inclino~eter located on bzse 42. This is used to deter~ine average thread ~...................... . .

.

taper. Any suitable type of inclinometer may be used for this purpose; for instance, an inclino~eter from Transducers and Systems, Inc. of Branfora, CT whlc~ is c~pable or operating in u~right and inverted positions.
SFigures 5a & 5b are intended ~o be used together ror the puxposes of the followina 2escription.
Figure 52 is a very simplistic illus.ration of the tool shown in Fisure 2, but emphasizing the probes, LVDTs and inclinometer. It is to be understood that the 10transducers 1, 2, 3, S, 6, 7, 8, 9 & 10 of ~igures 5a &
b are equivalent to the transducers (LVDTs) 79~, 79D, 79F, 79G, 78B, 78D, 78P~ 78C and 73E, respectively, in Figure 2. Transducer 4 in Figures 5a & b is equivalent to LVDT 60 in Fisur2 1. Inclinometer 11 in Figures Sa '5 & b is eauivalent to inclinometer 46 of Figures 1 & 2.
The relationship between t~e transducers and probes in the tool and the various aspects of the thread being measured are clearly associated in Figure 5b. It is seen that all of the transducers are of the LVDT type in this embodiment. It is also noted that transducers 1-3 measure the lead error, ~1~ X2 and X3;
transducer 4 measures the s~andoff positiont X4;

~5'~3 transducer 5 measures the cumul2tive lead error, X~;
transducers 6~8 measure the pitch line deviation or non-linearity o the pitch line, over four intervals of the thread, Yl, Y2 and Y3; -nd transducers 9 znd 10 measure the thre~d height error, ~1 and ~2. Average taper, I, is measured by inclinometer 11.
Comparing Ficures 3 and 4 to Figure 2, it is noted that the structure of Flgure 3 is used with probes 28C and 28E while the structure of ~igure 4 is used with probes 28B, 28D and 28F. Thus, the reference surface 204 or the collar 206 of the thread height measuring zssembly in Figure 3 contacts ,he crests of the thréad 22 ~hile the point 76 is urged further into the root of the thread 22. The electrical signals of . l5 the transducers 78C and 7aE are operatively connected to probes 28C and 28E and indica.e the dis~lacement of the point 76 relative to the collar 206 and case 208 and, ac.cordingly, the height error of the thread 22.
In .the case of the probes 28B, 28D and 28F, the transducers 84 are more directly supported by the slides 64. The location of a trough of the thread 22, as sensed by a ball point 66, relative to the base 42 is indicated by the output signals of each of the transducers 78~, 78D and 78F of the probes 28B, 28D and 28F, respectively. It is ncted that with respect to the probes 28B, 28D anc 28F, the base 42 serves as a reference plane due to the supporting of the base 42 u~on the probes 28A and 28G.
- ~ A better appreciation of the thread measuring technique provided by the tool in accordance wi~;~ the invention can be had by rererence to Figures 7 to 11 in conjunction with the following descrl?tion. ~11 types or threads can be measured with the tool; for e~ample, pi?e threads, screw threads, helical cams, etc.
~owever, for the purposes or this descriptlon, the measurement techni~ue is ~escribed in conjunction witr.
~'5 8 round thread as set out in Supplement 1 to A~I Std 5B
(Tenth ~dition) "Specification for Threading, Gaaing, and Thread Inspection of Casing, Tubins and Line Pipe Threads, n issued on March, l9aO by the Amerlcan Petroleum Institute, Production Department, ~11 N.
Ervay, suite 1700, Dallas, TX 75201. This Supplement is incorporated herein by reference in its entirety.
Table 2.9, page 11, of this specirication ~z~

contains a grzphiccl 2epiction of 8 ~ound thread profile. Figure 7 depicts the same thread in an abbrevizted graphical form for claritv in conjunction wi,h this disclosure. Threzd taper is defined 2S the increase in pitch di2meter of the thread in inches per foot of thread~ Thread lead is aerined as the distance rrom a point on the thread turn to a corresponding point on the next thread turn measurea parallel to the thread axis and shown as "Xl" in Figure 7. Thread height is the distance between the crest and root normal to the axis of the pipe and 2epicted as "~1 n in Figure 7. Figure 8, which is similar to Fisure 7, shows hcw the ball probes used in the tool interact with the threads when placed in the .roughs of the -; threads for taking a measurement. The size or the ball is matched to the type of thread being measured and the pro~e contacts the thread flank on the pitch line as shown.
The measurement of pitch line deviation is possible by the tool in addition to taper, lead error and height error measurementsO Pitch line deviation or non-linearity of pitch line, is defined as the 4 b~

deviation of the pitch line from a s~-aisht line drawn be.ween the ends of the interval of tnreacls mezsured by the tool. From top and bottom pltch line or diameter ce~iation readinas ta~en by the probes on the tool, a profile of the pitch llne ca~ ~e developed. No other method of 2ccomplishins a true prorile of the pipe pi~ch line is known other than ro~atlng the pipe on a contour profilometer which is impractical in ~ost cases. As shown in Figure 9, a nypothetical 8 Round pipe having external threads is being measured by the tool. In this case, the tool is shcwn as havina four sesments or intervals over which the pitch line deviation is being measured, the intervals being designated 1st through 4th. Each interval is one inch ~s in length ~n2 since, in this embodiment, ~ round .hread is being measured, there are eight full threads in each interval.
Figure 9 depicts a theoretical condition for the pitch line; that is, there is absolutely no pitch line deviation and the pitch line is linear. Figure 10, on the otner hand, depicts the same three intervals being measured in a pipe thread wherein there is pitch .. . . . .. ~ . , - - .

~'~5~3 line deviation. The ~'theoretical7 or perfect pitch line is also shown in ~igure 10 for reference purposes.
In both Fisures 9 and 10, the t~o readinys carried out by the tool are on the top and bottom of the pipe and ~re so marked "top reading~ and "bottom readingn~ The tool readings obtained from the four intervals aetermine the non-linearity of the pitch line and can create a profile of the actual pitch line which Figure 10 essentially represents.
One tool reading ma~ be taken for lead errorj thread height error, and pitch line deviation at any circumferential location on the pipe measured. When pipe thread taper is to be also measured, there must be .wo readi!ngs taken. The second reading is angularly .5 displaced from the first. For instance, the first and second readings can be generally opposite one another.
Figure 6 depicts the approach of measuring average taper, t~e pipe being measured in this embodiment having an external thread. The pipe length does not have to be in a hor1zontal position for accurate measurements to be taken. The tool can be placed on the pipe in any convenient position to take ~2~3 -measurements. The tool, f or example, may be installed on the pi pe in the vicinity of the top dead center and bottom dead center positions, (the 12 h 6 o' clock positions, respectively) of the pipe end if measurement of average taper is desired. For instance, the proper positions could be plus or minus 10 degrees, and preferably plus or minus 5 degrees, of top and bottom dead center positions. An instrument for this purpose which can be made part of the tool system is shown schematically in Figure 12. Such an instrument includes sensors which indicate that the instrument is within the proper measuring position on the top and bottom of the pipe. The sensors can be four mercury switches, switches 216 and 217, to control the top reading position of the tool and switch 218 and 219 to control the bottom reading position of the tool. Any suitable type of switch can be used for this purpose;
for instance, mercury switches having the part number 3677 supplied by Durakool, Inc~
The angle of the switches relative to the tool, such as the angle from vertical, can be made adjustable as shown in ~igure 12 to precisely control :
,i,, .~

~;~S~3 the proper measuring positions of the tool. on the pipe.
Each switch has a movable contact 220 that only completes the circuit through the switch when tne movable contaGt hits fixed contacts 222a or b.. ~hen this happens, the 9 volts coming into the switches ~asses through the switch wherein contact was made and carries the voltage to a display, such zs LEDS 2Z1, 'o li~ht them ~p and indicate an improper positioning of the tool. Thus by properly setting the angle or the switches on the tool so that when the tool is o~tside the Zesired range of ~ositions for pro~er m~asurement, such as when a top reading is desired, the LED will be lighted-by eitner switch 216 or 217 and the o~erator can be automatically notified that a repositioning of

5 the tool is required.
As can be seen from Figure 12, as the tool is inverted between the top and bottom readings, switches 216 and 217 become inactive and switches 218 and 219 become active. When the tool is switched from.bottom to top position readings on the pipe, switcnes 218 and 219 become inactive and switches 216 and 217 become activa~ed in controllins the LEDs.

.

The tool, when seated on the pipe thread, is supported i~ position on the thread side bv probes 28A
and 28G basically. Since probe 28A is fixed rela.ive to the frame, the reading on the inclinometer depends upon the seating of probe 28G. As shown in Fi~ure 6, the inclinometer is re~d while the tool is in ~oth the top and bottom positions in order to provide an average taper measurement. In the top position, the inclinometer generates a signal equivalent to its angle relative to the horizontal or parallel to the axis of the pipe shown as "A" in Figure 6. Then, in the bottom position, it generates a second signal again equivalent to its angle relative to the horizontal or parallel to i the axis of the pipe and shown as "B~ in the same .5 Figure. These signals are sent to the processor 36 where by are subtracted from one another to thereby produce the average taper of the pipe thread. The computation leading to the average taper T(o 0) of the pipe thread is shown in the first column of Figure 11.
The interval taper is also calculated according to Figure 11. For example, the actual taper over the 1st interval is designated as T(l,l) + T(2,1). It is ... .. , . ., , . . . . . ... . , .. . .. .,., - . . . -~5~3'~

calculated by the signal processor by taking the reading of transducer 6 and dividing by unity minus the reading from transducer 1 and this quot:ient i5 then added to the average taper T~o 0) As mentioned above, S a zero reading on the transducers, in this case transducers 6 and 1, is indicative that there is not : any error in these readings and, thus, the 1st interval taper would equal the average taper. It is understood that the number of intervals may vary in accordance with specific measurement requirements.
Either or both of the transducers could indicate a positive value error or a nesative value error. For instance, referring to IFigure 10, transducer 6 would indicate a positive value greater than zero since the actual taper for this 1st interval is greater than theoretical or zero value. Conversely, in the 3rd interval, transducers 8 would indicate a negative value less than zero since the actual taper for the 3rd interval is less than theoretical or zero value. This is indicated by ~Y(l 3~ < o" ~d "Y(2 3) '' at the actual values. For reference purposes only, Figure 11 also shows the theoretical values for each ~25~3~

interval.
The chart in Figure 11 also shows the calculations for cumulative lead, lead in each of the intervals, pitch line non-linearity and thread height.
It is seen that the reading of transducer 5 gives a cumulative lead value; the readings of transducers l, 2t & 3 develop the leads for the 1st, 2nd, 3rd and 4th intervals, respectively; the readings of 6, 7, and 8 develop the pitch line non linearity; and the readings of transducers 9 and lO develop the thread height, all in conformance with the computations shown.
In order to conform with API specifications, all measuring intervals must be located on one inch cen~ers. Thread depth transducers should be located on i ~ 15 the center line of each interval but also have one inch intervals. It has been found that by using the measuring concept as disclosed herein, the complete range of pipe sizes (for instance, all sizes of 8 round casins with the exception of a few odd sizes), can be readily measured by the use of three such tools.
j Figure 15 shows the three styles of tools that can ; accomplish such a wide range of pipe sizes.

., .

.. . . . .. .......... . . . .

~z~

-~ -i.h reference now to Figure 16, there is shown a sener21 description or the signal processor 36.
The processor 36 includes a computer 108, a signal conditionlng unit 110 a multiplexor 114, and an s analog-to-digital converter 116.
Any suitable control system and sisnal processor can be used in conjunction with the tool.
For instance, the system can include a seneral purpose microprocessor in the electronic module, which together with suitable software such as that in the Ap~endix herein, will carry out all necessary calculations and control functions. The entire system lncluding the electronic module, tool, dis~lay and printer can be ma2e portable and battery operated, if desired~
:- 5 The conditioning unit 110 receives electric signals from the tool ~6 via cables. Figure 16 sho~s cables 37, 38, 113, for example, however, it ls understood that other cables for the described signals as well as additional lines for other functions may be added. These signals, after conditioning, are multiplexed by the multiplexer 114 before transmission to the computer 108. The converter 116 converts the ~l~5~3~

signals of the multiplexer 114 from the analog formzt, as produced bv the tool 26, to a digital format for rurther processing by the computer 108.
The computer 108 can be a special purpose S computer specifically designed for co~bining the signals of the various probes 28, the transducers 78 and the transducer 60 for outputtins t~e desired dat~
on the display 32. ~owever, as hereinbefore mentioned, the calculations performed by the computer 108 can also be accomplished by a seneral purpose computer, or microprocessor, as will be described hereinafter by means of a flow chart suitable for such microprocessor.
The thread characteristics of lead error, height error, and deviation of diameter are ?rovided by :~ combining signals of the robes 28. The position of the base 42 relative to the end of the pipe 24 is communicated from the transducer 60 via a cable 118 to the processor 36. The construction and operation Qf the transducer 60 is the same as that described above ~itn respect to the transducers 79. The inclinometer 46 is used for the measurement of the thread characteristic of taper.

~25~3;~

The computer 108 has the standard components including timing and control units, address genecator, memory, electronic swi.ches shit registers subtractors, and 2verasing units. In operation, the signal processcr 36 receives input signals along the ca~les 37, 38 and 118, and outputs power for energizing ; the input windings of the various transducers and any reference input terminals for detection of the magnitude and sense of the voltage from the outputs of one of the transduce~s. Conditioning unit 110 can include band pass filters ror removlng any noise which may be present on a transducer signal.
The multiplexer 114 is operated under control of the timing unit for electronically sampling 1~ successive ones of the transducer signals and for outputting these signals serially to tne converter 116.
Each of these signals has a magnitude and a sense, and each sample is then converted by the converter 116 to a digital format containing the amplit~lde and sense aata.
The digital signals or the converter are outputted to the memory 1~4 of the computer 108.
The memory and other components in the ~25~6~3~

~7 computer operate under control of the computer unit 120, as required, Eor receiving digital signals and for output-ting digital signals. To measure the pitch line deviation and develop pitch line non-linearity, of the threaded portion of the pipe 24, the signals o:E the probes 28B, 28D and 28F are taken into the signal processor for computation which is then shown on the unit's display 32.
To provide the thread height, signals from the probes 28C
and 28E are likewise taken into the signal processor for computation, the results of which are also displayed in display unit 32. For measurement of the cumulative thread lead, the signals of transducer 79G coupled to the probe 28G are sent to the computer for processing and display.
It is noted that probe 28A serves as a reference point.
For measurement of the taper, the signal from inclinometer 11 is fed to the signal processor.
A more general form of test routine can be accomplished by use of a general purpose computer by use of the flow sheets and tabulations presented in the Appendix at the end to this specification. The ~259~

~8 material presented therein is in standard format and, accordingly, readily understood. Accordingly, this material will be reviewed briefly. At the beginning of the flow sheet, a keyboard entry would indicate whether a calibration measurement is to be made or whether the operation is to proceed for actual measurement.
Calibration is employed, such calibration being accomplished by attaching the tool 26 to a calibrated gage and, thereafter, noting the transducer measurements presented on the display 32. These latter results are also stored in the memory of the computer for comparison to the actual measurements. This, in effect, amounts to a zeroing of the tool 26 so that the discrepancy between the standard values and the ~actual values can be attained.
Proceeding with the flow chart in the Appendix, the system contemplates the use of a printer (not shown) which operates in conventional fashion for outputting information from the computer. The keyboard ins-tructions are then followed as to whether the instructions to the tool 26 are to be printed out or not.

12S9LC?3~

~ hereafter, the program continues with the inputting and storage of data. Then a decislon block decides whether the last data has been entered or not~
In the event that more data is to be entered then ,he S process is repeated for the lnputting of further data~
If the last parameter has been entered, then the process contlnues to identify the nature of the thread, if a pipe or if a couplin~. ThereaLter, identification number may be applied and input parameters printed out.
During the ensuing steps in the flow chart, symbols are presented so as to simpliry the amount of legends presented in each box of the flow c~art. The symbols are identified in the table following the flow ~ chart in the Appendix. The computer can operate with the tool 26 for reception of the raw data and for calculation of the desired thread characteris,ics.
All of the patents and publications referred to in this description are incorpora.ed by reference in their entireties herein. It is to be understood that the above aescribed embodiment of the invention is illustrative onlirr and that modifications thereof may occur to those skilled in the ar.. Accordingly, this . ~5~3 Lnvention is not to be resarded as llmited to the embodiment disclosed herein, but is to limited only zs defineà by the appended claims.

51 ~l2 APPENDIX

(. .
~ ., TH 2EAD INSPECTION FLOW CHA~T ~ z54433~

OP'RATIONAL NoTE5 1. Bcfor~ stCrt-uD select ~A~ ~r 9' tool mode.
D I S ~ Y
SQ~CT ?qOr~cq roo~ 2. For complrrt~ API Insoectiorl, tool ~A~ must ~o xlec1ed firsl.
.i - wAlr FO~ J~ 700L
!~ SELSr t r~EY TO a PFlESSen 3. Aftor oli pcrrlmeter3 hrJv~ ~en ^ntered, if 'A~/ 9' tool ~witrn is ogslea S-qOUt O dUTrRES3 prr~5rcrn ~ecu~icn 50c~ to(3 I
If R~'iET '~rr i~ pr~sed, ;~rc9r~n e~eCutir~ go~rs 10 ( S ~A F~
2 ~ ~ 5. If RE-INSPECT ~y is pressed, prr~grrm exe~utirn g~es 70 (~) E~ll __ _ __ 1 6. rhis module rnu~t hav~r he crJocoility to disoloy inrJividu~l rr:nsc~c:~
/ \ rrocing5, /UOOE\ clLlaq ~TY
< OPTlo)~ > ---~
~ Com~ In~lurJ~-y ¦r ~ L 1~ R ~. T U O O E I T O O ~ C O ~ f F C ~
~ WAIT FO~ 1 r ,~L " r ,~ 5, ~API-~8 r~-clllc~llon~ :llUDI Olr l CO).I~ ;n nOn-VO~ m~mOrr ThO ~
PRINT ~UAL I RESUMe ~EN IJODE OPTION ~UI ~. ~U~DII-d ;.D.~ r.
\OPTION/ ~ ~WITCX la TOGGLEO TO OPEfATE
\~ 1 1 J-ROUND I 9UTTFIESa ;~Lp o! ~IPe SIZE--I ei -r ~1 1 El--¦AUTOilATIC palNTouT Of ~
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L~.T O .~ TA /
~ IINPUT 1~7 /~\ 'I IPIY~ O= COUI~ G7 ~PAqA~6rE;1 3EEN >~
ENTEilED _~
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IIF COUPLINO C= 1 1 ..,_,, ¦ Io=~oENTlFic~TloN NO~ ~
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I IF0R J=Z) Doa T00L A 30T ID~ .
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f~ , . _._J_ ., =-~1 I aL=0 / 015P~AY I
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a h C ,~ Y
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HT~ .0702 HT~ . j0~725 E~ ~1 ~t~ PIPQ/ P1P~ OP~ COUP~
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AL~THONY STORACE r~D ALBERT YANNELLA

FOR: ~READ MEASUR MEN'T'~.QOI~

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STOF~E Al~ L DATA 11 ot-voL,~r~ UEMO~l .. __ . _ <P~ t>~
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p~ r OUTPUT 1 \ /
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~ ' 58 ~lt~S9t~3 Ent~r m-a~ur-d ~ol~ n~s ~z~80 coe~ d~ l~tlon on t~r~ rn~lo~ (TOOi COeFF) Er~ r tool ~cc r;cr ~ no r~
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OISPL~Y
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\ / ~PLAY j USE INCLlNOAtETER
y IP081TIOH TOOL~ ZEiiO GAUaE
_ ¦ OISPL~Y I ~ CONTINUE ~FTEFi iENTER CilANMEL NUMaEFil I EiiTEi;i 1:1 PRESSED
l jl N PU ,T U ~ ? ~ I
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¦ D I S P LA Y~
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l ISTORE ZERO¦
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D13PLiY ¦ use IHCLlNOUETEFt SPAN AOJUST GAUGE
CONTINUE AFTeR
~i ENTER IS P4e5SED
N P U T M i,~1 ~3 1,,z 51 N ( S P ( t ~ - Z D ~ 1 1 ) I ?I 1 :51 ¦ f C,TOft 5~1J 1 1 DISPLAY 1 USE PITCII DLAMETER, 1 . COP~TI!IUE AFTER
L~ E N 7 ~e j't I S P R E S S E D
~i~
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I STCRE LVOT
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ZERO OFFSET Zt!ll ¦
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I ?~USE ENTER Ig PRESSED
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~ SCALE FACTOR SlNh IINPUT U~NI¦ .
_~D .

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SCALe FACTOF? S~N~¦ ( RE I URN~

Y Y
C~

~;ZS9~3 FLOW Cl IART VAR1ABLE TABLE

VARIABLE SIC;NIFICA~CE . D1MENSION
.

A Number of in~ervals on tool A(, ) A(,I) Inclinometer reading Deg.
A( ,2-16) LVDT readings in AT( ) Average Tap r AT = AT(ID) in/in ATF Average Taper Flag ee 8uttress tool error fGctor in 8el Buttress tool error factor in/in E~uttress gross error fcctor in ~gl auttress gross error factor in/in C 0 if pipe I if coupling CAN Coefficient Access Number CL( ) Cumu lat ive Lead in CLF( ) Cumul~tive Lead Flag CLT Cumulative Le~d Tolerance in D(, ) Diameter de~iation I in DA DiGmeter Actual in DZ Diarneter when Zeroed !
~D Delta Diameter in ,: The number of channels that the tool uses El El dimension from API sa in e Tool error factor in el Tool error fc~ctor ~ in/Tn ~RL Flashing red light 0-off l~n GL Green light 0-off l~n g aross error foctor in gl gross error factor in/in H(, ) (thread) Height in HF(, ) (thread) Height Flag HTH (thread) Height Tolerance High in HlL (threod) Height Tolerance Low in ID Current Identification Number IT( ) Interval Taper in/in ~5~

ITF( ) Interval Taper Flag J Incrementql subscript I for top of ~ipe 2 for bottom of pipe L(, ) Lead error in LF~, ~ Lead error Flas LT Lead Tolerance in Ll Ll dimension from API SB in LIC Ll dimension Calculated - in LIF Ll Flag M Half of Gverage taper in/tn M( ) LVDT Mi I livolt data mv N Incremental subscript meaning channel number or interval P Print option flag û for manuc~l print, I for auto print Re. 8-Rour~ tool error factor in Rel 8-Round tocl error factor in/in Rg ~Round gross error factor in Rgl 8-Round gross error factor in/in RL Red light 0-off l~n.
S~ ) Scale factor mv/in SAI`I SPAN Access Number aO Stand Off in SOZ Stand Off when Zeroed in SP( ) Span coefficient Ceg. or in T 0 for 8-round pipe I for buttress T(, ) Tope~ inlin Tl Temporary Input TTH Taper Tolerance High in/in l~L Taper Tolerance Low in/in Z(, ) Zero offset mv ZAN Zero coefficient Access Number ZD( ) Zero gauge Deviation ~eg. or in ~S~Q3~

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Claims (3)

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

1. A portable, automatic thread inspection tool for measuring a plurality of parameters on a pipe thread and the like in situ irrespective of whether the thread is internal or external to the pipe, comprising:
(a) frame means adapted to be readily installed over the wall of a pipe from the pipe end;
(b) means located on the frame means for generating a first signal representative of the thread height error, (c) means located on the frame means for generating a second signal representative of the thread lead error;
(d) means located on the frame means for generating a third signal relating to average taper of the thread;
(e) means associated with the frame means for receiving the first, second and third signals and generating a display of the thread height error, thread lead error and average thread taper relating to the thread being measured.

2. The inspection tool of claim 1 further including means on the frame means for generating a fourth signal representative of cumulative lead error and means associated with the frame means for receiving the fourth signal and generating a display of the cumulative lead error.

3. The inspection tool of claim 1 further including means on the frame means for generating signals representa-tive of pitch line deviation over a given number of intervals of the thread and means associated with the frame means for receiving the pitch line deviation signals and combining them with the third signal to produce a representation of the non-linearity of thread pitch line.