CA1102847A - Pipe section and coupling - Google Patents

Abstract

IMPROVED PIPE SECTION AND COUPLING

Abstract of the Disclosure This invention relates to an oilfield flow line pipe section having a connector fitted to the end thereof for connecting a plurality of sections together in series.
The section is comprised of a length of tubing having mating male and female threads formed on the tubing adjacent ends thereof for use in connecting sections together. A compressible seal is mounted on the tubing adjacent one end. A seal engaging surface is formed on the tubing adjacent the end which is opposite the compressible seal. The surface has a frusto-conical section shape. The lead of the male and female threads is related to the apex angle of the sealing surface and to the allowable diametric clearance for the effective sealing of the seal for providing effective seal engagement between the seal and the seal engaging surface during at least 360 degrees of relative axial rotation between two connected sections while providing thread engagement whereby interconnected sections can be relatively rotated at least one full turn while still providing a seal therebetween.

Description

1~2~L7 This ;s a division of Canadian patent application Serial No. 292,545 which was filed on 7 December 1977.
BACKGROUND OF THE INVENTION
The present invention relates to improvements in pipe sections having couplings on the end thereof. In another aspect, this invention relates to an improved pipe section having couplings which allow at least one full turn of a relative axial rotation between connected sections while providing effective sealing. According to another aspect the present invention relates to an improved pipe section having indicia thereon for indicating proper engagement of the sections. According to an even further aspect, this invention relates to an improved pipe section having a - required makeup torque for effective sealing which is in the range of application by hand by one worker without the necessity of using equipment, tools and the like.
In the provision of piping systems such as in oilfield flow line pipe applications, it has been common to use pipe sections having threaded couplings on the end thereof for interconnecting the sections to form the system. It has also been typical to utilize pipe sections formed from resin impregnated filament wound materials to form the pipe sections such as is disclosed in the U.S. patents to ~IcLarty, 3,572,392, issued March 23, 1971; Carter, et al., 3,784,239, issued January 8, 1974; and Meher, 3,540,757, issued November 17, 1970. These filament wound sections have proved particularly advantageous for use in an oilfield flow line pipe environment because of their light weight, ability to withstand the pressure ranges of this use and because of their non-corrosive nature.

- 2 -1 28~7 The use of non-corrosive pipe sections has been hindered by problems present in effectively joining the sections of pipe together. One method of assembling the same is to lay the sections of pipe at the place of intended use and then connect the sections by bonding with adhesive.
This method of assembly poses problems such as the necessity of forming a complete bond between the sections to provide an effective seal and the necessity of waiting while one bond is taking place before the next section can be positioned and connected. In addition, these connections are made under less than ideal conditions wherein contamination may reduce the integrity of these connections.
To eliminate these bonded joints, systems such as is disclosed in the above-identified U.S. patent to Carter, No. 3,784,239, have been attempted wherein threaded connections are made to couple the sections together.
The sections using threaded connections also possess problems in that resin impregnated filament pipe sections do not lend themselves well to the use of wrenches. When wrenches are used they tend to compress the pipe, which may result in damage to the pipe that would later cause a failure of the section. In addition, it is sometimes necessary to utilize fittings in the pipe sections such as an elbow to make a right hand turn in the pipe system. It has been found that it is extremely difficult to provide effective sealing between these screw type joints while orientating the fitting in the required direction. One method that has been attempted to alleviate this problem 2~

is to cut a section of pipe and bond an elbow or another type of fitting to the end thereof. Unless this bonding is accomplished after the pipe is installed the orientation of the fitting in the proper direction cannot be assured. In addition, if the bond is formed after the section is coupled the additional risk of contamination of the bond occurs.
Thus, although these resin impregnated filament pipe sections have advantages, they are very difficult to use and install.

SUMMARY OF THE INVENTION
Therefore, there is provided according to one embodiment of the present invention an improved resin impregnated filament pipe section having male and female threaded couplings formed on the ends thereof which can be interconnected by hand.
The present invention also contemplates the use of an improved pipe section in which a connection between sections provides at least one full turn of relative axial adjustment between the sections while providing an effective seal.
In addition, the present invention contemplates the use of an improved pipe section having indicia on the exterior thereof indicating to the worker installing the sections when sufficient engagement of the threads is present.

In accordance with an aspect of the invention there is provided in an oilfield flow line pipe section with connecting means on the ends thereof for conneeting a plurality of sections together in series, having a length of tubing, mating male and female threads formed on said tubing adjaeent the ends thereof for use in eonneeting sections together; a compressible seal means mounted on said tubing adjacent one end thereof, sealing surfaee means formed on said tubing adjaeent the end opposite the eompressible seal means, the improvement whieh eomprises means mounting said seal means for providing effeetive sealing during at least one full turn of relative axial rotation between two eonnected sections.
The present invention taken in conjunction with the invention described in Canadian patent application Serial No. 292,545 which was filed on 7 December 1977, will be described hereinbelow in detail with the aid of the accompanying drawings, in which:

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!I BRI_F_DESCRIPTION OF THE DR~I~INGS
!I The present invention will be readily appreciated by j~those of ordinary skill in the art as the same becomes better llunderstood by reference to the following detailed description when llconsidered in connection with the accompanying drawings in ~Ihich:
! FIGURE 1 is a side elevation view of the improved pipe ¦~section of the present invention;
il FIGURE 2 is an enlarged elevation view of the male or llpin end oE the improved pipe sec~ion of FIGU~E l;
FIGURE 3 is an enlarged sectional view of the female or i socket end of the section illustrated in FIGURE 1 drawn to the same scale as FIGURE 2;
FIGURE 4 is a partial longitudinal section of a l connection between two of the sections illustrated in FIGURE l;
FIGURE 5 is a partial enlarged sectional view of the connected pin and socket ends of two sections of tubing illustrating the threads of the two ends engaged to the point of initial effective sealing; and ¦ FIGUR~ 6 is a view similar to FIGURE 5 illustrating the enos completely engaged.

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~jDESCRIPTION OF THE PR~FER~ED Et~BODIll~NT
j; _ ____-- _ ___ __ __________ ____.__ __ _ __ ___ Referrin~ now to the drawings, wherein like reference characters designate like or corresponding parts throughout the ! several views~ there is shown the improved pipe section of the ''present invention, which for purposes of this description is ,¦identified by reference numeral 10. The section 10 is provided ¦Iwith a female, socket or bell end 12 and a male pin or spigot end 14 joined together by a central tubing portion 16. The ends 12 !~and 14 have appropriate r,latins threads. The section 10 can be lliconstructed in accordance wit]l a conventional me.hod from resin impregnated fiber material.
~¦ The section 10 can be used in numerous environments, ¦llsuch as in an oilfield flow line pipe system. When the section 10 ¦!is used as an oilfield flow line pipe the sections are constructed ll~with an end to end length!of approximately t~lenty feet and are Imade in 2 inch, 3 inch and ~ inch and other standard pipe sizes.
¦In an oilfield using pipe system a number of the sections 10 are ,connected together in series by use of the male and female ends.
¦¦According to a particular feature of the present invention, the I,section 10 is constructed in such a manner that it can be jiconnected to another section by hand without the use of special ¦iequipment or tools. In addition, couplings can be releasably made ¦I to allow disassembly and reuse. No permanent bonds at the joints llare necessary to provide an effective seal between the sections.
¦ 1t is to be understood, of course, that standard ¦fi tings tnot shown) with thr-ads mating the th~eads oE the ~z~

'lsection 10 can also be provided. ~1hen the dimensional requirements of the environment of use of the sections are such that a right angle fitting is required at the end of one of the ~isections, a fitting can be provided with mating threads to engage ,one of the ends of the section 10. When a fitting is required at ¦la spacing located intermediate the length of one of the pipe sections, the section can be cut and a fitting such as a right ¦angle fitt~ng bonded onto the sectlon at the desired location.
According to another particular feature of the present invention, an adjustability is provided in the couplings to provide effective sealing bet~een fittings and sections while allowing the fittings to be positioned in any desired radial direc~ion.
~ In addition, as will be hereinafter described in detail, ¦I the section 10 is provided with indicia on the outside thereof ¦which indicate when a joint is properly ~ade up to pro~ide an ¦effective seal. These indicia allow the workmen installing the pipe to quickly determine when a proper coupling is ~nade between the various sections and fittings.
The socket end 12 and pin end 14 will be described in detail by referring to Figures 2 through 6.
Referrin~ particularly to Figure 2 that details of construction of the pin end 14 will be described. As can be seen, ~Ithe central tubing portion 16 is flared at 18 to form the pin end 1~14. The pin end 14 has a larger wall thicl;ness than the central ,tubing portion 16, but the internal diameter of the central tubing ¦portion 16 is continuous or equal completely through the pin end 2~7 '14. The flared portion 18 extends from the tubing portion 16 to a guide alignment portion 20 forrned on the exterior of the section.
The guide portion 20 is frusto-conical shaped and converges in a ,direction toward the pin end of the section. The frusto-conical Isection 14 has an ape~ angle ~. A male threaded portion 22 is ,¦formed on the exterior of the pin end 14 adjacent to the guide ¦¦portion 20. In the preferred embodiment the threads 22 have a ~arcurate cross-section and are bounded on one side b~ the guide ¦por.ion 20 and on the other side by a second guide portion or seal ~¦carrying surface 24. Portion 24 is frusto-conical shaped and in the preferred embodiment its apex angle is equal to A.
¦ A groove 26 is formed in the second guide portion 24 and is of a size and shape to receive an annular compressible seal 28 lltherein. This seal 28 is eliminated from Figure 2 for purposes of lldescription but is shown in Figures 4 through 6.
¦ Referring now to Figure 3, it can be seen that the socl:el-end 12 is formed by flared portion ~0 wllich extends from the ¦central tubing portion 16. A sealing or seal engaging surrace 42 iis $ormed on the interior of the flared portion 40 and has a !frusto-conical shape with an apex angle ~ . In the preferred embodiment of the angle 9 equals the angle A and surface 42 is appropriately dimensioned to cooperate with the guide portion 24 carrying the seal 28. Surface 42 provides an annular seal jengaging surface of the seal 28 to seal the connection of two Isections. As can be seen in ~igure 3 the wall thic~ness of the socket erd 12 increases over the wall thickness of the central ,~ _ g _ i, .
!, ~ 2~g7 ,interior of the end 12. The threads of portion 44 are selected of a size to provide threaded engagement with the threads 22 and to ¦allow innerconnection of two sections 10 together. Threads 44 i have an arcurate cross-section corresponding to the cross-S ', section of the threads 22.
il A guide or alignment portion ~A6 iS formed adjacent to the ¦~portion 44 and extends to end 52. Portion 46 iS frusto-conical lshaped and has an apex angle B. In the preferred embodiment apex iangle B is equal to the apex angle A of the portion 20 and angle ¦ of portion 42~ This sur~ace or portion 46 iS closely dimensioned to the major pitch of the threads 22 and the guide portion 20 and thus when two sections o~ pipe are being coupled , Itogether the threads 22 and portion 20 engage and are guided by ~ ¦surface 46 to provide axial alignment of the two sections and Icontributes to the proper alignment of the threads 22 and ~4 to prevent cross-threading thereof. This alignment function of the engaging surfaces on ~he en~s 12 and 1~ facilitates the connection process and reduces the time and labor required to make such an lassembly.
I According to a particular feature of the present linvention end 14 iS provided with indicia on the exterior thereof i ¦!in the area of the ~uide portion 20 to indicate the amount of ¦!telescope threaded engagement of the two sections during the l¦assembly process. These indicia in the preferred embodiment lappear as axially spaced lines 48 and 50 extending around the Isurface 20 as shown in Figure 4. During connection of the end 14 l - 10 -~2~7 of the section 10 and the end 12 and section 1~' the end 52' will first align with the indicia 48. Further engagement of the thread will cause end 52' to align with the indicia 50.
! According to a particular feature of the present ~! invention when the end 52' aligns with the indicia 48 effective sealing is present in the pipe and tlle workman knows that he is beginning the area of acceptable engagem,ent for an effective sealing. Further relative axial ro~ation of the section 10 and 110' will cause the seal 28 to move longitudinally into the section ¦12 in the direction of arrow 5~ while remair,ing in contact with the surface 42. Since the surface 42 tapers inwardly as shown in Figure 3 further movement in the direction of arrow 54 will cause ¦adflition21 co~pression of the seal 28. lhis tightening of the ¦sections can be continued until the end 52' aligns with the ¦indicia 50, thus indica~ing to the workman ~hat the ~wo sections ¦are completely engaged. To align a fitting on the end of one of ¦the sections 10 or 10' in a desired direction the threaded lengagement can be unscrewed or backed off to some extent. The ¦workm~n knows by observing the indicia how far the two sections llcan be backed off while still maintaining an effective seal.
¦ According to a particular feature of the present invention the relative rotation between the two sections provided between the two indicia 40 and 48, is at least one full turn or 360 l¦degrees. This feature provides for orientation of the fitting on j~the end of the section in any direction while still ~aintainlng an ~efective seal. This is accomplished by relating the lead of the -11- ' 'I
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.f)2~47 ~ v ~
I!threads 22 and 44 and the angle of the sealing surface 42 such i,that the allowable diametric clearance bet~een the surface 2~ and ,1 the surface 42 is within the operational range of the seal through Ilat least 360 degrees of relative rotation between the two sections.
~~ The structure providing this will be described in more ldetail by reference to Figures 5 and 6 which are enlarged vie~s of - Iltwo threads. In E~igure 5, sections 10 and 10' are shown ¦¦inter-engaged to the poin~ where the seal 2R has been sufficiently l'compressed by the surface 42' to a point where the diametric Illclearance bet~een the surfaces 24 and 42' is equal to Eo~ As ¦shown, the sections 10 and 10' are threadedly engaged to a point ¦Iwhere at least one full turn or one thread of engagement remains ¦,before full engagement. By appropriately dimensioning the size l and axial position of surfaces 24, 92' and the threads, the diame-! tric clearance El can be selected ~o be within the acceptable design parameters of the particular seal 2~ ~o provide an effectiv~
seal between the surfaces 24 and 92'. In the preferred embodil~ent the configuration in Figure 5 ~lould be reached wl-en the end 52' lis in alignment with the indicia 98. Thus, the workman performing Ithe assembly of the sectiolls would know that he had reached the point where an effective seal was present between the sections 10 land 10'. Further rélative axial rotation of the sections would liicause further axial movement o~ the section and seal 28 in the !idirection of arrow 54 into the section 10'. Since the surface 42 ¦is frusto-conical shaped and has an apex angle 9 the seal will be ¦further compressed b~ this movement.
¦ In Figure 6 the sections 10 and 10' are shown with full Ithread engagement of the two sections and the seal moved further 11, 1 Z~L7 ~6313 !l il into section 10' to a point wherc the diametric clearance E is Ivirtually zero. By selecting the lead L such that the diametric clearances E is ~ithin the design parameters of the particular seal 28 during an axial movement o~ distance L or within one ithread o~ fu]l ~nakeup, one complete relative revolution of the two sections can be obtained while providing effective sealin~ there-!'bet~een. It has beerl found that the apex angle 0 of the sealing ~ D X~ 9O
surface is less than ~he angle ~ ~there ~an X - E/L~ L is equal to Ithe lead of the thread and E is eq~ial to the ~aximum allo~table Idiametric clearance. In the present embodiment the efective . !diametric clearance, E, for the particular seal 2~ is maintained ~through one complete relative revolution of the t~!o sections ~hen the thread lead, L = .25 inch and the angle ~ is 0 degrees and 30' I Thus the pipe section of the present invention provides lends which can be connected to anotler section and provide at jleast 360 de~.-ees of relative a~:ial adjus~ment bet\teen the sections while providing an ef~ective sec)ling.
¦ In accordance with another aspect of the present linvention it has been found that by rela~ing the apex angle o~ the ¦sealing 5urface to the lead of the threacls that the torque required to ma~e up a joint to provide an effective seal can be less than the torque an ordinary ~torker can apply solely by hand to the sections whereby the hand makeup o~ the connections are Ipossible. By reducing the ape~ angle and decreasing the lead the 1 amount o~ torque required can be reduced. In the present inven-tion the provision of a seal en~aging surface 42 whose apex angle is 0 degrees and 30 min. and thread \-ith a lead of 1/~ in/rev.
provided a mechanical advanta9e such that th,e torque \~hich must b~

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applied to the sections necessary to compress the seal is within the range of possibility of one worker applying a torque to the pipe by hand witho~, the use of additional equipment or tools.
!! It has been found that the ma~eup torques for joints of ,this type for 2 inch pipe is in the range of 70 to 90 inch pounds.
In the present embodirilent the makeup torque is 80 inch pounds.
ll the above torques are in the range which can be applied by jihand by an ordinary t~orker to the exterior of the pipe without ¦1tools. In a 3 inch pipe it has been found tllat the torque in the ¦Irange of llO to 130 inch pounds can be applied by hand. In such a 1~3 inch embodiment the makeup torque is 120 inch pounds. In the 4 ,¦inch pipe a torque in the range of 140 to 160 inch pounds can be ¦lapplied by hand, with present embodi~ent the makeup torque is 150 11inch pounds.
!1 It is believed that other sizes could be desiqned which ¦¦would have a necessary makeup torque in the rallge that can be ¦applied by an ordin3ry worl~er Witl1out the use of equipment or l¦wrenches or the lile.
¦1 Therefoee, according to the present invention, a pipe !jsection is provided which is versatile in application, in that, ¦!the joints between the sections and the joints between the sections and fittings are such that 360 degrees of axial relative ;1rotation between sections can be provided to allow for adjustment ¦1of the dir~ctions of fittings on the end of the sections. This is 1lacco~.plished by rela.inq the apex angle of the sealinq surface to Ithe dia~,etric clearance of the seal and the lead of the screw.
, Z~7 B6313 ll ~¦ In addition the pipe section of the present invention is particularly designed and the lead of the threads, sealing surface apex angle and compressibility of the seal are selected to allo~ the sections to provide hand makeup thus reducing the amount Iof labor and time required to properly install the sections and eliminatinq the possibility of damaging the pipe ~lith wrenches.
In addition the improved pipe sec~ion of the present invention "provides an indicia on the exterior of the pipe to indicate to the l'worker when the sections are properly connected.
,1 It should be understood, of course, that the foregoing disclosure relates only to a preferred embodiment of the present ¦invention and that numerous modifications or alterations may be made therein without depa~ting from the spirit and scope of the ~linvention as s.t iorth in the appended clairs.

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Claims (14)

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

1. An oilfield flow line pipe section with connecting means on the end thereof for connecting a plurality of sections together in series, said section comprising:
a length of tubing, mating male and female threads formed on said tubing adjacent the ends thereof for use in connecting sections together;
a compressible seal means mounted on said tubing adjacent one end thereof; and seal engaging surface means formed on said tubing adjacent the end opposite said compressible seal means, said seal engaging surface means having a frusto-conical section shape, the lead of the male and female threads is related to the apex angle of the sealing surface means and to the allowable diametric clearance for effective sealing of the seal means for providing an effective seal engagement between said seal means and said seal engaging surface during at least 360 degrees of relative axial rotation between two connected sections while providing thread engagement whereby interconnected sections can be relatively rotated at least one full turn while still providing a seal therebetween.

2. The pipe of claim 1 wherein said seal means is mounted adjacent the end having said male threads thereon and said seal surface means is positioned adjacent the end having said female threads thereon.

3. The pipe of claim 1 wherein said seal means comprises an annular seal member and wherein a groove receiving said seal means is formed on said tubing and is positioned adjacent to said male threads on the end opposite the end containing the female threads.

4. The pipe of claim 1 wherein said pipe has a continuous internal diameter along the length of the tubing and through the end having the male threads thereon.

5. The pipe of claim 1, 2 or 3 wherein said pipe is unitary and is formed from filament and thermosetting resin materials.

6. The pipe of claim 4 wherein said pipe is unitary and is formed from filament and thermosetting resin materials.

7. An oil field flow line pipe section with connecting means on the ends thereof for connecting a plurality of sections together in series, having in combination a length of tubing, mating male and female threads formed on said section adjacent the ends thereof for use in connecting sections together; a compressible seal means mounted on said tubing adjacent one end thereof, sealing surface means formed on said tubing adjacent the end opposite the compressible seal means, the improvement which comprises the lead of the threads being related to the apex angle of the sealing surface means and to the amount of allowable diametric clearance for providing effective sealing of the seal means over a range of at least 360 degrees of thread engagement.

8. The pipe of claim 7 wherein said seal means is mounted adjacent the end having said male threads thereon and said seal surface means is positioned adjacent the end having said female threads thereon.

9. The pipe of claim 7 wherein said seal means comprises an annular seal member and wherein a groove receiving said seal means is formed on said tubing and is positioned adjacent to said male threads on the end opposite the end containing the female threads.

10. The pipe of claim 7 wherein said pipe has a continuous internal diameter along the length of the tubing and through the end having the male threads thereon.

11. The pipe of claim 7, 8 or 9 wherein said pipe is unitary and is formed from filament and thermosetting resin materials.

12. The pipe of claim 10 wherein said pipe is unitary and is formed from filament and thermosetting resin materials.

13. In an oilfield flow line pipe section with connecting means on the ends thereof for connecting a plurality of sections together in series, having a length of tubing, mating male and female threads formed on said tubing adjacent the ends thereof for use in connecting sections together; a compressible seal means mounted on said tubing adjacent one end thereof, sealing surface means formed on said tubing adjacent the end opposite the compressible seal means, the improvement which comprises means mounting said seal means for providing effective sealing during at least one full turn of relative axial rotation between two connected sections.

14. In an oilfield flow line pipe section with connecting means on the ends thereof for connecting a plurality of sections together in series, having a length of tubing, mating male and female threads formed on said tubing adjacent the ends thereof for use in connecting sections together; a compressible seal means mounted on said tubing adjacent one end thereof, sealing surface means formed on said tubing adjacent the end opposite the compressible seal means, the improvement which comprises means mounting said seal means for providing effective sealing between two sections when said sections are connected together and while simultaneously providing at least 360 degrees of relative axial rotation between the two sections.