CA1102848A - 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 with a connector on the end thereof for releasably 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 to ends thereof for use in releasably connecting sections together. A compressible seal is carried by the tubing adjacent one end thereof for sealing connections to other sections. A frusto-conical sealing surface is formed on the tubing end opposite the compressible seal for sealingly engaging the seal on an adjacent connected section. The apex angle of the cone of the sealing surface, the compressibility of the seal, the lead of and the friction between the threads and the outside diameter of the pipe are so interrelated that the necessary torque to connect the sections together by threaded engagement and to provide an effective seal by compression of the seal is less than the torque an ordinary worker can apply solely by hand to the section whereby hand makeup of the connection is possible.

Description

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This is 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 requiréd 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 McLarty, 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.

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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 betweèn 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 `\ ~z~
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 prov-iding 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 an oilfield flow line pipe section with connection means on the end thereof for releasably 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 to ends thereof for use in releasably connecting sections together; a compressible seal means carried by said tubing adjacent one end thereof for sealing connections to other sections; a frusto-conical sealing surface means formed on the tubing adjacent the end opposite said compressible seal means for sealingly engaging said seal means on an adjacent connected section; and wherein the apex angle of - the cone of the sealing surface, the compressibility of the seal, the lead of and the friction between the threads and the outside diameter of the pipe are so interrelated that the necessary torque to connect the sections together by threaded engagement and to provide an effective seal by compression of the seal means is less than the torque an ordinary worker can apply solely by hand to the section whereby hand makeup of the connection is possible.
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 BRIEF DESCRIPTION_OE THE DR~IIINGS
!I The present invention will be readily appreciated by i!those of ordinary skill in the art as the same becomes better llunderstood by reference to the following detailed description when i¦considered in connection with the accompanying draw;ngs in which:
¦¦ FIGURE 1 i5 a side elevation vie~ of the improved pipe ¦section of the present invention;
FIGUR~ 2 is an enlarged elevation view of the male or llpin end of the i~proved pipe section of FIGU~E l;
FIGURE 3 is an enlarged sectional view of the female or socket end of the section illustrated in FIGURE 1 drawn to the sa~e scale as FIGURE 2;
FIGURE 4 is a partial longitudinal section of a l connection between two of the sections illustrated in FIGURE l;
1 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 FIGUP~E 6 is a view similar to FIGURE 5 illustrating the ends comp etely eng~ged.

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~,DESCRIPTION OF THE_PREFERRED_E~IBODIl!ENT
Referring 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 ijpresent invention, which for purposes of this description is ,¦identified by reference numeral 10. The section 10 is provided ¦!with 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 rnatins threads. The section 10 can be l¦constructed in accordance with a conventional method from resin Iimpregnated fiber material.
¦¦ The section 10 can be used in numerous environments, ¦¦such as in an oilfield flow line pipe system. When the section 10 llis used as an oilfield flo~ line pipe the sections are constructed Il¦with an end to end len~th!of approximately twenty feet and are made 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 2~ section 10 is constructed in such a manner that it can be ¦iconnected to another section by hand without the use of special ¦iequipment or tools. In addition, couplings can be releasably made ¦Ito allow disassembly and reuse. No permanent bonds at the joints l¦are necessary to provide an effective seal between the sections.
!It is to be understood, of course, that standard f i tt ing s not sho~ n ~ w i th th r ead s m a t ing th e th r ead s o ~ th e 1! 7 _ I

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B6313 .l !Isection 10 can also be provided. When the dimensional Irequirements of the environment of use of the sections are such Ilthat a right angle fitting is required at the end of one of the sections, a fitting can be provided with mating threads to engage ~one of the ends of the section 10. ~Yhen a fitting is required at ¦a spacing located intermediate the length of one of the pipe sections, the section can be cut and a fi.ting such as a right ¦¦angle fittlng bonded onto the sectlon at the desired location.
. According to another particular feature of the present : 10 invention,.an adjustability is provided in the couplings to provide effective sealing between fittings and sections while . lallowing the fittings to be positioned in any desired radial . ¦direc~ion.

¦¦ In addition, as will be hereinaf~er described in detail, ¦~the section 10 is provided with indicia on the outside thereof ¦which indicate when a joint is properly made up to provide an ¦effective seal. These indicia allow t.he workmen installing the .
¦pipe to quickly determine when a proper coupling is made between the various sections and fittings.
The socket end 12 and pin end 14 will be described in i detail by referring to Figures 2 through 6.
Referring 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 25 ~14. The pin end 14 has a larger wall thicl;ness than the central ¦Itubing portion 16, but the internal diameter of the central tubing portion 16 is continuous or equal completely through the pin end ~ _.g_ -9~ z~

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14. The flared portion 1~ extends from the tubing portion 16 to a guide alignment portion 20 formed 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 apex angle A. A male threaded portion 22 is formed on the exterior of the pin end 14 adjacent to the guide ¦lportion 20. In the preferred embodiment the threads 22 have a arcurate cross-section and are bounded on one side by the guide Ipor.ion 20 and on the other side b~ 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.
Il 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 itherein. This seal 28 is eliminated from Figure 2 for purposes of l¦description but is shown in Figures 4 througll 6.
¦ Referrinq now to Figure 3, it can be seen that the socl;el-end 12 is formed by flared portion 40 which extends frorn the central tubing portion 16. A sealing or seal engaging surrace 42 lis formed on the interior of the flared portion 40 and has a ¦ frusto-conical shape with an apex angle ~ . In the preferrea embodiment of the angle 9 equals the angle A and surface 42 is appropriately dimensioned to cooperate with the guide portion 24 Icarrying the seal 2~. Surface 42 provides an annular seal iengaging surface of the seal 2~ to seal the connection of two sections. As can be seen in ~igure 3 the wall thic~ness of the socket el~ 12 increases over the wall thickness of the central il !
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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 have an arcurate cross-section corresponding to the cross-, section of the threads 22.
A guide or alignment portion ~6 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 llangle B is equal to the apex angle A of the portion 20 and angle ¦1 of portion 42. This surLace or portion 46 is closely dimensioned to the major pitch of the threads 22 and the guide portion 20 and thus when two sections of pipe are being coupled 'together the threads 22 and portion 20 engage and are guided by ¦surface 46 to provide axial alignmen'; of the two sections and !contributes to the proper alignment of the threads 22 and 44 to ¦!prevent cross-threading thereof. This alignment function of the ¦engaging surfaces on the ends 12 and 1~ facilitates the connection ¦process and reduces the time and labor required to make such an ¦assembly.
¦ According to a particular feature of the present linvention end 14 is provided with indicia on the exterior thereof ¦jin the area of the guide portion 20 to indicate the amount of telescope threaded engagement of the two sections during the l¦assembly process. These indicia in the pre~erred embodiment li appear as axially spaced lines 48 and 50 extending around the surface 20 as shown in Figure 4. During connoction Oe the end 14 o-2Z~

B6313 ,1 of the section 10 and the end 12' and section 10' the end 52' will jfirst align with the indicia 48. Further engagement of the thread 'will cause end 52' to align with the indicia 50.
I~ According to a particular feature of the present ,linvention when the end 52' aligns with the indicia 48 effective sealing is present in the pipe and the workman knows that he is beginning the area of acceptable engager1ent for an effective ,sealing. Further relative axial rotation of the section 10 and ¦10' will cause the seal 2~ to move longitudinally into the section ¦12 in the direction of arrow 5~ while re.~aining in contact wiLh ¦the surface 42. Since the surface 42 tapers inwardly as shown in I Figure 3 further movement in the direction of arrow 54 will cause ¦ addition21 compression of the seal 28. Tllis tightening o the ~¦sections can be continued until the end 52' aligns with the indicia 50, thus indica',ing to the wo.kman that the ~wo sections are completely engaged. To ali~n a fi~ting on the end of one of the sections 10 or 10' in a desired diroction the threaded !engagement can be unscrewed or bac~ed off to some extent. The ¦¦workman knows by observing the indicia how far the two sections l¦can 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 Ibetween 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 ,¦the end of the section in any direction while still maintaining an - effect_ve seal. This is accomplished by lelating the lead of the Il I

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threads 22 and 44 and the angle of the sealing surface 42 such ¦that the allowable diametric clearance between the surface 24 and jthe surface 42 is within the operational range of the seal theough ',at least 360 degrees of relative rotation between the two sections.
~~ The structure providing this will, be described in more detail by reference to Figures 5 and 6 which are enlarged views of two threads. In Figure S, sections 10 and 10' are shown ~¦inter-engaged to the poin~ where the seal 28 has been sufficiently l',compressed by the surface 42' to a point where the diametric ¦!clearance hetweell the surfaces 24 and 42' is equal to ~0. As ¦shown, the sections 10 and 10' are threadedly engaged to a point where at least one full turn or one thread of engagement remains before full engagement. By appropriately dimensioning the size and axial posi~ion of surfaces 24, 42' and the threads, the diame-!~tric clearance El can be selected ~o be within the acceptable ¦Idesign parameters of the particular seal 2~ to provide an effective seal between the surfaces 24 and ~2~. In the preferred emhodiment ¦Ithe configuration in Figure 5 ~rould be reached when the end 52' is in alignment with the indicia 48. Thus, the workman performing Ithe assembly of the sections wo~ld know that he had reached the ,point where an effective seal was present between the sections 10 land 10'. Further relative axial rotation of the sections would licause further axial movement of the section and seal 28 in the !Idirection of arrow 54 into the section 10'. Since the surface 42 ¦iis frusto-conical shaped and has an apex angle 9 the seal will be ¦further compressed by this movement.
¦ In Figure 6 the sections 10 and 10' are shown with ~ull hread engagement of the two sections and the seal ~oved further Il .

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~6313 !l into section 10' to a point ~JI-Iere the diametric clearance E is virtually zero. ~y selecting tlle lead L such that the diametric clearances E is within the design parameters of the particular ,seal 28-during an a~ial movement o~ distance L or within one ithread o full makeui>, one comp]ete rclative revolution of the two sections can be obtained ~7hile providing effective scaling there-bet~een. It has been found that the aj?e~: angle ~ of the sealing ¦isurface is less th2n t}le angle X ~lhere tall X = E/L~ L is.equal to ¦the lead of the thread and ~ i5 eq~ial to the maximum allo~/able 'diametric clearance. In the pr~sent embodiment the effective . !diametric clearance, E, for the particular seal 2~ is maintained through one complete relative revolution of the t~70 sections when the thread lead, L = .25 inch and the angle ~ is 0 degrees and 30i I Thus the pipe section of the present invention provides lends which can be connected to another section and provide at . ¦least 360 degLees of rela'cive a~:ial adju.stment bet~ecll the sections ~h ile providing an ef~ective sealing.
¦ In accordance with another aspect of the present ¦invention it has been found tha~ by relating the apex angle of the 20 . ¦sealing sur~ace to the lead of the tl-reads that the torque required to make up a joint to provide an e~fective seal can be . lless than the torque an ordinary ~orker can apply solely by hand to the sections whereby the hand makeup of the connections are Ipossible. By reducing the ape~ angle and decreasing the lead the l¦amount of torque required can be reduced. In the present inven-¦tion the provision of a seal engaging sul-~ace 42 ~hose ape~ angle ¦~ is 0 degrees and 30 min. and thread with a lead of 1/4 in/rev.
'provided a mechanical advantage such that the torque which must be I
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~6313 ¦!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 withou. the use of additional e~uipment or tools.
It has been found that the makeup torques for joints of S ,this type for 2 inch pipe is in the range of 70 to 90 inch pounds.
¦IIn the present embodiri~ent the makeup torque is 80 inch pounds.
11 the abo-~e torques are in the ranqe which can be applied by ihand by an ordinary worker to the exterior of the pipe without lltools. In a 3 inch pipe it has been fo~nd that the torque in the ¦Iran~e of 110 to 130 inch pounds can be applied by hand. In such a i3 inch e~bodiment 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 ¦applied by hand, with present embodiment the makeup torque is lS0 llinch pounds.
!1 It is believed that other sizes could be designed which would have a necessary ma~eup torque in the range that can be ¦applied by an ordinary worker without the use of equipment or l¦wrenches or the lil~e.
¦I Therefore, according to the present invention, a pipe llsection 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 j!rotation between sections can be provided to allow for adjustment ¦¦of the directions of fittings on the end of the sections. This is llacco~plished by rela,ing the ape~ angle of the sealing surface to the dia~,etric cle~rence of the seal and the lead of the scre~/.

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~! 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 aee selected to allow the sections to provide hand makeup thus reducing the amount I.. of labor and time required to properly ins~all the sections and eliminating the possibility of damaging the pipe ~Jith orenches.
In addition, the improved pipe section of the present invention 'provides an indicia on the exterior of the pipe to indicate to the '~rorker ~rhen the sections are proper.ly connected.
I 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 invention as set forth in the appended claims .

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Claims (28)

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 connection means on the end thereof for releasably 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 to ends thereof for use in releasably connecting sections together;
a compressible seal means carried by said tubing adjacent one end thereof for sealing connections to other sections;
a frusto-conical sealing surface means formed on the tubing adjacent the end opposite said compressible seal means for sealingly engaging said seal means on an adjacent connected section; and wherein the apex angle of the cone of the sealing surface, the compressibility of the seal, the lead of and the friction between the threads and the outside diameter of the pipe are so interrelated that the necessary torque to connect the sections together by threaded engagement and to provide an effective seal by compression of the seal means is less than the torque an ordinary worker can apply solely by hand to the section whereby hand makeup of the connection is possible.

2. The pipe section of claim 1 wherein the torque on a two inch section of pipe is in the range of 70 to 90 inch pounds.

3. The pipe section of claim 1 wherein the torque on a two inch pipe is 80 inch pounds.

4. The pipe section of claim l wherein the torque on a three inch section of pipe is in the range of 110 to 130 inch pounds.

5. The pipe section of claim 1 wherein the torque on a three inch section of pipe is 120 inch pounds.

6. The pipe section of claim 1 wherein the torque on a four inch section of pipe is in the range of 140 to 160 inch pounds.

7. The pipe section of claim 1 wherein the torque on a four inch section of pipe is 150 inch pounds.

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

9. 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.

10. 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.

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

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

13. The pipe of claim 1 wherein mounting means are provided for mounting said seal means for providing effective sealing during at least one full turn of relative axial rotation between two connected sections.

14. The pipe of claim 1 wherein the lead of the threads is additionally 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 during at least 360 degrees of relative axial rotation between two connected sections while providing thread engagement whereby interconnected sections may be relatively rotated at least one full turn without effecting the seal therebetween.

15. In an oilfield flow line pipe section with connection means on the ends thereof for releasably connecting a plurality of sections together in series having a length of tubing, mating male and female threads formed on said section adjacent the ends thereof for use in releasably connecting sections together; a compressible seal means carried by said tubing adjacent one end thereof for sealing connections to other sections; a frusto-conical sealing surface means formed on the tubing adjacent the end opposite said compressible seal means for sealingly engaging said seal means on an adjacent connected section; the improvement which comprises the apex angle of the cone of the sealing surface, the compressibility of the seal, the lead of and friction between the threads and the diameter of the pipe are so interrelated that the necessary torque to connect two sections together by threaded engagement and to provide an effective seal by compression of the seal means is less than the torque an ordinary worker can apply solely by hand to he section whereby hand makeup of the connection is possible.

16. The pipe section of claim 15 wherein the torque on a two inch section of pipe is in the range of 70 to 90 inch pounds.

17. The pipe section of claim 15 wherein the torque on a two inch pipe is 80 inch pounds.

18. The pipe section of claim 15 wherein the torque on a three inch section of pipe is in the range of 110 to 130 inch pounds.

19. The pipe section of claim 15 wherein the torque on a three inch section of pipe is 120 inch pounds.

20. The pipe section of claim 15 wherein the torque on a four inch section of pipe is in the range of 140 to 160 inch pounds.

21. The pipe section of claim 15 wherein the torque on a four inch section of pipe is 150 inch pounds.

22. The pipe of claim 15 wherein said seal means is mounted adjacent the end having said male threads thereon and said sealing surface means is positioned adjacent the end having said female threads thereon.

23. The pipe of claim 15 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.

24. The pipe of claim 15 wherein said pipe has a continuous internal diameter along the length of the tubing and through the end having the male threads thereon.

25. The pipe of claim 15 wherein said pipe is unitary and is formed from filament and thermosetting resin materials.

26. The pipe of claim 22, 23 or 24 wherein said pipe is unitary and is formed from filament and thermosetting resin materials.

27. The pipe of claim 15 wherein mounting means are provided for mounting said seal means for providing effective sealing during at least one full turn of relative axial rotation between two connected sections.

28. The pipe of claim 15 wherein the lead of the threads is additionally 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 during at least 360 degrees of relative axial rotation between two connected sections while providing thread engagement whereby interconnected sections may be relatively rotated at least one full turn without effecting the seal therebetween.