CA1118469A - Pipe section and coupling - Google Patents

Abstract

IMPROVED PIPE SECTION AND COUPLING
Abstract of the Disclosure This invention relates to an oilfield line pipe section. The section is comprised of a length of tubing having mating male and female threads formed on the tubing adjacent the ends for releasably connecting two of the sections together. A compressible seal is carried adjacent the end of the tubing. A cooperating sealing surface is provided adjacent the ends of the tubing for axially compressing the seal to form an effective seal through at least 360 degrees of relative axial rotation when two sections are connected together. An indicia is provided on the tubing which is visible during assembly of two sections of tubing to indicate the range of allowable thread engagement providing effective sealing.

Description

'~18~
This is a division of Canadian patent application Serial No. 292,545 which was filed on 7 December 1977.
B~CKGROUND 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 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.

~L

~L~184~9 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 cGnnections.
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 themsel~es 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 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.

6~
In accordance with an aspect of the invention there is provided an oilfield flow line pipe section comprising: a length of tubing, mating male and female threads formed on said tubing adjacent the ends thereof for releasably connecting two of said sections together, a compressible seal means carried adjacent the end of said tubing, cooperating sealing surface means adjacent the ends of said tubing for axially compressing said seal means to form an effective seal through at least 360 degrees of relative axial rotation when two sections are connected together; and an indicia means on said tubing visible during assembly of two sections of tubing to indicate the range of allowable thread engagement providing effective sealing.
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:

q~

~6313 !~ ~
¦~BRIEF DESCRIPTION OF THE DR~INGS
ll The present invention will be readily appreciated by - !~ those of ordinary skill in the art as the same beco~es better understood by reference to the following detailed description when ~Iconsidered in connection with the accompanying draw;ngs in ~Jhich:
¦¦ FIGURE 1 is a side elevatioll view of the improved pipe ; l¦section of the present invention;
¦I FIGURE 2 is an enlarged elevation view of the male or jlpin end oE the improved pipe section of FIGU~E l;
FIGUR~ 3 is an enlarged sectional view of the female or socket end of the section illustrated in FIGURE 1 drawn to the same scale as FIGURE 2;
FIGUR~ 4 is a partial longitudinal section of a l connection between two o~ 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 enyaged to the point or initial effective sealing; and j FIGUP~ 6 is a view similar to FIGUR~ 5 illustrating the ends com letely engaged.

Il - 6 l l I

iDESCRIPTION OF THE PR~FERr~ED Et~BODI~lENT
1, _ ____ _ ___ __ ______ ____ ____ ____ _ __ ___ I
',l Referring now to the drawings, wherein li~e 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 ¦'with a female, socket or bell end 12 and a male pin or spigot end jll4 joined together by a central tubing portion 16. The ends 12 I,and 14 have appropriate Mating threads. The section 10 can be ¦iconstructed in accordance with a conventional me~hod from resin impregnated fiber material.
¦ The section 10 can be used in numerous environments, ¦such as in an oilfield flow line pipe system. When the section 10 ~is used as an oilfield flow line pipe the sections are constructed with an end to end lengthJof approximately twenty feet and are made in 2 inch, 3 inch and ~ inch and other standard pipe sizes.
In an oilfield usin~ pipe system a number of the sections 10 are I connected together in series by use of the male and female ends.
According to a particular feature of the present invention, the section 10 is constructed in such a manner that it can be iconnected to another section by hand without the use of special ¦equipment or tools. In addition, couplil1~s can be releasably made to allow disassembly and reuse. No permanent bonds at the joints lare necessary to provide an effective seal between the sections.
! It is to be understood, of course, that standard f itting (not sho-ln) w~th threads mating the threads of the Il ., B6313 ¦ , lisection 10 can also be provided. ~7hen the dimensional requirements of the environment of use of the sections are such Ithat a right angle fitting is required at the end of one of the ,Isections, a fitting can be provided with ~ating threads to engage 'one of the ends of the section 10. ~hen a fitting is required at ¦la spacing located inter~ediate the length of one of the pipe sections, the section can be cut and a fi.ting such as a right jangle fitting bonded onto the section at the desired loca~ion.
I According to another particular feature of the present invention, an adjustability i5 provided in the couplings to 'provide effective sealing betweell fittings and sections while lallowing the fittings to be positioned in any desired radial . Idirection ¦ In addition, as will be hereinafter described in detail, jlthe section 10 is provided with indicia on the outside thereof ~which indicate when a join' is properly made up to pro~ide an ¦¦effective seal. These indicia allo~ the wor~men installing the ¦pipe to quickly determine when a proper coupling is made between the vario~ls sections and fittings.
The socket end 12 and pin end 14 will be described in 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 1~14. 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 i8 continuoas or equal completely throaah the pio end r ,¦14. The flared portion 18 extends ~rom the tubiny portion 16 to a guide alignment portion 20 formed on the exterior of the section.
,iThe guide portion 20 is frusto-conical shaped and converges in a direction toward the pin end of the section. The frusto-conical ~section 14 has an apex angl'e ~. A mal,e thre~ded portion 22 is formed on the exterior of the pin end 14 adjacent to the guide llportion 20. In the preferred embodi~ent the threads 22 have a ¦arcurate cross-section and are bounded on one side by the guide ,¦portion 20 and on the other side by a second guide portion or seal carrying surface 24. Portion 24 is frusto-conical shaped and in ¦Ithe 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 Itherein. This seal 28 is eliminated from Figure 2 for purposes of !description but is shown in Figures 4 through 6.
¦I Referring now to Figure 3, it can be seen that the socl;et ¦end 12 is formed by flared portion 4~ which extends from the ¦central tubing portion 16. A sealing or seal engaging surrace 42 is ~ormed on the interior of the flared portion ~0 and has a ~0 !frusto-conical shape with an apex angle ~ . In the preferreu embodiment of the angle ~ e~uals the angle A and surface 42 is appropriately dimensioned to cooperate with the guide portion 24 carrying the seal 2~. Surface 42 provides an annular seal lengaging surface of the seal 2~ to seal the connection of two isections. As can be seen in ~igure 3 the wall thic~ness of the . socket end 12 increases over the wall thickness of the central .
!
i !1 9 _ 1.

4~

B6313 ¦' I
interior of the end 12. The threads of portion 44 are selected of lj a size to provide threaded engagement ~ith the threads 22 and to ¦!allow innerconnection of two sections 10 toqether. Threads 44 , have an arcurate cros5-section correspondinq 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 ~6 is frusto-conical jlshaped and has an ape~ angle B. In the preferred embodiment apex ¦jangle ~ is equal to the apex angle A of the portion 20 and angle ll of portion 42. This surface 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 enqaye and are guided by ¦surfacc ~6 ~o provide axial alignm,ent of the ttto sec~ions and 1¦ contributes to the ~roper alignment of the threads 22 and 44 to prevent cross-threading thereof. This alignment function of the !engagin~ surfaces on the ends 12 and 1~ facilitates th~ connection ~process and reduces the time and labor requirecl to make s~1ch an ~assembly.
¦ According to a particular feature of the present invention end 14 is provided with indicia on the exterior thereof in the area Of the ~uide portion 20 to indicate the amount of telescope threaded engagement of the t~o sections during the !l assembly process. These indicia in the preferred embodiment jappear as axially spaced lines 48 and 50 extendinq around the s rEac~ 20 as shown in riqurs 4. Durill~ connection oE the enù 14 I
I
1~ - 10-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 ~-hen the end 52' aligns with the indicia 48 effective sealing is present in the pipe and the ~70rkman kno~s that he is beginning the area of acceptable engagement for an effective sealing. Further relative axial rotation of the section 10 and 1lO' will cause the seal 28 to move longitudinally into the section ~12 in the direction of arro~ 5~ while re.~aining in contact wi';h the surface 42. Since the surface 42 tapers inwardly as shown in Figure 3 further movement in the direction of arrow 54 will cause ladditional co~pression of the seal 28. rlhis tightening of the ¦sections can be continued until the end 5~' aligns with the indicia 50, thus indicating to the t~orkman that the two sections are completely enqaged. To align a fitting on the end of one of the ~ections 10 or 10' in a desired direction the threaded engagement can be unscrewed or bac~ed off to some extent. The l workmzn knows by observing the indicia ho\-~ far the two sections 1 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 between the two indicia 40 and 48 is at least one full turn or 368 l¦degrees. This feature provides for orientation of the fitting on the end of the section in any direction while still maintaining an effective seal. This is accomplished h~ relating the lead of the I , i i 4~;~

threads 22 and 44 and the angle of the sealing surface 42 such that the allowable diametric clearance between the surface 24 and the surface 42 is within the operational range of the seal through ~'at least 360 degrees of relative rotation between the t~o sections.
, The structure providing this will be described in more .ldetail by reference to Figures 5 and G which are enlarged views of jtwo threads. In E~igure 5, sections lO and lO' are shown ~¦inter-en~aged to the poin~ where the seal 28 has been sufficiently ¦!com~ressed by the surface 42' to a point where the diametric j~clearance bet~een the surfaces 24 and 42' is equal to ~0. As shown, the sections lO and lO' are threadedly en~aged to a point whe.e at least one full turn or one thread of engagement remains before full engagement. By appropriately dimensioning the size land axial positi.on of surfaces 24, 42' and the threads, the diame-i¦tric clearance El can be selected to be ~7ithin the acceptable design parameters of the particular seal 28 to provide an effective ¦seal between the surfaces 24 and 42'. In the preferred embodiment ¦!the configuration in Figure 5 ~lould be reached when the end 52' is in alignment with the indicia 48. Thus, the workman performing the assembly of the sectiolls would know that he had reached the point where an effective seal was present between the sections lO
!and 10l. Further relative axial rotation of the sections would i¦cause further axial movement of the section and seal 28 in the !jdirection of arrow 54 into the section lO'. Since the surface 42 iis frusto-conical shaped and has an apex angle ~ the seal will be further compressed by this movement.
. In Figure 6 the sections lO and lO' are shown ~ith full thread engagement of the two sections and the seal moved further !
I 1, - 12 - , ~6313 !l into section 10' to a point where the diametric clearance E is Ivirtually zero. By selecting the lead L such that the diametric clearances E is within the desi~n parameters of the particular , sea1 28 during an a~ial movement of distance L or within one ithread of full makeup, one comple~e r~la~ive revolution of the two lisections can be obtained ~7hile providiny effective sealing there-!ibet~een. It has been follnd that the apex angle 0 of the sealing uP ~ 70~
surface is less than the angle X ~here tan X ~ E/L~ ~ is.e~ual to Ithe lead of the thread and ~ is eq~ial to the ~aximum allo~able lldi~metric clearance. In the present e1nbodiment the effective ; ¦diametric clearance, E, for the particular seal 2~ is maintained ¦through one complete relative revolution of the t~70 sections ~hen the thread lead, L ~ .25 inch and the angle ~ is O desrees and 30' I ThUS the pipe section of the present invention provides lends which can be connected to al)other section and provide at ~least 360 de~rees of Lelative a~.ial adju.stment betwecn the sections whi1e providing an effective sealing.
In accordance ~rith another aspect of the present linv~ntion it h~S been found that by relating the apex angle of the 20 . ¦sealing sulface to the lead of the tl~reads that the torque quired to ma~e up a joint to provide an effective seal can be ¦1ess than the torque an ordinary worker can appl~ solely by hand Ito the sections whereby the hand ma~eup of the connections are Ipossible. By reducing the apex 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¢~ging suLface 42 ~hose apex an~le is O degrees and 30 min. and tl~read with a lead oE 1/~ in/rev.
provided a mechanical advanta9e such that th,e torque which must b~

a~3l3 i!
¦¦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 equipment or tools.
Il It has been found that the makeup torques for joints of ,this type for 2 inch pipe is in the range of 70 to 90 inch pounds.
IlIn the present embodirilent the makeup torque is 80 inch pounds.
~ll the above torques are in the range which can b~ applied by !ihand by an ordinary uorker to the exterior of the pipe without lltools. In a 3 inch pipe it has been found that the torque in the ¦!ran~e of 110 to 130 inch pounds can be applied by hand. In s~ch a i3 inch embodiment the makeup torque is 120 inch pounds. In the 4 !¦inch pipe a torque in the ran~e of 140 to 160 inch pounds can be ¦!appli.ed by hand, with present embodiment the makeup torque is 150 llinch pounds.
!i It is believed that other sizes could be designed which would have a necessary ma~eup torque in the ral-ge that can be Ijapplied by an ordin3ry ~orl~er ~-ithout ~he use or equip~nent or ~¦wrenches or the lil:e.
li 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 ;Irotation between sections can be provided to allow for adjustmlent ¦!of the directions of fittings on the end of the sections. This is llaccomplished by rela.in~ the ape~ angle of the ~ealing surEace to the diar~etric clearance of the seal and the lead of the scre-/.

B6313 ,l ! 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 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 ~he possibility of damaging the pipe with wrenches.
,IIn addition, the improved pipe section of the present invention ,'provides an indicia on the exterior of the pipe to indicate to the l',worker when the sections are proper.ly 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 llinvention as set forth in the appended claims.

Ii .
l , ~1 - 15 -

Claims (6)

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 comprising:
a length of tubing, mating male and female threads formed on said tubing adjacent the ends thereof for releasably connecting two of said sections together, a compressible seal means carried adjacent the end of said tubing, cooperating sealing surface means adjacent the ends of said tubing for axially compressing said seal means to form an effective seal through at least 360 degrees of relative axial rotation when two sections are connected together; and an indicia means on said tubing visible during assembly of two sections of tubing to indicate the range of allowable thread engagement providing effective sealing.

2. The section of claim 1 wherein said indicia is located adjacent the male end of said section.

3. 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.

4. 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.

5. 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.

6. The pipe of claim 1 wherein said pipe is unitary and is formed from filament and thermosetting resin materials.