CA1241038A - Tubular joint with trapped mid-joint metal-to-metal seal having unequal tapers - Google Patents
Tubular joint with trapped mid-joint metal-to-metal seal having unequal tapersInfo
- Publication number
- CA1241038A CA1241038A CA000445364A CA445364A CA1241038A CA 1241038 A CA1241038 A CA 1241038A CA 000445364 A CA000445364 A CA 000445364A CA 445364 A CA445364 A CA 445364A CA 1241038 A CA1241038 A CA 1241038A
- Authority
- CA
- Canada
- Prior art keywords
- female
- male
- sealing surface
- angle
- conical
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Landscapes
- Earth Drilling (AREA)
Abstract
ABSTRACT
A joint and male and female tubular element are disclosed where the threads of the female and male members have negative load flanks and have two or more radial steps axially separated one from another by a reverse angle torque shoulder having one or two adjacent conical sealing surfaces.
The reverse angle torque shoulder produces radial positional interference of the conical sealing surfaces when the male and female members are fully assembled and serves as a pos-itive assembly stop. The negative load flank angle of the threads and the reverse torque shoulder angle combine to interlock the male and female members and to prevent dif-ferential radial separation of the conical sealing surfaces when the joint is exposed to internal pressure, external pressure or both. Tapered threads and sealing surfaces and interference threads may advantageously be used in joint construction.
Tapered conical sealing surfaces are provided in a preferred embodiment where the taper of the member having the thinner wall thickness at the seal surface is inclined at a smaller angle with respect to the axis of the threaded connection than the complementary conical seal surface of the mating member, may advantageously be used to that the bearing load across the entire axial width of the male and female sealing surfaces has a relatively even distribution at final make-up.
A joint and male and female tubular element are disclosed where the threads of the female and male members have negative load flanks and have two or more radial steps axially separated one from another by a reverse angle torque shoulder having one or two adjacent conical sealing surfaces.
The reverse angle torque shoulder produces radial positional interference of the conical sealing surfaces when the male and female members are fully assembled and serves as a pos-itive assembly stop. The negative load flank angle of the threads and the reverse torque shoulder angle combine to interlock the male and female members and to prevent dif-ferential radial separation of the conical sealing surfaces when the joint is exposed to internal pressure, external pressure or both. Tapered threads and sealing surfaces and interference threads may advantageously be used in joint construction.
Tapered conical sealing surfaces are provided in a preferred embodiment where the taper of the member having the thinner wall thickness at the seal surface is inclined at a smaller angle with respect to the axis of the threaded connection than the complementary conical seal surface of the mating member, may advantageously be used to that the bearing load across the entire axial width of the male and female sealing surfaces has a relatively even distribution at final make-up.
Description
12~0~8 This invention relates generally to oil and gas well tubing and more particularly has to do with the con-stru~tion of high pressure tubular joints operable when made-up and run into a well to withstand extreme fluid 5 pres3ures, both internal and external, that seek escape throlgh the tubular assembly at the joints.
The search for oil and gas reserves has brought abou~ the exploration of ever deeper formations. These deep~r formations require longer strings of production pipe, 10 casing, liners and drill pipe used in the exploration and production of oil and gas at extremely high pressures.
This increased length of tubular strings imposes the upper portion of the string to very high tensile loads and in addition, the tubular strings are exposed to extremes of 15 pressure both from within the tubing and also from the exterior of the tubing.
Prior art metal-to-metal sealing mechanisms have provided seals that resist mainly internal pressure or mainly external pressure, as long as the surrounding tubu-20 lar ~eometry remains in the elastic range. The prior artsealing mechanisms have not solved the sealing problem of withstanding extremes of internal pressure, or external pressure, either pressure acting during circumstances of high tension, torque or compression forces acting on the 25 tubing.
.~.
~.2~038
The search for oil and gas reserves has brought abou~ the exploration of ever deeper formations. These deep~r formations require longer strings of production pipe, 10 casing, liners and drill pipe used in the exploration and production of oil and gas at extremely high pressures.
This increased length of tubular strings imposes the upper portion of the string to very high tensile loads and in addition, the tubular strings are exposed to extremes of 15 pressure both from within the tubing and also from the exterior of the tubing.
Prior art metal-to-metal sealing mechanisms have provided seals that resist mainly internal pressure or mainly external pressure, as long as the surrounding tubu-20 lar ~eometry remains in the elastic range. The prior artsealing mechanisms have not solved the sealing problem of withstanding extremes of internal pressure, or external pressure, either pressure acting during circumstances of high tension, torque or compression forces acting on the 25 tubing.
.~.
~.2~038
- 2 -U.S. Patent No. 2,992,019 to M.D. MacArthur shows a casing joint having metal-to-metal sealing means responsive primarily to extremes of inside fluid pressure. The dis-closed interior sealing for the pin and box provides a 5 fourteen degree (14) interior seal that is spaced a distance from the threaded inner connection to enable the deformation or strain on the pin, in response to the in-side fluid pressure, to flex the pin interior sealing sur~
face against the box interior sealing surface and obtain 10 a greater sealing force. In addition, during such strain, the sealing contact area decreases which increases the sealing force over the reduced area. In particular, the distance between the pin and the seal surface remains the same while the center of the sealing area moves slightly 15 toward the thread during such sealing flexing.
U.S. Patent No. 4,009.893 issued to Schatton, et al. discloses a tubing or casing joint with box and pin members having two axially spaced thread sections separated by a radial step zone which includes for the pin member, an 20 annulus having an axial undercut. The endface of the an-nulus bears against a complementary face in the step zone of the box member and serves to act as a complementary thread stopface, in addition to a stopface at the end of the pin member and in the box member.
There has been a long-felt need for metal-to-metal sealing mechanisms for use in tubular joints which are able to hold mating members together for complete leak resistance against both internal and external pressures, regardless of the forces of tension, compression, inter- .
face against the box interior sealing surface and obtain 10 a greater sealing force. In addition, during such strain, the sealing contact area decreases which increases the sealing force over the reduced area. In particular, the distance between the pin and the seal surface remains the same while the center of the sealing area moves slightly 15 toward the thread during such sealing flexing.
U.S. Patent No. 4,009.893 issued to Schatton, et al. discloses a tubing or casing joint with box and pin members having two axially spaced thread sections separated by a radial step zone which includes for the pin member, an 20 annulus having an axial undercut. The endface of the an-nulus bears against a complementary face in the step zone of the box member and serves to act as a complementary thread stopface, in addition to a stopface at the end of the pin member and in the box member.
There has been a long-felt need for metal-to-metal sealing mechanisms for use in tubular joints which are able to hold mating members together for complete leak resistance against both internal and external pressures, regardless of the forces of tension, compression, inter- .
3~ nal pressure, external pressure, torque or any combina-tion thereof that are applied to the joint.
It is therefore a primary object of this inven-tion to provide a trapping mechanism in a joint to hold the mating members together for complete leak resistance in 35 the face of multiple forces acting on the joint.
Not only must the joint be sealed, it must be capable of being made up and disassembled numerous times _3~ 38 without galling and without the danger of stripping threads or cross-threading. It is of course, desirable and therefore an advantage of the joint according to the invention disclosed herein in that it may be "stabbed" and that thereafter it can be made up with a relatively small number of turns.
It is common to use an integra~~ or upset joint wherein the threaded portion of the pipe is thickened by a .' forging technique so as to provide more metal in the area ~?
where threads are cut. The invention disclosed below may advantageously be used with an integral or upset type of joint, and it may also be used with a threaded and coupled joint wherein both ends of the tubular elements are pro-vided with male joining elements and a coupling member is provided with female joint elements.
The Dresent invention therefore provides a joint - for tubular elements comprising, an internally threaded female member and an externally threaded male member adapted to be threadably connected, the threads of the female and male members having negative angle load flanks and at least two radial steps axially separated from one another by a reverse angle torque shoulder having at least one adjacent conical sealing surface where the taper angle of the conical sealing surface of the member having the thinner wall thickness at the seal surface is inclined at a smaller angle with respect to the axis of the threaded connection than the complementary conical seal surface of the mating member, whereby, said shoulder serves as a positive assembly stop and produces radial Dositional inter-ference of the conical sealing surfaces when the male andfemale members are fully assembled, and the negative load flank angle of the threads and the reverse torque shoulder angle are selected to interlock the male and female members and to prevent differential radial separation of the conical sealing surfaces when the joint is exposed to internal pressure, external pressure or both.
Further features and advantages of the invention will be better understood from the following description of preferred embodiments of the invention taken in con-~4~038
It is therefore a primary object of this inven-tion to provide a trapping mechanism in a joint to hold the mating members together for complete leak resistance in 35 the face of multiple forces acting on the joint.
Not only must the joint be sealed, it must be capable of being made up and disassembled numerous times _3~ 38 without galling and without the danger of stripping threads or cross-threading. It is of course, desirable and therefore an advantage of the joint according to the invention disclosed herein in that it may be "stabbed" and that thereafter it can be made up with a relatively small number of turns.
It is common to use an integra~~ or upset joint wherein the threaded portion of the pipe is thickened by a .' forging technique so as to provide more metal in the area ~?
where threads are cut. The invention disclosed below may advantageously be used with an integral or upset type of joint, and it may also be used with a threaded and coupled joint wherein both ends of the tubular elements are pro-vided with male joining elements and a coupling member is provided with female joint elements.
The Dresent invention therefore provides a joint - for tubular elements comprising, an internally threaded female member and an externally threaded male member adapted to be threadably connected, the threads of the female and male members having negative angle load flanks and at least two radial steps axially separated from one another by a reverse angle torque shoulder having at least one adjacent conical sealing surface where the taper angle of the conical sealing surface of the member having the thinner wall thickness at the seal surface is inclined at a smaller angle with respect to the axis of the threaded connection than the complementary conical seal surface of the mating member, whereby, said shoulder serves as a positive assembly stop and produces radial Dositional inter-ference of the conical sealing surfaces when the male andfemale members are fully assembled, and the negative load flank angle of the threads and the reverse torque shoulder angle are selected to interlock the male and female members and to prevent differential radial separation of the conical sealing surfaces when the joint is exposed to internal pressure, external pressure or both.
Further features and advantages of the invention will be better understood from the following description of preferred embodiments of the invention taken in con-~4~038
- 4 -~ection with the accompanying drawings in which:
. Figure 1 illustrates a longitudinal cross-sec-tional section through a joint according to the invention showing in detail in Figures lA and lB, the negative flank
. Figure 1 illustrates a longitudinal cross-sec-tional section through a joint according to the invention showing in detail in Figures lA and lB, the negative flank
5 angle and the reverse torque shoulder features of the in-vention;
Figure 2 illustrates an alternative embodiment of ~-the invention with a longitudinal cross-section showing threads cut on a taper angle with respect to the axis of 10 the male and female members of the joint;
Figure 3 and Figure 3A shows an embodiment of the invention where the conical sealing surfaces of the male and female ~embers are machined at slightly different angles;
and Figures 4A and 4B illustrate alternative embodi-ments O.c the invention where Figure 4A shows conical seal-ing sur~aces on both sides of the reverse angle torque shoulder and Figure 4B illustrates the use of a reverse angle torque shoulder between two or more stepped threads.
Figure 1 illustrates, according to the invention, a joint shown generally at 10 comprising female or box mem-ber 20 in threaded connection with pin or male member 30 and having ~wo step threads shown generally at 70 and 80 inter-connect~d by a conical sealing surface 40. The joint is 25 characterized, according to the invention, by providing a negative angle load flank 44 on the threads shown general-ly in more detail in Figure lA and a reverse angle torque shoulder 43 shown in more detail in Figure lB.
Figure lA illustrates that the load flank 44 on 30 the thr~ads is at an angle ~ which is measured counter- ~-clockwi;e from the vertical to the longitudinal plane of i!
the thr-ads.
Figure lB illustrates that the sealing surfaces 41 and ~2 of the ~in and box members terminate in the tor-35 que shoulder 43 which is at a reverse angle ~ measured clockwise from the ~erpendicular to the longitudinal axis of the joint.
The initial sealing surface contact of surfaces 41 and 42 is established at assembly by metal-to-metal interference. The seal pressure retention characteristic p of the threaded connection is related to the ability of the sealing surfaces 41 and 42 to remain in contact with one another as radial deflection of the joint occurs from either internal pressure or external pres-sure. The unique seal retention according to the inven-tion results from the trapping effect of the negative load flank threads of both the large step threads 70 and the small step threads 80 in co~ination with the -reverse angle shoulder 43 in the intermediate region between the steps thereby preventing loss of surface contact between surfaces 41 and 42. The trapping effect causes the two surfaces 41 and 42 to deflect as one.
The seal is establishea regardless of differences in the annular section areas of each member 41 and 42 thus providing a pressure containment wherein forces act from either side of the seal. In addition, the ap~lication of an axial tensile load will cause the seal surface to remain in contact. Similarly, torque forces on the ioint do not ad~ersely affect the seal of the joint. Advantageously, the only way that the seal-ing surfaces can separate is for extreme forces acting on the joint to cause the threads to ,~
, .._ ,_ shear, the shoulder to shear, or both.
Although Figure 1 shows the threads 70 and 80 to be cut parallel to the axis of box member 20 and pin member 30, an alternative embodiment is shown in Figure 2 where threads 5 70 and 80 are cut on a taper angle shown generally as ~ . ~
Although Figure 2 illustrates the sealing surfaces 41 and -42 to be cut at the same taper angle ~ as are the threads 70 and 80, they may advantageously be provided at a taper an-gle different from the thread taper.
Figure 3 shows another alternative embodiment of the invention whereby the conical sealing surfaces 41 and 42 of the top step are machined to slightly different angles with respect to the axis of the joint. According to a fur- `
ther preferred aspect of the invention, the conical seal 15 surface of the member having the thinner wall thickness at the seal surface may be machined to a smaller angle with respect to the axis of the threaded connection than the com-plementary conical seal surface of the mating member. In-dividual sealing shoulder members are shown in more detail 20 in Figure 3A. Because the conical seal at the upper step illustrated in Figure 3A occurs at a region where the female member 20 wall thickness is less than the wall thickness of the male member, the sealing surface 42 of the female member is machined to an angle of incline which is slightly less 25 than the angle of incline of sealing surface 41. Figure 3A
indicates the angle difference to be ~ . The mismatch of the angles of inclines of conical sealing surfaces 42 and 41 is selected for any particular seal geometry such that at final make-up, the bearing load has a relatively even 30 distribution across the entire sealing surface in contact, thus broadly distributing make-up stresses and minimizing their negative effects.
Referring to Figure 3A where for the upper step having the female conical sealing surface 42 machined at an 35 angle slightly less than that of male surface 41, when the ~Z4~038 pin member 30 initially mates with box member 20, the bear-ing load is substantially on the leadi~g edge of the box sealing surface 42 with the trailing edge of the pin seal-ing surface 41. After the sealing surfaces are fully made-5 up, the stress as a function of axial width becomes moreuniform than for the case where the taper angles of the sealing surfaces are the same or where the taper angle of the box sealing surface is greater than the taper angle of the pin sealing surface.
Metal-to-metal seal taper angles commonly are provided in a range of from two degrees (2) to fourteen degrees (14). The exact angular taper mismatch of the sealing angles of surfaces 41 and 42 varies depending on the seal angle of the more rigid member, the width of the seal-15 ing surface, the thickness of the thinner member, desired tolerances and other factors. It can be shown that seal mismatch for very low angle seals of approximately one-half (1~2") inch in axial width can be as low as one-quarter degree (1/4~. High angle seals of equal axial width may 20 require a mismatch of one degree tl) or more for complete balancing of bearing loads upon full make-up. Finite ele-ment analysis may be used as a tool to verify the optimum - ~
seal angle mismatch on any given seal and connection geometry.
Figure 3 also shows that threads 70 and 80 may be 25 interference fitting threads.
Figures 4A and 4B illustrate alternati~e embodi-ments of the invention. Figure 4A illustrates the reverse angle torque shoulder 43 between the two step thread.s and having not only conical sealing surface 40 (as illustrated 30 in Figure 1) on the large step, but also conical sealing surface 45 on the small step. Alternatively a conical seal-ing surface 45 could be provided solely on the small step with no sealing surface being provided on the large step.
Thus, one conical sealing surface provided on either step 35 adjacent the reverse angle torque shoulder, or two seal-- 8 _ ~2A~038 ing surfaces, one provided on each of the steps, serve in ~onjunction with the reverse angle torque shoulder and the negative angle load flank threads to create the uni~ue trapping effect of the invention.
Where as illustrated in Figure 4A, a conical seal-ing surface is provided as at 45 on the small step and the female member 20 wall thickness is greater than the thick- e ness of the male member, the sealing surface of the female ~
member is machined to an angle of incline which is slightly 10 greater than the angle of incline of the sealing surface of the male member.
Figure 4B illustrates that the combination of negative load flank threads and reverse angle torque shoulder between stepped threads may be used for tubular 15 connections or joints having two or more stepped threads.
For example, triple radial step threads 170, 190, and 180 may advantageously be used for thick walled tubulars. Ac-cording to the invention, reverse angle torque shoulders 43' and 43" are provided between thread steps 170 and 190 20 and between thread oteps 190 and 180. Providing one conical sealing surface such as 40' or 40" on each axial side of shoulder 431 and one conical sealing surface such as 41' or 42' or both 41' and 42' on each axial side of shoulder 43" serves to achieve the trapping effect discussed above 25 when used in combination with negative load flank threads.
More stepped threads with intermediate reverse angle torque shoulders and associated conical sealing surfaces could ad-vantageously find applications for tubulars having extreme-ly thick walls.
In all the embodiments of this invention the mag-nitude of the negative thread flank angle or the angle of the reverse angle shoulder should not exceed thirty degrees (30). In addition, it has been found that the magnitude of the angle of the conical sealing surfaces relative to 35 the joint axis should not be greater than fifteen degrees (15). Finally, for that embodiment of the invention il-lustrated in Figure 3, the dissimilarity of the angles of ~241038 incline of the sealing surfaces of the male and female members should be less than one degree where the angle of incline of the member having the greater wall thickness should be greater than that of the member having the les-5 ser wall thickness.
From the foregoing, it is apparent that there has been provided a sealing surface for use in joints, and in- j terconnecting tubular members especially useful in oil and r gas wells. Various modifications and alterations in the 10 described structures will be apparent to those skilled in the art from the foregoing description which do not depart from the scope of the invention.
Figure 2 illustrates an alternative embodiment of ~-the invention with a longitudinal cross-section showing threads cut on a taper angle with respect to the axis of 10 the male and female members of the joint;
Figure 3 and Figure 3A shows an embodiment of the invention where the conical sealing surfaces of the male and female ~embers are machined at slightly different angles;
and Figures 4A and 4B illustrate alternative embodi-ments O.c the invention where Figure 4A shows conical seal-ing sur~aces on both sides of the reverse angle torque shoulder and Figure 4B illustrates the use of a reverse angle torque shoulder between two or more stepped threads.
Figure 1 illustrates, according to the invention, a joint shown generally at 10 comprising female or box mem-ber 20 in threaded connection with pin or male member 30 and having ~wo step threads shown generally at 70 and 80 inter-connect~d by a conical sealing surface 40. The joint is 25 characterized, according to the invention, by providing a negative angle load flank 44 on the threads shown general-ly in more detail in Figure lA and a reverse angle torque shoulder 43 shown in more detail in Figure lB.
Figure lA illustrates that the load flank 44 on 30 the thr~ads is at an angle ~ which is measured counter- ~-clockwi;e from the vertical to the longitudinal plane of i!
the thr-ads.
Figure lB illustrates that the sealing surfaces 41 and ~2 of the ~in and box members terminate in the tor-35 que shoulder 43 which is at a reverse angle ~ measured clockwise from the ~erpendicular to the longitudinal axis of the joint.
The initial sealing surface contact of surfaces 41 and 42 is established at assembly by metal-to-metal interference. The seal pressure retention characteristic p of the threaded connection is related to the ability of the sealing surfaces 41 and 42 to remain in contact with one another as radial deflection of the joint occurs from either internal pressure or external pres-sure. The unique seal retention according to the inven-tion results from the trapping effect of the negative load flank threads of both the large step threads 70 and the small step threads 80 in co~ination with the -reverse angle shoulder 43 in the intermediate region between the steps thereby preventing loss of surface contact between surfaces 41 and 42. The trapping effect causes the two surfaces 41 and 42 to deflect as one.
The seal is establishea regardless of differences in the annular section areas of each member 41 and 42 thus providing a pressure containment wherein forces act from either side of the seal. In addition, the ap~lication of an axial tensile load will cause the seal surface to remain in contact. Similarly, torque forces on the ioint do not ad~ersely affect the seal of the joint. Advantageously, the only way that the seal-ing surfaces can separate is for extreme forces acting on the joint to cause the threads to ,~
, .._ ,_ shear, the shoulder to shear, or both.
Although Figure 1 shows the threads 70 and 80 to be cut parallel to the axis of box member 20 and pin member 30, an alternative embodiment is shown in Figure 2 where threads 5 70 and 80 are cut on a taper angle shown generally as ~ . ~
Although Figure 2 illustrates the sealing surfaces 41 and -42 to be cut at the same taper angle ~ as are the threads 70 and 80, they may advantageously be provided at a taper an-gle different from the thread taper.
Figure 3 shows another alternative embodiment of the invention whereby the conical sealing surfaces 41 and 42 of the top step are machined to slightly different angles with respect to the axis of the joint. According to a fur- `
ther preferred aspect of the invention, the conical seal 15 surface of the member having the thinner wall thickness at the seal surface may be machined to a smaller angle with respect to the axis of the threaded connection than the com-plementary conical seal surface of the mating member. In-dividual sealing shoulder members are shown in more detail 20 in Figure 3A. Because the conical seal at the upper step illustrated in Figure 3A occurs at a region where the female member 20 wall thickness is less than the wall thickness of the male member, the sealing surface 42 of the female member is machined to an angle of incline which is slightly less 25 than the angle of incline of sealing surface 41. Figure 3A
indicates the angle difference to be ~ . The mismatch of the angles of inclines of conical sealing surfaces 42 and 41 is selected for any particular seal geometry such that at final make-up, the bearing load has a relatively even 30 distribution across the entire sealing surface in contact, thus broadly distributing make-up stresses and minimizing their negative effects.
Referring to Figure 3A where for the upper step having the female conical sealing surface 42 machined at an 35 angle slightly less than that of male surface 41, when the ~Z4~038 pin member 30 initially mates with box member 20, the bear-ing load is substantially on the leadi~g edge of the box sealing surface 42 with the trailing edge of the pin seal-ing surface 41. After the sealing surfaces are fully made-5 up, the stress as a function of axial width becomes moreuniform than for the case where the taper angles of the sealing surfaces are the same or where the taper angle of the box sealing surface is greater than the taper angle of the pin sealing surface.
Metal-to-metal seal taper angles commonly are provided in a range of from two degrees (2) to fourteen degrees (14). The exact angular taper mismatch of the sealing angles of surfaces 41 and 42 varies depending on the seal angle of the more rigid member, the width of the seal-15 ing surface, the thickness of the thinner member, desired tolerances and other factors. It can be shown that seal mismatch for very low angle seals of approximately one-half (1~2") inch in axial width can be as low as one-quarter degree (1/4~. High angle seals of equal axial width may 20 require a mismatch of one degree tl) or more for complete balancing of bearing loads upon full make-up. Finite ele-ment analysis may be used as a tool to verify the optimum - ~
seal angle mismatch on any given seal and connection geometry.
Figure 3 also shows that threads 70 and 80 may be 25 interference fitting threads.
Figures 4A and 4B illustrate alternati~e embodi-ments of the invention. Figure 4A illustrates the reverse angle torque shoulder 43 between the two step thread.s and having not only conical sealing surface 40 (as illustrated 30 in Figure 1) on the large step, but also conical sealing surface 45 on the small step. Alternatively a conical seal-ing surface 45 could be provided solely on the small step with no sealing surface being provided on the large step.
Thus, one conical sealing surface provided on either step 35 adjacent the reverse angle torque shoulder, or two seal-- 8 _ ~2A~038 ing surfaces, one provided on each of the steps, serve in ~onjunction with the reverse angle torque shoulder and the negative angle load flank threads to create the uni~ue trapping effect of the invention.
Where as illustrated in Figure 4A, a conical seal-ing surface is provided as at 45 on the small step and the female member 20 wall thickness is greater than the thick- e ness of the male member, the sealing surface of the female ~
member is machined to an angle of incline which is slightly 10 greater than the angle of incline of the sealing surface of the male member.
Figure 4B illustrates that the combination of negative load flank threads and reverse angle torque shoulder between stepped threads may be used for tubular 15 connections or joints having two or more stepped threads.
For example, triple radial step threads 170, 190, and 180 may advantageously be used for thick walled tubulars. Ac-cording to the invention, reverse angle torque shoulders 43' and 43" are provided between thread steps 170 and 190 20 and between thread oteps 190 and 180. Providing one conical sealing surface such as 40' or 40" on each axial side of shoulder 431 and one conical sealing surface such as 41' or 42' or both 41' and 42' on each axial side of shoulder 43" serves to achieve the trapping effect discussed above 25 when used in combination with negative load flank threads.
More stepped threads with intermediate reverse angle torque shoulders and associated conical sealing surfaces could ad-vantageously find applications for tubulars having extreme-ly thick walls.
In all the embodiments of this invention the mag-nitude of the negative thread flank angle or the angle of the reverse angle shoulder should not exceed thirty degrees (30). In addition, it has been found that the magnitude of the angle of the conical sealing surfaces relative to 35 the joint axis should not be greater than fifteen degrees (15). Finally, for that embodiment of the invention il-lustrated in Figure 3, the dissimilarity of the angles of ~241038 incline of the sealing surfaces of the male and female members should be less than one degree where the angle of incline of the member having the greater wall thickness should be greater than that of the member having the les-5 ser wall thickness.
From the foregoing, it is apparent that there has been provided a sealing surface for use in joints, and in- j terconnecting tubular members especially useful in oil and r gas wells. Various modifications and alterations in the 10 described structures will be apparent to those skilled in the art from the foregoing description which do not depart from the scope of the invention.
Claims (6)
1. A joint for tubular elements comprising, an internally threaded female member and an externally threaded male member adapted to be threadably connected, the threads of the female and male members having nega-tive angle load flanks and at least two radial steps.
axially separated from one another by a reverse angle torque shoulder having at least one adjacent conical sealing surface where the taper angle of the conical sealing surface of the member having the thinner wall thickness at the seal surface is inclined at a smaller angle with respect to the axis of the threaded connec-tion than the complementary conical seal surface of the mating member, whereby, said shoulder serves as a posi-tive assembly stop and produces radial positioned inter-ference of the conical sealing surfaces when the male and female members are fully assembled, and the negative load flank angle of the threads and the reverse torque shoulder angle are selected to interlock the male and female members and to prevent differential radial separa-tion of the conical sealing surfaces when the joint is exposed to internal pressure, external pressure or both.
axially separated from one another by a reverse angle torque shoulder having at least one adjacent conical sealing surface where the taper angle of the conical sealing surface of the member having the thinner wall thickness at the seal surface is inclined at a smaller angle with respect to the axis of the threaded connec-tion than the complementary conical seal surface of the mating member, whereby, said shoulder serves as a posi-tive assembly stop and produces radial positioned inter-ference of the conical sealing surfaces when the male and female members are fully assembled, and the negative load flank angle of the threads and the reverse torque shoulder angle are selected to interlock the male and female members and to prevent differential radial separa-tion of the conical sealing surfaces when the joint is exposed to internal pressure, external pressure or both.
2. A joint for tubular elements comprising, an internally threaded female member and an externally threaded male member adapted to be threadably connected, the threads of the female and male members having nega-tive angle load flanks and having two radial steps axially separated from one another by a reverse angle torque shoulder having an adjacent conical seal between the upper step and the reverse angle torque shoulder where the conical sealing surface of the female member is tapered with respect to the female member axis at a first angle, and the conical sealing surface of the male member is tapered with respect to the axis of the male member at an angle greater than the taper angle of the female member, whereby on initial mating of said male conical sealing surface with the female conical sealing surface, the bearing load is substantially on the lead-ing edge of the female sealing surface with the trailing edge of the male sealing surface, and wherein the angle difference between the male sealing surface and the female sealing surface is selected such that the bear-ing load across the entire axial width of the seal of mating female conical sealing surface and male conical sealing surface is a relatively even distribution at final make-up.
3. A joint for tubular elements comprising, an internally threaded female member and an externally threaded male member adapted to be threadably connected, the threads of the female and male members having nega-tive angle load flanks and having radial steps axially separated from one another by a reverse angle torque shoulder having an adjacent conical seal between the lower step and the reverse angle torque shoulder where the conical sealing surface of the female member is tapered with respect to the female member axis at a first angle, and the conical sealing surface of the male member is tapered with respect to the axis of the male member at an angle less than the taper angle of the female member, whereby on initial mating of the male conical sealing surface with the female conical sealing surface, the bearing load is substantially on the leading edge of said male sealing surface with the trailing edge of the female sealing surface, and where-in the angle difference between the male sealing sur-face and the female sealing surface is selected such that the bearing load across the entire axial width of the seal of mating female conical sealing surface and male conical sealing surface is a relatively even distribution at final make-up.
4. A joint for tubular elements comprising, an internally threaded female member and an externally threaded male member adapted to be threadably connected, the threads of the female and male members having nega-tive angle load flanks and having two radial steps axially separated from one another by a reverse angle torque shoulder having a first adjacent conical seal between the upper step and the reverse angle torque shoulder where the first conical sealing surface of the female member is tapered with respect to the female mem-ber axis at an angle, and the first conical sealing sur-face of the male member is tapered with respect to the axis of the male member at an angle greater than the taper angle of the female member, and a second adjacent conical seal between the lower step and the reverse angle torque shoulder where the second conical sealing surface of the female member is tapered with respect to the female axis at an angle and the second conical sealing surface of the male member is tapered with respect to the axis of the male member at an angle less than the taper angle of the female member, whereby, on initial mating of said first male conical sealing sur-face with the first female conical sealing surface, the bearing load is substantially on the leading edge of the first female sealing surface with the trailing edge of the first male sealing surface, wherein the angle difference between the first male sealing sur-face and the first female sealing surface is selected such that the bearing load across the entire axial width of the seal of mating first female conical seal-ing surface and first male conical sealing surface is a relatively even distribution at final make-up, whereby on initial mating of the second male conical sealing surface with the second female conical sealing surface, the bearing load is substantially on the leading edge of the second male sealing surface with the trailing edge of the second female sealing surface, and wherein the angle difference between the second sealing surface and the second female sealing surface is selected such that the bearing load across the entire axial width of the seal of mating second female conical sealing sur-face and second male conical sealing surface is a rela-tively even distribution at final make-up.
5. A male tubular member adapted for use for coaxial threaded interconnection with female tubular member, the female tubular member having internal threads with negative angle load flanks and at least two radial steps axially separated from one another by a reverse angle torque shoulder having at least one adjacent conical sealing surface, said male member comprising, external threads with negative angle load flanks and at least two radial steps axially separated from one another by a reverse angle torque shoulder with at least one adjacent conical sealing surface where the male or female member having the thinner wall thick-ness at the seal surface is inclined at a smaller taper angle with respect to the axis of the threaded connection than the complementary conical seal surface of the mating member, whereby said male torque shoulder when mated with said female torque shoulder produces radial positional interference of the conical sealing surface, and where-by the male negative load flank angle and the male torque shoulder angle are selected to mate with the female negative load flank angle and the female torque shoulder angle to interlock the male and female members and to prevent differential radial separation of the conical sealing surfaces when the mated threads are exposed to internal pressure, external pressure or both and, where-by on initial mating of each of the male conical sealing surfaces with the corresponding female conical sealing surface, the bearing load is substantially on the lead-ing edge of the sealing surface of the member having the thinner wall thickness with the trailing edge of the sealing surface of the member having the thicker wall thickness, and wherein the angle difference between said male sealing surface and said female sealing sur-face is selected such that bearing load across the entire axial width of the seal of mating female coni-cal sealing surface and male conical sealing surface has a relatively even distribution at final make-up.
6. A female tubular member adapted for use for coaxial threaded interconnection with a male tubu-lar member, the male tubular member having external threads with negative angle load flanks and at least two radial steps axially separated by a reverse angle torque shoulder having at least one adjacent conical sealing surface, said female member comprising, inter-nal threads with negative angle load flanks and at least two radial steps axially separated from one another by a reverse angle torque shoulder with at least one adja-cent conical sealing surface where the male or female member having the thinner wall thickness at the seal surface is inclined at a smaller taper angle with res-pect to the axis of the threaded connection that the complementary conical seal surface of the mating mem-ber, whereby said female torque shoulder when mated with said male torque shoulder produces radial positional interference of the conical sealing surface, and where-by, the female negative load flank angle and the female torque shoulder angle are selected to mate with the male negative load flank angle and the male torque shoulder angle to interlock the female and male mem-bers and to prevent differential radial separation of the conical sealing surfaces when the mated threads are exposed to internal pressure, external pressure or both, and whereby on initial mating of each of the female conical sealing surfaces with the male conical sealing surface, the bearing load is substantially on the lead-ing edge of the sealing surface of the member having the thinner wall thickness with the trailing edge of the sealing surface of the member having the thicker wall thickness, and wherein the angle difference between said female sealing surface and said male sealing sur-face of the member having the thicker wall thickness, and wherein the angle difference between said female sealing surface and said male sealing surface is se-lected such that the bearing load across the entire axial width of the seal of mating female conical seal-ing surface and the male conical sealing surface has a relatively even distribution at final make-up.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US45873483A | 1983-01-17 | 1983-01-17 | |
| US458,734 | 1983-01-17 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1241038A true CA1241038A (en) | 1988-08-23 |
Family
ID=23821878
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000445364A Expired CA1241038A (en) | 1983-01-17 | 1984-01-16 | Tubular joint with trapped mid-joint metal-to-metal seal having unequal tapers |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1241038A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US9683684B1 (en) | 2015-12-09 | 2017-06-20 | Certus Energy Solutions, Llc | Tubular coupling |
| US11466800B2 (en) | 2015-12-09 | 2022-10-11 | Certus Energy Solutions, Llc | Tubular coupling |
-
1984
- 1984-01-16 CA CA000445364A patent/CA1241038A/en not_active Expired
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US9683684B1 (en) | 2015-12-09 | 2017-06-20 | Certus Energy Solutions, Llc | Tubular coupling |
| US9970576B2 (en) | 2015-12-09 | 2018-05-15 | Certus Energy Solutions, Llc | Tubular coupling |
| US11028948B2 (en) | 2015-12-09 | 2021-06-08 | Certus Energy Solutions, Llc | Tubular coupling |
| US11466800B2 (en) | 2015-12-09 | 2022-10-11 | Certus Energy Solutions, Llc | Tubular coupling |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US4662659A (en) | Tubular joint with trapped mid-joint metal-to-metal seal having unequal tapers | |
| EP0131621B1 (en) | Tubular joint with trapped mid-joint metal to metal seal | |
| US4570982A (en) | Tubular joint with trapped mid-joint metal-to-metal seal | |
| CA2185251C (en) | Threaded joint for tubes | |
| EP1179700B1 (en) | Double flex seal for tubular connection | |
| CA1236502A (en) | Tubular connection having a chevron wedge thread | |
| US5462315A (en) | Stabilized center-shoulder-sealed tubular connection | |
| US4762344A (en) | Well casing connection | |
| US4521042A (en) | Threaded connection | |
| EP0241521B1 (en) | Seal for threaded pipe connection | |
| USRE30647E (en) | Tubular connection | |
| CA1042943A (en) | Tubular connection | |
| US4822081A (en) | Driveable threaded tubular connection | |
| US6578880B2 (en) | Wedgethread pipe connection | |
| EP0131622B1 (en) | Tubular coupling with improved metal to metal seal | |
| CA1059551A (en) | Dovetail connection for pin and box joints | |
| EP1175577B1 (en) | Threaded connection with high compressive rating | |
| EP1106778B1 (en) | Seal for expandable tubular connections | |
| EP1506064B1 (en) | Threaded connection especially for radially plastically expandable conduit | |
| EP0149612B1 (en) | Tubular connection with cylindrical and tapered stepped threads | |
| CA1241038A (en) | Tubular joint with trapped mid-joint metal-to-metal seal having unequal tapers | |
| EP0454148A2 (en) | Pipe joint | |
| US20040108720A1 (en) | Double flex seal for tubular connection | |
| RU2796572C1 (en) | Screw connection and its application | |
| EP4073340B1 (en) | Threaded connection partially in a self-locking engagement with an external shoulder capable to resist elevated torque |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |