CA1182490A - Tool joint with internal/external make-up shoulder - Google Patents
Tool joint with internal/external make-up shoulderInfo
- Publication number
- CA1182490A CA1182490A CA000410430A CA410430A CA1182490A CA 1182490 A CA1182490 A CA 1182490A CA 000410430 A CA000410430 A CA 000410430A CA 410430 A CA410430 A CA 410430A CA 1182490 A CA1182490 A CA 1182490A
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- CA
- Canada
- Prior art keywords
- pin
- face
- shoulder
- box
- internal
- 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
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Classifications
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B17/00—Drilling rods or pipes; Flexible drill strings; Kellies; Drill collars; Sucker rods; Cables; Casings; Tubings
- E21B17/02—Couplings; joints
- E21B17/04—Couplings; joints between rod or the like and bit or between rod and rod or the like
- E21B17/042—Threaded
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- Engineering & Computer Science (AREA)
- Geology (AREA)
- Life Sciences & Earth Sciences (AREA)
- Mining & Mineral Resources (AREA)
- Physics & Mathematics (AREA)
- Environmental & Geological Engineering (AREA)
- Fluid Mechanics (AREA)
- Mechanical Engineering (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Geochemistry & Mineralogy (AREA)
- Earth Drilling (AREA)
- Cutting Tools, Boring Holders, And Turrets (AREA)
- Forging (AREA)
- Surgical Instruments (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
A tool joint for earth boring drill pipe members has features that increase the amount of torque required to yield the connection. The tool joint has both external and internal make-up shoulders. The pin and box are dimensioned so that the box face contacts the external shoulder while there still is a clearance between the pin face the internal shoulder. At normal make-up torque, the external shoulder will be tightened to its normal amount. The internal shoulder will tighten to its yield only if additional torque is encountered while drilling.
The internal shoulder adds to the amount of torque required to yield the tool joint connection.
A tool joint for earth boring drill pipe members has features that increase the amount of torque required to yield the connection. The tool joint has both external and internal make-up shoulders. The pin and box are dimensioned so that the box face contacts the external shoulder while there still is a clearance between the pin face the internal shoulder. At normal make-up torque, the external shoulder will be tightened to its normal amount. The internal shoulder will tighten to its yield only if additional torque is encountered while drilling.
The internal shoulder adds to the amount of torque required to yield the tool joint connection.
Description
1 ~2d~!9~3 BACKGROUND O~ THE INVENTION
This in~ention relates in general to earth boring drill pipe, and in particular to the tool joints for connecting the sections of drill pipe together.
Deep wells such as for oil and gas are drilled with a rotary drill bit rotated by a string of drill pipe. The drill pipe is made-up of indi~idual members, each about 30 foot in length. The members are secured together by a threaded connection, called a tool joint. The tool joints must with-stand the normal torque encounted during drilling, and also pro~ide sealing to prevent drillin~ fluid being pumped down the drill pipe from leaking out the joints. Leakage out the tool joints causes wear due to the abrasiveness of the drilling fluid, which would lead to early fallure.
The tool joint is made-up of a pin member and a box member. The pin member has external threads and an external annular make-up shoulder. The box member has internal threads and a rim or face that makes up against the make-up shoulder.
In conventional drill pipe, there is no internal shoulder in the box member for contact by the nose or face of the pin.
When the tool joint members are made-up at the surface, normally they will be made-up to a tor~ue that exerts a pressure that is ; about one-half the yield strength between the box face and pin ~ make-up shoulder.
i ~ 4 ~ ~
Should additional torque be encountered while drilling, such as due to the bit or pipe becoming stuck, it is possible ~or the yield strength of -the pin and box to be exceeded and to part. Consequently, it is very important to have tool joints with high torque withstanding abilities, preferably in excess of the drill pipe itself.
SUMMARY OF THE INVENTION
In this invention, a tool joint is provided that has a substantially increased yield stren~th without any additional thickness in the pin or box, and without further hardening of the steel. The box is provided with an internal shoulder located below its threads. The pin has a face on the end of its nose that mates with the internal shoulder in the box.
The dimensions of the pin and box are calculated so that when hand tightenedl the box face will contact the external shoulder of the pin. A clearance, however, will exist between the pin face and the internal shoulder of the box. ~hen the tool joint is fully made-up to its normal make-up torque, the box face will engage the external make-up shoulder to the normal pressure, which is about one half the yield strength of the tool joint. The pin face will exert little or no pressure against the internal shoulder at normal make-up torque.
During drilling operation, if additional torque is encountered, the joint will further tighten, causing the pin face to engage and tighten against the internal shoulder.
The counterbore of the box, and the base and nose sections of the pin are selected so that the nose section of the pin will reach its yield strength approximately the same and no later than the time at which the box counterbore and pin base reach their yield strengths. The internal make-up shoulder increases the amount of torque required to part the tool joint.
This in~ention relates in general to earth boring drill pipe, and in particular to the tool joints for connecting the sections of drill pipe together.
Deep wells such as for oil and gas are drilled with a rotary drill bit rotated by a string of drill pipe. The drill pipe is made-up of indi~idual members, each about 30 foot in length. The members are secured together by a threaded connection, called a tool joint. The tool joints must with-stand the normal torque encounted during drilling, and also pro~ide sealing to prevent drillin~ fluid being pumped down the drill pipe from leaking out the joints. Leakage out the tool joints causes wear due to the abrasiveness of the drilling fluid, which would lead to early fallure.
The tool joint is made-up of a pin member and a box member. The pin member has external threads and an external annular make-up shoulder. The box member has internal threads and a rim or face that makes up against the make-up shoulder.
In conventional drill pipe, there is no internal shoulder in the box member for contact by the nose or face of the pin.
When the tool joint members are made-up at the surface, normally they will be made-up to a tor~ue that exerts a pressure that is ; about one-half the yield strength between the box face and pin ~ make-up shoulder.
i ~ 4 ~ ~
Should additional torque be encountered while drilling, such as due to the bit or pipe becoming stuck, it is possible ~or the yield strength of -the pin and box to be exceeded and to part. Consequently, it is very important to have tool joints with high torque withstanding abilities, preferably in excess of the drill pipe itself.
SUMMARY OF THE INVENTION
In this invention, a tool joint is provided that has a substantially increased yield stren~th without any additional thickness in the pin or box, and without further hardening of the steel. The box is provided with an internal shoulder located below its threads. The pin has a face on the end of its nose that mates with the internal shoulder in the box.
The dimensions of the pin and box are calculated so that when hand tightenedl the box face will contact the external shoulder of the pin. A clearance, however, will exist between the pin face and the internal shoulder of the box. ~hen the tool joint is fully made-up to its normal make-up torque, the box face will engage the external make-up shoulder to the normal pressure, which is about one half the yield strength of the tool joint. The pin face will exert little or no pressure against the internal shoulder at normal make-up torque.
During drilling operation, if additional torque is encountered, the joint will further tighten, causing the pin face to engage and tighten against the internal shoulder.
The counterbore of the box, and the base and nose sections of the pin are selected so that the nose section of the pin will reach its yield strength approximately the same and no later than the time at which the box counterbore and pin base reach their yield strengths. The internal make-up shoulder increases the amount of torque required to part the tool joint.
2 'i 9 ~
BRIEF DESCRIPTI~N OF _HE DRAWINGS
Fig. 1 is the sole figure, and it shows a cross-sectional view of a tool joint constructed in accordance with this invention, DESCRIPTION OF THE PREFERRED EMBODIME~T
Fig. 1 shows an upper drill pipe member 11 secured into a lower drill pipe member 13. The ends of the drill pipe members 11 and 13, when connected together, are ~nown as a tool joint. A pin 15 is formed on the lower end o~
upper drill pipe member 11, and also on the lower end (not shown) of the lower drill pipe member 13. Pin 15 has an external, annular make-up shoulder 17. A relief groove 19 is located at the inner diameter of external shoulder 17.
A base section 21 extends downward from external should 17. Base section 21 is cylindrical and does not contain any threadsO A bench mark shoulder 23 is formed a short distance downward from make-up shoulder 17 for use in measuring the amount of metal removed from make-up shoulder 17 when redressed. A set oE threads 25 is formed on pin 15 helow base section 21. Threads 25 are tapered ; and terminate in a cylindrical nose section 27. Nose section 27 terminates in a face ~9, which is a circular rim located in a plane perpendicular to the axis of the drill pipe member 11.
~5 The upper end of lower drill pipe member 13, as well as the upper end (not shown) of the upper drill pipe member 11, has a box 31 formed on it. Box 31 receives pin 15 and includes a rim or face 33 on its upper extremity.
Face 33 is a circular, flat surface located in a plane perpendicular to the axis of lower drill pipe member 13, Face 33 engages external shoulder 17 of pin 15. The inner bore of box 31 includes an upwardly facin~ shoulder 35 formed a short distance below face 33 for servin~ as a bench mark.
2~a Bench mark 35 enables the user to determine how much metal has been removed from face 33 during redressing operations.
~ cylindrical counterbore section 37 is located immediately below bench mark 35. Counterbore section 37 extends about the same length as base section 21, but has an inner diameter that is greater than the outer diameter of base section 21. This results in an annular cavity between the base section 21 and counterbore section 37. A set of internal threads 39 are located below the counterbore section 37. Threads 39 are tapered and sized to engage threads 25.
Box 31 has a cylindrical base section 41 located below threads 39. Base section 41 terminates in an annular upwardly facing internal shoulder 43. Shoulder 43 is located ir, a plane perpendicular to the axis of lower drill pipe member 13, and is adapted to be engaged by pin face 29. A
relie~ groove 45 is formed at the intersection of internal shoulder 43 and base section 41. An axial passage 47 of box 31 below internal shoulder 43 is equal tc, the diameter of an axial passage 49 of pin 15. An annular recessed area 51 is formed on the exterior sidewall of counterbore section 37, Recessed area 51 has a slightly smaller diameter than the outer diameter of the portion con-taining threads 39.
The box 31 and pin 15 are dimensioned so that the distance from the external shoulder 17 to pin face 29 is slightly less than the dis-tance from the box face 33 to internal shoulder 43. The box 31 and pin 15 are dimensioned so that at the surface, when two members 11 and 13 are made~
up manually hand tight without the use o~ wrenches or tools, a clearance will exist between pin face 29 and internal shoulder 43. At hand tight, there will be no pressure between box ~ace 33 and external shoulder 17, although they will contact each other.
In operation the drill pipe members 11 and 13 are made-up to a torque that pro~ides pressure equal to about one-half the yield strengths o~ the pin base 21 and box I ~ ~ 2 ~
counterbore section 37. The yield strength is the pressure, either compression or tension, at which either the pin base 21 or the box counterbore section 37 will permanently deform~
As tor~ue is applied, counter~ore sectlon 37 compresses and 5 pin base 21 lengthens, resultin~ in the pin face 29 advancing downward. At make-up torque, pin face 29 will be spaced closely to, or possibly even in contact with the internal shoulder 43. However any pressure at internal shoulder 43 is less than at external shoulder 17 at make~up.
The drill pipe members are then lowered into the well and rotated or drilling. During drilling, additional torque might be encountered if the drill bit or structure on the lower end of the drill string becomes stuck. Further compression of counterbore section 37 and lengthening of pin 15 base 21 b" the additional torque will cause the pin face 29 to press against the internal shoulder 43 and make-up tightly.
Ideally, t:he dimensions are such that the yield strength of the nose section 27 will be reached approximately the same time or no later than the time at which the cumulative yield 20 strengths of the pin base section 21 and box counterbore section 37 are reached. The additional pressure exerted by the pin face 29 against the internal shoulder 43 increases the amount of torque required to yleld the tool joint considerably.
The base section 21, countexbore section 37 and nose section 27 serve as spring means for causing the box face 33 to tighten against external shoulder 17 to a pressure at make-up torque in excess of the pressure, if any, that pin face 29 imposes against internal shoulder 43. The lengths 30 are selected to provide sufficient spring to allow deflection of these members and result in the ma3~e~up of the internal shoulder 43 if additional torque is encountered during drilling. To explain how these dimensions are determined, an actual example for modification of an A.P.I. (American 35 Petroleum Institute~ standard 3 1/2 inch I~Fo tool joint ~AIill be discussed. First, the ~ores 47 and 49 are o standard diameter bores for this size of tool joint, this dimension being 2.688 inch, The outer diameter of base section 21 is selected to be 3.668 inch, which is the minimum outer diameterof a standard tool joint pin at its last engaged pin thread. This minimum thickness of the base section 21 is selected to assure that the pin 15 will not have less strength than a base section of a prior art pin.
The cross-sectional area of the base section 21 calculates to be 4.892 square inches.
To assure that the counterbore section 37 dGes not fail substantially earlier than the pin base section 21, the cross-sectional area of the counterbore section 37 is selected to be substantially the same as that of the base section 21. In the preferred embodiment, to achieve this, the count~rbore diameter is determined by the standard counterbore diameter of a tool joint box. The outer diameter of the recessed area 51 is then calculated to result in the cross-sectional area of the counterbore section 37 being substantially the same as that of the pin base section 21.
The recessed area 51 serves to prevent wear on the outer diameter of counterbore section 37, which might otherwise reduce the cross-sectional area to below the design amount.
If reduced below the design requirements, the counterbore section 37 might fail earlier than the base section 21. In the preferred embodiment, the outer diameter of the recessed section 51 is 4.813 inch. In the preferred embo~iment, the inner diameter chosen is 4O073 inch, this resulting in a cross-sectional area of 5.132 square inches. The difference in areas of pin base section 21 and counterbore section 37 is .24 square inches, a difference of about 5 percent.
Next, the length of the counterbore section 37 is selected. This length must be sufficient to provide a considerable deflection when torque is applied. In the preferred embodiment, a length of two inches was selected for the counterbore section 37~ This results in a length of the base section 21 being slightly greater due to the engagement of the threads, this becoming 2.19 inch.
The amount of deflection at yield can then be determined by dividing the yielcl strength for the steel for this tool joint by Young's ~lodulus, this being 120,000 divided by 28,600,000, resulting in .004 inch per inch.
That is, at the yield stress of 120,000 psi (pounds per square inch) being exerted on a steel member of this type, the member will deflect, either in compression or in tension, .004 inch for each inch of length of the member.
During make-up, the counterbore section 37 will compress and the base section 21 will elongate. At a torque that results in one-half the yield strength, 60,000 psi ~pouncls per square inch), the base section 21 elongation will be 2.19 inch multiplied by .004 inch per inch, and divided b~ 2, equaling .00438 inch. The counterbore section 37 will compress by an amount equal to two inches in length times .004 inch per inch divided by two, and multiplied by the ratio of the cross-sectional area of the base section 21 over the cross-sectional area of the counterbore section 37. This results in a total de~lection at one-half yield strength of .00381 inch. Consequently, the total relative motion of the pin face 29 at one-half the yield strength is the sum of .00433 and .00381 or .00819 inch. At three-fourth yield strength the deflection is .0122~ inch and atfull yield, the deflection is ~01638 inch.
The dimensions of the nose section 27 are selected by choosing a length that will cause the nose section to reach yield strength simultaneously or slightly sooner than the pin base section 21 and counterbore section 37. To avoid making the length longer than necessary, a criteria that the pin face 29 contact initially internal shoulder 43 only at three-fourth yield was chosen. At this point, pin base section 21 and counterbore section 37 will have moved pin face 29 down~ard .01228 inch. To reach full yield, pin base section 21 and counterbore section 23 must deflect an additional .00409 inch. Nose section 29 will compress .00~09 inch because of this deflection. The length of nose section 29 is selected to reach full yield when compressed .00409 inch. We previously noted that deflection of this type of steel is the yield strength over Young's Modulus or .004 inch per inch. Since approximately .004 inch of com-pression is needed in nose section 29 to reach full yield simultaneously with pin base section 21 and counterbore section 37, the len~th of nose section 29 should be one inch.
For the outer diameter of nose section 29, the threads 25 and 39 were truncated as much as possible without reducing their strength. The selected length is about 2 3/8 inches.
A diameter slightly less than the minimum outer diameter at the truncated end of the threads was selected to be the outer dia~eter of nose section 27, which in the preferred embodiment is 3.188 inch.
The next dimension to determine is the positioning of the in1:ernal shoulder 43. A criteria in the design is that at full make-up torque, which is one-half yield strength at external shoulder 17, the pin ~ace 29 will exert little i~ any pressure against the internal shoulder 43.
We have previously determined that pin face 29 will move downward .00319 inch at full make-up torque and one-half yield strength. A clearance of .012 inch between pin face 29 and internal shoulder k3 at hand tight would thus reduce to about .004 inch at full ma~e-up torque because oE the .00819 inch movement due to the deflection of pin base section 21 and counterbore section 37. Additional torque encoun-tered up to three-fourths of the yield at the external shoulder 17 would result in a de~lection of pin base section 21 and counterbore section 37 of an additional ~00~09 inch. ~his places the pin face 29 initially in contact with the internal shoulder 43 at three-fourth yield. Additional torque from three fourths yield to full yield would cause the pin face 29, if unrestrained, to mo~e downward an additional .30409 inch.
However, since the pin ~ace 29 contacted the internal shoulder ~ ~2`~`YO
43 at three-fourth yield strength, the nose section 27 will compress for .00409 inch. This is the amount of deflection that the nose section 27 undergoes at full yield. This results in the nose section 27 reaching full yield simultaneously with the pin base section 21 and counterbore section 37.
To achieve the desirecl yap between pin face 29 and internal shoulder 43 at hand tight of .012 inch, the distance from the box face 33 to the internal shoulder 43 is selected to be .012 inch greater than the distance from the pin shoulder 17 to the pin face 29, or 5.742 inch. While this is the ideal dimension, a reaslistic manufacturing tolerance for these dimensions is plus 0 and minus .005 inch from the total dimensions of 5.730 and 5.742 inches. This results in a hard tight gap between pin face 29 and internal shoulder 43 of a minimum of .007 inch and an ideal maximum of .012 inch.
If a tool joint has a minimum gap rather than the ideal gap, the nose section 27 will yield before the pin base section 21 or counterbore section 37 yields. ~lsof at full make-up torque, pin face 29 will exert some compression against internal shoulder 43. This occurs because with a total defleetion frGm hand tight to half yield of .00819 inch, a minimum hand tight gap of .007 inch will place the nose section 27 under .001 inch compression. A deflection of .001 inch places nose section 27 at one-fourth yield, while pin base section 21 and counterbore section 37 will be at one-half yield. Nose section 27 will reach its full yield strength at a compression of .004 inch. Increasing the torque from one-half yield to three-fourth yield of pin base section 21 and counterbore section 37 causes .00409 deflection of these members. Consequently, the nose section 27 will reaeh full yield slightly before the base section 21 and counterbore section 37 reach three-fourth yield. This might result in cracking of the nose section 27, however, this will be less detrimental than cracking occurring in the base section 21 or counterbore section 37. Cracking of 2 ~
the nose section 27 will not result in parting of the drill string. Up to, and beyond the point at which the nose section 27 yields, it does provide additional torque withstanding abilities.
Through standard calculations, the torque to yield pin base section 21 or counterbore section 37 on the above described tool joint at the ideal dimensions is 25,583 foot pounds. A conventional tool joint having a five inch outer diameter and ~ 11/16 inner diameter, as does this tool join-t, has a torque withstanding ability of only 18,100 ~oot pounds at full yield. This increase in torque required to yield a tool joint furthex reduces the chances for parting of the drill string while drilling. The increase in the strength of the tool joint is accomplished without additional metal 5 thicknesses or higher steel strengths.
h'hile the invention has been shown in only one of its forms, it should be apparent to those skilled in the art that it is not so limited but is susceptible to various changes and modifications without departing from -the scope of the invention.
BRIEF DESCRIPTI~N OF _HE DRAWINGS
Fig. 1 is the sole figure, and it shows a cross-sectional view of a tool joint constructed in accordance with this invention, DESCRIPTION OF THE PREFERRED EMBODIME~T
Fig. 1 shows an upper drill pipe member 11 secured into a lower drill pipe member 13. The ends of the drill pipe members 11 and 13, when connected together, are ~nown as a tool joint. A pin 15 is formed on the lower end o~
upper drill pipe member 11, and also on the lower end (not shown) of the lower drill pipe member 13. Pin 15 has an external, annular make-up shoulder 17. A relief groove 19 is located at the inner diameter of external shoulder 17.
A base section 21 extends downward from external should 17. Base section 21 is cylindrical and does not contain any threadsO A bench mark shoulder 23 is formed a short distance downward from make-up shoulder 17 for use in measuring the amount of metal removed from make-up shoulder 17 when redressed. A set oE threads 25 is formed on pin 15 helow base section 21. Threads 25 are tapered ; and terminate in a cylindrical nose section 27. Nose section 27 terminates in a face ~9, which is a circular rim located in a plane perpendicular to the axis of the drill pipe member 11.
~5 The upper end of lower drill pipe member 13, as well as the upper end (not shown) of the upper drill pipe member 11, has a box 31 formed on it. Box 31 receives pin 15 and includes a rim or face 33 on its upper extremity.
Face 33 is a circular, flat surface located in a plane perpendicular to the axis of lower drill pipe member 13, Face 33 engages external shoulder 17 of pin 15. The inner bore of box 31 includes an upwardly facin~ shoulder 35 formed a short distance below face 33 for servin~ as a bench mark.
2~a Bench mark 35 enables the user to determine how much metal has been removed from face 33 during redressing operations.
~ cylindrical counterbore section 37 is located immediately below bench mark 35. Counterbore section 37 extends about the same length as base section 21, but has an inner diameter that is greater than the outer diameter of base section 21. This results in an annular cavity between the base section 21 and counterbore section 37. A set of internal threads 39 are located below the counterbore section 37. Threads 39 are tapered and sized to engage threads 25.
Box 31 has a cylindrical base section 41 located below threads 39. Base section 41 terminates in an annular upwardly facing internal shoulder 43. Shoulder 43 is located ir, a plane perpendicular to the axis of lower drill pipe member 13, and is adapted to be engaged by pin face 29. A
relie~ groove 45 is formed at the intersection of internal shoulder 43 and base section 41. An axial passage 47 of box 31 below internal shoulder 43 is equal tc, the diameter of an axial passage 49 of pin 15. An annular recessed area 51 is formed on the exterior sidewall of counterbore section 37, Recessed area 51 has a slightly smaller diameter than the outer diameter of the portion con-taining threads 39.
The box 31 and pin 15 are dimensioned so that the distance from the external shoulder 17 to pin face 29 is slightly less than the dis-tance from the box face 33 to internal shoulder 43. The box 31 and pin 15 are dimensioned so that at the surface, when two members 11 and 13 are made~
up manually hand tight without the use o~ wrenches or tools, a clearance will exist between pin face 29 and internal shoulder 43. At hand tight, there will be no pressure between box ~ace 33 and external shoulder 17, although they will contact each other.
In operation the drill pipe members 11 and 13 are made-up to a torque that pro~ides pressure equal to about one-half the yield strengths o~ the pin base 21 and box I ~ ~ 2 ~
counterbore section 37. The yield strength is the pressure, either compression or tension, at which either the pin base 21 or the box counterbore section 37 will permanently deform~
As tor~ue is applied, counter~ore sectlon 37 compresses and 5 pin base 21 lengthens, resultin~ in the pin face 29 advancing downward. At make-up torque, pin face 29 will be spaced closely to, or possibly even in contact with the internal shoulder 43. However any pressure at internal shoulder 43 is less than at external shoulder 17 at make~up.
The drill pipe members are then lowered into the well and rotated or drilling. During drilling, additional torque might be encountered if the drill bit or structure on the lower end of the drill string becomes stuck. Further compression of counterbore section 37 and lengthening of pin 15 base 21 b" the additional torque will cause the pin face 29 to press against the internal shoulder 43 and make-up tightly.
Ideally, t:he dimensions are such that the yield strength of the nose section 27 will be reached approximately the same time or no later than the time at which the cumulative yield 20 strengths of the pin base section 21 and box counterbore section 37 are reached. The additional pressure exerted by the pin face 29 against the internal shoulder 43 increases the amount of torque required to yleld the tool joint considerably.
The base section 21, countexbore section 37 and nose section 27 serve as spring means for causing the box face 33 to tighten against external shoulder 17 to a pressure at make-up torque in excess of the pressure, if any, that pin face 29 imposes against internal shoulder 43. The lengths 30 are selected to provide sufficient spring to allow deflection of these members and result in the ma3~e~up of the internal shoulder 43 if additional torque is encountered during drilling. To explain how these dimensions are determined, an actual example for modification of an A.P.I. (American 35 Petroleum Institute~ standard 3 1/2 inch I~Fo tool joint ~AIill be discussed. First, the ~ores 47 and 49 are o standard diameter bores for this size of tool joint, this dimension being 2.688 inch, The outer diameter of base section 21 is selected to be 3.668 inch, which is the minimum outer diameterof a standard tool joint pin at its last engaged pin thread. This minimum thickness of the base section 21 is selected to assure that the pin 15 will not have less strength than a base section of a prior art pin.
The cross-sectional area of the base section 21 calculates to be 4.892 square inches.
To assure that the counterbore section 37 dGes not fail substantially earlier than the pin base section 21, the cross-sectional area of the counterbore section 37 is selected to be substantially the same as that of the base section 21. In the preferred embodiment, to achieve this, the count~rbore diameter is determined by the standard counterbore diameter of a tool joint box. The outer diameter of the recessed area 51 is then calculated to result in the cross-sectional area of the counterbore section 37 being substantially the same as that of the pin base section 21.
The recessed area 51 serves to prevent wear on the outer diameter of counterbore section 37, which might otherwise reduce the cross-sectional area to below the design amount.
If reduced below the design requirements, the counterbore section 37 might fail earlier than the base section 21. In the preferred embodiment, the outer diameter of the recessed section 51 is 4.813 inch. In the preferred embo~iment, the inner diameter chosen is 4O073 inch, this resulting in a cross-sectional area of 5.132 square inches. The difference in areas of pin base section 21 and counterbore section 37 is .24 square inches, a difference of about 5 percent.
Next, the length of the counterbore section 37 is selected. This length must be sufficient to provide a considerable deflection when torque is applied. In the preferred embodiment, a length of two inches was selected for the counterbore section 37~ This results in a length of the base section 21 being slightly greater due to the engagement of the threads, this becoming 2.19 inch.
The amount of deflection at yield can then be determined by dividing the yielcl strength for the steel for this tool joint by Young's ~lodulus, this being 120,000 divided by 28,600,000, resulting in .004 inch per inch.
That is, at the yield stress of 120,000 psi (pounds per square inch) being exerted on a steel member of this type, the member will deflect, either in compression or in tension, .004 inch for each inch of length of the member.
During make-up, the counterbore section 37 will compress and the base section 21 will elongate. At a torque that results in one-half the yield strength, 60,000 psi ~pouncls per square inch), the base section 21 elongation will be 2.19 inch multiplied by .004 inch per inch, and divided b~ 2, equaling .00438 inch. The counterbore section 37 will compress by an amount equal to two inches in length times .004 inch per inch divided by two, and multiplied by the ratio of the cross-sectional area of the base section 21 over the cross-sectional area of the counterbore section 37. This results in a total de~lection at one-half yield strength of .00381 inch. Consequently, the total relative motion of the pin face 29 at one-half the yield strength is the sum of .00433 and .00381 or .00819 inch. At three-fourth yield strength the deflection is .0122~ inch and atfull yield, the deflection is ~01638 inch.
The dimensions of the nose section 27 are selected by choosing a length that will cause the nose section to reach yield strength simultaneously or slightly sooner than the pin base section 21 and counterbore section 37. To avoid making the length longer than necessary, a criteria that the pin face 29 contact initially internal shoulder 43 only at three-fourth yield was chosen. At this point, pin base section 21 and counterbore section 37 will have moved pin face 29 down~ard .01228 inch. To reach full yield, pin base section 21 and counterbore section 23 must deflect an additional .00409 inch. Nose section 29 will compress .00~09 inch because of this deflection. The length of nose section 29 is selected to reach full yield when compressed .00409 inch. We previously noted that deflection of this type of steel is the yield strength over Young's Modulus or .004 inch per inch. Since approximately .004 inch of com-pression is needed in nose section 29 to reach full yield simultaneously with pin base section 21 and counterbore section 37, the len~th of nose section 29 should be one inch.
For the outer diameter of nose section 29, the threads 25 and 39 were truncated as much as possible without reducing their strength. The selected length is about 2 3/8 inches.
A diameter slightly less than the minimum outer diameter at the truncated end of the threads was selected to be the outer dia~eter of nose section 27, which in the preferred embodiment is 3.188 inch.
The next dimension to determine is the positioning of the in1:ernal shoulder 43. A criteria in the design is that at full make-up torque, which is one-half yield strength at external shoulder 17, the pin ~ace 29 will exert little i~ any pressure against the internal shoulder 43.
We have previously determined that pin face 29 will move downward .00319 inch at full make-up torque and one-half yield strength. A clearance of .012 inch between pin face 29 and internal shoulder k3 at hand tight would thus reduce to about .004 inch at full ma~e-up torque because oE the .00819 inch movement due to the deflection of pin base section 21 and counterbore section 37. Additional torque encoun-tered up to three-fourths of the yield at the external shoulder 17 would result in a de~lection of pin base section 21 and counterbore section 37 of an additional ~00~09 inch. ~his places the pin face 29 initially in contact with the internal shoulder 43 at three-fourth yield. Additional torque from three fourths yield to full yield would cause the pin face 29, if unrestrained, to mo~e downward an additional .30409 inch.
However, since the pin ~ace 29 contacted the internal shoulder ~ ~2`~`YO
43 at three-fourth yield strength, the nose section 27 will compress for .00409 inch. This is the amount of deflection that the nose section 27 undergoes at full yield. This results in the nose section 27 reaching full yield simultaneously with the pin base section 21 and counterbore section 37.
To achieve the desirecl yap between pin face 29 and internal shoulder 43 at hand tight of .012 inch, the distance from the box face 33 to the internal shoulder 43 is selected to be .012 inch greater than the distance from the pin shoulder 17 to the pin face 29, or 5.742 inch. While this is the ideal dimension, a reaslistic manufacturing tolerance for these dimensions is plus 0 and minus .005 inch from the total dimensions of 5.730 and 5.742 inches. This results in a hard tight gap between pin face 29 and internal shoulder 43 of a minimum of .007 inch and an ideal maximum of .012 inch.
If a tool joint has a minimum gap rather than the ideal gap, the nose section 27 will yield before the pin base section 21 or counterbore section 37 yields. ~lsof at full make-up torque, pin face 29 will exert some compression against internal shoulder 43. This occurs because with a total defleetion frGm hand tight to half yield of .00819 inch, a minimum hand tight gap of .007 inch will place the nose section 27 under .001 inch compression. A deflection of .001 inch places nose section 27 at one-fourth yield, while pin base section 21 and counterbore section 37 will be at one-half yield. Nose section 27 will reach its full yield strength at a compression of .004 inch. Increasing the torque from one-half yield to three-fourth yield of pin base section 21 and counterbore section 37 causes .00409 deflection of these members. Consequently, the nose section 27 will reaeh full yield slightly before the base section 21 and counterbore section 37 reach three-fourth yield. This might result in cracking of the nose section 27, however, this will be less detrimental than cracking occurring in the base section 21 or counterbore section 37. Cracking of 2 ~
the nose section 27 will not result in parting of the drill string. Up to, and beyond the point at which the nose section 27 yields, it does provide additional torque withstanding abilities.
Through standard calculations, the torque to yield pin base section 21 or counterbore section 37 on the above described tool joint at the ideal dimensions is 25,583 foot pounds. A conventional tool joint having a five inch outer diameter and ~ 11/16 inner diameter, as does this tool join-t, has a torque withstanding ability of only 18,100 ~oot pounds at full yield. This increase in torque required to yield a tool joint furthex reduces the chances for parting of the drill string while drilling. The increase in the strength of the tool joint is accomplished without additional metal 5 thicknesses or higher steel strengths.
h'hile the invention has been shown in only one of its forms, it should be apparent to those skilled in the art that it is not so limited but is susceptible to various changes and modifications without departing from -the scope of the invention.
Claims (6)
1. In a drill pipe tool joint having a pin with external threads formed between an external shoulder and a pin face, and a box with internal threads and a box face for connection with the pin, the improvement comprising:
an internal shoulder located in the box;
spring means in the box and the pin for causing the box face to exert a pressure against the external shoulder of the pin when the drill pipe tool joint is made-up that exceeds any pressure imposed by the pin face against the internal shoulder, and for causing the pin face to tighten against the internal shoulder if additional torque is encountered while drilling.
an internal shoulder located in the box;
spring means in the box and the pin for causing the box face to exert a pressure against the external shoulder of the pin when the drill pipe tool joint is made-up that exceeds any pressure imposed by the pin face against the internal shoulder, and for causing the pin face to tighten against the internal shoulder if additional torque is encountered while drilling.
2. In a drill pipe tool joint having a pin with external threads formed between an external shoulder and a pin face, and a box with internal threads located below a box face for connection with the pin, the improvement comprising:
the box having an internal annular shoulder and a counterbore section between the internal threads and box face;
the pin having a base section between the external shoulder and the external threads and a nose section between the pin face and the external threads;
the lengths and thicknesses of the counterbore, base and nose sections being selected so that when the drill pipe tool joint is made-up, the box face will tighten against the external shoulder to a pressure that exceeds any pressure being exerted by the pin face against the internal shoulder, with the pin face tightening against the internal shoulder if additional torque during drilling is encountered.
the box having an internal annular shoulder and a counterbore section between the internal threads and box face;
the pin having a base section between the external shoulder and the external threads and a nose section between the pin face and the external threads;
the lengths and thicknesses of the counterbore, base and nose sections being selected so that when the drill pipe tool joint is made-up, the box face will tighten against the external shoulder to a pressure that exceeds any pressure being exerted by the pin face against the internal shoulder, with the pin face tightening against the internal shoulder if additional torque during drilling is encountered.
3. In a drill pipe tool joint having a pin with external threads formed between an external shoulder and a pin face, and a box with internal threads located below a box face for connection with the pin, the improvement comprising:
the box having an internal annular shoulder and a counterbore section between the internal threads and box face;
the pin having a base section between the external shoulder and the exterrlal threads and a nose section between the pin face and the external threads;
the distance from the box face to the internal shoulder being greater than the distance from the pin face to the external shoulder, providing a clearance between the pin face and internal shoulder when the box face and external shoulder are made-up hand tight;
the thicknesses and lengths of the counterbore, base, nose sections being selected tG cause the pin face to tighten against the internal shoulder prior to the base and counterbore sections exceeding their yield strengths, if additional torque during drilling is encountered.
the box having an internal annular shoulder and a counterbore section between the internal threads and box face;
the pin having a base section between the external shoulder and the exterrlal threads and a nose section between the pin face and the external threads;
the distance from the box face to the internal shoulder being greater than the distance from the pin face to the external shoulder, providing a clearance between the pin face and internal shoulder when the box face and external shoulder are made-up hand tight;
the thicknesses and lengths of the counterbore, base, nose sections being selected tG cause the pin face to tighten against the internal shoulder prior to the base and counterbore sections exceeding their yield strengths, if additional torque during drilling is encountered.
4. In a drill pipe tool joint having a pin with external threads formed between an external shoulder and a pin face, and a box with internal threads and a box face for connection with the pin, the improvement comprising:
the box having an internal annular shoulder and a counterbore section between the internal threads and box face;
the pin having a base section between the external shoulder and the external threads and a nose section between the pin face and the external threads;
the distance from the box face to the internal shoulder being greater than the distance from the pin face to the external shoulder, providing a clearance between the pin face and internal shoulder when the box face and external shoulder are made-up hand tight;
the thicknesses and lengths of the counterbore and, base sections being selected to deflect under a load equal to full yield strength of the pin base and counterbore sections a distance that is no less than the clearance plus the amount of compression in length that the nose section undergoes under a load equal to the full yield strength of the nose section.
the box having an internal annular shoulder and a counterbore section between the internal threads and box face;
the pin having a base section between the external shoulder and the external threads and a nose section between the pin face and the external threads;
the distance from the box face to the internal shoulder being greater than the distance from the pin face to the external shoulder, providing a clearance between the pin face and internal shoulder when the box face and external shoulder are made-up hand tight;
the thicknesses and lengths of the counterbore and, base sections being selected to deflect under a load equal to full yield strength of the pin base and counterbore sections a distance that is no less than the clearance plus the amount of compression in length that the nose section undergoes under a load equal to the full yield strength of the nose section.
5. In a drill pipe tool joint having a pin with external threads formed between an external shoulder and a pin face, and a box with internal threads and a box face for connection with the pin, the improvement comprising:
the box having an internal annular shoulder and a cylindrical counterbore section between the internal threads and box face;
the pin having a cylindrical base section between the external shoulder and the external threads and a cylindrical nose section between the pin face and the external threads;
the distance from the box face to the internal shoulder being greater than the distance from the pin face to the external shoulder, providing a clearance between the pin face and internal shoulder when the box face and external shoulder are made-up hand tight;
the thicknesses and lengths of the counterbore and base sections being selected to deflect under a load equal to full yield strength of the pin base and counterbore sections a distance that is no less than the clearance plus the amount of compression in length that the nose section undergoes under a load equal to the full yield strength of the nose section;
the outer diameter of the box at the counter-bore section being less than the outer diameter of the box at the threaded section, to avoid wear on the exterior of the counterbore section.
the box having an internal annular shoulder and a cylindrical counterbore section between the internal threads and box face;
the pin having a cylindrical base section between the external shoulder and the external threads and a cylindrical nose section between the pin face and the external threads;
the distance from the box face to the internal shoulder being greater than the distance from the pin face to the external shoulder, providing a clearance between the pin face and internal shoulder when the box face and external shoulder are made-up hand tight;
the thicknesses and lengths of the counterbore and base sections being selected to deflect under a load equal to full yield strength of the pin base and counterbore sections a distance that is no less than the clearance plus the amount of compression in length that the nose section undergoes under a load equal to the full yield strength of the nose section;
the outer diameter of the box at the counter-bore section being less than the outer diameter of the box at the threaded section, to avoid wear on the exterior of the counterbore section.
6. In a drill pipe tool joint having a pin with external threads formed between an external shoulder and a pin face, and a box with internal threads and a box face for connection with the pin, the improvement comprising:
the box having an internal annular shoulder and a counterbore section between the internal threads and box face;
the pin having a base section between the external shoulder and the external threads and a nose section between the pin face and the external threads;
the distance from the box face to the internal shoulder being greater than the distance from the pin face to the external shoulder, providing a clearance between the pin face and internal shoulder when the box face and external shoulder are made-up hand tight;
the thicknesses and lengths of the counterbore, base and nose sections being selected to cause the pin face to tighten against the internal shoulder and reach the yield strength of the nose section no later than the time at which the base and counterbore sections reach their yield strengths;
the cross-sectional area of the base section being substantially the same as the cross-sectional area of the counterbore section,
the box having an internal annular shoulder and a counterbore section between the internal threads and box face;
the pin having a base section between the external shoulder and the external threads and a nose section between the pin face and the external threads;
the distance from the box face to the internal shoulder being greater than the distance from the pin face to the external shoulder, providing a clearance between the pin face and internal shoulder when the box face and external shoulder are made-up hand tight;
the thicknesses and lengths of the counterbore, base and nose sections being selected to cause the pin face to tighten against the internal shoulder and reach the yield strength of the nose section no later than the time at which the base and counterbore sections reach their yield strengths;
the cross-sectional area of the base section being substantially the same as the cross-sectional area of the counterbore section,
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US33193481A | 1981-12-17 | 1981-12-17 | |
| US331,934 | 1994-10-31 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1182490A true CA1182490A (en) | 1985-02-12 |
Family
ID=23295982
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000410430A Expired CA1182490A (en) | 1981-12-17 | 1982-08-30 | Tool joint with internal/external make-up shoulder |
Country Status (6)
| Country | Link |
|---|---|
| JP (1) | JPS58110793A (en) |
| CA (1) | CA1182490A (en) |
| DE (1) | DE3245819A1 (en) |
| FR (1) | FR2518635B1 (en) |
| IT (1) | IT1155427B (en) |
| MX (1) | MX159396A (en) |
Families Citing this family (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2561747B1 (en) * | 1984-03-22 | 1986-08-14 | Vallourec | NEW JOINT FOR STEEL TUBES, ITS MANUFACTURING PROCESS AND TOOLS FOR IMPLEMENTING THE PROCESS |
| JPS63159546U (en) * | 1987-04-07 | 1988-10-19 | ||
| US4946201A (en) * | 1989-03-08 | 1990-08-07 | Baroid Technology, Inc. | Oil field tubular connection |
| DE19827821C1 (en) * | 1998-06-17 | 1999-11-25 | Mannesmann Ag | Joint for drill rod sections |
| DE19955377C2 (en) * | 1999-11-10 | 2002-05-02 | Mannesmann Ag | pipe connection |
| CN102061893B (en) * | 2004-03-31 | 2013-07-10 | Nkk钢管株式会社 | Double shoulder tool joint |
| PL1861578T3 (en) * | 2005-03-02 | 2019-08-30 | Tuboscope Vetco (France) Sas | Drill stem connection |
| RU2486396C1 (en) | 2009-09-29 | 2013-06-27 | Сумитомо Метал Индастриз, Лтд. | Threaded connection for connection of steel pipes |
Family Cites Families (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2239942A (en) * | 1939-05-17 | 1941-04-29 | Hydril Company Of California | Well pipe joint |
| FR1126723A (en) * | 1954-07-01 | 1956-11-29 | American Iron & Machine Works | Pipe connection |
| DE1000311B (en) * | 1954-09-22 | 1957-01-10 | Mobil Oil Deutschland | Detachable drill collar connection for deep drilling purposes |
| FR1223674A (en) * | 1958-02-26 | 1960-06-20 | American Iron & Machine Works | Pipe connection |
| US3489445A (en) * | 1967-10-18 | 1970-01-13 | Archer W Kammerer Jr | Threaded sucker rod joint |
| DE2438387C3 (en) * | 1974-08-07 | 1978-03-09 | Mannesmannroehren-Werke Ag, 4000 Duesseldorf | Threaded connection for oilfield pipes |
| DE2641767B2 (en) * | 1976-09-14 | 1979-05-31 | Mannesmann Ag, 4000 Duesseldorf | Threaded connection for oil field pipes |
-
1982
- 1982-08-30 CA CA000410430A patent/CA1182490A/en not_active Expired
- 1982-12-10 DE DE19823245819 patent/DE3245819A1/en active Granted
- 1982-12-15 FR FR8221011A patent/FR2518635B1/en not_active Expired
- 1982-12-16 IT IT24800/82A patent/IT1155427B/en active
- 1982-12-16 MX MX195676A patent/MX159396A/en unknown
- 1982-12-17 JP JP57221716A patent/JPS58110793A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| MX159396A (en) | 1989-05-22 |
| IT1155427B (en) | 1987-01-28 |
| JPS58110793A (en) | 1983-07-01 |
| JPS6221956B2 (en) | 1987-05-15 |
| DE3245819C2 (en) | 1989-07-27 |
| IT8224800A1 (en) | 1984-06-16 |
| FR2518635A1 (en) | 1983-06-24 |
| FR2518635B1 (en) | 1986-05-16 |
| DE3245819A1 (en) | 1983-06-30 |
| IT8224800A0 (en) | 1982-12-16 |
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