RU2808401C1 - Threaded connection of pump-compressor pipes - Google Patents

Abstract

FIELD: threaded connections of tubing pipes.

SUBSTANCE: claimed invention can be used to connect elements of tubing pipe columns used in the construction and operation of wells in oil, gas and gas condensate fields. The threaded connection of pump-compressor pipes contains male and female elements. At the ends of the female and male elements on the outer and inner surfaces, respectively, there are trapezoidal threads with a taper of 1:16 and sealing and thrust end surfaces forming an internal sealing unit, made at an angle of 14-16° to the normal of the thread centreline. The threads of the male and female elements are made with an inclination angle of the support face of the coil profile from -1 to +1° to the normal of the centre line of the thread and the angle of inclination of the embedded face of the thread profile 14-16° to the normal of the thread centreline. The tops of the thread profile are parallel to the centre line of the thread. The internal sealing unit is formed by sealing surfaces made on the male and female element with an inclination angle of 17-19° to the centre line of the thread, and the thrust end surfaces of the male and female elements. The internal sealing unit is equipped with additional surfaces made between the sealing surfaces and the thrust end surfaces on the male and female elements. The connection of the sealing surfaces with additional surfaces is made in the form of a concave spherical surface on the male element and a convex spherical surface on the female element.

EFFECT: tightness of the threaded connection of pump-compressor pipes is increased under the influence of combined multidirectional mechanical loads.

9 cl, 3 dwg

Description

The invention relates to threaded connections of tubing pipes and can be used to connect elements of tubing columns used in the construction and operation of vertical, directional and horizontal wells in oil, gas and gas condensate fields.

Tubing pipes used in oil, gas and gas condensate fields are operated in difficult conditions, under significant mechanical loads. At the same time, the main requirements for pumping and compressor pipes are maintaining tightness under high multidirectional mechanical loads and wear resistance.

In addition, in connection with the assembly of threaded connections of pump-compressor pipes in “field” conditions, their necessary property is high make-up characteristics - speed and ease of assembly and disassembly of the connection, reliable alignment, stabilization of the connection elements relative to each other, withstanding repeated make-up and unscrewing without damage (scoring) of the contacting surfaces of the threads, sealing and thrust end surfaces.

A threaded connection of pump-compressor pipes is known (patent RU No. 182758, E21B 17/042, F16L 15/00, published on August 30, 2018), adopted as a prototype, containing male and female elements, at the ends of which there are, respectively, external and internal thread with a taper of 1:16, pitch 3.175 or 4.233 mm, with a supporting edge made at an angle of 1÷5° to the normal of the thread center line, and a embedded face made at an angle of 8÷12° to the normal of the thread center line.

The internal sealing unit is formed by sealing surfaces made at an angle of 55÷65° to the normal of the thread center line, and thrust end surfaces made at an angle of 10÷20° to the normal of the thread center line.

However, the threaded connection of pump-compressor pipes does not have the necessary make-up characteristics that allow the connection to withstand repeated make-up and unscrewing without damage (the formation of scuffing) of the contacting surfaces of the thread, sealing and thrust end surfaces. Jamming of the connection at the initial stage of make-up and damage (formation of scoring) of the thread surfaces, sealing and thrust end surfaces of the connection during its operation leads, under the influence of high-level mechanical loads, to loss of tightness of the connection.

The technical result provided by the claimed invention is a high degree of tightness of the connection under the influence of combined multidirectional mechanical loads due to improved characteristics of the connection's make-up - ensuring, at the initial stage of make-up, reliable alignment of the female element relative to the male and preventing jamming of the connection, no damage to the connection surfaces during repeated make-up - unscrewing.

The specified technical result is achieved due to the fact that the threaded connection of pump-compressor pipes contains male and female elements, at the ends of which, on the outer and inner surfaces, respectively, trapezoidal conical threads with a taper of 1:16 are made and forming an internal sealing unit, sealing and thrust end surfaces made at an angle of 14÷16° to the normal of the thread center line. According to the invention, the threads of the male and female elements are made with an inclination angle of the support face of the thread profile from -1 to +1° to the normal of the center line of the thread and an inclination angle of the embedded face of the coil profile of 14÷16° to the normal of the center line of the thread, with the tops of the coil profile parallel to the axial thread lines and recesses of the coil profile, made with a taper of 1:16,

The internal sealing unit is formed by sealing surfaces made on the male and female element with an inclination angle of 17÷19° to the center line of the thread, and thrust end surfaces of the male and female elements, while the internal sealing unit is equipped with additional

surfaces made between the sealing surfaces and the thrust end surfaces on the male and female elements, and the connection of the sealing surfaces with additional surfaces is made in the form of a concave spherical surface on the male element and a convex spherical surface on the female element.

In a particular case, the trapezoidal tapered threads of the male and female elements are made with a pitch of 3.175 mm.

In a particular case, the trapezoidal tapered threads of the male and female elements are made with a pitch of 4.233 mm.

In a particular case, the supporting face of the thread profile of the male element is equipped with an additional section adjacent to the cavity and made at an angle of 4÷^6° to the normal of the thread centerline.

In a particular case, the concave spherical surface connecting the sealing and additional surfaces of the male element is made with a radius of 7÷9 mm.

In a particular case, the convex spherical surface connecting the sealing and additional surfaces of the female element is made with a radius of 4÷6 mm.

In a particular case, the additional surfaces on the male and female elements are made cylindrical.

In a particular case, the additional surfaces on the male and female elements are made with a taper of 1:10.

In a particular case, the additional surface on the male element is made with a taper of 1:10, and the additional surface on the female element is made cylindrical.

The invention is illustrated by drawings, Fig. 1 shows a threaded connection of pump-compressor pipes in an assembled state, Fig. 2 shows view A, Fig. 1 - profile of the thread of the connection, Fig. 3 shows view B, Fig. 1 - internal sealing node

The threaded connection of pump-compressor pipes contains male (1) and female (2) elements, at the ends of which, on the outer and inner surfaces, respectively, trapezoidal tapered threads (3) are made.

The threads (3) made on the outer surface of the male element (1) and on the inner surface of the female element (2) have a taper of 1:16. Making threads (3) with a taper of 1:16 ensures an optimal combination of a high degree of engagement of the threads of the male (1) and female (2) elements with each other when screwing up the joint, the ability of the joint to absorb bending and tensile loads acting during operation of the joint, and maintain high characteristics of joint make-up, prevention of thread jamming.

The profile of the thread turn (3) is an unequal trapezoid, the sides of which are made in the form of support (4) and embedded (5) faces, having different angles of inclination to the normal of the thread axial line.

The profile of the thread turn (3) of the male (1) and female (2) elements is made with an inclination angle of the supporting face (4) from -1 to +1° to the normal of the center line of the thread and an inclination angle of the embedded face (5) of 14÷16° to normal to the center line of the thread.

The normal of the center line of the thread is understood as a perpendicular drawn to the center line of the thread.

Making the angle of inclination of the supporting face (4) of the profile of the thread turn (3) from -1 to +1° to the normal of the center line of the thread ensures that the thread turns (3) of the male (1) and female (2) elements do not come out of engagement with each other. under significant tensile and bending loads (loss of tightness) affecting the connection under the influence of its own weight of the column lowered into the well.

In a particular case of the claimed invention, the implementation of the supporting edge (4) of the profile of the thread turn (3) of the male element (1) with an additional section adjacent to the cavity (7) and made at an angle of 4÷6° to the normal of the center line of the thread, eliminates contact of the supporting edges (4) the profile of the thread turn (3) of the male (1) and female (2) elements in the area adjacent to the cavity (7), which eliminates damage to the surfaces of the supporting edges (4) in this area (the formation of scoring) and is an additional factor ensuring possibility of repeated screwing and unscrewing of the connection without damaging the surfaces.

The height of the specified additional section of the supporting edge (4) of the profile of the thread (3) of the male element (1) can reach 30÷40% of the height of the profile of the thread (3).

Making the angle of inclination of the embedded face (5) of the thread coil profile (3) to the normal of the thread center line equal to 14÷16° stabilizes the position of the male element (1) relative to the female element (2) at the initial stage of making up the connection, which prevents jamming of the connection, damage to the surfaces of the threads (3), the formation of scoring and provides the possibility of repeated screwing and unscrewing of the connection while maintaining the tightness properties.

In addition, a structural gap is formed along the embedded edges (5) of the profile of the coil of threads (3) of the connection in the screwed state, which provides the possibility of repeated screwing and unscrewing without damage (formation of scuffing) along the embedded edges (5) of the profile of the coil of threads (3).

The vertices (6) of the profile of the thread turn (3) are made parallel to the center line of the thread, which eliminates jamming and jamming of the thread at the initial stage of make-up, ensures deep free entry of the male element (1) into the female element (2) during make-up, and the absence of scoring on the vertices ( 6) thread profile (3).

In this case, the depressions (7) of the profile of the thread turn (3) are made with a taper of 1:16, just like the taper of the threads (3), which reduces the loss of wall thickness of the male element (1) when threads (3) are applied to it and provides a general increase in strength male element (1).

The threaded connection is made with an internal sealing unit formed by sealing surfaces (8), (9) in contact with each other and thrust end surfaces (10), (11) made on the male (1) and female (2) elements of the connection.

The sealing surfaces (8), (9) of the joint in the screwed state are in contact with each other with significant contact stresses, with the occurrence of deformation in the elastic region and the formation of a metal-to-metal seal, ensuring high tightness of the joint, including gas, when exposed to it multidirectional combined mechanical loads in any combination.

The sealing surfaces (8), (9) are made with an inclination angle of 17÷19° to the center line of the thread.

The specified angle of inclination of the sealing surfaces (8), (9) provides an optimal area of their contact and a high level of stress of the contacting sealing surfaces (8), (9), ensuring the tightness of the connection under all combinations of loads in the entire range of tolerance fields.

The contact of the sealing surfaces (8), (9), located at the specified angle of inclination, occurs with interference over a relatively small area, and significant contact stresses arise, ensuring high tightness. In addition, when reassembling the connection, damage to the sealing surfaces (8), (9) does not occur due to the rapid achievement of the radial interference value during the assembly process.

The thrust end surfaces (10), (11) of the male (1) and female (2) elements are made at an angle of 14÷16° to the normal of the thread center line, which ensures “pressing” and fixation of the sealing surfaces (8), (9) of the connection , creates its resistance to compressive loads, provides an additional sealing barrier. In addition, it ensures clear positioning of the male (1) and female (2) elements relative to each other, precise fixation of the specified amount of interference and torque during the process of making up the joint - that is, improved make-up characteristics, the ability to control the make-up of the connection. The increased contact area of the thrust end surfaces (10), (11) with each other due to the angle of inclination (14÷16°) allows, when making up a connection, to increase the make-up torque while maintaining contact stresses at the required level within the limits of elastic deformation, that is, to ensure the absence damage (scoring) of the thrust end surfaces (10), (11).

Between the sealing surfaces (8), (9) and the thrust end surfaces (10), (11) on the male and female elements there are additional surfaces (12), (13) not in contact with each other, forming a gap. Additional surfaces (12), (13) can be made either cylindrical or conical with a taper, for example, 1:10.

Making the sealing surfaces (8), (9) at a distance from the thrust end surfaces (10), (11), that is, removing the contact zone of the sealing surfaces (8), (9) from the contact zone of the thrust end surfaces (10), (11 ), ensures a reduction in the dependence of the sealing and thrust end surfaces on the seal from each other and, accordingly, ensures maximum tightness of the connection under any combination of loads, including gas tightness.

The connection of the sealing surfaces (8), (9) with additional surfaces (12), (13) is made in the form of a concave spherical surface (14) on the male element (1) and a convex spherical surface (15) on the female element (2).

During the screwing process of a threaded connection, after the interaction of the threads (3) of the male (1) and female (2) elements, the sealing surfaces (8), (9) of the male (1) and female (2) elements move relative to each other, which begins from the interaction of the concave spherical surface (14) on the male element (1) and the convex spherical surface (15) on the female element (2), which facilitates the passage of the sealing surfaces (8), (9) relative to each other in the first moments of contact, ensuring safety sealing surfaces (8), (9), their protection from damage (formation of scoring) when screwing together the joint.

In addition, the convex spherical surface (15) on the female element (2) increases the contact area of the sealing surfaces (8), (9) of the male (1) and female (2) elements, which has a positive effect on the tightness of the connection.

The inventive threaded connection of pump-compressor pipes works as follows.

When carrying out the operation of making up a joint, after centering the male (1) and female (2) elements relative to each other, the interaction of the male (1) and female (2) elements is initially carried out due to conical trapezoidal threads (3) made on the outer surface of the male ( 1) element and the inner surface of the female (2) element.

Next, the spherical surfaces (14), (15) and the sealing surfaces (8), (9) of the male (1) and female (2) elements come into contact, due to the plastic deformation of which a metal-to-metal seal is created.

The completion of the process of making up the connection is carried out by forceful contact of the thrust end surfaces (10), (11) made on the male (1) and female (2) elements, as a result of which contact stresses also arise on the thrust end surfaces (10), (11) , the magnitude of which is in the region of elastic deformations.

An example of the invention.

To test the proposed threaded connection of pump-compressor pipes, two samples were made. For sample No. 1, a pump-compressor pipe with a nominal diameter of 73 mm was used as a workpiece. Trapezoidal conical threads with a taper of 1:16, a pitch of 3.175 mm, an inclination angle of the embedded face of the coil profile of 14° and an inclination angle of the supporting face of the coil profile of -1° to the normal of the center line of the thread are applied to the outer surface of the male element and the inner surface of the female element of this sample. The apexes of the coil profile are parallel to the center line of the thread, and the valleys of the coil profile are made with a taper of 1:16.

The elements of the internal sealing assembly are formed: the sealing surfaces of the male and female elements are made with an inclination angle of 17° to the center line of the thread, the additional surfaces are made cylindrical, the concave spherical surface connecting the sealing and additional surfaces of the male element is made with a radius of 7 mm, and the convex spherical surface, connecting the sealing and additional surfaces of the female element is made with a radius of 4 mm.

For sample No. 2, a pump-compressor pipe with a nominal diameter of 114 mm was used as a blank. Trapezoidal conical threads with a taper of 1:16, a pitch of 4.233 mm, an inclination angle of the embedded face of the coil profile of 16° and an inclination angle of the supporting face of the coil profile of 1° to the normal of the thread center line are applied to the outer surface of the male element and the inner surface of the female element of this sample. The apexes of the coil profile are parallel to the center line of the thread, and the valleys of the coil profile are made with a taper of 1:16.

Elements of the internal sealing assembly are formed: the sealing surfaces of the male and female elements are made with an inclination angle of 19° to the center line of the thread, additional surfaces are made with a taper of 1:10, the concave spherical surface connecting the sealing and additional surfaces of the male element is made with a radius of 9 mm, and the convex spherical surface connecting the sealing and additional surfaces of the female element has a radius of 6 mm.

In addition, sample No. 3 was manufactured, which had the geometric parameters of the prototype, for which a pump and compressor pipe with a nominal diameter of 114 mm was used as a blank. On the outer surface of the male element and the inner surface of the female element of sample No. 3, trapezoidal conical threads with a taper of 1:16, a pitch of 3.175 mm, an inclination angle of the embedded face of the coil profile of 10° and an inclination angle of the supporting face of the coil profile of 3° to the normal of the center line of the thread are applied.

The elements of the internal sealing unit are formed: the sealing surfaces are made at an angle of 30° to the thread center line, the thrust end surfaces are made at an angle of 15° to the normal of the thread center line.

Tests of the samples were carried out on the number of screwings and unscrewings that a threaded connection can withstand until damage to the thread surfaces and the internal sealing unit appears.

Tests of the samples showed the presence of damage (formation of scuffing) of the surfaces during five-fold screwing-unscrewing of sample No. 3, made according to the prototype, and the absence of jamming of the connection and damage (scoring) of the surfaces during nine-fold screwing-unscrewing of samples No. 1, 2, made in accordance with the claimed invention.

When using the proposed threaded connection of pump-compressor pipes, the tightness of the connection is ensured when the magnitude of combined multidirectional mechanical loads increases by 20%.

Claims (9)

1. Threaded connection of pump-compressor pipes containing male and female elements, at the ends of which, on the outer and inner surfaces, respectively, are made trapezoidal threads with a taper of 1:16 and forming an internal sealing unit, sealing and thrust end surfaces made at an angle of 14- 16° to the normal of the center line of the thread, characterized in that the threads of the male and female elements are made with an inclination angle of the support face of the coil profile from -1 to +1° to the normal of the center line of the thread and an inclination angle of the embedded face of the coil profile of 14-16° to the normal center line of the thread, the tops of the thread profile are parallel to the center line of the thread and the valleys of the thread profile are made with a taper of 1:16, the internal sealing unit is formed by sealing surfaces made on the male and female element with an inclination angle of 17-19° to the center line of the thread, and thrust the end surfaces of the male and female elements, while the internal sealing unit is equipped with additional surfaces made between the sealing surfaces and the thrust end surfaces on the male and female elements, and the joint of the sealing surfaces with the additional surfaces is made in the form of a concave spherical surface on the male element and a convex spherical surface on the covering element. 2. The connection according to claim 1, characterized in that the trapezoidal tapered threads of the male and female elements are made with a pitch of 3.175 mm. 3. The connection according to claim 1, characterized in that the trapezoidal tapered threads of the male and female elements are made with a pitch of 4.233 mm. 4. The connection according to claim 1, characterized in that the supporting face of the thread profile of the male element is equipped with an additional section adjacent to the cavity and made at an angle of 4-6° to the normal of the center line of the thread. 5. The connection according to claim 1, characterized in that the concave spherical surface connecting the sealing and additional surfaces of the male element is made with a radius of 7-9 mm. 6. The connection according to claim 1, characterized in that the convex spherical surface connecting the sealing and additional surfaces of the female element is made with a radius of 4-6 mm. 7. The connection according to claim 1, characterized in that the additional surfaces on the male and female elements are made cylindrical. 8. The connection according to claim 1, characterized in that the additional surfaces on the male and female elements are made with a taper of 1:10. 9. The connection according to claim 1, characterized in that the additional surface on the male element is made with a taper of 1:10, and the additional surface on the female element is made cylindrical.

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