RU2446266C1 - Quick-release tight joint of tubular parts and method of its assembly-disassembly - Google Patents

Abstract

FIELD: machine building.

SUBSTANCE: device comprises nipple and coupling with their conical surfaces in contact jointed by sleeve screwed on said coupling. Said conical surfaces allow their guaranteed negative allowance. Ring groove is made on nipple to form flat annular thrust surface perpendicular to joint axis to interact with mating flat thrust surface of extra span of pipe expander drive yoke. In assembly, thrust ledges of nipple and bushing get in contact to allow tightening of conical joint between nipple and coupling, and between coupling and bushing. In disassembly, flat annular thrust surface of nipple interact with mating flat thrust surface of extra span of expander drive yoke to allow unlocking coupling and bushing, hence, tightened conical joint between nipple and coupling.

EFFECT: higher strength and tightness.

2 cl, 4 dwg

Description

The invention relates to oil-producing equipment, in particular to tubing (tubing).

Known for the closest analogue adopted for the prototype, "Quick disconnect tight connection, mainly for oil pipes" (European patent EP 0626535 BI or US patent 5494320 from 02.27.96).

A distinctive feature of such a connection in comparison with widely used tubing according to the API standard and GOST 633 is that it consists of not three, but three parts: a nipple, a sleeve and a sleeve. In this case, the nipple with the coupling is contacted on smooth conical surfaces and fastened together by a sleeve covered by the nipple, screwed onto the coupling by means of a thread, which speeds up and facilitates the assembly-disassembly process of the connection.

However, this connection is significantly inferior to the connection of standard tubing in terms of strength and tightness, since it does not have a guaranteed interference fit and, as a result, there are no prestressing stresses on the mating conical surfaces of the nipple and the coupling. It cannot be performed with a guaranteed interference fit, since otherwise the nipple with the coupling cannot be disconnected only by unscrewing the sleeve, since it does not create an axial force to unfasten the conical surfaces on the nipple. Therefore, this will require the involvement of special technical means and additional time.

The objective of the invention is to increase the strength and tightness of the connection by creating a prestress on the contact of the conical surfaces of the nipple with the coupling while maintaining the quick disconnect of the connection.

To solve this problem, in the connection of tubular parts containing a sleeve firmly attached to the end of the pipe, a nipple firmly attached to the end of the other pipe, interacting with the sleeve on tapered surfaces and screwed onto the sleeve external thread by a sleeve on which two support axes are made parallel to the connection axis surfaces that interact with mating flat supporting surfaces made on the throat of the driving fork, which provide assembly and disassembly of the threaded connection of the coupling with the sleeve, conical the surfaces of the nipple and the coupling are placed with the possibility of their fit with a guaranteed interference fit, which is why during assembly as a result of contact of the thrust ledges of the sleeve and the nipple, the conical connection of the nipple with the coupling is tightened. In addition, an annular groove is made on the nipple, which forms a flat annular supporting surface perpendicular to the axis of the connection, which interacts with the mating flat supporting surface of the additional throat of the leading fork of the pipe-turn, due to which the tightened conical connection of the nipple with the coupling is released when it is disassembled.

The invention is illustrated by drawings, which depict:

figure 1 - quick disconnect tight connection:

a - at the beginning of assembly; b - at the beginning of the disassembly; c - at the end of the disassembly.

figure 2 - quick disconnect tight connection (section aa in fig.1b)

On the sleeve 3 two parallel supporting axes of the connection are made flat supporting surfaces 5, 6, and on the nipple 1, an annular groove 7 is machined, forming a flat annular supporting surface 8 perpendicular to the connection axis.

When assembling (Fig. 1a), the nipple 1 is installed in the coupling 2. In this case, a gap H is formed between the thrust end of the coupling and the thrust shoulder of the nipple, due to the placement of the conical surfaces of these parts with the possibility of landing them with a given guaranteed interference fit. Next, a conventional drive plug 4 with a throat is put on the connection, having flat supporting surfaces 9, 10 that come into contact with the mating flat supporting surfaces 5, 6 of the sleeve 3, and, having turned on the pipe turn, first screw the sleeve 3 onto the sleeve 2 and then create forks and bushings 3 the axial tightening force of the conical connection of the nipple 1 with the coupling 3, thereby completely eliminating the gap H and, finally, tighten the thread.

When disassembling (Fig.1b and Fig.2), another drive plug 12 is put on the connection, which, unlike the usual one, has an additional throat with a flat supporting surface 11. Next, by turning on the pipe turn, the thread is first unfastened and, by the action of the flat supporting surface 11 of the fork 12 on the annular flat supporting surface 8 of the nipple 1, its conical connection with the coupling 2 is unfastened, then the sleeve 3 is unscrewed from the coupling 2, the drive fork 4 is removed and, finally, the nipple 1 is removed from the coupling 2 (Fig. 1c).

The inventive device allows to solve the problem.

Indeed, in the claimed connection of tubular parts, the conical surfaces of the nipple and the coupling are placed with the possibility of landing them with a given guaranteed interference fit by displacing the main planes of these surfaces by an amount of H (Fig. 1a). When assembling as a result of contact of the persistent ledges of the sleeve and the nipple, the conical connection of the nipple with the coupling is tightened and, therefore, high preliminary contact stresses are created in this conical connection, which are absent in the prototype connection due to the impossibility of creating a preliminary tightening force due to the peculiarities of its device. In addition, due to the annular groove 7 made on the nipple 1 and the resulting flat annular abutment surface 8 (Fig. 1b and Fig. 2), which interacts with the mating abutment surface 11 of the additional throat of the drive fork 12, the axial force during disassembly the unfastening of the threaded connection of the coupling 2 with the sleeve 3 through the last and leading yoke 12 is used to unfasten the tightened conical connection without involving special technical means and additional time costs (1c).

Thus, there is an increase in the strength and tightness of the connection of tubular parts while maintaining its quick disconnect.

In addition, a method for assembling and disassembling the foregoing quick-disconnect tight connection of tubular parts is proposed.

A known method of assembly-disassembly of the connection of tubular parts containing a sleeve, firmly fixed to the end of the pipe, a nipple firmly attached to the end of another pipe, interacting with the sleeve on tapered surfaces and screwed onto the external thread of the sleeve with a sleeve on the body of which two parallel connection axes are made flat supporting surfaces, including tightening the thread during assembly and unfastening it during disassembly of the connection due to the contact of the flat supporting surfaces made on the body of the sleeve, and the reciprocal flat supporting x surfaces made on the throat of the usual leading fork of a pipe-turn (see Bulgakov ES and others. Hoisting devices, rotation and feeding mechanisms of drilling rigs - M .: Russian State Geological Exploration University, 2007., p.334, Fig. 7.8) .

In this method, the arising axial force of the thread unfastening of the connection adopted for the prototype when it is disassembled is transmitted only to the sleeve, due to which it is disconnected from the coupling, and this force is not transmitted to the nipple, and since the conical connection of the nipple with the coupling is made without guaranteed interference, it easily disconnected without the participation of this force.

For the proposed quick-tight seal, this method is unacceptable, since when it is assembled, not only the thread is tightened, but also the conical connection of the nipple and coupling with a guaranteed tightness, which makes it necessary to unfasten it during disassembly, i.e. in creating the axial force of the release on the nipple.

The objective of the invention is to increase the strength and tightness of the connection by creating a prestress on the contact of the conical surfaces of the nipple with the coupling while maintaining the quick disconnect of the connection.

To solve this problem, in a method of assembling and disassembling a connection of tubular parts containing a sleeve firmly fixed to the end of the pipe, a nipple firmly attached to the end of the other pipe, interacting with the sleeve on tapered surfaces and screwed onto the external thread of the sleeve with a sleeve on which two parallel connection axis flat supporting surfaces, including tightening the threaded connection of the coupling with the sleeve during assembly and unfastening it during disassembly due to the contact of the flat supporting surfaces made on the sleeve ke, and mating flat supporting surfaces made on the throat of the leading fork of the pipe turn, the conical surfaces of the nipple and the coupling are placed with the possibility of landing them with a guaranteed interference fit, due to which the contact of the thrust ledges of the sleeve and the nipple during assembly successively tighten the conical connection of the nipple to the coupling and the threaded coupling coupling with sleeve. In addition, an annular groove is made on the nipple, forming a flat annular supporting surface perpendicular to the axis of the connection, which engages with the mating flat supporting surface of the additional throat of the drive fork, so that when disassembling, the threaded connection of the coupling with the sleeve is sequentially loosened and, through the last and drive fork, is tightened conical connection of the nipple with the coupling.

The inventive method allows to solve the problem.

Indeed, in the inventive method, due to the placement of the conical surfaces of the nipple 1 and the sleeve 2 with the possibility of landing them with a guaranteed interference fit by shifting the main planes of these surfaces by an amount of H (Fig. 1a), when assembled before tightening the threaded connection of the coupling 2 with the sleeve 3, an axial torque force is created , and therefore, prestresses in the conical connection (Fig. 1b and Fig. 2). In addition, due to the annular groove 7 made on the nipple 1 and the resulting flat annular abutment surface 8, which interacts with the mating abutment surface 11 of the additional throat of the drive fork 12, when disassembling, the axial force of the threaded connection of the coupling 2 with the sleeve 3 through by means of the last and leading plugs 12, they are used to unfasten the tightened conical connection without involving special technical means and additional time costs (Fig. 1c).

Thus, there is an increase in the strength and tightness of the connection of tubular parts while maintaining its quick disconnect.

An example of the implementation of the method of assembly-disassembly of the connection of tubular parts. For example (Fig. 1 and Fig. 2)), we accept a connection for a pipe with a diameter of 73 mm with a wall thickness of 7 mm and the ends of strength group K upside down (GOST 633). The material of the parts of the connection corresponds to the strength group M.

The outer diameter of the sleeve 3 is equal to D _n = 93 mm, the inner diameter of the passage channel of the connection 59 mm The thread connecting the sleeve 3 with the sleeve 2, conical with an outer diameter in the middle of the thread length D _p = 80 mm The working length of the landing surface of the conical connection of the nipple 1 with the coupling 2 L _k = 50 mm, the average diameter of the conical connection d _cp = 68 mm, taper 1:30.

The calculation is carried out for two types of guaranteed interference - minimum and moderate. For the minimum guaranteed interference fit (for example, fit H7 / p6), the maximum fit value does not exceed δ = 0.051 mm, and for moderate fit (for example, fit H7 / s6), δ = 0.078 mm.

The gap in the thrust junction of the nipple and the coupling before tightening (figa), respectively, will be:

- for the minimum guaranteed interference fit H = 0.051 / (1:30) = 1.54 mm;

- for moderate guaranteed interference fit H = 0.078 / (1:30) = 2.36 mm.

The contact pressure on the conical surfaces q is related to the interference value δ by the following relationship (see Birger I.A. et al. “Strength Analysis of Machine Parts”: Handbook - 4th ed., Revised and additional - M .: Mechanical Engineering , 1993, p. 98)

Where

δ is the amount of interference;

d _cf is the average diameter of the conical compound;

C ₁ and C ₂ are coefficients that take into account the ratio of the diameters of the parts to be joined and the Poisson's ratio of their material (for the accepted compound, C ₁ = 4.73; C ₂ = 2.98);

E is the elastic modulus of the first kind.

After substituting the corresponding values in the formula (1), we obtain the following contact pressure values:

- for the minimum guaranteed interference fit q = 20.8 MPa;

- for moderate guaranteed interference fit q = 32.0 MPa.

The axial force And necessary to tighten the conical connection, we find from the expression

Where

µ is the coefficient of friction (µ = 0.12);

k - gearing safety factor (k = 1.5).

After substituting the corresponding values in the formula (2), we obtain the following values of the axial tightening force:

- with a minimum guaranteed interference fit A = 174 kN;

- with moderate guaranteed interference fit A = 266 kN.

The torque required to create the axial tightening force of the conical connection M _z.k. , determined according to the dependence

Taking the value of the friction coefficient for the threaded connection as in the conical connection (µ = 0.12), and substituting the corresponding values in the formula (3), we have the following torques for tightening the conical connection:

- for the minimum guaranteed interference _fit M _s.k. = 1670 Nm;

- for moderate guaranteed interference _fit M _s.k. = 2554 Nm.

The tightening torque of the threaded connection is found from the expression

Where

F _o.s. - area of the dangerous section in the threaded connection (in this connection, the dangerous section is in the thrust joint, the area of which is 6.9 · 10 ^-4 m ² );

υ _r.s. = 1,5 - margin of safety of a threaded connection when it is tightened.

With the known values of the other quantities included in formula (4), after substituting them into this formula, we have:

M _z.r. = 3200 Nm.

From the practice of using threaded joints, it is known that the torque required to unfasten the thread is 10-15% less than the torque used to tighten it. Therefore, it will amount to 2720-2880 Nm and will ensure the release and quick disassembly of the connection.

To assess the margin of safety according to the contact stresses of the conical connection (υ _cc ), we find the value of the interference pressure δ _t at which they will be equal to the yield strength of the material of the mating parts from the following expression

Where

σ _t - yield strength of the material of the mating parts of the conical connection (for the strength group M according to GOST 633 σ _t = 724 MPa).

Substituting the corresponding values in the formula (5), we obtain δ _t = 0.385 mm.

Therefore, the margin of safety for the contact stresses of the conical connection will have the following values:

- with a minimum guaranteed tightness υ _sg = 0.385 / 0.051 = 7.5;

- with moderate guaranteed interference fit and υ _c.p. = 0.385 / 0.078 = 4.9,

which is enough to prevent plastic deformation and, as a consequence, cold welding and jamming of mating conical surfaces.

In order to more reliably protect these surfaces from seizing, it is proposed to subject the connection parts to chemothermal treatment - carbonitration, the effectiveness of which at high contact loads in the tapered threads of the drill joints has been experimentally verified and confirmed by many years of practice in exploration drilling (see L. Lachinyan “Drilling work Columns ”- 2nd ed., revised and enlarged. - M .: Nedra, 1992. - 214 pp., ill.).

From the implementation example, it follows that when assembling the claimed connection, high tightening voltages are created at the contact of the conical surfaces of the nipple and the coupling with a safety factor of at least 4, 9, ensuring its strength and tightness during operation, and when disassembling, the fastening of the tightened conical connection and quick disconnection nipples and couplings without the use of special technical means and additional time costs.

Claims (2)

1. The connection of tubular parts, containing the coupling, firmly fixed at the end of the pipe, a nipple firmly fixed at the end of another pipe, interacting with the coupling on the conical surfaces screwed onto the external thread of the coupling by a sleeve on which are made two parallel supporting axes of the plane supporting surfaces included in interaction with mating flat supporting surfaces made on the throat of the driving fork, providing assembly-disassembly of the threaded connection of the coupling with the sleeve, characterized in that the conical The nipple and the coupling are placed with the possibility of their seating with a guaranteed interference fit, due to which, during assembly, as a result of contact of the thrust ledges of the sleeve and the nipple, the conical connection of the nipple with the coupling is tightened, and also that an annular groove is made on the nipple, forming a perpendicular axis the connection is a flat annular supporting surface, which interacts with the mating flat supporting surface of the additional throat of the leading fork of the pipe-turn, due to which there is a release of the onical connection of the nipple with the coupling when disassembling it. 2. The method of assembly-disassembly of the connection of tubular parts containing a sleeve firmly fixed to the end of the pipe, a nipple firmly attached to the end of the other pipe, interacting with the sleeve on tapered surfaces and screwed onto the external thread of the sleeve with a sleeve on which two parallel connection axes are made flat supporting surfaces, including tightening the threaded connection of the coupling with the sleeve during assembly and unfastening it during disassembly due to the contact of the flat supporting surfaces made on the sleeve and the reciprocal flat bearings surfaces, made on the throat of the leading fork of the pipe turn, characterized in that the conical surfaces of the nipple and the coupling are placed with the possibility of their seating with a guaranteed interference fit, due to which, during assembly, as a result of the contact of the thrust ledges of the sleeve and the nipple, the conical connection of the nipple to the coupling is sequentially tightened and threaded connection of the coupling with the sleeve, as well as the fact that an annular groove is formed on the nipple, forming a flat annular supporting surface perpendicular to the axis of the connection action with the mating flat supporting surface of the additional throat of the driving fork, due to which, when disassembling, the threaded connection of the coupling with the sleeve is sequentially unfastened and, through the last and driving fork, the tightened conical connection of the nipple with the coupling.

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