RU88054U1 - HIGH SEALED THREADED JOINT CONNECTION - Google Patents

Abstract

A highly tight threaded connection of casing pipes, including internal and external conical mating elements, on which a trapezoidal unequal thread is made, having support and embedded faces and a sealing assembly formed by the outer and inner radial tapered surfaces and the outer and inner end resistant tapered surfaces, characterized in that radial conical outer and inner surfaces are made with a taper of 1:10, and end conical outer and inner surfaces ited angled 15 ° to the normal to the thread axis, wherein the first inner and outer coils of the threads are configured such that the coil height gradually increases from 0 mm at the beginning of call to the full profile height over a length not less than half of the coil arc.

Description

The utility model relates to the field of attachment of oil and gas wells, as well as wells for any purpose, including water, injection, structural, etc. whose trunk is lined with pipes with highly tight threaded connections. In addition, the utility model relates to the field of construction and repair of wells using casing pipes, the assembly of which is carried out vertically above the wellhead.

A high-tight threaded connection includes external and internal radial conical sealing surfaces, external and internal end conical sealing surfaces, external and internal conical threads, the first (entry) turn of which (external and internal threads) is made in a special way. These elements are made on male (nipple) and female (coupling) pipes and are in contact with each other.

The internal conical trapezoidal thread is made on the female pipe and contacts during assembly with the external conical trapezoidal thread made on the male pipe. The taper of the threads is 1:16. The coil profile has supporting and embedded faces.

The inner conical radial sealing surface is made on the female pipe and contacts during assembly with the external conical radial sealing surface made on the male pipe. The taper of the sealing radial surfaces is 1:10.

The inner conical end sealing surface is made on the female pipe and is in contact with the external conical end sealing surface made on the male pipe during assembly.

Conical end sealing surfaces are made with an angle of 15 ° relative to the normal to the axis (pipe) in the direction of the tapered thread on the corresponding pipe.

The first turn of the internal and external threads, respectively, on the coupling and the nipple, in known constructions is made in such a way that its beginning has the appearance of a burr, i.e. minimum thickness at a relatively high height. Further, the thickness of the coil is gradually increasing, and at a length of at least half its length, the coil becomes full-profile.

Known hermetic threaded connection of oilfield pipes, including the outer and inner radial tapered sealing surfaces, the outer and inner end tapered sealing surfaces, the outer and inner tapered threads, with a circumferential groove for extruding oil on the enclosing pipe at the transition of the tapered thread to the pipe body, and “Buttress” type tapered thread with a profile angle of 13 ° is made with turns in cross section having the form of an uneven trapezoid with a support face of the turn, aspolozhennoy under an increased angle to the direction of action of the load (RU patent №2297512, E21V 17/642, F16L 15/00 opublikovan 2007.04.20).

This technical solution was made as a prototype for the claimed utility model.

However, the specified threaded connection of casing pipes has the disadvantage associated with the lack of protection of the sealing surfaces from possible breakage of the elements of the first turn of the nipple and the coupling (especially of its vanishing thin part).

The casing string is assembled vertically in the well in such a way that the stacked casing, suspended vertically on the hook of the rig with all its weight before leaning, rests through its external conical thread on the mating internal conical thread of the pipe coupling already lowered into the well. Almost any contact of the incomplete first turn of the nipple or coupling leads to a breakdown of their parts and the possible contact of debris on the contact of sealing and threaded surfaces. Continued make-up leads to scuffing on contact surfaces and a possible loss or reduction of joint tightness.

The execution of the chamfer on the first turns of the thread of the pipe and coupling (GOST 632-80) reduces the possibility of breakage of these structural elements, but does not exclude the problem as a whole.

This utility model eliminates the possibility of breaking the elements of the first turn, providing external tightness and durability of the developed compound.

The technical result achieved is to increase the reliability and tightness of the connection during its installation and operation.

The specified technical result is achieved by the fact that a high-tight threaded connection is made with the external and internal mating tapered trapezoidal threads of the “Buttress” type with a taper of 1:16 having bearing and embedded faces, and a sealing assembly with mating radial sealing surfaces of the outer and inner with a taper of 1:10 , and mating end sealing surfaces of the outer and inner with a cone angle of 15 ° to the normal to the axis of the thread, outer and inner, the first turns of which are made us with increasing height of 0 mm (coil set) to the height of the complete profile over a length not less than half of the coil arc.

These features are significant, interconnected with the formation of a stable set of essential features sufficient to obtain the specified technical result.

The proposed design allows not only to protect the sealing assembly and the external and internal tapered threads from possible hits of the breakage elements of the first turns of the connection, but will significantly increase the number of assembly-disassembly cycles of the connection due to the absence of deformations or breakages of the most vulnerable during the assembly of the first turns of the external and internal tapered threads .

The figure 1 shows a General view of the highly tight threaded connection of casing pipes with internal and external elements, described in the proposed technical solution.

The figure 2 shows the profile change of the first turn of the outer conical trapezoidal thread for half its arc through 15 °, made respectively on the prototype and the proposed technical solution with this utility model. Similarly, the shape of the first thread on the coupling changes.

The figure 3 presents a diagram of the formation of fractures of the first turns of a threaded connection when assembling it in the well.

Crumbled threads, cold welded bridges, completely cut first threads are all the consequences of getting the first turn scraps on contact surfaces.

Figure 4 illustrates the pattern of formation of chips of the first thread. Even the slightest misalignment of the external thread of the nipple relative to the internal thread of the coupling (angle α) leads to the contact of the first (weakened by the thread thread) turn of the nipple with the thread of the coupling, and the entire weight of the pipe falls on it at point 1. A similar loading and possible breakdown of the first turn of the coupling occurs at point 2. In the proposed utility model, the thickness of the first turn increases simultaneously with its height, providing good resistance to its action by the weight of the upper pipe.

In the proposed high-tight threaded connection, a trapezoidal thread with a taper of 1:16 is used (1), the supporting face (2) of which is made at an angle of 3 °, and the embedded face (3) with an angle of 10 ° to the normal to the axis of the thread. The height of the first turn of the external and internal threads varies from 0 mm at the beginning of the call of the thread to the full height of the profile along the length of at least half the length of the first turn (figure 2). Such parameters of the thread provide the threaded joint with improved tensile and bending operation, and the absence of disappearing thin elements (see figure 2) of the first turns of the external and internal threads ensures the safety of threaded and conical sealing surfaces and, accordingly, increased tightness of the joint.

A radial seal (Fig. 1) made of outer (5) and inner (3) conical surfaces with a taper of 1:10, an end seal with conical thrust surfaces of the outer (3) and inner (4) made at an angle of 15 ° to the normal to the thread axis form a sealing assembly, and the first turns of the thread of which ensure the absence of elements that impede the implementation of multiple defect-free assembly of the joint even in fishing conditions.

With repeated make-up, the external (1) and internal (2) thread elements interact, then, due to make-up, the external threaded element (1) moves along the internal (2), then the radial conical (3) and conical end (4) sealing surfaces interact with conical radial (5) and conical end (6) surfaces of the outer element (1).

When the specified tightening torque is applied, the sealing surfaces (3), (4) of the inner and (5), (6) of the outer elements are contacted, as a result of which contact stresses arise on their surfaces, the magnitude of which must be in the region of elastic deformations, sealing the metal assembly -metal". During subsequent make-up with a set tightening torque, contact stresses ensure tightness of the connection.

The advantage of the inventive high-tight threaded connection in comparison with the known is to increase the reliability of tightness and increase its wear resistance.

This utility model is new and industrially applicable, increases the reliability of the tightness of the connection compared with the known technical solutions used for the manufacture of thread ends of pipes and couplings.

Claims (1)

Highly tight threaded connection of casing pipes, including internal and external conical mating elements, on which a trapezoidal unequal thread is made, having support and embedded edges and a sealing assembly formed by external and internal radial conical surfaces and external and internal end contact conical surfaces, characterized in that radial conical outer and inner surfaces are made with a taper of 1:10, and end conical outer and inner surfaces ited angled 15 ° to the normal to the thread axis, wherein the first inner and outer coils of the threads are configured such that the coil height gradually increases from 0 mm at the beginning of call to the full profile height over a length not less than half of the coil arc.