JPS61500924A - Protective device for joint support surfaces of metal tube threads and butts - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] Protective device for joint support surfaces of threaded portions and abutting portions of metal pipes; Device as an object of the present invention Before using metal pipes, protect the joint support surfaces that form the threads and butt parts. This allows the metal tubes to be screwed together and ensures fluid tightness at the joint. It is. The devices of the present invention may be connected directly to each other or with threaded joints. It also relates to a threaded portion of metal tubes that are joined via a sleeve.

The device of the invention is particularly suitable for poling, chinny bing or casing oil wells. This invention relates to the protection of joint support surfaces and threaded parts that form the abutting parts of the pipes used.

Among the various types of threaded parts that have already been developed, in particular, the French patent No. 1.4 The one described in No. 89.013 is known.

A joint support surface forming an abutting surface that should ensure liquid tightness of the joint described in this patent. has a concave frustoconical annular surface machined into the externally threaded end of the tube; convex frustoconical annular with an annular surface machined near the male-threaded inner end butted against the surface.

The liquid tightness of a joint depends on the quality of the joint support surfaces that form the threads and butts. for example by impact during transport or in particular in contact with sewage or other aggressive media. There is a risk of damage due to corrosion due to contact.

Various devices have been proposed to protect threaded tube joints.

West German Patent Application DE-O3 No. 2.834.489 describes a method for coating the outer threaded part of a pipe. Protective caps of elastomeric or plastic materials are described. tube The U-shape on the inside parallel to the shaft ensures that the cap is seated on the screw thread. . This device can also be applied to protect internal threads.

However, this device is not intended to protect joint support surfaces and is not liquid-tight. It does not provide any protection against corrosion.

West German utility model registration application DC-GBM No. 78004849 states that steel tubular reinforcement A male or female frustoconical screw at the end of a steel tube made of flexible material to which the parts are joined. Disclosed is a protective member for the ridge portion. The protective member made of flexible material is a screw of steel pipe. Part and screw.

It has a mating truncated conical thread and two liquid-tight zones, one zone at the front of the steel tube. It is in contact with the end.

In such a device, for example, the conical device disclosed in French Patent No. 1.489.013 It is not possible to effectively protect mating support surfaces forming an abutment, such as trapezoidal support surfaces. I can't. Additionally, it is difficult to accurately thread threads in flexible materials, and the It is also difficult to achieve a liquid-tight abutment at the joint. Furthermore, it is covered with reinforcing material. It is not sufficient to provide protection with impact-flexible materials in areas that are not protected.

British patent application no. 2.093.426 discloses that a protective cap on the outer thread of a tube can be opened. It is shown. This protective cap has an outer case, preferably made of steel, and a preferably and an inner wall of impact-resistant plastic material. On the inner wall, at the end of the tube The screws are cut so that they fit together. The edge of the tube should be covered by the round cap that covers it. Protected by a textured edge.

However, this device does not require a mating support that forms an abutment, such as a frustoconical support surface. Not designed to protect surfaces from corrosion. This device is covered by a cap. They do not even have the means to ensure protection against corrosion in areas exposed to corrosion. Therefore , this device is not applicable to the protection of the internal threads of the tube.

A joint support surface that forms a threaded part and abutting part that can form a threaded part of a metal pipe. , the manufacture of equipment that can effectively protect the pipes against corrosion and impact before use. The possibilities of production were being pursued. In particular, for example French Patent No. 1.489.013 Threaded supports forming inner and outer threads and abutments as described in No. The possibility of protecting surfaces has been pursued.

Furthermore, the joint support surface forming the abutment is held in contact with a certain amount of protective fluid. Possibilities were pursued.

Finally, it can be installed and removed without disassembly if necessary using tools or jigs. protection against shock and vibration, which allows the material to pass freely inside the metal tube. The possibility of creating a protective device was explored.

According to the protection device for the threaded part of a metal tube, which is an object of the present invention, the above problems can be easily solved. Resolve effectively. The device of the present invention is a joint support surface of a threaded portion and a butt portion of a metal tube. in particular the truncated cone according to French patent no. 1.489.013 The present invention relates to the protection of joint support surfaces forming an abutment having a shaped surface.

The device of the present invention provides a connection support for forming an abutment of metal tubes or cylindrical joint members. A rigid member having a threaded portion that threadably engages a male or female threaded portion of a mating area with a bearing surface. Equipped with a plastic ring. Furthermore, the ring has an annular abutment area. , the corresponding contact area is the protrusion of the metal tube when the ring is screwed into the metal tube to the bottom. A front surface is provided facing the joint support surface forming the mating portion.

The inner edge of this front surface is connected to the joining support surface forming the abutting surface of the metal tube and its inner edge. A tenth annular liquid-tight means is provided which cooperates with the liquid-tight means near the part to ensure liquid-tightness. Before Considering the shape of the joint support surface of the throttle tube, the surface is determined to be the same as the joint support surface that forms the butt part. , having a shape such that an annular closed space is formed between it and the facing front surface. There is.

Additionally, this annular enclosure at least partially protects the grease-like joint. However, it is particularly preferable that it be filled with a corrosion-resistant fluid.

The ring further comprises a second annular liquid tight means in combination with the tenth liquid tight means. I can do it. This 20th liquid-tight means prevents the butt from tightening when the ring is screwed to the bottom. of the metal tube opposite the end of the threaded part, where the joint support surface forming the part is located in the vicinity It is arranged so as to be located near the end of the threaded part. The first liquid-tight means is the front of the ring. Preferably, the lip is formed by the inner edge of the lip. The second liquid-tight means is also a ring. It is formed by an annular lip integrated with the ring, and its shape is such that the ring is screwed to the bottom. The tube wall is formed in liquid-tight contact with the pipe wall. This number.

2. The liquid-tight means is a mounting such as an O-ring provided in an annular housing within the ring. It may be a curved joint.

When the ring is screwed all the way to the bottom, the ring will be located facing the threaded part of the metal tube. It may have slight threads in some areas and be smooth in others.

The ring further has a rear portion that extends beyond the tube end when screwed all the way to the bottom. It is preferable to A gripping part like a relief part is formed in this area, and it can be screwed on. makes it easier to hold the tool for screw removal. This relief part is parallel to the tube axis. Preferably, they are located on the inner and outer walls of the ring.

To increase the impact strength of the ring, its unthreaded surface is An integral metal sleeve is provided. This sleeve should be plugged in the direction away from the metal tube. It may extend beyond the ends of the stick ring. At this time, this sleeve has , an area provided with gripping means to facilitate gripping of tools for screwing or unscrewing; It is possible to

The inner diameter of the plastic ring may be coated with a metal sleeve or not. ＼However, it is possible to insert a tool or jig without drawing out the protective fluid. Ru. Conversely, in some applications, the protective fluid is contained in a plastic ring or Closed by a liquid-tight circular bottom integral with the sleeve. This bottom part is removable good.

To manufacture the rings, materials such as polyurethane-based materials are used for strength and elasticity. It is preferable to use a plastic material with excellent properties. In particular, metal sleeves When not in use, use plastic materials that have excellent impact resistance, especially at low temperatures. is preferable. For example, modified polyamides with improved impact resistance or certain polyamides Preferably, polyethylene is used.

Examples of metal sleeves that cover the ring include ordinary steel, alloy steel, and stainless steel. Vine made of a suitable metal or alloy, such as steel.

The device of the invention provides protection for the joint area of metal tubes with external or internal threads of frustoconical shape. It is particularly preferably used for protection. At this time, the ring is preferably limited to several rotations. It has a corresponding threaded part. In this way, it is easy to align the ring before screwing it on. This prevents screws from clogging due to overlapping threads, and reduces the time required for screwing or unscrewing. reduce Finally, the present invention relates to metal.

The plastic material itself may be covered with a plastic sleeve or not. The present invention relates to a ring made of metal, which allows the device of the present invention to be manufactured.

However, these illustrate the main features of the protective device of the present invention and the equipment of the present invention. Supplementary features of the embodiments of the device will be more clearly understood.

Figure 1 includes a ring made of plastic material threaded onto the male threaded end of a metal tube. FIG. 3 is an axial half-sectional view of the protection device of the present invention.

Figure 2 shows the arrangement of the 20th liquid tight means provided in the ring made of plastic material. FIG. 1 is a partially enlarged view of FIG.

Figure 3 includes a ring made of plastic material threaded onto the female threaded end of a metal tube. FIG. 3 is an axial half-sectional view of the protection device of the present invention.

Figure 4 shows a plug screwed onto the male threaded end of a metal tube and covered with a metal sleeve. 1 is an axial half-sectional view of a protection device according to the invention with a ring made of stick material; FIG.

Figure 5 shows a plug screwed onto the female threaded end of a metal tube and covered with a metal sleeve. 1 is an axial half-sectional view of a protection device according to the invention with a ring made of stick material; FIG.

FIG. 6 is an end view in the direction of arrow F of the portion beyond the metal sleeve of FIG. Ru.

As shown in Fig. 1, which shows half of the axial cross-sectional view, the rotation centering on the axes X and -X2 The metal tube 1 of the rolling element has its externally threaded joint area 2 protected by the device of the invention. There is. This joint area 2 has an external truncated conical threading 3 and its generatrix axes X, -X .

A joint support surface 4 forming an abutting portion inclined at an angle of about 15 to 25 degrees with respect to the It is equipped with The support surface 4 is connected to the end of the threaded part 3 via a beveled surface 5 .

The device of the invention comprises a single block glue jig made of plastic material with an internal thread 7. It is equipped with 6. This ring 6 has only a few threads and is butt-tightened. It is screwed all the way to the bottom of the tube threading until it is attached. The abutment area 8 of the ring is It has an annular front area or front surface 9 facing the carrying surface 4.

The inner edge of this front section is provided with an annular first liquid-tight means constituted by a lip 10. Ru. When this lip 10 is tightened onto the tube, the inner edge R4 of the joint support surface It is liquid-tightly seated on the support surface near A. In the embodiment of the invention shown in FIG. In this case, the annular lip 10 is oriented towards the inside of the tube and is secured by the inside edge 4A of the support surface 4. It should be noted that they engage on the inside of the circular shape formed by the two.

In this way, the outer edge 10A of the lip 10 has a shape that allows the ring to be screwed all the way to the bottom. and facing the inner surface of the tube in the joint area 4B at the inner edge 4A of the joint support surface 4. . In this state, the inner edge 4A is connected to the outer edge 10A of the lip 10 and the joint support surface 4. on the front face 9 in the joint area between the front area or the front part facing the are in contact. An annular closed space 11 is left between this front surface and this joint support surface. It will be done. In the illustrated example, this space, which has a Σ° triangular cross section, is filled with protective fluid such as grease. Preferably filled with body. Joined by special arrangement of lips 10 as shown The support surface 4 is covered over its entire surface by a protective fluid held in patchy closed spaces ll. is protected. Furthermore, the front part of the lip 10 is located inside the tube in a direction parallel to the axis. Towards the sides, it forms a kind of labyrinth. The inner edge 4A of the support surface 4 and the ring 6 If a break in the liquid tightness occurs at the point of contact between the abutment area 8 and the front face 9, this labyrinth to limit the loss of protective fluid.

To improve the fluid tightness of this confined space and protect the threaded area, a second fluid is added to the ring. A secret means may be provided. This 20th liquid-tight hand has a threaded area against the joint support surface 4. Located beyond 3. This liquid-tight means No. 20 is enlarged in Fig. 2, which is a detailed view of Fig. 1. Make a big deal of it. In FIG. A pulley 14 is provided radially aligned in the direction of the axis X, -X. lip 14 is seated on the outer wall of the tube to form a twentieth fluid-tight means. This lip is a ring dimensioned so that when screwed to the bottom, it seats elastically in a fluid-tight manner on the outer wall of the tube. . In this way, the corrosion between the ring and the tube in the direction of the threaded part 3 and the closed space 11 is Entry of edible fluids is prevented.

The minimum internal diameter of the ring is larger than the internal diameter D2 of the tube in the normal section, and therefore the tool or can pass the jig. The area 15 beyond the tube end of the ring includes its Relief portions as shown at 16.17 are provided on the outer and inner walls, respectively. child These relief parts are parallel to the axis and serve as gripping parts for tools when screwing in and unscrewing. . The thickness of the ring is such that it can withstand shock from handling the tube and effectively protect the end area of the tube. It is sufficient to carry out Similarly, a thickened portion 18 is provided near the introduction area 12 of the ring. are provided so that this part is subjected to large stresses and shocks. This thick part is especially The impact perpendicular to the axis X1-Xz can be alleviated.

FIG. 3 shows axes X, -X to protect the female threaded joint area 20.

The protective device according to the present invention is placed on the end of a metal tube 19 which is a rotating body centered on It is a sectional view of half. This area forms an abutment with a truncated conical internal thread 921. A concave truncated conical support surface 22 is provided. The tube also has a truncated conical external thread. a fitting or sleeve used for assembly with a pipe having a joint area having Good too.

The generatrix of the joint support surface 22 is in the range of 15 to 25 degrees with respect to the plane perpendicular to the axis X3-X. It is sloping. This mating support surface contacts the end of the threaded section of the tube via a beveled surface 24. Continue.

The protection device comprises a single block ring 25 made of plastic material. This resource The ring has several turns of threading and is threaded to the bottom onto the internal thread of the pipe until the abutment is tightened. be included. The abutment area 27 of the ring is provided with a front surface 28 facing the mating support surface 22. I'm being kicked.

As in the case shown in FIG. 1, an annular lip 29 oriented towards the interior of the tube They engage within a circle formed by the inner edge 22A of the mating support surface 22. Of this The side edge W22A is located at the intersection of the support surface 22 and the inner wall 23 of the tube 19.

When the ring is screwed all the way to the bottom, in the case shown in Figure 3, this inner edge 22Δ is between the outer edge 29A of the lip 29 facing the joint support surface 22 and the front surface 28. is supported against the front face 28 in the connection area of the front face 28. The generatrix in this part of the front is the joint support surface. An annular closed space 30 is formed at an angle with respect to the above. In this closed space, green It may also be filled with a protective fluid such as water. The front part of the lip 29 towards the inside of the tube 19 is of a kind between the inner edge 22A of the joint support surface 22 and the front surface 28. Limits the leakage of the protective fluid and therefore corrosive fluids when the liquid tightness is breached at the contact point Prevent the infiltration of

In order to supplement the protection especially with respect to the threaded part of the tube 20, the ring and the end section 31 of the tube are combined. A 20th liquid-tight means is provided at a position beyond this threaded portion with respect to the joint support surface 22 between Let's go. This second liquid-tight means seats resiliently and liquid-tightly on the end face 35 of the tube 20. An annular lip provided in the fault section 33 of the reinforced rear wall 34 of the jig 25 It consists of 32 pieces. The dimensions of the ring 25 are the first dimension when the ring is screwed all the way to the bottom. and the twentieth liquid-tight means, such that liquid-tight contact is obtained at the same time. This way In this way, the threaded portion 21 and the and the enclosed space 30 are protected.

The reinforced annular section 34 of the ring ensures that the end section 31 and end face 35 of the tube collide. protected from attack. This reinforced area 34 has 36 and 37 parts on the outer and inner walls, respectively. A relief part as shown is provided, which makes it possible to hold the tool when screwing in and unscrewing. . Main parts so that it is possible to insert tools or jigs of the usual type In this case, the minimum inner diameter Ds of the ring may be smaller than the inner diameter D4 of the tube.

Figures 4 to 6 are made of plastic material for added impact resistance. 2 shows an embodiment of the device according to the invention in which the ring is covered with a metal sleeve.

FIG. 4 shows a truncated conical external threaded portion 40 and a concave truncated conical portion forming an abutting portion at the end. The axis XSX has a joint support surface 41 of the shape.

A cross section of a particular embodiment according to the invention realized around the end of the metal tube 39 centered on shows half of This device is a link made of plastic material with only a few turns of the screw. 42.

Over more than half of the frustoconical support surface, the entrance area 44 of this ring is smooth. . The ring is shown tubular and threaded to the bottom.

At the forward end of the ring 420 inlet area 44, a small annular lip 45 connects the outside of the metal tube 39. It comes seated on the side cylindrical wall. This small lip constitutes the 20th liquid-tight means. difference Furthermore, the ring 42 has an abutment area 47 and a lip forming the inner edge of its front face 49. 48 abuts against the inner edge 50 of the joint support surface 41. This lip 48 is the first constitutes a liquid-tight means. In this way, between the support surface 41 and the front surface 49 there is a A closed space 52 is formed.

The outer wall of the ring 42 is covered with a metal sleeve 51. sleeve 51 extends beyond the end of the ring located beyond the end of the tube and Protect the tube from This sleeve may be made of mild steel, for example. ring and sleeve Preferably, the connection is as strong as possible. For this reason, the sleeve should be attached to the mold wall. It may be used as one unit to mold a ring of plastic material. In addition, A relief part and/or a recess is provided on the inner wall of the rib 51, and a plastic is applied to this part. material may be engaged. Other coupling means can be used as well.

FIG. 5 shows a metal tube having a truncated conical female screw portion 55 and centered around the rotation axes X, X. 54 is an axial section through a half of a protective device 53 according to the invention realized at the end of 54; FIG. . A ring 56 made of plastic material is provided at the large diameter end of the engagement area at the end of the tube 54. It merely has a threaded portion 57 that only rotates. Formed on the rear edge 60 of the ring An annular lip 59 is supported on the forward edge 61 of the tube 54.

An abutment area 62 is formed at the forward end of ring 56 . In the case shown in Figure 3 As shown, the annular lip 63 is oriented inwardly of the tube 54 and has an abutment forming an abutment. They engage within a circle defined by the inner edge 65 of the mating support surface 66 . This inner edge 65 , exists at the intersection of the joint support surface 66 of the tube 54 and the inner wall 66A. Shown in Figure 5 In this case, when the ring is screwed all the way to the bottom, the inner edge 65 will meet the edge 63A of the lip 63. abutting the front surface 64 in the connection area between the portion of the front surface 64 facing the joining support surface 66; Supported. This front generatrix is inclined with respect to the generatrix of the joint support surface to form an annular closed A chain space 67 is formed. This closed space 67 is filled with a protective fluid such as grease. Good too. The front part of the lip 63 towards the inside of the tube 54 forms a kind of labyrinth, If the liquid tightness is compromised at the point of contact between the inner edge 65 and the front surface 64, the protective fluid leakage and thus limit the risk of ingress of corrosive fluids.

The lip 59 forming the 20th liquid-tight means covers the entire space between the ring 56 and the tube 54. further improves the protection of pipes, especially preventing moisture from entering and corroding pipe threads. .

The sleeve 68 is integral with the ring as described above.

The radially expanded portion 69 is covered by the ring 56 via the recessed portion 70. connected to the parts. This can reduce the impact received from the outside. . As shown in FIG. 6, which is a view of the end of the sleeve in the direction of arrow F, the sleeve 6 Two further bosses 71 and 72 are provided on the enlarged portion 69 of 8 parallel to the generatrix line, and A relief portion is formed on the side. With this configuration, only the end portion 73 is shown in the cross section. A rotary tool can be introduced into the enlarged section. These bosses 71 and 7 2, the sleeve is rotated by the rotary tool 73, and the protective device 53 is removed very quickly. It can be attached and detached.

For certain applications, the ring 6.25.42 may have a central It may have a real circular wall. This circular wall allows a passage through the ring, thus can be used to close the entrance of the metal tube into which the ring is screwed. ring is metal When covered by the sleeve 51.68 of the sleeve, this solid circular wall It may also be connected to the server itself. This circular wall may also be removable.

Many variations can be made to the device of the invention without departing from the scope of the invention. be. As shown in Fig. 4, the lip is connected to the inner wall edge as a liquid-tight means. Near this inner edge instead of engaging with the circular interior formed by the holding tube. It may be made to face the joining support surface. An O-ring or a second annular liquid-tight means may use other types of fittings.゛r5 v4 inspection report NI'OEX To T'kL: INτ = Shibutsu τZONN-5EARCEI R E? ORT ONWrEMAτZOMAE, APPLZCAτZON No, P (Go/nu 8500003 (S^8593) US-^-2255!06 6　8oneυ5-A-41571000S706779　NoneυS-人・ 29 pieces 0X18 NoneDE-A-2 158 pieces 12/) O/fu 8 N on.

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Claims (13)

[Claims] (1) Concerning the liquid tightness of the male threaded part or female threaded part of the metal pipe and the screw connection between the metal pipes. In order to protect the annular joint support surface forming the abutment section before use of the metal tube. , comprising a ring made of plastic material that is screwed onto the threaded part of the joint area of the metal tube. In the protection device, the ring (6, 25, 42, 56) is at least several strokes The ring is provided with a threaded portion (7, 26, 43, 57), and the ring is connected to a metal tube ( 1, 19, 39, 54) in the joint area (3, 21, 40, 55). In addition, the core ring is provided with an annular abutment area (8, 27, 47, 62) and has a corresponding abutment area (8, 27, 47, 62). The area is located at the butt part of the metal tube ( 4, 22, 41, 66) of such dimensions as to be located facing the bonding support surface forming the a front surface (9, 28, 49, 64), the inner edge of the front surface is the butt of the metal tube; In the vicinity of the joint support surface forming the surface and its inner edge (4A, 22A, 50, 65) Annular first liquid-tight means (10, 29, 48, 63) that work together to ensure liquid-tightness. The front surface includes a joining support surface forming the abutting portion, and the front surface facing thereto. A shape in which an annular closed space (11, 30, 52, 67) is formed between A protective device featuring: (2) The annular first liquid-tight means (10, 29, 48, 63) is located inside the metal tube. consists of a lip oriented in the direction of the ring, the lip screwing the ring to the bottom. When tightened, the inside of the joint support surface forming the abutting portion (4, 22, 41, 66) engaging inside the circle formed by the side edges (4A, 22A, 50, 65); The inner edge (10A, 29A, 63A) of the first liquid-tight means is the connection area therewith. is configured to face the inner wall (4A, 23, 66A) of the metal tube at A protective device according to claim 1, characterized in that: (3) The inner edge (4A, 22A, 65) of the nuclear lip (10, 29, 63) The outer edge (10A, 29A, 63A) and the joint support surface (4, 22, 66) The front surface of the corresponding contact area of the nuclear ring in the connection area between the part of the front surface located facing (9, 28, 64) Place. (4) The rings (6, 25, 42, 56) are screwed into the metal tube. When seated, the joining support surface forming the abutment part will be attached to the threaded part located near it. An annular second liquid-tight seal located near the end of the threaded part of the metal tube on the opposite side of the end. The method according to any one of claims 1 to 3, characterized in that the method comprises a means. protection device. (5) The joint support surface (4, 22, 41, 66) and/or the male threaded portion or The female screw part has a truncated conical shape, and the annular closed space (11, 30, 52, 67) is small. Claims characterized in that the claim is at least partially filled with a protective fluid, such as a grease. The protective device according to any one of items 1 to 4 above. (6) The ring (42, 56) has a main portion of its unthreaded surface. is covered with a metal sleeve (51, 68) integral with it. A protection device according to any one of claims 1 to 5. (7) The rear end of the ring and/or the metal sleeve is the end of the metal tube. Any one of claims 1 to 6, characterized in that it extends beyond Protective devices as described. (8) The ring or metal sleeve for gripping tools for screwing or unscrewing. gripping means such as reliefs (16, 17, 36, 37, 71, 72) at the rear end of the Any one of claims 1 to 7, characterized in that: Protective devices as described. (9) The through hole of the ring is closed by a fixed or removable liquid-tight circular bottom. According to any one of claims 1 to 8, the invention is characterized in that: protection device. (10) The ring shall be made of polyurethane, polyamide or polyethylene. A protective device according to any one of claims 1 to 9, characterized in that: (11) For example, a male threaded portion of a metal tube that can be threadedly engaged with a threaded portion of a joining area of the metal tube. Or the ring that forms the female thread and the butt part that is involved in the liquid tightness of the screw joint of the metal pipe. A plastic ring for a device for protecting a joint support surface of a The ring is engageable at least several times on the threaded portion (3, 21, 40, 55) of the tube. The ring further includes a first fluid-tight means (10) having an annular inner edge. , 29, 48, 63) with a front surface (9, 28, 49, 64). contact areas (8, 27, 47, 62), the dimensions of the contact areas are such that the ring (1, 19, 39, 54), the first liquid-tight means The metal tubes are butted near the inner edges (4A, 22A, 50, 65) of the mating support surfaces. Working together with the joining support surfaces (4, 22, 41, 66) to ensure liquid tightness Additionally, an annular closed space (11, 30, 52, 67) is provided between the joint support surface and the front surface. ) is formed. (12) The ring is such that the main part of its unthreaded surface is integral with it. Claimed in claim 1, characterized in that it is covered with a metal sleeve (51, 68) of The ring described in range item 11. (13) The ring shall be made of polyurethane, polyamide or polyethylene. The ring according to claim 11 or 12, characterized in that: