Sleeve joint for pipes
Patent Information
- Application Number
- EP2022768644
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2022-08-17
- Publication Date
- 2025-06-25
AI Technical Summary
Existing sleeve connections for steel pipes fail to provide a reliable, liquid-tight seal and efficient transmission of longitudinal tensile forces, especially under high internal pressure, due to the limitations of steel pipe geometry and the inability to design steel pipe ends as sleeves.
A socket connection system featuring a pipe fitting with two sleeves, conical contact surfaces at an acute angle, and a sealing ring with dovetail and fork-like sealing lips, designed to accommodate high internal pressures and prevent slippage, using ductile cast iron and EPDM sealing materials.
The system ensures a reliable, liquid-tight seal and effective transmission of longitudinal tensile forces without risking dislocation of the sealing ring, even under high pressure, by optimizing the conical contact surface angle and sealing ring geometry.
Smart Images
Figure 1.1
Abstract
Description
[0001] Socket connection for pipes
[0002] The invention relates to a socket connection for pipes.
[0003] It is well known to connect pipes at their longitudinal ends using a socket joint. A socket surrounds an axial end of a pipe, and a seal or a material connection between the socket and the pipe end creates a fluid-tight connection.
[0004] From DE 200 22 897 U1 and WO 2014 / 053216 A1, socket connections are known in which a pointed or insertion end of a first pipe is inserted into a pipe end of a second pipe designed as a socket, and the socket connection is secured in the axial direction with the aid of movable locks. The pipe end of the second pipe designed as a socket has a radially inwardly projecting, circumferential collar which has openings in the circumferential direction through which a respective lock can be inserted, so that the respective lock can then be displaced in a tangential direction and can be supported on the collar of the socket in the axial direction. On the insertion or seat end of the first pipe, a bead running in the circumferential direction, e.g.a weld bead must be provided on which the respective lock can also be supported in the axial direction of the pipes, so that the respective lock is located in the longitudinal direction of the socket connection between the collar of the socket on the second pipe and the bead on the pointed or plug-in end of the first pipe. In order to create a socket connection, the pointed or plug-in end of the first pipe is first inserted into the socket on the second pipe. The locks are then inserted through a respective opening in the collar on the socket into the interior of the socket until they rest against the bead on the plug-in end of the second pipe and are then moved radially to the left or right until a projection of the retaining lock rests against an edge of the respective opening in the collar of the socket on the second pipe.
[0005] The inwardly projecting collar that defines the end face of the socket has a slanted contact surface on the side facing the respective bolt in the axial direction of the pipe, against which the respective bolt rests with a similarly slanted face. The inwardly projecting collar of the socket defines a circumferential bolt receiving space.
[0006] In addition, the pipe end, designed as a socket, has a circumferential sealing chamber, which is separated from the bolt receiving space by a partition wall that also projects radially inward. A sealing ring is arranged in the sealing chamber, which serves to seal the socket connection and, as a result, rests against both the inner wall of the sealing chamber and the outer wall of the pipe end of the first pipe inserted into the socket. The partition wall between the bolt receiving space and the sealing chamber prevents the sealing ring from being forced out of the socket.
[0007] Longitudinal tensile forces between the pipes connected by the socket joint are absorbed by the bead on the first pipe, the collar of the socket on the second pipe and the bar in between.
[0008] The invention is based on the object of providing a socket connection for connecting two steel pipes which is reliably tight and can transmit longitudinal tensile forces.
[0009] To solve this problem, a socket connection system is proposed which comprises a pipe fitting, several bars and two sealing rings.
[0010] The pipe fitting has two longitudinal ends and has a socket at each longitudinal end into which a spigot end of a steel pipe with an outwardly projecting projection (e.g. a weld bead) extending at least partially in the circumferential direction can be inserted.
[0011] Each sleeve has a bolt receiving space running around the circumference on its front side and a sealing chamber for receiving a sealing ring, which is separated from the bolt receiving space by a partition wall running around the circumference and also runs around the circumference. The bolt receiving space is delimited on the front side by an inwardly projecting end wall which is interrupted in the circumferential direction in such a way that it has insertion openings for inserting bolts, wherein the end wall has a conical contact surface running at an acute angle to the radial direction, against which a counter contact surface running at a corresponding angle on a respective bolt can rest. In contrast to the prior art, the conical contact surface does not run at an obtuse angle to the radial seal of the sleeve, but at an acute angle. This means thatthe contact surface is at an angle of less than 45° to a plane perpendicular to the longitudinal axis of the sleeve.
[0012] The sealing chamber initially tapers from the partition wall in the longitudinal direction of the pipe fitting and then widens again to accommodate a correspondingly shaped sealing ring, which has a radially outwardly extending retaining bead for contact with the partition wall at one longitudinal end and two dovetail- or fork-like sealing lips at the other longitudinal end, which enclose a gap open at the end between them.The shapes of the sealing chamber and the associated sealing ring ensure, on the one hand, that the sealing ring cannot slip in the longitudinal direction of the socket connection even at high internal pressure and, at the same time, that the seal seals reliably because the sealing lips are pressed apart by the pressure of a fluid, so that a radially outer sealing lip of the sealing ring lies tightly against a corresponding inner wall of the sealing chamber, while the radially inner sealing lip lies tightly against the outer surface of the respective steel pipe.
[0013] Thus, a socket connection for connecting a pipe to a pipe fitting is proposed, into the socket of which a spigot end of the pipe, which has a radially outwardly projecting projection, can be inserted. The socket of the pipe fitting has a radially inwardly projecting edge (namely the end wall of the bolt receiving space) with two ring-segment-shaped recesses (which form the insertion openings). A locking device for locking the spigot end in the socket of the pipe fitting comprises four ring-segment-shaped locking elements (the bolts). In the locked state, the radially outwardly projecting projection of the pipe rests on the locking elements, and these rest on the end wall of the bolt receiving space.A sealing ring for a socket connection is characterized in that one part of the sealing ring is dovetail-shaped and the opposite part has a radially outwardly extending retaining bead, wherein the first dovetail-shaped part serves as the sealing part and the second bead-like part serves as the retaining part of the sealing ring. The invention includes the discovery that longitudinal ends of steel pipes - unlike longitudinal ends of cast pipes - cannot be designed as a socket. Therefore, instead of a socket at one end of a pipe, a pipe fitting with two sockets is provided. Steel pipes have the advantage of being able to withstand higher internal pressure. The invention includes the further discovery that higher internal pressure places greater demands on the longitudinal tensile forces to be transmitted by the socket connection and on the seal.In order to be able to transmit correspondingly high longitudinal tensile forces without the radial forces acting on the pipe fitting becoming too great, the angle of the conical contact surface was adjusted accordingly and deviates from the dimension known from the state of the art. The shape of the sealing chamber and the associated sealing ring were also designed differently from the state of the art in order to provide a seal that is reliable even at high pressure, which is tight and where there is no risk of the sealing ring dislocating due to the pressure. The geometry of the conical contact surface for the bars on the end wall of the bar receiving space also plays a role in terms of reliable sealing, because the angle of the conical contact surface prevents excessive widening of the pipe fitting and a potentially associated change in the geometry of the sealing chamber.
[0014] Preferably, the end wall of the bolt receiving space of a sleeve has two receiving openings. A bolt that can be moved counterclockwise or clockwise can then be inserted into the bolt receiving space through one of the receiving openings.
[0015] Preferably, the contact surface on the end wall of the bolt receiving space of a socket extends at an angle of between 30° and 40° with respect to a plane perpendicular to the longitudinal axis of the socket. The contact surface on the end wall of the bolt receiving space then comprises sections of a conical surface of a hollow cone with an obtuse apex angle.
[0016] The pipe fitting is preferably a casting made of ductile cast iron. Depending on the application (low-pressure or high-pressure), either an alloy according to GJS 400 or an alloy according to GJS 500 is used. Ductile cast iron is cast iron with spheroidal graphite and is therefore also referred to as globular gray cast iron or spheroidal cast iron.
[0017] The bolts are preferably also cast parts made of ductile cast iron, preferably GJS 400. Each bolt has an arcuate bolt section that has the counter-contact surface which, after insertion of the bolt, rests against the contact surface of the end wall of the bolt receiving space of a socket. Depending on whether the bolt is intended for clockwise or counterclockwise insertion, it has a projection at one or the other longitudinal end of its arcuate bolt section. This projection serves, particularly when the socket connection is released, to loosen a bolt again and remove it from the bolt receiving space. This is because the respective projection of a bolt is designed such that the projection protrudes from the respective insertion opening when the respective bolt is fully inserted into the bolt receiving space and pushed into its final position.
[0018] To prevent the bars from falling out after insertion and before the socket connection is subjected to tension, elastic molded parts are preferably provided. These are mounted between the projections on the bars inserted into the bar receiving space and pushed into their final position. A total of two elastic molded parts are provided for each socket. One elastic molded part is inserted between the two bars, which are inserted into the bar receiving space through the same insertion opening. The elastic molded parts are preferably made of ethylene propylene diene rubber (EDPM).
[0019] The seal is designed for the following operating conditions: an operating temperature between 0°C and 50°C, a maximum operating pressure of 100 bar and a test pressure of 150 bar.
[0020] The seal can be made from either a single material grade or two different material grades. If the seal is made from two different material grades, the area with the retaining bead is made from a harder material grade than the dovetail-shaped part, which performs the actual sealing function. The seal is preferably a sealing ring made from an elastomer, preferably ethylene propylene diene rubber (EPDM). Different sections of the sealing ring preferably have different hardnesses. In the area of the retaining bead, the hardness of the sealing ring is preferably between 75 and 95 Shore A, for example 85 + / - 5 Shore A, and in the area of the sealing lips, the hardness of the sealing ring is preferably between 40 and 60 Shore A, for example 55 + / - 5 Shore A.A further aspect of the invention is a method for producing a socket connection between two steel pipes by means of a pipe fitting, eight bars and two sealing rings of the type described above. The method comprises the steps:
[0021] Inserting a spigot end of a first pipe into a first socket on the pipe fitting,
[0022] Inserting four bars into the bar receiving space of the first socket and moving the respective bar in such a way that the respective bar is located in the longitudinal direction of the socket connection between a radially outwardly projecting projection on the insertion end of the first pipe and an end wall of the bar receiving space of the first socket, if necessary inserting elastic molded parts to secure the position of the bars
[0023] Inserting a spigot end of a second pipe into the second socket on the pipe fitting,
[0024] Inserting four bars into the bar receiving space of the second socket and moving the respective bar in such a way that the respective bar is located in the longitudinal direction of the socket connection between a radially outwardly projecting projection on the insertion end of the second pipe and an end wall of the bar receiving space of the second socket, if necessary inserting elastic molded parts to secure the position of the bars and
[0025] Stretching of the socket connection due to tension or internal pressure in the pipes.
[0026] Another aspect of the invention is a method for separating a socket joint between two steel pipes by means of a pipe fitting, eight locks and two sealing rings of the type described above. The method comprises the steps:
[0027] Releasing the clamping between the conical contact surface of the end wall of the bar receiving space, the bars and the radially outwardly projecting projection on the spigot end of the pipe by pushing the spigot end of a pipe into the socket base using a laying device and, if necessary, removing the elastic fittings. Grasping the bars at their projections, moving the bars and removing the bars from the bar receiving space of the socket of the pipe fitting through the insertion openings in the end wall of the bar receiving space.
[0028] The invention will now be explained in more detail using an exemplary embodiment with reference to the figures. The figures show:
[0029] Figure 1: a detail of a longitudinal section through a socket connection with a pipe fitting according to the invention and a sealing ring according to the invention;
[0030] Figure 2. a perspective view of the pipe fitting;
[0031] Figure 3a: a perspective view of a bolt,
[0032] Figure 3b: a cross-section through a bar; and
[0033] Figure 4: a representation of a sealing ring.
[0034] As can be seen from the preceding general description, the invention relates to a connection system for connecting the free ends of two steel pipes by means of a pipe fitting having two sockets, namely one socket at each longitudinal end of the pipe fitting. A section of such a connection system 10 is shown in Figure 1. Figure 1 shows a section of a free end of a steel pipe 12 with a circumferential, outwardly projecting projection 14. The free end of the steel pipe 12 is designed as an insertion end 16.
[0035] In the example shown, the steel pipe 12 has a nominal diameter (DN) of 400 mm (DN 400). A standardized steel pipe with a nominal diameter of 400 mm, for example, has an outer diameter of 406.4 mm and, depending on the wall thickness, an inner diameter between 392.2 mm (with a wall thickness of 7.1 mm) and 393.8 mm (with a wall thickness of 6.3 mm). The illustration in Figure 1 is approximately to scale, so that dimensions and dimensional relationships can be derived from Figure 1 at least approximately accurately.
[0036] In alternative, advantageous designs not shown, the steel pipe has a nominal diameter (DN) of 500 mm or 600 mm (DN 500 or DN 600). A standardized DN 500 steel pipe has an outer diameter of 508.0 mm. A standardized DN 600 steel pipe has an outer diameter of 610.0 mm.
[0037] In addition to the steel pipe 12, Figure 1 shows a section of a pipe fitting 20 that is symmetrically constructed with respect to a central plane of symmetry 22 (indicated by the dot-dash line). The pipe fitting 20 has a central stop 24 that limits the axial insertion of a respective insertion end 16 of a steel pipe 12. The central stop 24 encloses a central opening of the pipe fitting 20, the diameter of which is slightly smaller than the inner diameter of the steel pipe 12.
[0038] With respect to the longitudinal direction of the pipe fitting 20, it has a socket 26 on each side of the central stop 24. In the example shown, the free end (the insertion end 16) of the steel pipe 12 is inserted into one of the sockets 26.
[0039] Each of the two sleeves 26 of the pipe fitting 20 has a bolt receiving space 28 on the front side - that is to say on the respective outwardly open longitudinal end of the pipe fitting 20 - which serves to receive a plurality of bolts 30, the functions of which are explained in more detail below.
[0040] In the longitudinal direction of the pipe fitting 20, between the circumferentially extending bolt receiving space 28 and the central stop 24, a sealing chamber 32 is provided, which also extends circumferentially and into which an annular seal 34—hereinafter also referred to as sealing ring 34—is inserted. The bolt receiving space 28 and the sealing chamber 32 are separated from each other by a partition wall 36, which also extends circumferentially.
[0041] The bolt receiving space 28 is bounded at the end by a radially inwardly projecting end wall 40, which is interrupted in the circumferential direction such that it has insertion openings 42 for inserting the bolts 30. Where it is not interrupted by the insertion openings 42, the end wall 40 has a conical contact surface 44 extending at an acute angle to the radial direction, against which a counter-contact surface 46 of a respective bolt 30 extending at the corresponding angle can rest.As is generally known from the prior art, the respective bolt receiving space 28 serves to accommodate curved bolts 30 (see also Figures 3a and 3b), which are inserted into the bolt receiving space 28 through the insertion openings 42 (see Figure 2) and can then be displaced in a tangential direction along the circumference of the insertion end 16 of the steel tube 12 such that the respective bolt can be supported on the contact surface 44 of the end wall 40 of the bolt receiving space 28. On the other side (seen in the longitudinal direction of the pipe fitting 20), each bolt 30 can be supported on the radially outwardly projecting projection 14 on the tube 10 that the respective insertion end 16 of the steel tube 12 has. This outwardly projecting projection 14 can, for example, be a weld bead welded onto the outer surface of the insertion end of the steel pipe 12.
[0042] When internal pressure prevails inside the line formed by the two steel pipes 12 and the pipe fitting 20, and the pipe connection system is stretched accordingly, a respective bar 30 rests with its counter-contact surface 46 on the contact surface 44 of the end wall 40 of the pipe fitting 20. As can be seen from Figure 1, both the contact surface 44 on the end wall 40 and the counter-contact surface 46 on the respective bar 30 are each inclined at an acute angle to an imaginary cross-sectional plane running perpendicular to the longitudinal axis of the pipe fitting 20. The contact surface 44 on the end wall 40 of the pipe fitting 20 and the counter-contact surface 46 on the bar 30 thus each have the shape of a section of a cone or a section of a conical surface. The corresponding cone has an obtuse apex angle ß and is indicated by the dashed lines 48 in Figure 1.In contrast to the prior art, the conical contact surface 44 thus does not extend at an obtuse angle to the radial direction of the sleeve, but at an acute angle. This means that the contact surface 44 extends at an angle a of less than 45° to a plane perpendicular to the longitudinal axis of the sleeve.
[0043] Each bolt 30 has an arcuate bolt section 58 having the counter-contact surface 46, which, after insertion of the bolt, rests against the contact surface 44 of the end wall 40 of the bolt receiving space 28 of a sleeve 26. Depending on whether the bolt 30 is intended for insertion clockwise (bolt 30.1) or counterclockwise (bolt 30.2), it has a projection 60 (here also referred to as a nose 60) at one or the other longitudinal end of its arcuate bolt section 58, which projection serves, in particular when releasing the sleeve connection, to loosen a bolt 30 again and remove it from the bolt receiving space 28. This is because the respective projection 60 of a bolt is designed such that the projection 60 protrudes from the respective insertion opening 42 when the respective bolt 30 is fully inserted into the bolt receiving space 28 and pushed into its final position.
[0044] To secure the bars 30 against falling out after insertion and before the socket connection is subjected to tension, elastic molded parts made of ethylene propylene diene rubber (EPDM) are preferably provided. These are attached between the projections 60 on the bars 30 inserted into the bar receiving space 28 and pushed into their final position. A total of two elastic molded parts are provided for each socket 26. One elastic molded part is inserted between the two bars 30, which are inserted into the bar receiving space 28 through the same insertion opening 42. In principle, the elastic molded parts can be made of any elastomer.
[0045] Four bolts 30 are provided for each sleeve 26, two of which are designed for counterclockwise movement and two for clockwise movement. The end wall 40 of each sleeve therefore only needs to have two insertion openings 42. This is because one insertion opening 42 can be used to insert a counterclockwise movable bolt 30 and a clockwise movable bolt 30. When inserted into the bolt receiving space and moved to their final position, the bolts 30 are each in a position in which the bolts 30 are diametrically opposed to each other in pairs.
[0046] The pipe fitting 20 is a casting made of ductile cast iron, specifically, depending on the application (low-pressure or high-pressure application), an alloy according to GJS 400 or an alloy according to GJS 500. The bars 30 are preferably also castings made of ductile cast iron, specifically, preferably, GJS 400.
[0047] The sealing chamber 32 is located between the bolt receiving space 28 and the central stop 24. The sealing chamber 32 initially tapers from the partition 36 in the longitudinal direction of the pipe fitting and then widens again to accommodate the correspondingly shaped sealing ring 34. The sealing ring 34 has, at one longitudinal end, a radially outwardly extending retaining bead 50 for engagement with the partition 36 and, at the other longitudinal end, two fork-like, separated sealing lips 52 and 54, which enclose a gap 56 open at the end between them.The shapes of the sealing chamber 32 and the associated sealing ring 34 ensure, on the one hand, that the sealing ring 34 cannot slip in the longitudinal direction of the socket connection even at high internal pressure and, at the same time, that the seal seals reliably because the sealing lips 52 and 54 are pressed apart by the pressure of a fluid, so that a radially outer sealing lip 52 of the sealing ring 34 lies tightly against a corresponding inner wall of the sealing chamber 32, while the radially inner sealing lip 54 lies tightly against the outer surface of the respective steel pipe 10.
[0048] The sealing ring 34 is made of ethylene propylene diene rubber (EPDM) and has different hardnesses. In the area of the retaining bead 50, the hardness of the sealing ring is preferably 85 + / - 5 Shore A, and in the area of the sealing lips 52 and 54, the hardness of the sealing ring is preferably 55 + / - 5 Shore A. In the cross-section of the sealing ring 34 shown in Figure 4, the different hardnesses of the material of the sealing ring 34 are indicated by correspondingly different hatching.
[0049] To create a socket connection, the locking elements 30, two for each 180° of the pipe circumference, are inserted through the ring-segment-shaped insertion openings 42 in the end wall of the socket 26 of the pipe fitting into the locking receiving space 28. A total of four locking elements 30 are provided for the entire circumference of a socket connection.
[0050] As soon as the connection is subjected to pressure or mechanically stretched, the locking elements 30 (the locks 30) are supported on the one hand by the radially outwardly projecting projection 14 on the spigot end 16 of the steel pipe 12 and, on the other hand, by the conical contact surface 44 of the end wall 40 of the lock receiving space 28 of the socket 26 of the pipe fitting 20. This makes the socket connection tensile-resistant.
[0051] To separate the socket connection, the spigot end 16 of the pipe 12 is pushed a few millimeters into the socket base by means of a laying device, thus releasing the clamping between the conical contact surface 44 of the end wall 40 of the bar receiving space 28, the bars 30 and the radially outwardly projecting projection 14 on the spigot end 16 of the steel pipe 12.
[0052] Now the bars 30 can be grasped by their projections 60 (noses) and moved in such a way that the bars 30 can be removed from the bar receiving space 28 of the sleeve 26 of the pipe fitting 20 through the ring-segment-shaped recesses serving as insertion openings 42.
[0053] Due to the special geometric shape of the conical end wall 40 of the bolt receiving space 28 and the counter-contact surfaces 46 on the bolts 30, the longitudinal forces resulting from the internal pressure are directed in an optimal direction onto the weld bead forming the radially outwardly projecting projection 14. List of reference symbols
[0054] 10 Connection system
[0055] 12 steel pipes
[0056] 14 outwardly projecting projection
[0057] 20 pipe fittings
[0058] 22 plane of symmetry
[0059] 24 central stop
[0060] 26 sleeve
[0061] 28 bolt receiving space
[0062] 30 bars
[0063] 32 Sealing chamber
[0064] 34 Sealing ring
[0065] 36 Partition wall
[0066] 40 front wall
[0067] 42 insertion openings
[0068] 44 contact surface
[0069] 46 Counter contact surface
[0070] 48 imaginary cone
[0071] 50 retaining bead
[0072] 52 outer sealing lip
[0073] 54 inner sealing lip
[0074] 56 open space between the outer and inner sealing lip
[0075] 58 arched bar section
[0076] 60 projection on the bar
Claims
AMENDED CLAIMS received by the International Bureau on December 19, 2023 (19.12.2023). Pipe fitting (20) for producing a socket connection between two steel pipes (12), wherein the pipe fitting has two longitudinal ends and at each longitudinal end a socket (26) into which a plug-in end (16) of a steel pipe (12) with an outwardly projecting projection (14) extending at least partially in the circumferential direction can be inserted, wherein each socket (26) has on its end face a circumferentially encircling bolt receiving space (28), as well as a sealing chamber (32) separated from the bolt receiving space (28) by a circumferentially encircling partition wall (36) for receiving a sealing ring (34), wherein the bolt receiving space (28) is delimited at the end face by an inwardly projecting end wall (40) which is interrupted in the circumferential direction in such a way thatthat it has insertion openings (42) for inserting bars (30), wherein the end wall (40) has a contact surface (44) running at an acute angle of less than 45° to the radial direction, against which a counter-contact surface (46) running at a corresponding angle on a respective bar (30) can rest, and wherein the sealing chamber (32), starting from the partition wall (36), initially tapers in the longitudinal direction of the pipe fitting (20) and then widens again in order to accommodate a correspondingly shaped sealing ring (34), which has at one longitudinal end a radially outwardly extending retaining bead (50) for bearing against the partition wall (36) and at the other longitudinal end two fork-like, separate sealing lips (52, 54) which enclose an intermediate space (56) open at the end between them. Pipe fitting (20) according to claim 1, in which the end wall (40) of the bolt receiving space (28) of a sleeve (26) has two receiving openings (42),through which the bolts (30) can be inserted into the respective bolt receiving space (28). Pipe fitting (20) according to claim 1 or 2, wherein the contact surface (44) on the end wall (40) of the bolt receiving space (28) of a sleeve (26) is inclined at an angle of between 30° and 40° with respect to a plane perpendicular to the longitudinal axis of the sleeve. AMENDED SHEET (ARTICLE 19) 4. Pipe fitting (20) according to at least one of claims 1 to 3, characterized in that the pipe fitting (20) is a casting made of ductile cast iron.
5. Pipe fitting (20) according to claim 4, characterized in that the pipe fitting (20) is a casting made of GJS 400 or GJS 500.
6. Sealing ring (34) for a pipe fitting (20) according to one of claims 1 to 5, wherein the sealing ring (34) has at one longitudinal end a radially outwardly extending retaining bead (50) for contact with the partition wall (36) of the sealing chamber (32) of the pipe fitting (20) and at the other longitudinal end two fork-like separated sealing lips (52, 54) which enclose between them an intermediate space (56) which is open at the end, wherein the sealing lips are formed from an elastomer, preferably a rubber, with a Shore hardness between 40 and 60 Shore A and the retaining bead (50) has a Shore hardness between 75 and 95 Shore A.
7. Sealing ring (34) according to claim 6, which is one-piece and consists of ethylene-propylene-diene rubber.
8. Sealing ring (34) for a pipe fitting (20) according to one of claims 1 to 5, wherein the sealing ring (34) has at one longitudinal end a radially outwardly extending retaining bead (50) for contact with the partition wall (36) of the sealing chamber (32) of the pipe fitting (20) and at the other longitudinal end two fork-like, separated sealing lips (52, 54) which enclose between them an intermediate space (56) which is open at the end, wherein the sealing ring (34) is in one piece and consists of ethylene-propylene-diene rubber and the retaining bead (50) has a Shore hardness between 75 and 95 Shore A.
9. Socket connection system with a pipe fitting (20) according to one of claims 1 to 5, two sealing rings (43) and eight locks (30) for insertion into the lock receiving spaces (28) and tangential displacement in the respective lock receiving space (28), wherein the sealing rings (34) have at one longitudinal end a radially outwardly extending retaining bead (50) for engagement with the partition wall (36) of the sealing chamber (32) of the pipe fitting (20) and at the other AMENDED SHEET (ARTICLE 19) 0. A method for producing a socket connection between two steel pipes by means of a pipe fitting (20) according to one of claims 1 to 5, eight locks (30) and two sealing rings (34), which have at one longitudinal end a radially outwardly extending retaining bead (50) for contact with the partition wall (36) of the sealing chamber (32) of the pipe fitting (20) and at the other longitudinal end two sealing lips (52, 54) which are separated from one another in a fork-like manner and enclose a gap (56) open at the end between them, comprising the steps: Inserting a spigot end of a first steel pipe (12) into a first socket (26) on the pipe fitting (20) Inserting four bolts (30) into the bolt receiving space (28) of the first sleeve (26) and displacing the respective bolt (30) such that the respective bolt is located in the longitudinal direction of the sleeve connection between a radially outwardly projecting projection (14) on the insertion end (16) of the first steel pipe (12) and an end wall (40) of the bolt receiving space (28) of the first sleeve (26), Inserting a spigot end of a second steel pipe (12) into the second socket (26) on the pipe fitting (20) Inserting four bolts (30) into the bolt receiving space (28) of the second sleeve (26) and displacing the respective bolt (30) such that the respective bolt is located in the longitudinal direction of the sleeve connection between a radially outwardly projecting projection (14) on the insertion end (16) of the second steel pipe (12) and an end wall (40) of the bolt receiving space (28) of the second sleeve (26), and Stretching the socket joint by tension or internal pressure in the steel pipes (12).
1. Method according to claim 10, wherein, after inserting and displacing the locking bars (30), the locking bars (30) are secured in position by inserting elastic molded parts between the lugs (60) of the locking bars (30). AMENDED SHEET (ARTICLE 19) Method for separating a socket connection between two steel pipes by means of a pipe fitting (20) according to one of claims 1 to 5, eight bars 30 and two sealing rings (34), comprising the steps: Releasing the clamping between the conical contact surface (44) of the end wall (40) of the bolt receiving space (28), the bolts (30) and the radially outwardly projecting projection (14) on the spigot end (16) of the steel pipe (12) by inserting the spigot end (16) of a steel pipe (12) into the socket base by means of a laying device and Grasping the bolts (30) at their projections (60), moving the bolts (30) and removing the bolts (30) from the bolt receiving space (28) of the Sleeve (26) of the pipe fitting (20) through the insertion openings (42) in the end wall (40) of the bolt receiving space (28). Method according to claim 12, wherein elastic molded parts serving to secure the position of the bolts (30) are removed before the bolts (30) are moved. AMENDED SHEET (ARTICLE 19)