DE19718790A1 - Welded connection for plastic pipe used for burrowing into earth - Google Patents

Abstract

The adjoining ends of the plastic pipes are shaped to fit over each other to form a smooth inner and outer profile. This enables the welded pipe to be pulled through the earth with a minimum of resistance. The overlapping profiles are welded by electric heating coils applied to one of the mating surfaces. The adjoining ends can be sloped ie. with a conical profile or a simple stepped profile can be used. An alternate design has a T-shaped jointing insert between stepped end profiles.

Description

The invention relates to a connection for from pipe pieces of existing plastic earth cables.

Pipe connections made with heating coil sleeves are for example from German Patent 43 23 383 known. The pipe connection in question is in manufactured in such a way that a plastic sleeve with egg ner electrical coil on its inner surface on one pushed the connecting pipe ends and the coil with such a welding current is applied that the Plastic of the sleeve and the plastic of the pipe ends fuse together and then harden. The Plastic pipes and the plastic sleeves are available preferably made of polyethylene.

A disadvantage of this pipe connection is that they are not suitable for trenchless laying because the sleeves due to their overhang on the outside of the pipe knife when pulling into the ground a high resistance generate stand and easily in the earth hole, esp especially if the plastic pipe is in a previously destroyed old pipeline is pulled in, stuck or ver hooks. When pulling in such plastic pipes with a socket fen connection in newly created earth bores can the soil in front of the sleeves while pulling in s and significantly hamper the retraction if don't even prevent it.  

Pipe connections without the outside diameter of the pipes outstanding sleeves are also known, however these pipe connections have the disadvantage that the Pipe wall cross section, the transmission of tensile forces takes over, is weakened in the area of the pipe connection. But since the pulling in of pipes requires high tensile forces to the skin friction through the soil and / or due to pipe shards when renewing old pipes to overcome is such a pipe connection to the gra useless pulling in of pipe sections Plastic pipes are not suitable.

The invention is based on the problem, a Rohrver create a bond that is not possible when digging in trenchless NEN gives greater resistance than a plastic pipe without such pipe connections and high tensile forces grow that are almost as large as the permissible against tensile forces of the pipe itself.

The solution to this problem is a pipe joint manure, which according to the invention consists of no significant excess stood out directly or with the insertion of a ver connecting piece nested pipe ends and in de ren overlap area arranged, a full area Welding the pipe ends causing heating elements stands.

In particular, the pipe connection from an inside ko African and an outside conical tube end, which can be plugged into each other. The heating elements are then essentially along the entire conical Be contact surfaces arranged.  

Likewise, the pipe ends can have a wall thickness or Have jump in diameter, for example with a zy Lindrischer interior expansion and an outside diameter server reduction to about half the tube wall thickness be provided. The heating elements then extend in the essentially along the contiguous and over pushed together cylindrical wall surfaces. Here the abutting surfaces can either be perpendicular to the pipe axis run or be conical.

The under inserting a connector with each other Connected pipe ends can have a cylindrical interior extension or a reduction in diameter to about that half pipe wall thickness to slide one on accordingly molded connector, the heating elements essentially along the abutting and surfaces are arranged one above the other.

The connector can have a T-shaped cross section own, d. H. with a central cylindrical area essentially the same wall thickness as the pipe ends have so that the up on the connector inserted or inserted into the connector Butt pipe ends against the central cylindrical area and also in this area are welded.

The heating elements can be made of inductive heating coils or consist of resistance heating coils and on a pipe de or be arranged on the connector; she are preferably sealed against moisture  protected. The seals can be arranged so that the heating elements against moisture from outside and / or against moisture from inside before and during protect from merging.

The pipe connection according to the invention can be used for gra Use the seamless pulling in of plastic pipes. The This feeding can take place both in one after the in the German the patent 35 35 995 described Berstli ning process as well as into a existing line (relining) or also into a new, by drilling, preferably ramming and / or rinsing drilling produced earth drilling happen.

The invention is described below with reference to several in the drawing illustrated embodiments of the explained in more detail. The drawing shows:

Fig. 1 is a pipe connection according to the prior art,

Fig. 2 is a Z-shaped pipe joint,

Fig. 3 shows a modified Z-shaped pipe joint,

Fig. 4 shows a pipe connection with a connecting piece,

Figure 5 dung tee. A pipe connection with another Verbin,

Fig. 6 shows a pipe connection with conical pipe ends and

Fig. 7 is an axial longitudinal section through a composite tube.

The pipe connection according to the prior art ( Fig. 1) consists of a pipe section 1 with a cylindrical inner extension 3 and a pipe section 2 with a cylindrical outer diameter reduction 4 , so that in this area a kind of socket connection possible by pushing the pipe ends over or in one another is. The cylindrical extension 3 on the pipe section 1 and the cylindrical diameter reduction 4 on the pipe section 2 make up a jump in diameter or wall thickness of approximately half the wall thickness of the pipe sections 1 , 2 . Between the cylindrical extension 3 and the cylindrical diameter reduction 4 , a heating coil 9 is arranged, which causes heating of the tube ends in the region of the cylindrical extension 3 and the cylindrical diameter reduction 4 by heating. No heating coils are arranged in the area of the abutting surfaces 5 , 6 and 7 , 8 , so that melting of the pipe ends is not possible in this area. Therefore, only a part of the wall cross-section is available for the transmission of tensile forces, which is not sufficient with the high tensile forces that occur when trenchless pulling in of plastic pipes.

According to the invention, heating coils 10 , 11 are now arranged in the area of the butt faces 5 , 6 , 7 , 8 of the pipe connection according to FIG. 2, which cause these butt faces to be welded, so that essentially the entire pipe cross section is available for transmitting tensile forces stands.

In the embodiment according to FIG. 3 the surfaces 12 , 13 , 14 , 15 are conical. In this area heating coils 10 , 11 are arranged so that the entire pipe cross-section is also available for the force transmission in this embodiment.

In the embodiment of Fig. 4, the ends gleichar term pipe pieces 2 with same cylindrical diam are server rings stanchions 4 are provided. A cross-sectionally T-shaped connecting piece 16 with its cylindrical extension 17 is pushed onto the pipe ends. A central cylindrical inner collar 18 of the connecting piece 16 has the same inside and outside diameter as the pipe sections 1 , 2 , so that there is a continuous transition of the pipe wall both inside and outside. Abutment surfaces 24 , 25 of the connecting piece 16 which are perpendicular to the tube axis lie on the abutment surfaces 6 , 7 of the tube pieces 1 , 2 , and in this area, as already described with reference to FIGS . 2 and 3, 9 heating coils 10 , 11 in addition to the heating coils arranged.

In the embodiment of Fig. 5 is a reversal of the arrangement according to FIG. 4, since pieces of pipe 1, are provided with cylindrical inner extensions 3 2, blank insert 19 of a T-shaped connecting piece into which pipe portions 21. The connec tion piece 19 has a central outer collar 20 with the same inner and outer diameter as the pipe sections 1 , 2 . Between the perpendicular to the tube axis joint surfaces 26 , 27 on the connector 19 and the ent speaking abutment surfaces 5 , 8 on the pipe sections 1 , 2 , in turn, additional heating coils 10 , 11 are arranged, which together with the concentric heating coils 9 a completely surface fusion of the pipe sections 1 , 2 effect with the sleeve 19 .

The pipe joint according to Fig. 6 consists of a koni rule extension 22 on the pipe section 1 and a conical taper 23 on the pipe section 2, which can be plugged into each other. In the area of the contact surface, a heating coil 9 , 10 , 11 is arranged, which extends from the inner wall of the pipe to the outer wall of the pipe and causes the full-surface welding of the pipe sections 1 , 2 according to the invention.

The heating coils can be used as resistance heating coils forms, but it is also possible to use inductive heating to use spirals, which advantageously no lei outside.

In the pipe connection according to the invention, a composite pipe of the type shown in FIG. 7 can also be used, which consists of a core pipe 29 with a casing 28 . The casing is preferably made of plastic; it is shrunk onto the core tube and thus protects it against external damage when trenchless laying, but also when laying in open trenches.

Between the casing 28 and the core pipe 29 there can be a conductor which can be in contact with the heating elements of the pipe connections, so that preferably during the relining process, a complete pipe string after welding into the ground or into an old pipe is to be welded, the welding current over the mentioned conductor is introduced from outside the ground.

Furthermore, the pipe ends can be designed that they have annular, not shown locking lugs zen, which ensure that the pipes during welding are axially clamped.

Claims (14)

1. Pipe connection for existing plastic pipe with pipe sections

• - Pipe pieces connected to each other without overhang
• - Contact surfaces running at an angle to the pipe axis
• - And over the contact surfaces ( 3 to 8 ; 12 to 15 , 17 ; 20 to 27 ) distributed heating elements ( 9 , 10 , 11 ) for welding the pipe ends ( 1 , 2 ).

2. Pipe connection according to claim 1, characterized in that a pipe end ( 1 ) is flared on the inside and a pipe end ( 2 ) is tapered on the outside and the heating elements ( 9 , 10 , 11 ) substantially over the conical contact surfaces ( 22 , 23rd ) are distributed. 3. Pipe connection according to claim 1, characterized in that a pipe end ( 1 ) with a cylindrical inner extension ( 3 ) and a pipe end ( 2 ) with a reduced outer diameter ( 4 ) dergiffen sleeve-like and the heating elements ( 9 , 10 , 11 ) are distributed over the abutting and pushed surfaces ( 3, 4, 5, 6, 7, 8; 3, 4, 12, 13, 14, 15 ). 4. Pipe connection according to claim 3, characterized in that abutting contact surfaces ( 5 , 6 , 7 , 8 ) are perpendicular to the pipe axis. 5. Pipe connection according to claim 3, characterized in that abutting contact surfaces ( 12 , 13 , 14 , 15 ) are conical. 6. Pipe connection according to claim 1, characterized in that the pipe ends ( 1 , 2 ) have a diameter jump ( 3 , 4 ) and are connected to one another via a T-shaped connecting piece ( 16 , 19 ). 7. Pipe connection according to one of claims 1 to 6, characterized in that the heating elements ( 9 , 10 , 11 ) consist of inductive heating coils. 8. Pipe connection according to one of claims 1 to 6, characterized in that the heating elements ( 9 , 10 , 11 ) consist of resistance heating coils. 9. Pipe connection according to claim 7 or 8, characterized in that the heating elements ( 9 , 10 , 11 ) at the pipe end or on the connecting piece ( 16 , 19 ) are arranged. 10. Pipe connection according to one of claims 1 to 9, characterized in that the heating elements ( 9 , 10 , 11 ) are protected against moisture by seals. 11. Pipe connection according to one of claims 1 to 10, characterized in that the tube pieces consist of a core tube ( 29 ) with a casing ( 28 ). 12. Pipe connection according to claim 11, characterized in that an electrical conductor runs between the core tube ( 29 ) and the jacket ( 28 ). 13. Pipe connection according to one of claims 1 to 12, characterized in that the ends of the tube pieces ( 28 , 29 ) have locking lugs for bracing. 14. Use of a pipe connection according to one of claims 1 to 13 for trenchless pulling in of pipe sections ( 1 , 2 ) existing plastic pipes.