SU1492154A1 - Method of coupling metal tubes having inner thermoplastic lining - Google Patents

Abstract

The invention relates to pipeline transport, all-in-one joints of metal pipes provided with an inner sheath of thermoplastic materials, and can be used in the construction of pipelines. The purpose of the invention — improving the reliability of the joint — is achieved by ensuring the strength and durability of the inner shell of metal pipes in the weld zone. At the ends of the metal pipes 1, half-couplings 4 are placed, slots 3 are made for the length of the heat-affected zone. The coupling halves 4 are fixed at the ends of the pipes. An internal thermoplastic sheath 2 is introduced into the inside of the metal pipes, at the ends of which the cuts are also made, respectively, to the ends of the metal pipes, but of smaller width. A conical sleeve 5 with slots on the side of the larger base and an outer layer of thermoplastic material 6 is inserted into the cut ends of the pipes. At the same time, the ends of the pipes expand and partially press against the inner surface of the coupling half 4. The thermoplastic material of the shell 2 and layer 6 is partially pressed into slot 3 pipe ends. The pipes prepared in this way are arranged coaxially and are fastened by welding the coupling halves 4 to each other. The inner shell 2 and the layer of thermoplastic material 6, protected from the direct impact of the welding arc by the wall of the metal pipes 1 and air gaps in the gaps between the structural elements of the joint, are melted by the heat of the heated metal parts. As a result of the heat, elastic forces of the cut and reformed ends of the metal pipes 1 and the sleeves 5, the molten thermoplastic material flows, fills the gaps in the construction of the joint and welds. After cooling of the thermoplastic material in the joint zone, a metal-reinforced protective sheath is formed, additionally attached to the wall of the pipes 1 with sleeves 5. 3 Il.

Description

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ladies metal pipes, but smaller width. A conical sleeve 5 with slots on the side of the larger base and an outer layer of thermoplastic material 6 is inserted into the cut ends of the pipes. At the same time, the ends of the pipes expand and partially press against the inner surface of the coupling half 4. The thermoplastic material of the shell 2 and layer 6 is partially pressed into slot 3 pipe ends. The pipes prepared in this way are arranged coaxially and are fastened by welding half couplings 4 to each other. Inner shell 2 and layer of thermoplastic material 6, protected from direct exposure

The arc of the metal pipe 1 and the air gaps in the gaps between the structural elements of the joint are melted by the heat of the heated metal parts. As a result of exposure to heat, the elastic forces of the cut and deformed ends of the metal pipes 1 and the sleeves

5, the molten thermoplastic material flows, fills the gaps in the structure of the joint and is welded. After cooling the thermoplastic material in the bonding zone, a

a metal-reinforced protective sheath, additionally attached to the wall of pipes 1 is a sleeve 5. 3 Il.

The invention relates to a pipeline fy transport, namely to the connection of metal pipes equipped with an inner protective sheath of thermoplastic material, and can be used in the construction of pipelines.

The purpose of the invention is to increase the reliability of the joint by ensuring the strength and durability of the inner shell of metal pipes in the weld zone.

Fig. 1 shows a metal pipe with slots filled at the end and a coupling fixed to it; in FIG. 2 - pipe with a coupling end attached to the cut and wrinkled conical bushing, end of the coupling; in fig. 3 - connection of pipes after welding the ends of the inner shell and the coupling halves to each other.

Metal pipes 1 with an internal thermoplastic sheath 2, with slots 3 at the ends and with fixed coupling halves 4 are located coaxially. At the ends of metal pipes with an inner shell there are conical sleeves 3 with slots and with an outer layer 6 of thermoplastic material. The ends of the metal pipes of the inner thermoplastic shell and the coupling half are fastened together by welding 7, 8 (Fig. 1-3),

The method is carried out as follows.

At the ends of the metal pipes 1, the coupling halves 4 are placed;

slot 3 on the length of the heat-affected zone. The coupling halves 4 are fixed at the ends of the pipes by electric welding 7. An internal thermoplastic jacket is inserted inside the metal pipes.

2, at the ends of which also cuts are made, respectively, to the ends of the metal pipes, but of lesser width. A conical sleeve 5 with slots on the side of the larger base and an outer layer 6 of thermoplastic material is inserted into the cut ends of the pipes. The ends of the pipes expand and partially press against the inner surface of the coupling halves 4. The thermoplastic material of the shell 2 and layer 6

partially pressed into the slots of the ends of the pipes 3. The pipes prepared in this way are arranged coaxially and fastened by welding 8 half-couplings 4 between each other. Inner shell 2

and a layer 6 of a thermoplastic material, protected from direct influence of the welding arc by the wall of metal pipes 1 and air gaps in the gaps between the structural elements

the compounds are melted by the heat of the heated metal parts. As a result of the heat, elastic forces of the cut and reformed ends of the metal pipes 1 and the sleeves 5, the molten thermoplastic material flows, fills the gap in the construction of the joint and seals. After cooling thermoplastic

51

The material in the joint zone forms a metal-reinforced protective sheath, additionally attached to the wall of pipes 1 by bushings 5.

Example. On metal pipes 1 (Fig. 1) with a diameter of 100 mm, with a wall thickness of 7 mm, the coupling halves 4 are preliminarily placed with an outer diameter of 140 mm and a minimum wall thickness of 7 mm. At the ends of the metal pipes, three continuous, longitudinal slits are made with a width of 8 mm and a length of 100 mm. The optimal length and width of the slits was determined experimentally on natural samples of pipe joints. The coupling halves 4 are hermetically sealed to the ends by welding 7. A polyethylene sheath 2 with a wall thickness is inserted inside the metal pipes. 3 mm. At the ends of the polyethylene sheath, respectively, the ends of the metal pipes of the slot 3 are 2 mm wide. Inside the cut metal pipes with a thermoplastic sheath 2, a partially cut and reformed metal conical sleeve 5 is inserted, covered with an outer layer 6 of a thermoplastic material with a thickness of 10 mm. The cut ends of the metal pipes expand in this case, and the inner shell 2 and the layer 6 of the thermoplastic material are partially pressed into the slots 3.

The pipes 1 prepared in this way are arranged coaxially and the coupling halves 4 are fastened together by electric welding. Polyethylene inner sheath 2 and thermoplastic layer 6

with

0 5 0 5 0

five

0

546

the material is then heated, transferred to the flowable state. The pre-deformed and unbonded cutting elements of the ends of metal pipes and sleeves 5 are elastically straightened and immersed in a melt of a thermoplastic material. As a result of the action of heat and elastic forces of the split elements, the melt of the thermoplastic material fills the gaps in the structural elements of the joints, the ends of the inner shell are welded. Upon completion of welding of coupling half 4 and cooling in natural conditions of the joint, a metal-reinforced inner shell with an increased cross-sectional area and additionally attached to the walls of metal pipes 1 with sleeves 5 is formed in the welding zone.

Claims (1)

Invention Formula A method of joining metal pipes with an internal thermoplastic shell, including connecting coupling pipes to the pipes being connected, welding pipe ends, covers and coupling half between them, characterized in that, in order to increase the reliability of the connection, before welding, at each end of the pipe with the shell the end face of the longitudinal slits, the sleeve with a conical outer surface and the longitudinal slits from the larger end face and covered with a thermoplastic layer outside are inserted into the sleeve with a smaller base at the end of the pipe. and shifting the span of pipe. f 2  five 3 W8./