RU2005259C1 - Method for building pipeline - Google Patents

Description

protective sheath made of thermoplastic material.

This goal is achieved by the fact that in the proposed method for the construction of pipelines with an inner protective sheath of thermoplastic material, comprising sequential joining of metal pipes and thermoplastic shells and welding them. the welds of the thermoplastic sheath joints are crimped with washers.

Shim rings are placed in the area of the welded joints of the metal pipes and sheath between their walls. After welding the ends of the shell segments, when the metal pipes are joined for welding, the backing ring is reduced in diameter and it tightly covers the outer surface of the protective shell. Then the ends of the metal pipes are welded on a washer ring. The backing ring is then welded to the walls of the metal pipes and, if necessary, fused into the wall of the containment shell (the backing ring is heated by the heat of the welding arc). Outside the area of the backing ring, the containment is forcibly or due to its elastic properties expanded to fit snugly against the inner surface of the metal pipes without compromising its protective properties. The inner protective sheath is fixed in the pipeline from axial and radial movements due to the stepped shape and its fastening to the walls of metal pipes with underlay rings.

Figure 1 illustrates conventionally the process of deforming a polyethylene sheath and introducing it into a metal pipe; figure 2 - coaxially arranged metal pipes with an inner protective sheath; in Fig.3 - a section of the pipeline in the weld zone of the inner protective sheath and metal pipes.

In the metal pipes 1, the inner protective shell 2 is located, which interacts with the crimp rollers 3. The inner protective shell 2 is inserted into the pipes 1 with an annular gap 4. The metal pipes 1 (see Fig. 2) are aligned with the inner shell 2. The segments of the inner shell 2 are connected by a weld seam 5. On the surface of the protective shell there is a washer ring 6. The ends of the metal pipes 1 (see Fig. 3) are connected by a weld seam 7.

The method is carried out in the following sequence.

In the previously prepared metal pipes (see Fig. 1), a protective sheath 2 is introduced using crimp and

feed rollers 3. The protective shell 2 is placed in the pipes 1 with an annular gap 4. In this case, the shell 2 is deformed in the rollers 3 and reduce its initial diameter. Metal pipes 1 with an inner shell 2 (see Fig. 3) are placed coaxially. A spacer ring 6 is placed on the end of the sheath 2 protruding from the metal pipe 1, on its outer surface. The spacer ring is made in the form of a cylindrical or corrugated pipe in the form of a split cylinder or pipe spirally rolled from a sheet. When it is needed, it is made in the form of a spring collet element. The underlay ring is provided with heat protection elements (not shown in the drawing). The surface of the backing ring is embossed. The backing rings are provided with reinforcing elements (not shown in the drawing). Coaxially located (see, FIG. 2) adjacent ends of the inner shells 2 of the pipes 1 are welded together by a seam 5 by any known method. The outer burr (not shown in the drawing) and the reinforcement of the seam are removed. The underlay ring b is moved over the surface of the protective sheath 2 and overlaps with it the zone of the weld 5. The adjacent ends of the pipes 1 (see Fig. 3) are closed for welding using special devices (not shown in the drawing). The backing ring 6 is crimped, reduced in diameter and introduced into the ends of the joined pipes 1. At the same time, the protective sheath 2 located in them is also crimped in the zone of the weld 5. The joined ends of the pipes 1 are welded to the backing ring 6 and connected by a weld 7 The sealing ring 6 overlaps the zones of the welds 5 and 7. If necessary, adjust the heat protection of the ring 6, heat it with a welding arc and fuse it into the protective shell 2. After welding, one pair of adjacent ends of the metal pipes and the inner protective shells are welded with the construction of the pipeline, proceed likewise. During the construction of the pipeline, the elastic material of the sheath 2 or its initial force is restored by the elastic forces of the shell 2, it is given a stepped shape and fixed in the pipeline from axial and radial movements.

PRI me R. In pre-prepared metal pipes (see Fig. 1) with a diameter of 114 mm, a wall thickness of 9 mm, a polyethylene protective shell 2 with a diameter of 98 mm, a wall thickness of 4.5 mm was introduced using crimp and feed rollers 3 (conventionally shown in the drawing). The protective shell 2 was placed in the pipes 1

with an annular gap of 3 mm. In this case, the shell 2 was deformed in the rollers 3 and its initial diameter was reduced to 91 mm. Metal pipes 1 with a shell 2 (see figure 2) were placed coaxially. An outer ring 6 was placed on the outer surface of the casing 2 with thermal protection (not shown in the drawing) made in the form of a split nozzle 2 mm thick and 0.5 m long. The inner diameter of the lining ring was equal to the outer diameter of the casing 2. Coaxially adjacent adjacent ends of the shells 2 were welded together by flash welding. The outer burr and reinforcement of suture 5 were removed. The underlay ring B was moved and overlapped with it the zone of the weld 5. The adjacent ends of the pipes 1 were closed using a special clamp (not shown in the drawing). The backing ring was crimped by 2 mm and introduced into the ends of the pipes 1 to be joined. The protective sheath 2 was crimped and pressed tightly against the backing ring b.

The backing ring 6 overlapped the joints between the pipes 1 and the shells 2. The joined ends of the pipes were welded on the backing ring 6 by manual arc welding. After connecting the metal pipes 1 with a seam 7, the process of constructing the pipeline was repeated. During the construction of the pipeline, the dimensions of the inner shell were restored by increasing the internal pressure in it to 0.2 MPa and it was in accordance with the invention

METHOD FOR PIPELINE CONSTRUCTION. WATER with an inner protective sheath of thermoplastic material, enclosing

It was stepped in shape, pressed against the surface of metal pipes. After the construction of the three-kilometer pipeline, it was compressed to an internal pressure of 18 MPa and put into operation.

The technical and economic effect of the implementation of the proposed technical solution can be obtained by increasing the service life of the pipeline. The pipeline constructed according to the prototype was put out of action due to destruction of the inner shell by compressed air in the annular gap at the first stop of the pipeline 4 months after putting it into operation.

This happened because when the ends of the metal pipes for welding were closed, the inner shell tightly seated in them was compressed in the zone of the weld and lost stability. It formed transverse corrugations filled with air. When the pipeline was operating with internal pressure, the corrugations and air in them were compressed. When the pipeline stopped, the pressure in it fell, the air in the corrugations sharply expanded and crushed the protective shell, destroying it. The pipeline constructed by the proposed method worked for two years without any complications.

(56) Copyright certificate of the USSR No. 1188437, cl. F 16 L 13/11. 1985.

welding with each other respectively thermoplastic shells and metal pipes, characterized in that the welds of the joints of thermoplastic shells

which are in serial connection and are pressed by backing rings.

Editor

Compiled by. N.Kudr seam

Tehred M. Morgenthal Corrector N. Revska

2005259

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