JPS6146238B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improved construction method for welding joints of internally lined steel pipes used for slurry flow, etc.

In slurry flow, etc., inner-lined steel pipes, in which the inner surface of the steel pipe is lined with a wear-resistant organic material such as polyurethane, are widely used. Conventionally, as a joint for such an internally lined steel pipe, a flange joint has been generally used instead of a welded joint due to the problem of resin burning of the lining due to welding. However, flange joints have construction cost problems in that they are more expensive than ordinary welded joints, and their lining costs are also higher.

For this reason, a construction method has been proposed for welding joints in which unlined parts are provided at both ends of the steel pipes to be joined, a core is inserted into the parts, and resin is cast after welding. ,
This has the problem of poor workability and reduced construction efficiency.

The present invention was devised to solve the above-mentioned conventional drawbacks, and it is possible to weld a welded joint of an inner-lined steel pipe without causing the problem of resin burning of the inner lining, and with good workability. The purpose is to provide a method for constructing welded joints for lined steel pipes.

For this reason, the present invention provides a lining that extends from a base inside one end of each steel pipe in the direction of the pipe end and outward thereof without contacting the inner surface of the steel pipe, and that at least the diameter of the tip is equal to that of the other steel pipe. A lining resin extending tube with a diameter smaller than that of the other steel tube is made, and a non-lining portion of a predetermined length from the end is formed inside the other end of each steel tube. The basic feature is that the tube end is butted against the tube end of the mating steel tube so as to be inserted into the lining surface on the side where the lining portion is formed, and then this butted portion is welded.

Next, embodiments of the present invention will be specifically described based on the drawings.

Figures 1 to 5 show an embodiment of the welded joint construction method according to the present invention, and the feature of this embodiment is that the lining resin extending tube is coated in a process after painting the inner surface of the steel pipe. The point is that I tried to get it.

To explain this embodiment specifically, silicone oil is applied to the inner surface of one end of each steel pipe 1 up to a predetermined length from the end, and then silicone oil is applied to the inner surface and the same as that of the steel pipe 1 is applied. A dummy tube 2 with an inner diameter is attached to the one end, and a cap 3, which is shorter than the dummy tube 2, is fitted to the other end of each steel tube 1. After that, resin (for example, polyurethane) is injected into the inside of the steel tube 1. After the resin has hardened, remove the dummy tube 2 and cap 3. Note that the dummy tube 2 can be easily removed since its inner surface is coated with silicone oil.

Through the above steps, the lining 4 is formed on the inner surface of the steel pipe 1, but at one end side of the steel pipe 1, the lining 4 is formed by the action of the silicone oil.
A non-adhesive lining portion 41 that is not adhered to the inner surface is formed with a predetermined length from the end, and a lining portion 4 that extends outward from the end of the non-adhesive lining portion 41 is formed.
2 is formed, and a non-lining 43 having a predetermined length from the end is formed on the other end side of the steel pipe 1.

Next, rings 5 as shown in FIGS. 2 and 3 are fitted into multiple locations of the non-adhesive lining part 41 and the extended lining part 42, and the non-adhesive lining part 41 and the extended lining part 42 are squeezed. Try to reduce its diameter. That is, it goes without saying that the inner diameter of the ring 5 is smaller than the inner diameter of the steel pipe 1 in order to keep the inner surface of the steel pipe 1 and the lining 4 in a non-contact state. The ring 5 for reducing the diameter of the vicinity is required to have an inner diameter smaller than the diameter of the lining 4' of the counterpart steel pipe 1'.

Further, as a means for reducing the diameter of the non-adhesive lining part 41 and the extended lining part 42 as described above, as shown in FIG. However, even when such a cylindrical object 6 or tape is used, it goes without saying that the degree of diameter reduction must satisfy the above-mentioned conditions.

Further, in this embodiment, the ring 5, the cylindrical object 6, the tape, etc. described above are made of a water-soluble substance (for example, polyvinyl alcohol) or a substance that has the property of dispersing finely when it comes into contact with water. However, in a later step, these rings 5, cylinders 6, or tapes can be dissolved or dispersed in water.

As described above, inside one end of the steel pipe 1, there is a tube extending from the base 44 inside the pipe end in the direction of the pipe end and outward thereof without contacting the inner surface of the steel pipe 1, and at least at the tip thereof. Lining resin extension tube 7 whose diameter is smaller than the diameter of the lining 4' of the counterpart steel pipe 1'
is made.

Next, each steel pipe 1 configured as described above
To butt the ends of the pipes and weld them, as shown in FIG. At the same time, the pipe end is butted against the pipe end of the counterpart steel pipe 1' so that its tip is inserted into the surface of the lining 4' inside the non-lining 43'.

In this way, the tips of the lining resin extending tubes 7 are overlapped on the inside of the lining 4' surface of the mating steel pipe 1', and the abutting portion 8 and the lining 4 in the circumferential direction in the vicinity thereof are aligned with the inner surface of the steel pipes 1, 1'. The abutting portion 8 is welded in a non-contact state, and in this way, resin burning of the welded portion 9 and the lining 4 in its vicinity can be appropriately prevented.

After completion of the welding work, the material to be flowed such as slurry is flowed in the direction of the arrow in FIG. It dissolves in water that penetrates through the joint between the tip of the resin extension tube 7 and the lining 4' surface of the counterpart steel pipe 1', but if you want to dissolve it in a shorter time, water should be added before slurry flow. It goes without saying that a method such as transporting the materials in the opposite direction in the direction of the arrow may also be used.

7 and 8 show another embodiment of the present invention, and in the above embodiment, the lining resin extending tube 7 is obtained by molding after painting the inner lining of the steel pipe. In contrast, in this embodiment, this can be obtained at the stage of lining painting. To explain this specifically, a dummy tube 10 whose inner surface is coated with silicone oil or the like is attached to one end of each steel tube 1, as shown in FIG. That is, the outer diameter of this dummy tube 10 substantially matches the inner diameter of the steel tube 1, and the inner diameter is smaller than the diameter of the lining 4' of the counterpart steel tube 1', and the inner diameter of one end thereof is tapered outward. The pipe is expanded into a shape, and one end thereof is inserted into the steel pipe 1 by a certain length. In addition, such dummy pipe 1
0 is such that the lining resin extending tube 7 formed by this, which will be described later, is in a state of non-contact with the inner surface of the steel pipe 1, and the diameter of its tip is smaller than the diameter of the lining 4' of the counterpart steel pipe 1'. It goes without saying that any structure that can be used is sufficient, and therefore is not limited to the above-mentioned structure.

Further, a cap 3 is attached to the other end of the steel pipe 1 as in the previous embodiment. The length of this cap 3 is shorter than the length of the non-inserted portion of the dummy tube 10, that is, the portion that protrudes from the end of the steel tube 1. Next, as in the previous embodiment, resin is injected into the inside of the steel pipe 1 and subjected to rotating centrifugal coating, and after the resin has hardened, the dummy pipe 10 and cap 3 are removed.

Thus, on one end side of the steel pipe 1, there is a base portion 44 extending in the direction of the pipe end and the outside thereof without contacting the inner surface of the steel pipe 1 from the base 44 inside the pipe end, and at least the diameter of the tip thereof is equal to that of the other end. A lining resin extending tube 7 having a diameter smaller than the diameter of the lining 4' of the steel pipe 1' is made, and the lining resin extending tube 7 is provided on the other end side of the steel tube 1 over a predetermined length from the end. A non-lining portion 43 is formed which is shorter than the length of the portion protruding from the pipe end of the steel pipe 1.

The subsequent butting of the pipe ends of the steel pipes 1, 1' and welding of the butt portions are almost the same as in the previous embodiment, and the lining resin extending tube 7 is connected to the non-lining 43' side of the steel pipe 1'. While inserting it into the tube end, the tube ends are abutted so that the tip thereof is inserted into the surface of the lining 4' inside the non-lining 43', and then the abutted portion is welded as shown in FIG. . If this is done, resin burning of the welded portion 9 and the lining in its vicinity can be appropriately prevented, as in the previous embodiment.

Next, an experimental example based on the embodiment described above will be shown below.

Experimental Example 1 The linings 4, 4' of the steel pipes 1, 1' (inner diameter 155 cm) were prepared by the method according to the first embodiment described above.
The non-lining part 43': 250 mm, the non-adhesive lining part 41: 250 mm, and the extending lining part 42: 300 mm. After that, when making the lining resin extending tube 7, a ring 5 made of polyvinyl alcohol is formed.
(inner diameter 130mm) as shown in Figures 2 and 3.
Non-adhesive lining portion 41 and extended lining portion 4
2, and then the steel pipes 1 and 1' were butted and welded.

After the welding work was completed, the welded portion 9 was inspected and it was found that the lining 4 was not burned at all by the resin. Further, when the slurry flow test was carried out for about one hour, the ring 5 made of polyvinyl alcohol had dissolved and disappeared. Furthermore, the steel pipes joined by such welded joints have an average grain size of 1
mm, weight concentration: 40% sand slurry flow rate 3 m/s
No abnormality was observed in the joint even after 500 hours had passed since the start of the flow.

Experimental Example 2 By the method according to the second embodiment, the linings 4, 4' of the steel pipes 1, 1' (inner diameter 155 mm) were removed, the non-lining part 43': 250 mm, the inner part of the steel pipe of the lining resin extension tube 7: 250 mm, and the portion protruding from the end of the tube: 300 mm, and then the steel tubes 1 and 1' were butted and welded.

In this case, as in the above experimental example, no resin burning of the lining 4 occurred, and no abnormality was observed in the joint even when the sand slurry was flowed under the same conditions as in the above experimental example.

According to the method for constructing a welded joint for internally lined steel pipes of the present invention as described above, when welding a joint for steel pipes, the internal lining is in a non-contact state with the internal surface of the steel pipe in the vicinity of the welded part, so that the occurrence of resin burn is prevented. This can be properly prevented, and there is no need to perform lining treatment after welding, so the workability of joint construction is not impaired, and welded joints can be constructed properly and efficiently in this way. As a result, it has excellent effects such as being able to be constructed at a much lower cost than conventional flange joint systems.

[Brief explanation of the drawing]

Figures 1 to 6 show an embodiment of the welded joint construction method according to the present invention, in which Figure 1 is a longitudinal cross-sectional view of the steel pipe after the inner lining coating process is completed, and Figure 2 is a longitudinal cross-sectional view of the steel pipe after the inner lining coating process is completed. A vertical cross-sectional view partially showing the lining resin extension tube, FIG. 3 is also a front view, and FIG.
The figure is a vertical cross-sectional view partially showing a lining resin extension tube configured in another way, Figure 5 is a vertical cross-sectional view showing the steel pipe after butting, and Figure 6 is a joint section after welding and slurry flow. 7 and 8 show other embodiments of the present invention.
The figure is a longitudinal sectional view showing the steel pipe after the inner lining painting process is completed, and FIG. 8 is a longitudinal sectional view showing the joint after welding has been completed. In the figure, 1 and 1' are steel pipes, 4 and 4' are linings, 7 is a lining resin extension tube, 8 is a butt portion, 43 is a non-lining portion, and 44 is a base portion.

Claims (1)

[Claims] 1 Inside one end of each steel pipe, it extends from the base inside the pipe end toward the pipe end and outward thereof without contacting the inner surface of the steel pipe, and the diameter of the tip is at least larger than the diameter of the lining of the other steel pipe. A small lining resin extension tube is also made, and a non-lining portion of a predetermined length from the end is formed on the inside of the other end of each steel tube. A welding joint construction method for internally lined steel pipes, characterized in that the pipe end is butted against the pipe end of a mating steel pipe so as to be inserted into the lining surface on the side where the part is formed, and then this butted part is welded.