JPS5936561B2 - Method for lining metal pipes with branch pipes - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of lining a metal pipe having branch pipes with a resin pipe.

BACKGROUND ART In fields such as chemical plants that handle highly corrosive fluids, metal pipes (for example, iron pipes, steel pipes) lined with thermoplastic resin pipes are widely used as piping materials for transporting fluids.

These piping materials, such as joint pipes such as cheese pipes, Y-shaped pipes, and cross pipes, tend to have areas where corrosive fluids can easily enter near the branch pipes that branch from the main pipe, resulting in such inconvenience. It is very difficult to obtain lined pipes without. For example, in the conventional method, a heat-expandable vinyl chloride resin pipe is inserted into the main pipe of a metal pipe, heated, and its diameter is enlarged so that it comes into close contact with the inner surface of the pipe, and it is also slightly protruded into the branch pipe. A known method is to make an opening to communicate with the main pipe, insert another vinyl chloride resin pipe into the posterior branch pipe, line it, and weld the contact part of the main pipe with the lined pipe to line the pipe. However, with this method, the part of the main pipe formed before welding that protrudes into the branch pipe is thermally deformed, causing the lining layer to rise, and the strength of the lining layer to be reduced by nearly half due to welding, or the welded area The quality of the product is considerably degraded, with pinholes appearing on the surface of the product, and depending on the conditions, the resulting product may cause an accident during use. The present inventor has completed the present invention through extensive research in order to solve these problems. The object of the present invention is to provide a method for easily obtaining a metal pipe lined with a resin pipe without mechanical weaknesses and having branch pipes as a product. In the method of lining the inner surface of a metal tube with a resin tube, first (2
) Line the branch pipe with a resin pipe, and then (2) insert a thermoplastic resin pipe into the main pipe of the metal pipe, soften the resin pipe by passing a heating medium through the resin pipe, and increase the internal pressure of the heating medium,
Expanding the diameter of the resin pipe until it adheres closely to the inner wall of the metal pipe body and at least partially penetrates into the branch pipe, and overlaps the lining pipe of the branch pipe with the lining pipe of the main pipe that has penetrated into the branch pipe, The method is characterized in that, after the resin pipe is cooled, the tip of the branch pipe entry portion of the resin pipe is cut off and opened. The present invention will be described in detail below in conjunction with the accompanying drawings.

In the method of the present invention, materials for the resin pipe lining the metal pipe include vinyl chloride resin (soft and hard), vinyl chloride copolymer resin, polyethylene, polypropylene, styrene resin (polystyrene, ABS resin), etc. Any known resin can be used.
The method of the present invention can be applied to any metal pipes having branch pipes such as cheese pipes, Y-shaped pipes, cross pipes, etc. Furthermore, if these metal pipes have flanges, the flanges can also be coated.

In the accompanying drawings, a case will be described in which a cheese having a flange is lined with a hard vinyl chloride resin pipe (hereinafter referred to as a vinyl chloride pipe). 1 to 4 show examples of embodiments of the method of the present invention, each in a schematic longitudinal sectional side view, following the sequence of operations.

FIGS. 5 to 7 show another embodiment in the order of operations in longitudinal sectional side views. First, the embodiment shown in FIGS. 1 to 4 will be described.

In the figure, 1 is a metal tube to be lined (in this example, cheese)
1' is the main pipe of metal pipe 1, 1 is the same branch pipe, 2 is a PVC pipe lining the main pipe 1', 3 is a resin pipe lined on the inner surface of the branch pipe, and 4 is installed at the end of main pipe V. A flange, 4' is a flange provided at the end of the branch pipe 1'', 5 is an intermediate plate for removing internal air, 6 is a gasket, and 7 is a register user 8.
9 is a blind flange, and 9 is a plug for closing the opening of the branch pipe 1'', which has a large number of through holes with a diameter of 1 to 2 m1.

11 is a synthetic resin caulking material, 12 is an inlet pipe for heating or cooling medium, and 13 is an outlet pipe.

FIG. 1 shows a state in which a branch pipe 1'' of a metal pipe 1 is lined with a resin pipe, in this case a PVC pipe 3.

Various methods can be used to carry out this lining method. For example, a heat-expandable resin tube may be inserted and heated to enlarge its diameter to achieve close contact. Further, since the branch pipe is generally smaller in size than the main pipe 1', a pre-formed short pipe (a flange portion may also be formed) may be inserted and bonded.
In this case, the short pipe should be inserted up to the point where the inner diameter of the branch pipe 1'' remains unchanged.For this lining, the inner surface of the metal pipe (both the main pipe and branch pipes) must first be pickled or sandblasted. It is recommended that the surface be treated with something like, and then coated with an adhesive (rubber-based or synthetic resin-based adhesive) and allowed to dry.Apply the same adhesive to the resin pipe and dry it.Next, as shown in Figure 2. Insert the PVC pipe 2 (this pipe may be heat-expandable or ordinary PVC pipe) into the main pipe 1', connect the cashier 7 to each end of the metal pipe, and connect the ends of the PVC pipe 2. Fold the part back and cover with the blank flange 8 to fix the PVC pipe.

- The branch pipe 1'' is capped with a stopper 9. This stopper is made of metal round wood,
It may be made of synthetic resin or the like, and since it does not need to be airtightly sealed, there is no need to specially finish the contact surface with the inner wall of the branch pipe 11. This stopper 9, as shown in FIG.
It is inserted to a depth halfway into the resin pipe 3 lined on the inner surface of the branch pipe. This plug 9 is provided with an exhaust hole that penetrates inside and outside for reasons that will be described later. For example, a large number of small holes with a diameter of about 1.511 are provided. In addition, if the plug 9 has a projecting edge formed at its upper end as shown in FIG. 2 and a bolt hole is provided in this, it can be fixed to the flange of the branch pipe 1'' with bolts. When you are ready, insert the inlet tube 12.
A heating medium is introduced from the outlet pipe 13 and discharged from the outlet pipe 13.

The heating medium may be a gas such as air or water vapor, or a liquid, but the latter is preferable from the operational and operational standpoints. The liquid may be an oil such as mineral oil, but a water-soluble liquid such as polyethylene glycol or glycerin is preferred because it is easy to wash afterwards. The medium is first passed through the PVC pipe at its softening temperature, and once the PVC pipe has softened, the internal pressure of the medium is gradually reduced, the diameter of the softened PVC pipe 2 is expanded, and the main pipe v
At the same time, it inflates to the inside of the branch pipe and reaches the bottom surface of the stopper 9. The state at this time is shown in FIG. Here, the lining pipe 3 of the branch pipe and the lining resin pipe 2 of the main pipe that has entered the branch pipe overlap. Then, the pressure of the medium introduced into the resin tube 2 firmly adheres the two. The purpose of providing the exhaust hole in the plug 9 is to remove air from the space surrounded by the inner wall of the metal tube 1 when the PVC tube expands. A gasket 6 and an intermediate plate 5 are sandwiched between the flange of the main pipe V and the flange 7' of the register user 7, and if this intermediate plate 5 is also provided with an exhaust hole that penetrates inside and out, this exhaust gas can be removed. Air is also vented through the holes when the PVC pipe 2 expands. However, exhaust through the intermediate plate 5 is not essential depending on the shape of the metal tube, and exhaust through the plug 9 may be sufficient. For example, the intermediate plate 5 has a thickness of 3011 mm.
0) A circular polyethylene plate with a diameter of about 11! A type with a large number of holes is used.

After increasing the internal pressure of the heating medium to obtain the state shown in FIG. 3, the PVC pipe 2 is heat-treated as required.

This operation flows as heating medium a medium maintained at a higher temperature than in the previous operation. In this way, the internal distortion of the PVC pipe 2 is eliminated, and there is no fear of deformation of the resulting product even when it is used for transporting high-temperature fluids. Therefore, if the product is used for relatively low-temperature fluid transport, the above heat treatment is not necessary. It is effective to keep the internal pressure of the medium high during this heat treatment as well. After the heat treatment, cooling is performed through a low temperature medium.

At this time as well, it is preferable to keep the internal pressure of the medium high. To give an example of the conditions when performing these operations on PVC pipes, the medium (polyethylene glycol) was heated at 110°C for 10 minutes for the first softening of the PVC pipes, and then in three stages for expanding the diameter of the PVC pipes. The first step is 110℃, 2kg/d for 1 minute, the second step is 110℃, 5K9/Clll for 1 minute,
In the third stage, the medium is passed at 110°C and 10k9/Cnt for 1 minute, and in the final cooling, the medium is passed at 15°C and 10kg/(V7f) for 5 minutes.The type of resin pipe is determined in this way, and the conditions for passing the medium are determined. Once set, multiple media tanks maintained at different temperatures can be installed, and valves attached to the piping can be operated using timers to automate all operations and improve productivity. After lining the lining in the order shown in Figures 1 to 3, remove the attached jigs,
When the part indicated by A in FIG. 3 is cut out and opened, the product shown in FIG. 4 is obtained.

Finally, apply caulking material to the locations indicated by 11.

In the products shown in FIGS. 1 to 4, flanges at both ends of the main pipe 1' are not provided with flanges.

Figures 5 to 7 show the manner in which the tsuba-gaeshi is formed. As shown in FIG. 5, before inserting the PVC pipe 2 into the main pipe 1', prepare a flanged short pipe 10 in advance, fit it into the flange of the main pipe 1' and glue it, and then sandwich the intermediate plate 5. Attach the cash register user, and process the rest in the same way as described for Figures 1 to 4. Figure 6 shows softening of PVC pipe.
Figure 7 shows the product after its diameter has been expanded. As described above, in the method of the present invention, when lining the inner surface of a metal pipe having a branch pipe with a resin pipe, the inner surface of the branch pipe is first lined with the resin pipe, and then the inner surface of the main pipe is lined with the resin pipe. That is essential.

By performing the lining in this order, the overlapping portions of the lining of the branch pipe and the lining of the main pipe are bonded extremely tightly and firmly to the metal pipe. That is, the lining of the main pipe is performed later, and the lining of the main pipe is done by softening the resin pipe inserted into the main pipe with a heating medium, and then increasing the pressure of the heating medium to expand the diameter of the resin pipe. The internal pressure held by can be increased as desired. Therefore, in the overlapping portion of the branch lining pipe and the main lining pipe, sufficient pressing force can be applied to exert adhesion to the metal pipe. On the other hand, if the main pipe is lined first and the branch pipes are lined later, the branch pipes may be lined with heat-expandable resin pipes, for example.
Alternatively, since a pre-formed short pipe is inserted, the overlapping parts of both the main pipe and branch pipes cannot be brought into close contact with the strong pressing force as in the method of the present invention, and the product is used to transfer corrosive fluids. When this is done, the fluid penetrates into the surface of the lined metal tube, causing problems such as corrosion.

Therefore, in order to prevent this intrusion, it is necessary to perform processing such as welding the joint between the two lined pipes. When such welding is performed, the resin part of the main pipe formed before welding that protrudes into the branch pipe may be thermally deformed, causing the lining layer to rise, or the strength of the lining layer may decrease due to welding. Alternatively, pinholes may occur in the welded portion, resulting in a product with poor quality. As mentioned above, in the method of the present invention, since the overlapping part of both lining pipes is firmly attached to the metal pipe, a simple treatment such as applying caulking material to the joint is sufficient, and moreover, as described above, Since no quality deterioration occurs in the overlapping portion, an extremely safe and durable lined pipe can be obtained.

[Brief explanation of drawings]

1 to 4 are schematic longitudinal sectional views at respective points in time, showing the embodiment of the method of the present invention in the order in which the operations proceed;
? The figure is a longitudinal sectional side view similarly showing another embodiment. In the figure, 1 is the metal pipe lined, 1' is the main pipe of the metal pipe 1,
1'' is a branch pipe of the metal pipe 1, 2 is a resin pipe lining the main pipe 1', 3 is a resin pipe lining the inner surface of the branch pipe 1'', 5
is the intermediate plate, T is the cash register user, 8 is the blank flange, 9
1 is a plug that closes the opening of the branch pipe 1'', and 10 is a short pipe with a flange inserted into the end of the main pipe 1'.

Claims (1)

[Claims] 1. In a method of lining the inner surface of a metal pipe with a branch pipe with a resin pipe, first (A) line the branch pipe with a resin pipe, then (B) insert a thermoplastic resin pipe into the main pipe of the metal pipe, and Passing a heating medium through the resin pipe to soften the resin pipe and increase the internal pressure of the heating medium to expand the diameter of the resin pipe until it comes into close contact with the inner wall of the metal pipe body and at least partially penetrates into the branch pipe. A method characterized by overlapping the lining pipe of the branch pipe and the lining pipe of the main pipe that has entered the branch pipe, cooling the resin pipe, and then cutting and opening the tip of the resin pipe where the branch pipe has entered.