JPS5928166B2 - How to line metal pipes with resin pipes - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION This invention provides a method for lining a metal tube with a thermoplastic resin tube;
In particular, it relates to a method suitable for lining metal pipes with flanges.

Metal pipes (e.g. steel pipes) are used as piping materials for transporting highly corrosive fluids in fields such as chemical plants.
A tube whose inner surface is lined with a thermoplastic resin tube is widely used.

Various methods are known for applying internal tension to thermoplastic resin pipes, but each method has its pros and cons.In particular, internal tension in joint pipes such as cashiers, elbows, etc. is more difficult to operate than that of straight pipes. I have a problem. The present inventor has completed research in order to obtain an industrially useful method for lining not only straight pipes but also joint pipes for which lining is difficult, and has completed the present invention.

That is, an object of the present invention is to provide a method for lining metal pipes with thermoplastic resin pipes with improved productivity, and the gist thereof is to line metal pipes with thermoplastic resin pipes. Then, the two metal tubes to be lined are butted in series, and an annular clamping plate having a vent hole that can discharge gas to the outside is sandwiched between the two metal tubes at the butt part of the metal tubes. A thermoplastic resin tube is inserted into the connected metal tubes, and as this metal tube is heated and softened, the internal pressure inside the resin tube is increased, the diameter of the resin tube is expanded, and the inside of the metal tube is increased. The method is characterized in that the resin tube is brought into close contact with a wall and after cooling, the resin tube is cut at the abutting portion of the two metal tubes to simultaneously obtain two metal tubes with internal tension made of thermoplastic resin tubes. The method of the present invention will be described in detail below in conjunction with the accompanying drawings.

The method of the present invention can be applied not only to straight pipes but also to curved pipes such as register users and elbows, and specially shaped pipes whose diameters vary.

Materials for the thermoplastic resin pipe that lines this metal pipe include vinyl chloride resin (hard and soft), vinyl chloride copolymer resin, polyethylene, poly-9-propylene, and styrene resin (
Any resin conventionally known for internal tension, such as polystyrene, ABS resin, etc., can be used. In the accompanying drawings, a case will be described in which a hard vinyl chloride resin pipe (hereinafter referred to as a vinyl chloride pipe) is internally tensioned to a flanged cash register user.

Figure 1 is a partially cross-sectional front view showing a state in which two register users are butt-connected in series and equipment and jigs are set for performing the lining b operation. Figure 2 is a front view showing a resin pipe. Figures 3 to 5 are explanatory diagrams showing the state from the state shown in Figure 2 until finishing; FIG. 6 is a partially cross-sectional schematic front view showing another embodiment of the method of the present invention, and FIGS. 7 to 9 are explanatory views showing other examples of reversing the flange portion.

First, the cases shown in FIGS. 1 to 5 will be explained.

Two flanged metal register users 1 and 15 are butted together with their larger diameters in contact.

In this case, an annular support plate 3 is sandwiched between the husband-and-wife flanges 4, 4 of the register users 1 and 1'', and then tightened with bolts and nuts.Next, the PVC pipe 2 is inserted into the register user, and both ends This protruding part is heated and softened, and the flange 4' is turned back.Then, it is sandwiched between blank flanges 5 and fixed with bolts and nuts.The diameter of the PVC pipe 2 is set according to the register. Any size may be used as long as it can be easily inserted into the user, but the above-mentioned flange processing should be done so that it touches the inner wall of the smaller diameter part of the cash register users 1 and v. This is preferable from an operational point of view.A heating medium conduit 6 is attached to the blind flange 5, and a flexible hose 9 is connected to a coupling universal joint (coupler) 7 provided thereon by a socket 8.

One end of the flexible hose is connected to the heating medium source, and the other end is the outlet side of the medium and is therefore connected to the system for circulation. Once the preparation for the lining D work is completed as described above,
A heating medium is introduced into the PVC pipe 2.

The heating medium used in this case may be a gas such as heated air or water vapor, or a heated liquid. The liquid may be mineral oil, but it is convenient to use a water-soluble liquid such as polyethylene glycol, ethylene glycol, or glycerin because it can be easily washed with water afterwards. The temperature of the heating medium is higher than the softening temperature of the resin pipe, in this case PVC pipe 2, and the PVC pipe 2 is passed through it.
When the PVC pipe 2 becomes soft, the internal pressure of the heating medium is increased, the diameter of the PVC pipe 2 is expanded, and the PVC pipe 2 is brought into close contact with the inner wall of the register user.

The clamping plate 3 is provided with a large number of ventilation holes penetrating from the inside to the outside. For example, a polyethylene plate with a thickness of 30 m1n is used, and a large number of through holes with a diameter of about 1 WI are provided from the inside to the outside. When ventilation holes are provided in this way,
The air in the space surrounded by the inner wall of the register user and the outer surface of the PVC pipe is pushed out when the PVC pipe expands, and the PVC pipe comes into close contact with the inner wall of the register user. Furthermore, the clamping plate 3 has a groove on the surface in contact with the flange 4, and the clamping plate 3 and the flange 4
It may also be a device that exhausts air from between. Alternatively, as described later, the holding plate 3 can be split into two for easy removal.
It is used in a form divided into 2 or 4 parts as necessary, but with a gap between the divided parts,
This gap may be used as a ventilation hole from which air is discharged to the outside. The lining work is carried out in this way, but since some distortion remains inside the enlarged PVC pipe, if this lining pipe is used for transporting high-temperature fluids, etc. During fluid transport, this strain exerts a restoring force on the PVC pipe, creating the risk of deformation. One way to prevent this is to use an adhesive (for example, neoprene rubber-based or other synthetic resin-based adhesive) on the surface of the PVC pipe and the inner wall of the register user. It is more effective to cause residual strain to disappear by passing a heating medium under pressure into the PVC pipe for a short period of time after the step of expanding the diameter of the pipe. However, this is especially true when the cash register user is used for transporting cryogenic fluids.
There is no need for heat treatment. Next, a low-temperature medium is passed through the PVC pipe for cooling, but in this case as well, it is preferable to use the medium under pressure.

When the lining D operation is thus completed, the equipment and jigs are removed.

The clamping plate 3 can be easily removed by dividing it into two halves b.If this is removed and the PVC pipe 2 is cut at this point, what is shown in FIG. 3 is obtained. As shown in Fig. 4, a resin flange 10 previously molded into a flange shape (this does not need to be the same type as the resin pipe lined with b as long as it can be bonded) is attached to this thing. Apply adhesive, insert, and adhere. In this way, a lining b metal tube with a flanged back as shown in FIG. 5 is obtained. In Figure 5, 11 shows the area where caulking material was applied after lining. In this way, two lined metal tubes are obtained at once. An example of introducing the pressurized medium described above is as follows.

The inner surface of the metal tube is surface-treated by a suitable method such as pickling or sandblasting, and then an adhesive is applied to the surface and dried.

Ethylene glycol is used as the medium, and for the first heating to soften the PVC pipe, heat it at 110°C for 10 minutes, then increase the pressure of the medium to expand the diameter, or do this in three stages. Ivy. The first stage is 110℃, 2Kf/C
d for 2 minutes, the second stage is 110°C and 5Kg/Cd for 1 minute, the third stage is 110°C and 10Kf/Cd for 1 minute, and finally the 15°C liquid medium is pressurized at 10K9/Cd. The mixture was cooled for 5 minutes.

When adopting a method using a liquid medium like this,
It is equipped with a medium tank heated and maintained at each temperature, and by switching the piping, it is possible to pass the medium at the temperature required for each process, and in combination with a timer, automation is possible.

In the example shown in FIG. 6, the holding plate 3 held between the flanges 4 is an annular plate whose inner diameter is larger than the larger inner diameter of the register users 1 and 1.

Other than that, operate in the same way as described above. As a result, as shown by A in FIG. 6, the PVC pipe 2 expands to the outer surface of the flange 4. In this way, the flange 4 can be turned back all at once. 7 to 9 show another embodiment in which a flange is formed on the flange 4. FIG.

In this example, first, on the flange part of cashier user 1 and
Insert the pre-formed tsuba and make a hexagram. FIG. 7 shows one of the two register users to be matched, register user 1. That is, the flanged short pipes 10 are fitted into the flanges at both ends of the register user 1, and then the two register users are connected together in the same manner as explained above with reference to FIGS. 1 to 3, and a PVC pipe is inserted, and the heating medium is The PVC pipe is heated by passing through it, expands the diameter of the PVC pipe, and cools it. Figure 8 shows the state with the PVC pipe inserted and the jigs attached, and Figure 9 shows the state after the lining b has been completed, the jigs have been removed, and the clamping plate 3 has been removed. By cutting the portions of the PVC pipe that protrude from the dovetail flanges 4 and 4', a flange-backed lined D pipe can be obtained.

Since there is no joint between the PVC pipes inside the pipe, which has been flailed in this way, even if it is used for transporting corrosive fluids, there is a risk that the metal pipe will be corroded by the corrosive fluid that enters through the joint. It disappears. The above is lined with PVC pipe for cashier users.
Although the case has been described above, elbows and other joint pipes can also be lined b in the same way.

In addition to the resin tubes, those made of thermoplastic resin as described above may be used, and in that case, the heating temperature and the like are selected in accordance with the softening temperature of each resin. In the above explanation, two metal pipes are connected in series to obtain two lined B pipes at once, but in the same way, three or more metal pipes are connected at once with lined B pipes.
You can also.

As described above, according to the method of the present invention, even for joint pipes where lining b is difficult, it is possible to easily line lining b with improved productivity.
operations can be carried out.

The above description and the accompanying drawings are representative examples of the present invention, and the present invention is not limited thereto. It is something that can be changed and transformed.

[Brief explanation of drawings]

The attached drawings show an example of a mode for carrying out the method of the present invention, and FIG. 1 shows an example in which two flanged metal cash register users are connected in series, a resin pipe is inserted, and the lining b is performed. Fig. 2 is a schematic front view showing a partial cross-section with the equipment and jig set up, and Fig. 2 shows the condition where the diameter of the resin pipe inserted into the register user has been expanded and the lining b has been completed. A schematic front view partially shown in cross section, Figures 3 to 5 are explanatory diagrams sequentially showing the states from the time shown in Figure 2 until finishing, and Figure 6 shows another example of implementing the method of the present invention. A schematic front view partially shown in cross section, and FIGS. 7 to 9 are explanatory views showing another example of turning back the flange portion.

Claims (1)

[Claims] 1. When lining a metal tube with a thermoplastic resin tube, two metal tubes subjected to internal tension are butted in series, and gas can be discharged to the outside from the butted portion of the metal tubes. Both metal tubes are connected by sandwiching an annular holding plate with ventilation holes, a thermoplastic resin tube is inserted into the connected metal tube, and the internal pressure inside the resin tube is increased as the resin tube is heated and softened. The diameter of the resin tube is increased to bring it into close contact with the inner wall of the metal tube, and after cooling, the resin tube is cut at the butt part of the two metal tubes, and two metal tubes lined with thermoplastic resin tubes are cut at the same time. A method characterized by obtaining pieces. 2 The metal pipe to be lined has a flange, and the inner diameter of the annular clamping plate is larger than the inner diameter of the metal pipe to be lined. The method according to claim 1, covered by: