JPH0134669B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for lining flanged steel pipes such as straight pipes, T-pipes, and L-pipes with tetrafluoroethylene resin (hereinafter referred to as PTFE resin).

Although PTFE resin has superior properties compared to other synthetic resins in terms of heat resistance, chemical resistance, and non-adhesion, its processing method is similar to powder metallurgy, and there is still room for further investigation. be.

Conventionally, the method of lining a flanged steel pipe with PTFE resin is to connect a jacket tube of an appropriate length to the flange surface of the steel pipe to be lined.
These steel pipes and jacket pipes are used as an outer mold, and in this
Pressure-molded PTFE resin and as it is.
A known method is to line a steel pipe with PTFE resin by firing at a temperature higher than the gelling temperature of PTFE resin (approximately 327°C). However, in the final step of this method,
After removing the sleeve, as shown in Figure 3, the PTFE resin lining tube protruding from the steel pipe flange surface A is heated and folded outward along the steel pipe flange surface using a conical jig C, so-called flaring. Requires processing. This is disadvantageous not only in production cost but also in functionality. In other words, this flaring process is
This is a method in which the PTFE resin lining tube is expanded almost at right angles and then folded back.This puts stress on the expanded portion, which tends to cause cracks during use. In addition, when used by connecting to other piping, especially if the fluid flowing inside the steel pipe is high temperature, the expanded part may try to return to its original state and the expanded part may collapse into the steel pipe. It has a fatal flaw.

The method of lining flanged steel pipes with PTFE resin according to the present invention has been developed with the aim of producing inexpensive, high-quality PTFE resin-lined steel pipes by eliminating the above-mentioned conventional drawbacks. The structure is such that the inner wall surface of the flanged steel pipe to be lined and the first
A diaphragm member is provided, and a second diaphragm member is provided on the flange surface of the steel pipe.
with a predetermined gap between the diaphragm member and the flange surface,
After arranging and forming a cavity between these diaphragm members and the steel pipe and filling the PTFE resin powder into the cavity, inflating the first diaphragm member and the second diaphragm member simultaneously, The powder is pressed onto the inner wall surface of the steel pipe and the flange surface of the steel pipe, and then fired at a temperature higher than the melting point of the PTFE resin, thereby simultaneously lining the inner wall surface of the steel pipe and the flange surface of the steel pipe with PTFE resin. It is something to do.

Next, embodiments according to the present invention will be described in detail with reference to the drawings.

1 is a T-shaped steel pipe with a flange, 3 is a core body 4 as the first
A cylindrical core covered with a diaphragm member 2 is disposed concentrically with the inner wall surface 5 of the steel pipe with a predetermined gap therebetween.
The first diaphragm member 2 has a cylindrical shape, is made of an elastic material such as rubber, and must be able to expand sufficiently under water pressure. Although the drawing shows a cross section of the T-type steel pipe in the short axis direction, the core 3 is similarly arranged in the long axis direction. In this case, the core body 4 in the short axis direction is fitted into the center of the core body 4' disposed in the long axis direction, and these are integrally covered with the first diaphragm member 2 to form a T-shaped structure. Form the core.

Thus, a substantially T-shaped cavity A is formed within the lining steel pipe. Next, 6 is a spacer ring fixedly disposed on the steel pipe flange surface 7 with bolts 8, and the inner diameter of this ring matches the lining outer diameter of the steel pipe flange to be lined. Further, the thickness of the ring 6 is appropriately determined depending on the lining thickness. 9
is a second diaphragm member, which, like the first diaphragm member, is made of an elastic material such as rubber, and its shape is a cross section in which the cylindrical lip portion 10 and the horizontal flange portion 11 are integrally formed. It consists of an L-shaped ring. Then, the cylindrical lip part 10 is inserted into the core 3 protruding from the end surface of the steel pipe, and the peripheral edge of the horizontal flange part 11 is brought into contact with the spacer ring 6, so that the cylindrical lip part 10 and the horizontal flange part A closing member 12 is clamped to the portion 11 to form a cavity B in the flange portion. Then, the PTFE resin raw material powder M fills these empty spaces A and B.
is filled evenly. As a preferred embodiment of the present invention, after filling the raw material powder M, a disc-shaped pressing plate 13 is placed on the raw material powder filled in the cavity B, and a second Diaphragm member 9
By expanding and pressing, the raw material powder M in the cavity B can be pressed uniformly. By the way, the closing member 12 is fixed to the spacer ring 6 with bolts 8'. After filling the raw material powder, the first diaphragm member 2 and the second diaphragm member 9 are removed.
In order to expand the raw material powder and press the raw material powder against the inner wall surface 5 of the steel pipe and the flange surface 7 of the steel pipe, at least one
By drilling more than one fluid hole 14,
is connected to the water pressure pump with piping 15, and the closing member 12
faces a position corresponding to the inner diameter side of the spacer ring 6 and opens toward the second diaphragm member;
A fluid passage hole 16 is drilled and similarly connected to a water pressure pump with a pipe 17. In addition, in order to prevent fluid leakage when the water pressure pump is operated to pump pressurized fluid and inflate the diaphragm member, a packing groove 18 is provided in the inner diameter of the closing member 12, and a packing 19 is attached to the sealing groove 18. By pressing with the seal holder 20, the pressurized fluid can be completely sealed.

Thus, if pressurized fluid is supplied to these fluid passage holes 14 and 16 at the same time, the diaphragm members 2 and 9 can simultaneously expand and press the raw material powder M. In this case, the pressing force and pressing time should be at least 100 kg on both the inner wall side of the steel pipe and the flange side of the steel pipe.
10 seconds or more at f/cm ² is sufficient. the result,
The PTFE resin powder is densely pressed onto the inner wall surface 5 of the steel pipe and the flange surface 7 of the steel pipe. Next, the water pressure pump is stopped, the pressure is released, and the fluid is expelled from the mold, and then the diaphragm member and the molds are removed and attached. Finally, the T-tube with PTFE resin pressed together on the inner wall surface 5 and flange surface 7 of the steel tube is placed in an electric furnace and fired at a temperature higher than the melting point of the PTFE resin (approximately 327°C or higher). . After firing, the T-tube may be directly dropped into water for rapid cooling, or may be slowly cooled in air.

As a result of the above, it was possible to simultaneously line the inner wall surface and flange surface of the T-type steel pipe with PTFE resin.

In addition, the lining for the T-tube this time is a non-adhesive type, but as disclosed in Japanese Patent Application Laid-Open No. 55-61961, the lining surface of the steel pipe is
Acid components containing chromium ions and hydrogen ions
PTFE dispersion is applied, a heat-melting fluororesin such as perfluoroalkoxy resin (PFA) is sprayed on top of the PTFE dispersion, and this is heated and sintered to a temperature higher than the decomposition temperature of the heat-melt fluororesin to form a metal surface. to
By forming an adhesive surface layer of PTFE resin, it is also possible to form a lining steel pipe that is firmly adhered to the steel pipe.

FIG. 2 shows another embodiment of the flanged L pipe 2.
This is an application of the present invention to No. 1. The lining method is the same as that for the T-tube, but the core 3' covered with the first diaphragm member 2' is arranged with a predetermined gap along the curvature of the inner wall surface 5' of the L-tube. . The second diaphragm member 9 is also arranged in the same manner as the T-tube. However, in the case of an L-tube, when the core 3' moves up and down, the lining thickness of the tetrafluoroethylene resin tends to become uneven. Therefore, a shoulder 23 is provided at the end of the core 3', and a step 24 is provided on the inner diameter side of the packing holder 20'.
It is preferable to provide a shoulder portion 23 of the core 3' in contact with this stepped portion 24 to prevent vertical movement of the core 3'.

As described above, the present invention is not limited to the T-tube mentioned above, but can of course be applied to the lining of L-tubes, reducer straight pipes, and the like. Furthermore, the PTFE resin used in the present invention is simply PTFE
In addition to resin, it may also be a PTFE resin mixed with a filler such as carbon or graphite.

As described above, the present invention is a method of lining the inner wall surface and the flange surface of the steel pipe to be lined at the same time, so there is a process of lining the inner wall surface of the steel pipe as in the conventional method, and a flaring process for lining the flange surface of the steel pipe. There is no need to separate the processing steps, and the number of manufacturing steps can be reduced.

In addition, since the present invention already compacts the PTFE resin powder closely along the flange surface of the steel pipe before firing, it does not apply unnecessary stress to the resin itself and prevents the occurrence of cracks. can do.

[Brief explanation of drawings]

FIG. 1 is a partially cutaway sectional view of an embodiment in which the present invention is applied to a T-shaped steel pipe, FIG. 2 is a partially cutaway sectional view of an embodiment in which the present invention is applied to an L-shaped steel pipe, and FIG. FIG. 2 is a cross-sectional view showing a conventional flaring method. 2, 2'... First diaphragm member, 5, 5'... Inner wall surface of steel pipe, 7... Flange surface of steel pipe, A, B...
Vacant part, M...tetrafluoroethylene resin raw material powder,
9...Second diaphragm member, 13...Disc-shaped pressing plate.

Claims (1)

[Claims] 1. A first diaphragm member is disposed with a predetermined gap from the inner wall surface of a flanged steel pipe to be lined, and a second diaphragm member is disposed on the flange surface of the steel pipe with a predetermined gap from the flange surface. After disposing the diaphragm member and the steel pipe to form a cavity between the diaphragm member and the steel pipe, and filling the vacancy with tetrafluoroethylene resin powder, the first diaphragm member and the second diaphragm member are disposed. By expanding the diaphragm member, pressing the powder against the inner wall surface of the steel pipe and the flange surface of the steel pipe, and then firing at a temperature higher than the melting point of the tetrafluoroethylene resin, the tetrafluoroethylene resin is bonded to the inner wall surface of the steel pipe. A method for lining a flanged steel pipe with a tetrafluoroethylene resin, the method comprising simultaneously lining the flange surface of the steel pipe. 2. When inflating the second diaphragm member and pressing the tetrafluoroethylene resin powder onto the flange surface of the steel pipe, place a disc-shaped pressing plate on the filled tetrafluoroethylene resin powder, A method for lining a flanged steel pipe with a tetrafluoroethylene resin according to claim 1, characterized in that pressing is performed via the pressing plate. 3. The method for lining a flanged steel pipe with tetrafluoroethylene resin according to claim 1 or 2, wherein the second diaphragm member is an annular body having an L-shaped cross section and consisting of a cylindrical lip portion and a horizontal collar portion. .