JPH06281555A - Method and apparatus for measuring pressure resistance of thermoplastic tube during heating - Google Patents

Abstract

PURPOSE:To correctly measure the pressure resistance of a sample tube by coating the sample tube loose around the outer circumference of a pressure tube which has both ends closed and many steam holes formed at the circumferential wall of the trunk, sealing and fixing both end parts of the sample tube, pressing and introducing the steam into the pressure tube, thereby heating and expanding the sample tube. CONSTITUTION:A pressure tube 1 is made of a metal, having both ends shut by end plates 1a, 1b. Many steam conduction holes 3 are formed at the circumferential wall of the trunk of the tube 1. A sample tube 2 of a synthetic resin is fitted loose outside the tube 1, and both end parts of the tube 2 are fastened by fastening members 9 at the position of packings 8, so that the sample tube 2 is fixed in the air-tight state. Then, the steam of a predetermined pressure and high temperatures is introduced into the tube 1 from a steam introduction port 4. The steam enters and fills the tube 2 through the conduction holes 3, thereby heating and softening the tube 2. In this state, the pressure inside the tube 2 is raised to expand the tube 2. A cooling air is sent from the introduction port 4 to cool the tube 2 after the tube 2 is kept in the state for a predetermined time. The presence/absence of the leak of the steam from the tube 2 when it is expanded is monitored and inspected. After cooling, the tube 2 is separated from the tube 1. The change of the thickness distribution, cracks and the partial breakage are investigated, and accordingly the pressure resistance of the tube 2 at the heating time is measured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a measuring method for investigating the hot pressure resistance of vinyl chloride resin pipes and other thermoplastic synthetic resin pipes used as a lining material for underground pipes, and the resistance used therefor. The present invention relates to a pressure measuring device.

[0002]

2. Description of the Related Art Recently, underground pipes for laying cables such as water supply and sewage, electric power wiring, communication wiring, etc., when they have cracked or damaged over the years, existing pipelines The so-called lining method of lining and repairing and reinforcing synthetic resin pipes in the interior of the linings has been attracting attention and has been partially put into practical use.

In the lining method as described above, a thermoplastic synthetic resin pipe such as a vinyl chloride resin pipe is used as a lining material, which is heated and softened and inserted into an existing pipe. By introducing and applying an internal pressure, the resin pipe is heated and expanded to be brought into close contact with the inner surface of the existing pipe, and then solidified as it is by using a cooling medium.

Therefore, in the resin pipe used for such a lining, not only does the peripheral wall uniformly expand during heating and expansion, but a remarkable flattened state does not occur,
Further, it is strongly required to have particularly good thermal withstand pressure, such as not having a defect in strength that may cause cracking or fracture during thermal expansion.

In practice, however, a thermoplastic synthetic resin pipe continuously produced by an extrusion molding method or the like is uniform and good due to changes in extrusion molding conditions, changes in management conditions after manufacturing, and other external factors. It is possible to generate a resin pipe that does not have a pressure resistance when heated.

Therefore, it is indispensable to sample a part of each lining resin pipe for each production lot and to inspect its thermal withstanding pressure prior to practical use. The same applies to resin tubes for other purposes such as being expanded by heating.

[0007] Conventionally, the pressure resistance of such a resin pipe under heat is measured,
The inspection was performed by the following method, for example.

That is, as shown in the attached FIG. 3, plugs (21) made of an elastic material such as synthetic rubber are provided at both ends of a thermoplastic synthetic test tube (20) cut into a predetermined length to be inspected. (twenty one)
After fitting and tightly plugging, the both ends of the test tube (20) are tightly secured and fixed around the plugs (21) and (21) by using a fastening member (22) such as a wire, and then one The pressurized steam is introduced into the test tube (20) from the steam inlet (23) provided in the stopper body (21), and the test tube (20) is heated and expanded, so that the flattened state is generated. It was done by the method of checking the presence or absence. At this time, as a safety measure to prevent the plugs (21) (21) from coming off due to an increase in internal pressure due to the introduction of the vapor pressure, a support frame ( twenty four)
By disposing (24) and connecting them with connecting tools (25) such as bolts and nuts, the distance between both plugs (21) and (21) is regulated.

[0009]

However, the conventional thermal pressure resistance measuring method as described above has the following problems.

First of all, the test tube (20) expands not only in the circumferential direction but also in the lengthwise direction by the introduction of pressurized steam. However, since the test tube (20) is supported only at both ends by the plugs (21) and (21), and the distance between both plugs is regulated, the test tube ( 20)
Irregular deformation occurs, especially meandering deformation. Due to this, a local stress concentration occurs due to the increase of the internal pressure load in a part of the tightening part of the sample tube (20) by the tightening member (22), and the resin in that part is concentrated. Pipe breakage,
Occasionally, a situation such as a steam leak may occur, making accurate pressure resistance measurement difficult.

In particular, in the case of a test tube (20) having a strength defect portion internally, if a crack or the like occurs in a part of the test tube due to an increase in vapor pressure at the time of inspection, the internal pressure is suddenly released from the damaged portion to the outside. The so-called explosion phenomenon may occur, and the danger to the worker was high.

Furthermore, since the length of the test tube (20) that can be inspected is restricted by the connecting member (25), the test tubes (20) of various lengths cannot be inspected and the The appropriateness of the tightening force of the attachment member (22) also affects the measurement result, which requires the measurement inspector to be skilled and has poor workability.

The present invention has been made in view of the above problems.
An object of the present invention is to provide a method and a device used therefor, which are simpler, more accurate and safer than the conventional methods, and capable of safely and safely measuring and inspecting the withstand pressure of the resin pipe under heat.

[0014]

According to the present invention, a metal pressure tube is used, and a resin test tube is fitted to the outside of the pressurization tube to perform a thermal expansion test on the test tube.

That is, according to one aspect of the present invention, a metal pressurizing pipe having both pipe ends closed and a large number of vapor conducting holes provided in the peripheral wall of the body is prepared, and the outer diameter of the pressurizing pipe is provided on the outer periphery of the pressurizing pipe. After the test tube made of a thermoplastic synthetic resin tube having a relatively larger inner diameter is loosely fitted to the test tube in a covered state, and tightly fixed at both ends with the outer peripheral surface of the pressurizing tube being hermetically sealed. A method for measuring the withstand pressure during heating of a thermoplastic synthetic resin tube, characterized in that the test tube is heated and expanded by introducing steam from one end into the pressurizing tube under pressure, and the withstand pressure is measured. To do.

A second aspect of the present invention is a measuring device used in the above method, which comprises a metal pressurizing pipe having an outer diameter relatively smaller than the inner diameter of a sample pipe made of a thermoplastic synthetic resin pipe, And a clamping pressure sealing means for fixing both ends of the test tube, which is loosely covered and attached to the outer periphery of the pressurizing tube in a sealed state, to the outer peripheral surface of the pressurizing tube. The pipe end is closed by an end face plate, a large number of steam conducting holes are provided on the outer periphery of the body, and a steam introducing pipe for introducing internal pressurized steam is provided at at least one end. It is what

As one of the preferred embodiments, the pressurizing tube itself may be capable of expanding and contracting following the test tube so as to be able to cope with thermal elongation of the resin test tube in the longitudinal direction. .

Further, in order to make it possible to more accurately measure the pressure resistance of the resin test tube under heat, a discharge pipe for discharging the drain accumulated at the bottom of the test tube is provided at one end of the pressurizing tube. Is recommended. The drain drain pipe has one end protruding outward from the lower peripheral wall of the pressurizing pipe to form a drain inlet facing the inside of the test pipe, the middle portion passing through the pressurizing pipe, and the other end from the end of the pressurizing pipe to the outside. It is configured so as to form an openable and closable discharge port that is opened in the.

[0019]

Embodiments of the present invention will be described below with reference to FIGS. 1 and 2.

In FIG. 1, (1) is a pressurizing tube as a measuring jig, (2) is a test tube made of thermoplastic synthetic resin to be measured, and the pressurizing tube (1) is the test tube (2). The outer diameter is relatively smaller than the inner diameter by about 5.0 to 50.0 mm.

The pressurizing pipe (1) is made of a steel pipe or other metal, and both pipe ends are closed by end face plates (1a) (1b), and the body peripheral wall (1c) is formed at an intermediate portion in the longitudinal direction. )
A large number of vapor conducting holes (3) are formed by punching. The vapor communication hole (3) is preferably formed with a hole diameter of, for example, about 8 to 15 mm, and is 5 to 10 in the circumferential direction of the pressurizing pipe (1).
Individual pieces are formed at a pitch of about 80 to 150 mm in the length direction. To give a specific example, in the pressurizing pipe (1) having an outer diameter of 140 mm, a wall thickness of 4.5 mm, and a length of 1.500 mm, the vapor conduction holes (3) have a hole diameter of 12 mm and eight equidistantly in the circumferential direction. The pitch in the length direction is set to 100 mm.

The pressurizing pipe (1) has a steam introducing pipe (4) at one end thereof. The steam introduction pipe (4) penetrates one end face plate (1a) and communicates with the inside and outside of the pressurizing pipe (1), and one end of the outside is connected to a steam supply source not shown, The steam of a predetermined pressure is introduced.

At the other end of the pressurizing pipe (1), an exhaust pipe (10) for adjusting the internal pressure and a drain drain pipe (5) for discharging condensed water are provided. The exhaust pipe (10) has a pressure adjusting valve (10a) so that the pressure in the pressurizing pipe (1) can be adjusted. On the other hand, the drain pipe (5) discharges condensed water accumulated in the inner bottom portion of the test pipe (2) as needed, and one end thereof penetrates the end peripheral wall of the pressurizing pipe (1) to the outside. To form a drain inlet (5a) that faces the inner bottom surface of the test tube (2), the middle portion passes through the pressurizing tube (1), and the other end horizontally penetrates the end face plate (1b) to the outside. The ejection port (5b) is formed so as to protrude to the outside. (6) is an automatic drain discharge valve for opening and closing the discharge port (5b).

Clamping pressure sealing means (7) is provided outside both ends of the pressurizing pipe (1). The means is an annular packing (8) for interposing between the inner surfaces of both ends of the test tube (2) to be fitted on the outer side of the pressurizing tube (1) and the outer surface of the pressurizing tube (1) to seal the two. And a fastening member (9) such as a band member or a wire for clamping and fixing the sample tube (2) from the outside of the packing.

In the above, the heating withstand pressure of the synthetic resin tube is measured as follows.

First, a test tube (2) having a predetermined length made of the above resin tube is loosely fitted onto the outside of the pressurizing tube (1) in a fitting state, and both ends thereof are located at the positions of the packings (8) and (8). The both ends of the sample pipe (2) are fixed to the outer peripheral surface of the pressurizing pipe (1) in an airtight state by being fixed by the lashing member (9) from the outside.

Next, from the steam inlet (4) into the pressurizing pipe (1), high temperature steam having a predetermined pressure, for example, a pressure of 0.5 kg.
/ Cm ² of steam is introduced. Incidentally, the vapor temperature at this time is 111 ° C. The introduced steam fills the test tube (2) through the steam passage hole (3) in the circumferential wall of the pressurizing tube (1). Therefore, by allowing the air in the pipe to escape from the exhaust pipe (10) at the same time as the above operation, the inside of the test pipe (2) can be replaced with the above steam, and the test pipe (2) can be heated and softened to a predetermined temperature. .

Next, by adjusting the amount of air escaped from the exhaust pipe (10), the pressure inside the pipe is increased and the test pipe (2) is expanded under a heated condition. At this time, the sample pipe (2) is in a state of being easily bent and deformed by heating and softening. However, the pressurizing pipe (1) acts as a backup member from the inside, and the pressurizing pipe (1) is evenly distributed on the peripheral wall of the pressurizing pipe (1). Due to the vapor pressure from the distributed vapor conduction holes (3), the sample tube (2) does not undergo a significant meandering deformation that is harmful, and as shown by the chain line in FIG. It expands, and the expansion in the axial direction is absorbed by the expansion.

Further, when the test tube (2) is expanded by the introduction of steam, the water condensed in the tube (2) is continuously discharged out of the tube through the drain drain pipe (5). It is desirable to prevent local cooling of the test tube (2) due to contact with water. For this purpose, during measurement, the entire device including the pressurizing pipe (1) is slightly tilted in the longitudinal direction,
It is preferred that the drain pipe (5) be located below.

Therefore, after maintaining the above-described heat-expanded state for a predetermined time, if necessary, cooling air is introduced from the steam introducing pipe (4) to cool the whole.

The test tube (2) at the time of expansion
In addition to monitoring and inspecting for steam leakage from the pipe, after cooling, it is removed from the pressurizing pipe (1) to check the change in wall thickness distribution in the circumferential direction and length direction of the test pipe (2), and also to check for cracks and Investigate the occurrence of local damage, etc., and measure the hot pressure resistance of the test tube (2).

In the above measuring device, when the length of the test tube (2) is relatively shorter than the length of the pressurizing tube (1), the pressurizing tube is corresponding to the length. One or a plurality of rows of vapor conduction holes on the end side of (1) (3)
Is closed by using an appropriate plug body, and the effective pressure resistance measurement at the same time as described above is performed by making the effective length of the pressurizing pipe (1) correspond to the length of the test pipe (2).

FIG. 2 shows a modification of the pressurizing pipe (11). The pressurizing pipe (11) has a body portion axially divided at a middle portion in the lengthwise direction, and the divided bodies are connected to each other via a slip joint (12) by concave and convex fitting, so that The pressure tube itself is configured to be expandable and contractable in the length direction. In this case, the pressurizing pipe (11) also expands following the expansion of the test pipe (2) in the lengthwise direction during the thermal expansion. Therefore, the withstand pressure of the test tube (2) at the time of heating can be measured more accurately and highly accurately.

[0034]

According to the present invention, as described above, a test tube made of a thermoplastic synthetic resin tube is mounted on the outside of the pressurizing tube in a fitted state, and steam is introduced from the pressurizing tube side to introduce the test tube. Since the pressure resistance of the test tube is measured by heating and expanding the sample, the meandering deformation of the test tube during heating and softening is restricted by the pressurizing tube. For this reason, the entire test tube is uniformly expanded in the circumferential direction, and local stress concentration due to the internal pressure load does not occur, which is accurate and highly accurate.
It is possible to perform pressure resistance measurement during heat.

Further, in the case of a test tube having a weak point in strength during expansion measurement of the test tube, cracks or local destruction may occur, but even if such damage occurs, The high-pressure steam primarily escapes to the outside with the amount of steam existing between the outer surface of the pressurizing tube and the inner surface of the test tube, and secondarily the steam in the pressurizing tube passes through the steam passage hole. It will escape to the outside via. Therefore, the pressurizing pipe functions as a kind of cushioning member, and it is possible to prevent the occurrence of a large explosion phenomenon in which the pipe internal pressure blows to the outside at once. That is, the explosion speed can be reduced, and the measurement work can be performed more safely.

Furthermore, as described above, if the length of the pressurizing pipe is within the range, even if the length of the test pipe changes, a part of the vapor passage hole of the peripheral wall of the pressurizing pipe is closed and closed properly. By using it, the heating and pressure resistance measuring operation can be executed without any trouble. Therefore, the length of the test tube to be inspected is not restricted and it is excellent in versatility, and the measurement work including the setting work of the pressurizing pipe to the test pipe can be done easily and requires no skill. Good nature.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view showing an embodiment of a thermal pressure resistance measuring device for a resin pipe according to the present invention.

FIG. 2 is a partial sectional view showing a modified example of the pressurizing pipe.

FIG. 3 is a vertical cross-sectional view showing a conventional thermal pressure resistance measuring device for a resin pipe.

[Explanation of symbols]

 1, 11 ... Pressurization pipe 2 ... Resin test pipe 3 ... Steam conduction hole 4 ... Steam introduction pipe 5 ... Drain drainage pipe 7 ... Clamping and sealing means 8 ... Packing 9 ... Fastening member 12 ... Slip joint

Claims (4)

[Claims] 1. A metal pressurizing pipe having both pipe ends closed and a large number of vapor conducting holes provided in a peripheral wall of a body is prepared, and an inner diameter of the pressurizing pipe is relatively larger than an outer diameter of the pressurizing pipe. A test tube made of a thermoplastic synthetic resin tube is loosely fitted to the press-fitting tube, and the outer circumference of the pressurizing tube is hermetically sealed at both ends, and then one end of the pressurizing tube is fixed. A method for measuring a pressure resistance of a thermoplastic synthetic resin tube under heat, wherein steam is introduced under pressure from the section to heat and expand the test tube, and the pressure resistance thereof is measured. 2. A pressurizing tube made of a metal having an outer diameter relatively smaller than an inner diameter of a test tube made of a thermoplastic synthetic resin tube, and the outer peripheral surface of the pressurizing tube being loosely covered and fitted in a covering state. A clamping pressure sealing means for fixing both ends of the test tube to the outer peripheral surface of the pressurizing tube in a hermetically sealed state, the pressurizing tube is closed at both tube ends by end face plates, and a large number of them are provided on the outer periphery of the body section. And a steam introduction pipe for introducing the internal pressurized steam into at least one end portion of the thermoplastic synthetic resin pipe. 3. The device for measuring a pressure resistance against heat of a thermoplastic synthetic resin pipe according to claim 2, wherein the pressurizing pipe is configured to be capable of expanding and contracting in a length direction. 4. A drain drain pipe provided at the end of the pressurizing pipe, wherein the exhaust pipe forms a drain inlet, one end of which projects outward from the lower peripheral wall of the pressurizing pipe and faces the test pipe, 3. An openable / closable discharge port, wherein the intermediate portion passes through the pressurizing pipe and the other end is opened to the outside from the end of the pressurizing pipe.
Alternatively, the device for measuring a pressure resistance of a thermoplastic synthetic resin tube under heat at the time of 3.