JP2000180292A - Evaluation method for metal joints - Google Patents

Abstract

(57) [Summary] [Configuration] A resin tube 12 made of a polyolefin resin is cut into a predetermined length to form a test piece 12a.
A test piece 48 is obtained by attaching a metal faucet with a saddle 10 to 2a. Then, at 80 ° C., 1.1
An internal pressure of 0 MPa is applied for 165 hours to realize a temporally deformed state of the test object 48. Thereafter, the test object 48 is cooled to 40 ° C. under no pressure, and the water tightness is confirmed in an internal pressure range from a low pressure to a high pressure. In other words, the watertightness is checked under the conditions assuming the actual use environment. [Effect] The long-term watertight performance when the metal faucet with saddle 10 is attached to the resin pipe 12 made of a polyolefin resin can be accurately evaluated in accordance with the actual use situation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for evaluating a metal joint, and more particularly to a method for evaluating a long-term watertightness when a metal joint is attached to a resin pipe made of a polyolefin resin. .

[0002]

2. Description of the Related Art When joining a branch pipe to a resin pipe made of a polyolefin resin such as polyethylene, a resin joint is fusion-bonded to the outer surface of the resin pipe, and the branch pipe is connected to the resin joint. Joining was common, and metal joints were only used exceptionally. Therefore, a method for evaluating long-term water tightness when a metal joint is joined to a resin pipe made of a polyolefin resin has not been established.

[0003]

In the conventional electrofusion bonding, a controller for applying a predetermined electric current to a heater for melting a bonding surface is required, and since the bonding portion needs to be cooled, a bonding operation is required. Takes a long time to perform.
Therefore, there has been a request from a contractor to use a metal joint that can be constructed more easily and quickly. On the other hand, when a metal pipe is joined to a resin pipe made of polyolefin resin and used for a long time, the resin pipe is deformed due to the constraint of the metal pipe and water leakage occurs at the joint between the resin pipe and the metal pipe. Was known.

However, conventionally, a method for evaluating long-term water tightness when a metal joint is joined to a pipe made of a polyolefin resin has not been established, so that it is possible to accurately predict the occurrence of water leakage at the joint. Did not. Therefore, a main object of the present invention is to provide an evaluation method capable of accurately evaluating long-term watertightness when a metal joint is attached to a resin pipe made of a polyolefin resin.

[0005]

SUMMARY OF THE INVENTION According to the present invention, there is provided a specimen in which a metal joint is attached to a resin pipe made of a polyolefin resin, the specimen is heated to a first temperature, and the resin pipe is heated at the first temperature. The test sample is left for a predetermined time while a predetermined internal pressure is applied to the test sample, and the test sample is cooled to a second temperature lower than the first temperature by a predetermined temperature.
This is a method for evaluating a metal joint, in which the test piece is cooled to a temperature and the watertightness of the test object is confirmed in an internal pressure range from low pressure to high pressure while maintaining the second temperature.

[0006]

When a metal joint is attached to a resin pipe made of a polyolefin resin, the resin pipe is subjected to a resilience of a gasket between the metal joint and the resin pipe, and a stress applied to the resin pipe, due to a tightening force of the metal joint. Are deformed inward over time. Therefore, in the present invention, a predetermined internal pressure is applied to the resin pipe at a first temperature for a predetermined time to realize a temporally deformed state of the specimen, and the specimen is cooled to a second temperature in the deformed state, Check the water tightness in the internal pressure range from low pressure to high pressure. In other words, the watertightness is checked under the conditions assuming the actual use environment.

[0007]

According to the present invention, the long-term watertightness when a metal joint is attached to a resin pipe made of a polyolefin resin can be accurately evaluated in accordance with the actual use situation.
The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description of embodiments with reference to the drawings.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The evaluation method (hereinafter simply referred to as "evaluation method") of a metal joint according to this embodiment shown in FIG. 1 is described in which a metal faucet with a saddle 10 as shown in FIG. Alternatively, it is for accurately evaluating long-term watertightness when attached to a resin tube 12 made of a polyolefin resin such as polypropylene.

The faucet with saddle 10 (FIG. 2) includes a split ring-shaped saddle 18 having an upper portion 14 and a lower portion 16. The upper portion 14 is formed of a metal such as cast iron, and mounting portions 22 for mounting bolts and nuts 20 are formed at both circumferential ends of the upper portion 14. A hole 26 corresponding to the branch hole 24 formed in the resin tube 12 is formed at the center of the upper portion 14, and a gasket receiving portion 28 and a joint portion 30 are formed by rising from the peripheral edge of the hole 26. . Further, a female screw 32 is formed on the inner peripheral surface of the joint 30. Then, the gasket 34 is mounted in the gasket receiving portion 28, and the joint 30
A male screw 40 formed at the connection port 38 of the water faucet 36 is screwed to the female screw 32 of the water faucet 36. In FIG. 2, the lip portion 34
Although the case where the lip-shaped gasket 34 having a is adopted is shown, a normal gasket without the lip portion 34a may be adopted instead.

On the other hand, the lower portion 16 is formed of a metal such as cast iron or the like.
A mounting portion 22 for mounting the bolt / nut 20 is formed. The upper part 14 and the lower part 16 are connected by bolts and nuts 20 on the outer peripheral surface of the resin tube 12. Therefore, the tightening force of the saddle 18 and the repulsive force of the gasket 34 act on the region A (hatched portion in FIG. 3) of the resin pipe 12 where the faucet with saddle 10 is attached. , Stress concentration occurs due to the water pressure in the resin tube 12, and these forces cause the resin tube 1
2 will be deformed over time. Therefore, in the evaluation method of this embodiment, long-term watertightness is evaluated by the following procedure in consideration of the temporal deformation of the resin tube 12.

First, as shown in FIG. 1A, a test piece 12a having a length of at least three times the outer diameter is cut out from a resin tube 12 to be used, and a saddle-attached portion is provided at the center of the test piece 12a. Fix the faucet 10 (FIG. 2). And the faucet 3
6 is inserted into the hole of the test piece 12a.
4 is formed, and a water valve of the water faucet 36 is closed by operating a ball valve (not shown) of the water faucet 36. In addition, the test piece 12
Both ends of “a” are closed by pressure-resistant caps 42.

Subsequently, as shown in FIG. 1 (B), a pressure-resistant hose 46 extending from a pressure device 44 is connected to one of the pressure-resistant caps 42, so that the test piece 12a and the water faucet with saddle 10 are integrated. (Hereinafter referred to as “test object”.) 48 is immersed in hot water of 80 ° C. filled in a water tank 50. At this time, the test piece 48 is heated to 80 ° C. by filling the inside of the test piece 12 a with water and leaving the test piece 12 a for at least one hour in that state. Thereafter, a pressure (water pressure) is applied to the inside of the test piece 12a by the pressurizing device 44, and the internal pressure of the test piece 12a is set to 1.10 MPa at a temperature of 80 ° C. And 16
Start time counting for 5 hours (about 1 week).

The heating temperature of the test object 48 (80 ° C.),
The internal pressure (1.10 MPa) and the standing time (165 hours) of the test piece 12a are set as conditions for realizing a deformed state in 50 years of use in a short period of time, and the heat specified by ISO This is based on the test conditions of the internal pressure creep test. However, other conditions shown in Table 1 may be employed instead of the above conditions.

[0014]

[Table 1]

When a predetermined leaving time (165 hours) elapses, the pressurization of the test piece 12a by the pressurizing device 44 is stopped, and the test object 48 is taken out of the water tank 50. Then, as shown in FIG. 1 (C), the specimen 48 was left in an atmosphere of 40 ° C. for 24 hours (1 day) or more,
Allow to cool naturally. Thus, by cooling the test object 48, a state assuming an actual use environment is obtained. Note that the temperature difference for cooling (40 ° C.) corresponds to the margin of temperature (20 ° C.) within the range of temperature change (about 20 ° C.) in the ground, which is the use environment.
° C).

When the cooling time (24 hours) elapses, the conditions at that time, that is, the temperature of 40 ° C. and the internal pressure of 0 MPa
Confirm the water tightness in a. This confirmation work is performed for the test object 48.
May be visually checked to see if water has leaked,
A sensor may be arranged below the test object 48 to automatically detect water leakage. If water leakage is confirmed,
The long-term watertightness of No. 8 is judged to be poor.

After confirming the watertightness under no pressure, the internal pressure of the test piece 12a is reduced to 0. 0 at the same temperature (40 ° C).
After raising the pressure to 05 MPa and leaving it for 2 minutes, water leakage under that condition is confirmed. Furthermore, 0.10MPa, 0.20M
Pa, 0.30MPa, 0.40MPa, 0.50MPa
a, 0.60MPa, 0.75MPa, 0.80MPa
a, 0.90MPa, 1.00MPa, 1.10MPa
Then, the internal pressure of the test piece 12a is increased stepwise, and water leakage under each condition is confirmed. When it is confirmed that no water leakage occurs under all conditions, it is determined that the long-term watertight performance of the test sample 48 is good. In addition,
The internal pressure range to be tested (0 to 1.10 MPa) is such that the lowest pressure in actual use is about 0.20 MPa and the highest pressure is 1.0
Since it is about 0 MPa, this is set with a margin. However, the width of the test water pressure rise is
It is not limited to the example (0.10 MPa),
It may be changed as appropriate.

According to this embodiment, the state of deformation over time is embodied, and the watertightness is checked in the deformed state in the internal pressure range from low pressure to high pressure. And can be evaluated accurately. In addition,
In the above embodiment, the test piece 12a
Is gradually increased from a low pressure, but may be gradually decreased from a high pressure.

In the above-described embodiment, the case where the long-term watertightness when the water faucet with saddle 10 is attached to the resin pipe 12 made of a polyolefin resin is evaluated is shown.
The long-term watertightness can be similarly evaluated when another metal joint such as a T-shaped joint 52 shown in FIG. 4 or a connecting ring 54 shown in FIG. 5 is attached. T shown in FIG.
The character joint 52 includes a split main body 56 made of metal such as cast iron or the like, and a gasket 58 and a retaining ring 60 are mounted on the inner surface of the main body 56. On the other hand, the connecting ring 54 shown in FIG. 5 includes a cylindrical main body 62 made of a metal such as cast iron or the like.
And a retaining ring 66. Therefore, even when the T-shaped joint 52 and the connecting wheel 54 are attached, the resin pipe 12 is deformed with time, but the long-term watertightness can be accurately evaluated by using the above-described evaluation method.

[Brief description of the drawings]

FIG. 1 is an illustrative view showing one embodiment of the present invention;

FIG. 2 is an illustrative view showing a water faucet with a saddle to which the embodiment of FIG. 1 is applied;

FIG. 3 is an illustrative view showing a region where a resin tube is deformed;

FIG. 4 is an illustrative view showing another metal joint;

FIG. 5 is an illustrative view showing another metal joint;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Dispense faucet with a saddle 12 ... Resin pipe 18 ... Saddle 36 ... Diffusion faucet 48 ... Test object 42 ... Water resistant cap 44 ... Pressurizing device 50 ... Water tank 52 ... T-joint 54 ... Spring ring

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Fukui Chitoku 64 Ishizu-Kitacho, Sakai-shi, Osaka F-term in Kubota Vinyl Pipe Factory (reference) 2G067 AA16 AA36 CC02 DD02 3H015 CA02

Claims (1)

[Claims] 1. A test article prepared by attaching a metal joint to a resin pipe made of a polyolefin resin is heated to a first temperature, and a predetermined internal pressure is applied to the resin pipe at the first temperature. The test object is left for a predetermined time in the applied state, the test object is cooled to a second temperature lower than the first temperature by a predetermined temperature, and in the internal pressure range from low pressure to high pressure while maintaining the second temperature. A method for evaluating a metal joint, which confirms the watertightness of the specimen.