Resin Tube Life Test Method and Life Test Device

Abstract

Provided are a life test method and a life test apparatus capable of calculating long-term characteristics of a resin tube through a short-term test. 【Solution means】The life test apparatus for a resin tube according to the present invention includes a tensile load jig that pulls a short tube cut out from a cylindrical resin tube as a test body in the vertical direction, a heat insulating device made of a heat insulating material that covers the front, rear, left, right, and upper parts of the tensile load jig, and a heat dissipation plate is attached to the inside thereof, a load loading device provided at the lower end of the tensile load jig that applies a mechanical tensile load to the test body, a heating device that warms the air inside the heat insulating device, a temperature controller that controls the heating device to keep the temperature inside the heat insulating device constant, a displacement meter that measures the amount of deformation of the test body, and a support having a lifting device that lifts the tensile load jig. In another embodiment, a strain gauge is provided instead of the displacement meter, and in still another embodiment, a load meter is provided instead of the displacement meter.

Description

Technical Field

[0001] The present invention relates to a method and an apparatus for testing the life of a resin pipe, and more particularly to a method and an apparatus for testing the life of a resin pipe that can easily perform an accelerated test under a high-temperature environment.

Background Art

[0002] It is known that resin pipes used for agricultural water or sewage, which are made of resin materials, deteriorate over the years, resulting in a decrease in their durability and a significant change in their rigidity. In recent years, due to this long-term deterioration phenomenon, resin pipes have suddenly burst, leading to the suspension of water supply and frequent secondary disasters such as the collapse of roads and surrounding facilities.

[0003] In the design standards and pipe rehabilitation manuals of resin pipes, it is stipulated to present the load-bearing capacity and rigidity of the resin pipes after 50 years of use. As test methods for obtaining the long-term characteristics of resin pipes, there are two types of characteristic evaluation methods. One is an external pressure test (Fig. 14) for the bending strength and deformation of the pipe, and the other is an internal pressure test (Fig. 15) for grasping the characteristics of the tensile strength. In both tests, a predetermined loading state is continuously maintained until the pipe breaks. Briefly, a water tank is maintained at a reference temperature of 23°C, and the test is carried out over a period of 10,000 hours (about 1.2 years) with load and pressure.

[0004] Therefore, testing resin pipes requires a long time, and since the breaking loads at different loads are also required, the test costs are extremely high. Moreover, by using a constant-temperature facility to maintain the water tank at a constant temperature, it becomes a large-scale facility. Therefore, it has been an obstacle to the development of new resin pipes. Although a series of test methods are acceptable as methods for grasping the long-term characteristics of test body materials, from the perspective of empirically evaluating resin pipes used for agricultural water and water supply and sewerage, they are not test methods that can be used in terms of time and economy. For this reason, a technology for grasping the long-term characteristics of resin pipes in a short period of time is required.

Prior Art Documents

Patent Documents

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-299734 [Summary of the Invention] [Problems to be Solved by the Invention]

[0006] An object of the present invention is to provide a resin tube life test method and a life test apparatus capable of calculating the long-term characteristics of a resin tube by a test in a short period. [Means for Solving the Problems]

[0007] A first resin tube life test method according to the present invention uses a short tube cut out from a cylindrical resin tube as a test specimen, sets the test specimen in a heat insulation device, and applies a mechanical tensile force to the test specimen with the air in the heat insulation device in a state higher than a reference temperature (T0) in which the resin tube is embedded. It is a resin tube life test method for predicting the life of a resin tube. After measuring the times (m1, m2) when the deformation amount of the test specimen reaches a predetermined value (λ) at each of at least two temperatures (T1, T2) higher than the reference temperature (T0) and obtaining the deformation rates (k1, k2) respectively, the deformation rate (k0) at the reference temperature (T0) is extrapolated from the deformation rates (k1, k2) at the two temperatures (T1, T2), and based on the extrapolated deformation rate (k0), the time (m0 = λ / k0) required for deformation at the reference temperature (T0) is calculated.

[0008] The second resin tube life test method according to the present invention uses a short tube cut out from a cylindrical resin tube as a test specimen, sets the test specimen in a heat preservation device, and applies a mechanical tensile force to the test specimen with the air in the heat preservation device in a state higher than the reference temperature (T0) at which the resin tube is embedded, to predict the life of the resin tube. The method is characterized in that at each of at least two temperatures (T1, T2) higher than the reference temperature (T0), the time (m1, m2) when the strain amount of the test specimen reaches a predetermined value (λ) is measured to obtain the strain rates (k1, k2) respectively, and then the strain rate (k0) at the reference temperature (T0) is extrapolated from the strain rates (k1, k2) at the two temperatures (T1, T2), and the time (m0 = λ / k0) required for strain at the reference temperature (T0) is calculated based on the extrapolated strain rate (k0).

[0009] The third resin tube life test method according to the present invention uses a short tube cut out from a cylindrical resin tube as a test specimen, sets the test specimen in a heat preservation device, and applies a mechanical tensile force to the test specimen with the air in the heat preservation device in a state higher than the reference temperature (T0) at which the resin tube is embedded, to predict the life of the resin tube. The method is characterized in that at each of at least two temperatures (T1, T2) higher than the reference temperature (T0), the time (m1, m2) when the fracture stress (σ) of the test specimen is reached is measured to obtain the fracture rates (k1, k2) respectively, and then the fracture rate (k0) at the reference temperature (T0) is extrapolated from the fracture rates (k1, k2) at the two temperatures (T1, T2), and the time (m0 = σ / k0) required for fracture at the reference temperature (T0) is calculated based on the extrapolated fracture rate (k0).

[0010] The mechanical tensile force is applied by lifting the test specimen.

[0011] The life test apparatus for the first resin pipe according to the present invention comprises a tensile load jig that pulls a short pipe cut out from a cylindrical resin pipe as a test specimen in the vertical direction, a heat insulation device made of a heat insulating material that covers the front, rear, left, right, and top of the tensile load jig, and a heat dissipation plate is attached to the inside, a load loading device provided at the lower end of the tensile load jig that applies a mechanical tensile load to the test specimen, a heating device that warms the air inside the heat insulation device, a temperature controller that controls the heating device to keep the temperature inside the heat insulation device constant, a displacement meter that measures the amount of deformation of the test specimen, and a support tool equipped with a lifting device that lifts the tensile load jig.

[0012] The life test apparatus for the second resin pipe according to the present invention comprises a tensile load jig that pulls a short pipe cut out from a cylindrical resin pipe as a test specimen in the vertical direction, a heat insulation device made of a heat insulating material that covers the front, rear, left, right, and top of the tensile load jig, and a heat dissipation plate is attached to the inside, a load loading device provided at the lower end of the tensile load jig that applies a mechanical tensile load to the test specimen, a heating device that warms the air inside the heat insulation device, a temperature controller that controls the heating device to keep the temperature inside the heat insulation device constant, a strain gauge that measures the amount of strain of the test specimen, and a support tool equipped with a lifting device that lifts the tensile load jig.

[0013] The life test apparatus for the third resin pipe according to the present invention comprises a tensile load jig that pulls a short pipe cut out from a cylindrical resin pipe as a test specimen in the vertical direction, a heat insulation device made of a heat insulating material that covers the front, rear, left, right, and top of the tensile load jig, and a heat dissipation plate is attached to the inside, a load loading device provided at the lower end of the tensile load jig that applies a mechanical tensile load to the test specimen, a heating device that warms the air inside the heat insulation device, a temperature controller that controls the heating device to keep the temperature inside the heat insulation device constant, a load meter that measures the load applied to the test specimen, and a support tool equipped with a lifting device that lifts the tensile load jig.

Advantages of the Invention

[0014] According to the first resin tube life test method of the present invention, since the resin tube deforms little by little over a long period of time, a deformation rate (k) (= deformation amount (λ) / time (m) until a predetermined deformation amount is reached) is introduced. Since a certain relationship (Arrhenius equation) holds between the test temperature (T) and the deformation rate (k), a tensile test is performed at a high temperature where the deformation rate (k) is large, the time (m) until a predetermined deformation amount (λ) is reached is measured, and from this, the deformation rate (k) at a low temperature is extrapolated and obtained. Therefore, by means of a short test of about one week, the time (m) until the deformation amount (λ) at the reference normal temperature of 23°C is reached can be calculated.

[0015] According to the second life test method of the present invention, from the time until the resin tube reaches a predetermined strain amount, a strain rate (k') (= strain amount (ε) / time (m) until a predetermined deformation amount is reached) is introduced. Since a certain relationship (Arrhenius equation) holds between the test temperature (T) and the strain rate (k'), a tensile test is performed at a high temperature where the strain rate (k') is large, the time (m) until a predetermined strain amount (ε) is reached is measured, and from this, the strain rate (k') at a low temperature is extrapolated and obtained. Therefore, by means of a short test of about one week, the required time (m) until the strain amount (ε) at the reference normal temperature is reached can be calculated.

[0016] According to the third life test method of the present invention, from the time until the resin tube reaches fracture, a fracture rate (k') (= fracture stress (σ) / time (m) until fracture) is introduced. Since a certain relationship (Arrhenius equation) holds between the test temperature (T) and the fracture rate (k'), a tensile test is performed at a high temperature where the fracture rate (k') is large, the time (m) until the fracture stress (σ) is reached is measured, and from this, the fracture rate (k') at a low temperature is extrapolated and obtained. Therefore, by means of a short test of about one week, the required time (m) until the judgment stress (σ) at the reference normal temperature is reached can be calculated.

[0017] The mechanical tensile force can be applied by lifting the test specimen, and the test can be easily carried out at the site or in the laboratory of the research institute regardless of the location.

[0018] According to the life test apparatus for the first to third resin pipes according to the present invention, since it is provided with a heat insulation device made of a heat insulating material and a heating device for heating the inside of the heat insulation device, the temperature inside the heat insulation device can be raised to a high temperature. By maintaining a constant temperature with a temperature controller, an accelerated test in a high temperature state can be performed. Since a large water tank for constant temperature equipment is not required, the equipment cost can be reduced, and the development of new resin pipes can be promoted. Since a support tool equipped with a lifting device capable of lifting the test piece is prepared, it becomes easy to lift a heavy load device, and the test can be easily performed even in a field or a laboratory. Since a short pipe cut out from a cylindrical resin pipe is used as the test piece, data closer to the actual burial environment can be obtained compared to the test of plate pieces.

Brief Description of the Drawings

[0019]

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Embodiments for Carrying Out the Invention

[0020] Hereinafter, with reference to the drawings, a method and apparatus for testing the lifespan of a resin tube according to the present invention will be described in detail.

[0021] FIG. 1 is an internal configuration diagram of a lifespan test apparatus 100 according to the present invention as viewed from the front. The test specimen 12 is a short tube obtained by cutting out a cylindrical resin tube with a diameter of about 470 mm and a length of about 50 mm. The test specimen 12 is equipped with a tensile load jig 5 so that the diameter is pulled in the vertical direction. The tensile load jig 5 includes two semi-circular split plates 5b, 5b inserted into the test specimen 12, connecting fittings 5d, 5d connecting the split plates 5b, 5b, and suspension fittings 5a, 5a pulling the split plates 5b, 5b up and down. The test specimen 12 equipped with the tensile load jig 5 is covered with a heat insulation device 4 on the front, back, left, right, and top. The heat insulation device 4 is formed of a polystyrene foam plate material that is a heat insulating material to keep the inside at a constant temperature. In this embodiment, the heat insulation device 4 is formed in a box shape. An exothermic device 3 is provided inside the heat insulation device 4 to warm the inside. Aluminum heat dissipation plates 2, 2 are provided inside the heat insulation device 4.

[0022] Specifically, the exothermic device 3 is a surface heater with a size (length × width × thickness) of 100 × 200 × 2 (mm) and a power of about 120 W. In FIG. 1, the round marks attached to the top, bottom, left, and right of the test specimen 12 indicate temperature measurement points 6. The temperature measurement points 6 measure a total of 13 locations, including 8 locations in the front and back of the test specimen 12, 4 locations of the exothermic device 3, and 1 location outside the heat insulation device 4. The exothermic device 3 is powered from a temperature controller 10 and controlled to a constant temperature. Since the temperature controller 10 is equipped with a thermocouple temperature sensor 11, it is brought into contact with the temperature measurement points.

[0023] Figure 2 is an internal configuration diagram of the life test apparatus 100 shown in Figure 1, as viewed from the right side. The heating device 3 is located inside the heat insulation device 4, and a total of four sheets are provided, two on the front side and two on the rear side. The tensile load jig 15 consists of a suspension fitting 5a that pulls the test piece 12 upward, connecting fittings 5d, 5d that connect the two split plates 5b, 5b so that they can move up and down, and a suspension fitting 5a that pulls the test piece 12 downward. The test piece 12 has a length of approximately 50 mm in the front-rear direction. The lower side of the heat insulation device 4 is open, and no bottom plate is provided.

[0024] Figure 3 is an explanatory diagram of the tensile load jig 5. The tensile load jig 5 is known as a tensile test jig (JIS K7037) that uses split plates. In the tensile load jig 5, the upper split plate 5b is lifted by the suspension fitting 5a, and the lower split plate 5b is pulled down by the suspension fitting 5a. The split plate 5b and the suspension fitting 5a are connected by a pin 5c. The split plates 5b, 5b are inserted into the test piece 12, and the tensile load jig 5 is assembled.

[0025] Figure 4 shows the application of a tensile force to the test piece 12 using the tensile load jig 5. Specifically, the load loading device 7 is a weight with a weight of approximately 100 kg. The upper part of the tensile load jig 5 is connected to a support by a wire and suspended. The pin holes of the connecting fittings 5d are made into long holes so that no load is applied. Since the test piece 12 is deformed by the weight of the load loading device 7, the deformation amount λ is measured by the displacement gauge 14. A laser displacement gauge can be used as the displacement gauge. In addition, a strain gauge 13 is provided outside the test piece 12 to measure the strain amount. The strain gauge 13 detects the expansion and contraction of the object by changing it into a change in resistance and detecting it as a voltage. Only one of the displacement gauge or the strain gauge may be provided. A load gauge 9 is arranged between the load loading device 7 and the suspension fitting 5a. The weight of the weight can be confirmed by the load gauge 9. Therefore, the load gauge 9 can measure the load at the time when the test piece 12 is destroyed. If the load (F) is known, assuming the stress at that time is the fracture stress (σ), the fracture stress (σ) can be calculated from σ = F / A. A is the cross-sectional area. The load gauge 9 may be arranged at the location of the upper suspension wire.

[0026] FIG. 5 is a photographic substitute for a drawing showing the tensile load jig 5 suspended from the support 15. Specifically, the support 15 is a tripod. However, it is not limited to this and may also be a rectangular frame. A scaffold is provided at the bottom of the tensile load jig 5 to support the tensile load jig 5. The scaffold can be made such that no load is applied to the test piece 12 in the stage before the start of the test. Further, the lifting device 8 is used to lift and lower the tensile load jig 5. Specifically, the lifting device 8 is a manual chain block. By operating the chain of the chain block, the load load device 7, which is a heavy object, and the tensile load jig 5 can be lifted. Not limited to the chain block, a lever block (registered trademark) that operates by moving a hoist lever up and down may also be used.

[0027] FIG. 6 is a photographic substitute for a drawing showing the heat insulation device 4 covering the tensile load jig 5 and suspended. The front panel of the heat insulation device 4 has been removed. A temperature controller 10 is attached to the support 15. Since the support 15 can be installed outdoors, it facilitates on-site testing. In a laboratory environment, a tensile life test can be performed even without special hanging tools on the ceiling.

[0028] FIG. 7 is a photographic substitute for a drawing showing the front panel 4a of the heat insulation device 4 viewed from the inside. Two heat dissipation plates 2 are attached, and heating devices 3, 3 are attached below the heat dissipation plates 2, 2. Since the heat dissipation plate 2 absorbs the heat of the heating device 3 and dissipates heat inside the heat insulation device 4, the internal temperature can be made uniform.

[0029] FIG. 8 is a photographic substitute for a drawing showing the side panel 4c and the back panel 4b of the heat insulation device 4 viewed from the inside. Two heat dissipation plates 2 are attached to the inside of the back panel 4b. Although heating devices 3, 3 are to be attached below the heat dissipation plates 2, 2, they are not attached in this photograph.

[0030] FIG. 9 is a perspective view of the heating device 3. As an example, the heat insulation device 4 has dimensions of height × width × depth of 850 mm × 700 × 300 mm. The inside of the heat insulation device 4 is heated by four heating devices 3.

[0031] Figure 10 is a photograph of the temperature controller 10. The temperature controller 10 includes a thermocouple temperature sensor 11 and a power supply line to the heating device 3. The temperature can be set with the push buttons on the panel, and the temperature can be controlled by controlling the current to the heating device 3. The set temperature can be set between 40 and 80 °C. In the heat preservation device 4 of this embodiment, when about 2 hours have elapsed since the start of energization to the heating device 3, a stable specified temperature can be reached.

[0032] Figure 11 shows the Arrhenius equation. k on the left side is the deformation rate or strain rate expressed in logarithm. This equation shows that k of the deformation rate or strain rate is a linear function of the reciprocal (1 / T) of the test temperature T expressed in absolute temperature. When the reference temperature is 23 °C in Celsius, it is 293 °C (= 23 °C + 273 °C) in absolute temperature. The scale on the horizontal axis is the reciprocal of the absolute temperature (1 / T) × 10 3 Taking this as the unit, 23 °C in Celsius is about 3.4, and 80 °C in Celsius is about 2.8.

[0033] Figure 12 is a graph showing the life test of the resin tube based on the deformation rate (k) of the test piece 12, and is a graph showing the relationship between the deformation rate and the reciprocal of the absolute temperature which is the test temperature. The vertical axis is the deformation rate (k) in logarithmic display. The deformation rate (k) is, as shown below Figure 12, the deformation rate (k) is the deformation amount (λ) divided by the time (m), and the time (m) is the time until that deformation. As an example, when a tensile test is performed at a high temperature of 80 °C, the deformation is accelerated, so the time until a predetermined deformation amount (λ) is reached in a short period can be known, and the deformation rate (k) can be obtained. As an example, when a tensile test is performed at a high temperature of 40 °C, the deformation is similarly accelerated, so the time until a predetermined deformation amount (λ) is reached in a short period can be known. Thereby, the deformation rate at 40 °C can be obtained. From the deformation rates (k) at 80 °C and 40 °C, the deformation rate at the reference temperature of 23 °C is extrapolated. If the extrapolated deformation rate is used as the denominator and the deformation amount (λ) is used as the numerator, the required time (m) until the deformation amount (λ) at 23 °C is reached can be calculated.

[0034] As shown in FIG. 12, measurements are performed at several deformation amounts (λ) of different sizes, and the deformation rate at the reference temperature of 23°C is extrapolated. Also, since the tests at 80°C and 40°C can be carried out in parallel, if two life test apparatuses 100 are prepared, two results can be obtained in approximately half the time.

[0035] FIG. 13 is a flowchart of a life test method based on the deformation rate of the test piece 12. S1 is a step of measuring the time (m1) when the deformation amount of the test piece reaches a predetermined value (λ) at a temperature (T1) higher than the reference temperature (T0) and obtaining the deformation rate (k1 = λ / m1). According to the example of FIG. 12, T1 can be set to 80°C. That is, an acceleration test is performed by setting the test temperature to a temperature higher than the reference temperature of 23°C.

[0036] S2 is a step of measuring the time (m2) when the deformation amount of the test piece reaches a predetermined value (λ) at a temperature (T2) higher than the reference temperature (T0) to obtain the deformation rate (k2 = λ / m2). According to the example of FIG. 12, T2 can be set to 60°C. Since 60°C is lower in temperature than 80°C, the deformation rate (k2) is slower and smaller than the deformation rate (k1).

[0037] S3 is a step of extrapolating the deformation rate (k0) at the reference temperature (T0) from the deformation rate (k1) at temperature (T1) and the deformation rate (k2) at temperature (T2). Coordinates P1 (1 / T1, k1) and coordinates P2 (1 / T2, k2) are determined on a plane where the horizontal axis is the reciprocal of the temperature and the vertical axis is the deformation rate, and the deformation rate (k0 = λ / m0) at the reciprocal of the reference temperature (1 / T0) is extrapolated from the slope connecting coordinates P1 and coordinates P1.

[0038] S4 is a step of calculating the time (m0 = λ / k0) required for deformation at the reference temperature (T0) from the extrapolated change rate (k0) and the deformation amount (λ). According to this, the deformation amounts after 5 years, 10 years, 50 years, etc. can be calculated.

[0039] In the present invention, a life test of the resin tube can be performed based on the strain rate of the test piece 12. The strain rate (k') is defined as the strain amount (ε) divided by the time (m) required to reach that strain amount. The strain amount (ε) can be measured by the strain gauge 13 as shown in FIG. 4. The Arrhenius equation can also be applied depending on the strain rate (k'), and by replacing the deformation rate (k) with the strain rate (k') according to the procedure shown in FIG. 13, the time (m0 = ε / k'0) required to reach the strain amount (ε) at the reference temperature (T0) can be calculated.

[0040] In the present invention, a life test of the resin tube can be performed based on the fracture rate of the test piece 12. The fracture rate (k') of the resin tube is defined as the fracture stress (σ) divided by the time (m) required to reach the fracture stress of the resin tube. The fracture stress (σ) is determined by constantly observing the load electrically with a load sensor by the load cell 9 and judging at the point when the load decreases. The fracture stress (σ) is the stress at which the resin tube reaches a "state where it can no longer be used or a limit state". When the elasticity of the test piece disappears, the semi-circular split plates 5b, 5b inserted into the test piece separate from each other, but are connected by connecting metal fittings 5d, 5d so as not to separate by more than a certain interval. Therefore, the subsequent load of 100 kg will be supported by the tensile loading jig 5. If the load (F) that becomes the fracture stress is known, the fracture stress (σ) can be calculated from σ = F / A. The Arrhenius equation can also be applied depending on the fracture rate (k'), and the deformation rate (k) can be replaced with the fracture rate (k'). By the same procedure as in FIG. 13, the time (m0 = σ / k'0) required to reach the fracture stress (σ) at the reference temperature (T0) can be calculated.

Industrial Applicability

[0041] The life test method and life test apparatus according to the present invention cover the test piece of the resin tube with a heat insulation device, raise the temperature of the test environment to accelerate the life test, and enable a test in a short period of about one week, so it is very convenient and easy to use.

Explanation of Reference Numerals

[0042] 1 Heat insulating material 2 Heat radiating plate 3 Heating device 4 Heat insulation device 4a Front panel 4b Rear panel 4c Side panel 5 Tensile load jig 5a Suspension fitting 5b Partition board 5c Pin 5d Connecting fitting 6 Temperature measurement point 7 Load loading device 8 Lifting device 9 Load cell 10 Temperature controller 11 Temperature sensor (thermocouple) 12 Specimen (resin tube) 13 Strain gauge 14 Displacement gauge 15 Support tool 100 Life test device T, T’, T” Temperatures higher than the reference temperature (T0) λ Deformation amount ε Strain amount

Claims

1. A short tube cut out from a cylindrical resin tube is used as a test specimen. The test specimen is set in a heat insulation device, and mechanical tensile force is applied to the test specimen with the air in the heat insulation device in a state higher than the reference temperature (T ０ ) in which the resin tube is embedded, and a method for testing the life of a resin tube for predicting the life of the resin tube. Reference temperature (T ０ ), at each of at least two temperatures (T １ , T ２ ) higher than the reference temperature, measure the time (m １ , m ２ ) when the amount of deformation of the test specimen reaches a predetermined value (λ) to obtain the deformation rates (k １ , k ２ ) respectively. Then, extrapolate the deformation rate (k ０ ) at the reference temperature (T ０ ) from the deformation rates (k １ , k ２ ) at the two temperatures (T １ , T ２ ), and calculate the time (m ０ = λ / k ０ ) required for deformation at the reference temperature (T ０ ) based on the extrapolated deformation rate (k ０ ). A method for testing the life of a resin tube, characterized in that.

2. A short tube cut out from a cylindrical resin tube is used as a test specimen. The test specimen is set in a heat insulation device, and the air in the heat insulation device is set to a state where it is at a temperature higher than the reference temperature (T ０ ) at which the resin tube is embedded, and a mechanical tensile force is applied to the test specimen to predict the life of the resin tube. This is a method for testing the life of a resin tube, Reference temperature (T ０ ), at each of at least two temperatures (T １ , T ２ ) higher than the reference temperature, measure the time (m １ , m ２ ) when the strain amount of the test specimen reaches a predetermined value (λ) to obtain strain rates (k １ , k ２ ) respectively. After that, extrapolate the strain rate (k ０ ) at the reference temperature (T ０ ) from the strain rates (k １ , k ２ ) at the two temperatures (T １ , T ２ ), and calculate the time (m ０ = λ / k ０ ) required for the strain at the reference temperature (T ０ ) based on the extrapolated strain rate (k ０ ). A method for testing the life of a resin tube, characterized in that.

3. A short tube cut out from a cylindrical resin tube is used as a test specimen. The test specimen is set in a heat-insulating device, and mechanical tensile force is applied to the test specimen with the air in the heat-insulating device being in a state at a temperature higher than the reference temperature (T ０ ). This is a method for testing the lifespan of a resin tube that predicts the lifespan of the resin tube. Reference temperature (T ０ ), at each of at least two temperatures (T １ , T ２ ) higher than the reference temperature, measure the time (m １ , m ２ ) required to reach the breaking stress (σ) of the test piece, and determine the breaking rates (k １ , k ２ ) respectively. After that, extrapolate the breaking rate (k １ , T ２ ) at the reference temperature (T １ , k ２ ) from the breaking rates (k ０ ) at the two temperatures (T ０ ), and calculate the time (m ０ ) required for the breaking stress (σ) at the reference temperature (T ０ ) based on the extrapolated breaking rate (k ０ = σ / k ０ ). A method for testing the life of a resin tube, characterized by the above steps.

4. The mechanical tensile force is applied by lifting the test piece, and the method for testing the life of a resin tube according to any one of claims 1 to 3, characterized in that.

5. A tensile load jig that pulls a short tube cut out from a cylindrical resin tube as a test piece in the vertical direction, A heat insulation device made of a heat insulating material that covers the front, rear, left, right, and top of the tensile load jig, and has a heat dissipation plate attached to the inside, A load loading device provided at the lower end of the tensile load jig that applies a mechanical tensile load to the test piece to deform the test piece, A heating device that warms the air inside the heat insulation device, A temperature controller that controls the heating device to maintain a constant temperature inside the heat insulation device, A displacement meter that measures the amount of deformation of the test piece, A support tool equipped with a lifting device that lifts the tensile load jig, The heating device sets the air inside the heat insulation device to a state higher than the reference temperature (T0) in which the resin tube is embedded, and the temperature controller maintains the temperature inside the heat insulation device at each of at least two temperatures (T1, T2) higher than the reference temperature (T0). The displacement meter measures the time (m1, m2) when the amount of deformation of the test piece reaches a predetermined value (λ) at each of the two temperatures (T1, T2) and operates to obtain the deformation rates (k1, k2) respectively. The deformation rate (k0) at the reference temperature (T0) is extrapolated from the deformation rates (k1, k2) at the two temperatures (T1, T2) obtained by the displacement meter, and the time (m0 = λ / k0) required for deformation at the reference temperature (T0) is calculated based on the extrapolated deformation rate (k0). A resin tube life test device, characterized in that.

6. A tensile load jig that pulls a short tube cut out from a cylindrical resin tube as a test piece in the vertical direction, A heat insulation device made of a heat insulating material that covers the front, rear, left, right, and top of the tensile load jig, and has a heat dissipation plate attached to the inside, A load loading device provided at the lower end of the tensile load jig that applies a mechanical tensile load to the test piece to distort the test piece, A heating device that warms the air inside the heat insulation device, A temperature controller that controls the heating device to maintain a constant temperature inside the heat insulation device, A strain gauge that measures the amount of strain of the test piece, A support tool equipped with a lifting device that lifts the tensile load jig, The heating device sets the air inside the heat preservation device to a temperature higher than the reference temperature (T0) at which the resin tube is embedded. The temperature controller maintains the temperature inside the heat preservation device at each of at least two temperatures (T1, T2) higher than the reference temperature (T0). The strain gauge operates to measure the time (m1, m2) when the strain amount of the test specimen reaches a predetermined value (λ) at each of at least two temperatures (T1, T2) higher than the reference temperature (T0), and respectively obtain the strain rates (k1, k2). A life test apparatus for a resin tube, characterized in that the strain rate (k0) at the reference temperature (T0) is extrapolated from the strain rates (k1, k2) at the two temperatures (T1, T2), and the time (m0 = λ / k0) required for the strain at the reference temperature (T0) is calculated based on the extrapolated strain rate (k0).

7. A tensile load jig that pulls a short tube cut out from a cylindrical resin tube as a test specimen in the vertical direction, A heat preservation device made of a heat insulating material, covering the front, rear, left, right, and upper parts of the tensile load jig, and having a heat dissipation plate attached to the inside, A load loading device provided at the lower end of the tensile load jig to apply a mechanical tensile load to the test specimen, A heating device for heating the air inside the heat preservation device, A temperature controller that controls the heating device to keep the temperature inside the heat preservation device constant, A load gauge for measuring the load applied to the test specimen, A support provided with a lifting device for lifting the tensile load jig, The heating device sets the air inside the heat preservation device to a temperature higher than the reference temperature (T0) at which the resin tube is embedded. The temperature controller maintains the temperature inside the heat preservation device at each of at least two temperatures (T1, T2) higher than the reference temperature (T0). The load gauge operates to measure the time (m1, m2) when the breaking stress (σ) of the test specimen is reached at each of at least two temperatures (T1, T2) higher than the reference temperature (T0), and respectively obtain the breaking rates (k1, k2). A resin pipe life test apparatus, characterized by extrapolating the fracture rate (k0) at the reference temperature (T0) from the fracture rates (k1, k2) at the two temperatures (T1, T2), and calculating the time (m0 = σ / k0) required for the fracture stress (σ) at the reference temperature (T0) based on the extrapolated fracture rate (k0).

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