Method for evaluating life of plastic pipe

A technology for plastic pipes and evaluation methods, applied in the direction of analyzing materials, using stable tension/pressure to test material strength, measuring devices, etc., can solve the inaccurate evaluation results, hinder the development speed of special resins for plastic pipes, and be difficult to observe Sample failure and other problems, to achieve the effect of reducing the evaluation cycle, increasing the development speed, and improving the accuracy

Inactive Publication Date: 2018-05-22
GUANGZHOU SPECIAL PRESSURE EQUIP INSPECTION & RES INST
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

The long evaluation cycle also hinders the development speed of special resins for plastic pipes
Moreover, during the evaluation period, it is difficult to observe the failure of the sample, and then it is impossible to observe the microscopic morphology of the sample after failure, resulting in inaccurate evaluation results

Method used

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  • Method for evaluating life of plastic pipe
  • Method for evaluating life of plastic pipe
  • Method for evaluating life of plastic pipe

Examples

Experimental program
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Embodiment 1

[0040] This embodiment provides a method for evaluating the life of a plastic pipe, which is based on figure 1 The sample 100 implementation shown in Please refer to figure 1 , the sample 100 is cylindrical and has an annular prefabricated notch 110 on its peripheral surface. It should be noted that the diameter of the sample 100 can be selected between 13mm-15mm, and the length of the sample 100 can be selected between 70mm-110mm. Further, the diameter of the sample 100 can be controlled between 13.5mm-14.5mm, and the length of the sample 100 can be controlled between 90mm-100mm. In this way, it is possible to avoid the problem that the test result cannot be accurately displayed due to the too small size of the sample 100 , and the problem that the evaluation cycle is too long due to the too large size of the sample 100 can be avoided. In this embodiment, the diameter of the sample 100 is 14 mm, and the length of the sample 100 is 95 mm. The prefabricated notch 110 is set...

Embodiment 2

[0074] In this example, the plastic pipe life evaluation method provided in Example 1 is used to test four different materials, PE100-1, PE100-2, PE100RC-3 and PE100RC-4, and the expressions T and △ The lines for the σ relationship are plotted in the same log-log plot. Figure 5 It is the log-log coordinate diagram in this embodiment. pass Figure 5 , the stretching time T of the above four materials can be compared under the same stress range Δσ. Under the same stress range △σ, the longer the stretching time T of the material, the longer the service life of the plastic pipe made of it. In this way, the service life of plastic pipes made of different materials can be compared and evaluated, so as to provide a reference for the research and development of special resins for plastic pipes.

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Abstract

The invention relates to the technical field of plastic pipe manufacturing, and provides a method for evaluating life of a plastic pipe. The method comprises the following steps: two ends of a sampleare clamped, and the sample is cylindrical and the circumferential surface is provided with a ring-shaped pre-formed notch; the sample is stretched at a preset frequency f, and the tensile stress gradually changes back and forth between a maximum preset stress Fmax and a minimum preset stress Fmin during the stretching process, and every change of the tensile stress is regarded as a cycle; when the surface of the sample is observed, and a new crack is generated near the pre-formed notch, the number of changes in the tensile stress Nini and the stress range delta sigma are recorded; the numberof changes Nini is converted into a stretching time T; the steps using different stress ranges delta sigma are repeated in order to obtain a plurality of stretching times T; a log-log coordinate graphis drafted according to a plurality of stress ranges delta sigma and corresponding stretching times T. By this method, the evaluation period can be greatly reduced.

Description

technical field [0001] The invention relates to the technical field of plastic pipe manufacture, in particular to a plastic pipe life evaluation method. Background technique [0002] At present, the test and evaluation methods of plastic pipe resistance to slow crack growth mainly include notched pipe test (NPT), fully notched tensile creep test (FNCT), Pennsylvania notched tensile test (PENT), notched ring test (NRT) and point load test (PLT), etc. The evaluation cycle of the above evaluation methods is too long, usually within one year or 104 hours (about 13 months). Long evaluation cycles also hamper the speed of development of resins for plastic pipes. Moreover, during the evaluation period, it is difficult to observe the failure of the sample, and it is impossible to observe the microscopic morphology of the sample after failure, resulting in inaccurate evaluation results. Contents of the invention [0003] The purpose of the present invention is to overcome the de...

Claims

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Application Information

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IPC IPC(8): G01N3/08
CPCG01N3/08G01N2203/0005G01N2203/0017G01N2203/0062G01N2203/0274
Inventor 翟伟杨波李茂东陈志刚黄国家张双红李仕平王志刚赖广运汪文峰伍振凌
Owner GUANGZHOU SPECIAL PRESSURE EQUIP INSPECTION & RES INST
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