PE mine pipe is a kind of PE pipe, which has the advantages of light weight, long service life and convenient construction. The weigh of PE pipe for mining is only 1 / 7 of the steel pipe and 1 / 2 of the glass pipe, but the service life is 4-5 times of the steel pipe. The transportation and installation are convenient, especially in the underground, which can greatly reduce the labor intensity of workers and improve the work efficiency. And it has strong corrosion resistance, no need to do anti-corrosion treatment, saving related expenses, the comprehensive benefit is 5-7 times of steel pipe, especially suitable for underground transportation of high sulfur water.
PE Mine Pipe Design Requirements
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Because of the rigidity and linear expansion coefficient of the material, when considering the strength problem, the number of fixed points must be increased to ensure the rigidity of the water supply network. When considering the linear expansion coefficient, it must be considered that the laying of long-distance pipeline must have a certain amount of expansion.
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The buried depth of the pipeline is determined according to the freezing degree, the external load and other factors. In general, the buried depth can be 0.2m below the freezing line, and the minimum buried depth of pipe top is 1.0m when the pipe diameter is greater than 110mm.
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The bottom of the trench is generally the outer diameter of the pipe plus 0.4 M. the side of the trench should be in a straight line, the bottom of the trench should be in a plane, and there should be no protrusions, crushed stones or other hard blocks in the trench. When mechanical trenching is used, 0.2-0.3 m thick soil layer shall be left at the bottom of the trench for the time being. Finally, the bottom of the trench shall be manually cleaned to the elevation.
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When the pipeline is laid, 20cm medium coarse sand is backfilled at the top of the pipeline, and 15cm sand cushion is made at the bottom of the pipeline.
Pressure Test of PE Mine Pipe
The pressure test of PE mine pipe is divided into two stages, namely pre-test stage and main test stage.
Pre-test Stage
In the pre-test stage, the steps are as follows:
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Reduce the pressure in the pressure test PE mining pipeline to atmospheric pressure for 60 minutes. Make sure that no air enters the pipe during this period.
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Slowly increase the pressure of PE mining pipeline to the test pressure and stabilize it for 30 minutes. During this period, if the pressure drops, water can be injected to make up the pressure (but not higher than the test pressure). Check whether there is leakage at the pipe joints and fittings (if any, stop the pressure test, find out the cause and take corresponding measures before organizing the pressure test).
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Stop water injection and pressurization and stabilize for 60 minutes. If the pressure drops below 70% of the test pressure after 60 minutes, stop the pressure test, find out the cause and take corresponding measures before organizing the pressure test.
Main Test Stage
In the main test stage, the steps are as follows:
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At the end of the pre-test stage, the pressure of the pipeline is reduced rapidly by 10-15% of the test pressure.
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Record the residual pressure of PE mining pipeline every 3 minutes for 30 minutes. If the residual pressure of the pressure test pipeline has an upward trend within 30 minutes, the hydrostatic test result is qualified.
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If there is no upward trend of the residual water pressure in the PE mining pipeline during the pressure test within 30 minutes, the observation shall be continued for another 60 minutes. If the pressure drop does not exceed 0.02MPa in the whole 90 minutes, the hydrostatic test result is qualified.