Laboratory polyethylene pipes

1.Melt Flow Rate Test

It is a function of the molecular weight of the polymer. Specifically, the gram of a polymer passes through a die in 10 minutes due to the pressure of a certain weight at a certain temperature, and based on 10 gr⁄ 10 min and according to the standard on raw materials. And the product is done both.

2.Strain test in failure according to ISO6259-1.3

This test is related to the mechanical properties of the product, which indicates the strength of the pipe against the applied stress, which the higher the tension, the better the performance of the product in the operating network.

3. Longitudinal reversion test according to INSO17614 standard (longitudinal reversion)

In this test, samples of a certain length of pipe are cut and placed in the oven at a certain temperature that is in the circulation for 1 hour. After cooling, the length changes are measured and according to the standard, the maximum permissible changes should not be more than 3 Be a percentage. This test actually shows changes in pipe length due to heat.

4. Soot dispersion test according to ISO18553 standard

In this test, a certain amount of sample is removed from the tube at a temperature of 190 ° C and a specific time is placed in the oven and then under a 10 * 10 microscope is examined that the distribution of soot in the sample should be uniform.

5. Lahide test instead of Squeezeoff according to EN12106 standard (Squeezeoff)

This test is for gas pipes, which is used to close the gas transmission line when the network is changing. In this test, the sample is frozen at a temperature of zero degrees and squashed by a squash machine for 1 hour, and finally subjected to a 165-hour hydrostatic test. The pipe should not burst or deform during this time.

6. Hydrostatic pressure test according to ISIRI12181-1,2 standard (HYDROSTATIC PRESSURE)

It is one of the most important tests that show the physical and mechanical properties of production pipes. Is a hydrostatic test. In this test, the pipe sample is cut according to the standard and the relevant caps are closed on both sides of the pipe and in cold water baths at 20 ° C for 100 hours or 80 ° C for 165 hours or 80 ° C. The powder is subjected to constant internal pressure for 1000 hours. During this time, the pipe should not burst or crack.

7. Bursting test according to ISIRI12181-1,2 standard

In this test, the tube samples are subjected to internal pressure in a hydrostatic tub at a temperature of 23 ° C, which is 3 times the pressure applied to the sample. In 60 to 70 seconds, an explosion must occur, and this explosion is in the form of a canary tip. In this case, the failure must be perpendicular to the longitudinal axis of the pipe. If this crack is in the form of a pipe crack, the sample will not be of good quality.

8. Thermal stability test according to ISIRI7186 standard

This test is a qualitative measure of the stability of oxygen-affected items. This test is applied to raw materials and products and is in fact simulated from welding pipes in the network that polyethylene should be able to withstand the temperature of 200-210 ° C in the presence of oxygen and not be destroyed in 20 minutes. . The device in Mehravand laboratory is capable of performing thermal stability and DSC in differential manner and its oxidation reaction is a function of temperature.

9. Density test according to INSO7090-1 standard (Density)

Density is expressed in grams per cubic centimeter, the density of raw materials affects the mechanical properties of the final product, the density test is determined based on the immersion method using scales four and three and the fluid whose density is known.

10. Tensile strength test of a butt welded joint according to INSO17304 standard

This test is a qualitative test based on the cut stated in the standard on the sample, and is subjected to stress at a constant speed. May be. This test is performed at a temperature of ° 23C

11. Dimensional test according to INSO2412 standard (Dimension)

Precise determination of thickness and diameter of polyethylene pipes is done using calipers and caliper diameter gauges, the thickness and diameter tolerance is based on standard tables. Another parameter that is used in dimensions is double width or (OVALITY) which Due to the deformation of the cross section of the pipe, the permissible limit of the two widths of the pipes is specified in the standard tables.

12. Soot percentage test according to ISO 6964A standard (Carbon Black content)

Polyethylene pipes are not resistant to the sun’s ultraviolet rays due to the destruction of polymer chains, so to prevent the destruction of pipes, the amount of 2 to 2.5% soot should be used, which is placed as a cover on the chains. The distribution of this soot should be appropriate, for this purpose, some of the sample is taken up to 550 ° C under the pyrolysis of pure nitrogen gas to determine the percentage of soot in the sample.

13. Crack growth test due to environmental stresses according to ISIRI8988 standard (ESCR)

This test is performed only for the tube (LDPE), which bends both sides of the tube and is placed in an alkaline solution containing alkaline surfactants for one hour at a certain temperature. After this period, there should be no small cracks in the bent part.