Longitudinal reversion test

Thermoplastic tubes are stressed by waste stress during the cooling of the production process. The aim of the test is to determine the method for measuring the longitudinal return of thermoplastic tubes during reheating. In this test, 20 cm of polyethylene pipe is marked and placed in the Avon with a known temperature of 110 °C (HDPE) for several hours (according to the thickness of the polyethylene pipe wall) and after testing and cooling at ambient temperature, the longitudinal changes of the sample are measured by caliper. The maximum allowable percentage of changes is 3%.

According to the standards:

National standard of Iran INSO: 17614
Latin reference standard ISO: 2505

Thermal Stability Measurement Test (OIT)

In this method, the relative strength of materials against oxidation-induced degradation is determined according to the time of oxidation induction.

In this test, the sample with a mass of approximately 15 mg is placed in the device and under oxygen gas and at 200 or 210 degrees Celsius, the thermal stability of the material against oxidation is measured.

The minimum stability time is greater than or equal to 20 minutes.

In accordance with the standards:

National Standard of Iran (INSO): 7186-6
International Standard (BS-ISO): 11978-6

Carbon Dispersion Test

The uniform distribution of soot particles in polyethylene products is very important because uniform particles in polyethylene products cause stress accumulation and reduce the lifespan of polyethylene pipes. This test is performed using a microscope and hot press machine.

Soot in the polyethylene pipe structure must be distributed in a unique way. This test is a method for evaluating the particle size and hunks of soot/pigment under the microscopic and determining the degree as degree of soot distribution, as well as investigating the distribution of particles and determining the type of distribution by comparing with the reference images in the relevant standard.

In accordance with the standards:

National standard of Iran INSO: 20059
ISO reference standard: 18553

Density measurement of polyethylene products

In this test, density measurement is measured by immersion of raw materials and polyethylene products.

Density is the ratio of mass to volume of a material which is expressed in kilograms per cubic meter or gram per cubic centimeter. Density quantity is often used to follow changes in the physical structure or composition of plastic materials and is classified based on the density of polyethylene. Density may also be useful in determining the uniformity of samples.

In accordance with the standards:

National Standard of Iran (INSO): 7090-1
Reference Standard (ISO): 1183-1

Investigation of polyethylene pipe cracking due to environmental stress (ESCR)

This test is specific to LDPE polyethylene materials and pipes. (HDPE materials are resistant to acidic environments). The samples are placed in tubes containing Eggy pal acid under mechanical stress (bending) and placed at the test temperature (according to the standard) for the necessary time. After the time of the test, the cracks will be examined in the eye.

In accordance with the standards:

National Standard of Iran (INSO): 7175-8
Reference Standard (ISO): 8796

Determination of carbon black content

By this test, the soot of raw materials and products is controlled, the color of the polyethylene pipe is effective on the long-term stability of the pipe against wind and sun, and soot or masterbatch, which is added to it for blackening polyethylene, creates very good stability against UV radiation.

Polyethylene pipes contain 2-2.5% soot as a UV stabilizer. In this test, the residual soot from the pyrolysis (thermolysis) test is measured. The test is carried out in a furnace with temperatures of 500 to 600 degrees Celsius in the vicinity of nitrogen gas. At 850-950 °C, the remaining carbon content is affected by oxygen, and carbon is removed as CO2 to determine the percentage of residual ash weighed and determined.

According to the standard:

National Standard of Iran (ISIRI): 7175-2
Reference Standard (ISO): 6964

Tensile test

The purpose of the tensile test is to determine the tensile properties of the sample such as yield stress (passing from elastic deformation to plastic in stress/strain diagram) and percentage of equilateral increase. The sample is prepared in the form of dumbbells by press or CNC based on specifications and is drawn by a traction device.

According to the standard:

National standard of Iran INSO: 17140-1
National standard of Iran INSO: 17140-3
Standard (ISO): 6259-1
Standard (ISO): 6259-3

Measurement of Molten Flow Rate (MFR) or (MFI)

This test is a method for measuring the mass flow rate of molten soft heat materials under specified temperature conditions in grams per 10 minutes.

Molten flow rate (MASS-FLOW RATE) is a measure of the viscosity of a thermoplastic polymer (thermoplastic) and the molecular weight function of the polymer. Specifically, the mass of a molten polymer that is lubricated by the force of weight at a specified temperature from a given circle to a certain length and diameter within 10 minutes is the molten flow rate of that polymer.

Also, the difference between raw materials and the final product is measurable in accordance with the standard of this method.

According to the standard:

National Standard of Iran (INSO): 6980-1
Reference Standard (ISO): 1133-1

Hydrostatic Pressure Test

This test is used to evaluate the quality of polyethylene pipes and fittings and the standardization of the product and raw materials used in the preparation of pipes and is a suitable method for determining the resistance of polyethylene pipes and polyethylene fittings against hydrostatic internal pressure at specified temperatures and specified pressures.

In this test, the polyethylene pipe sample is placed under constant hydrostatic internal pressure after closing the caps to the ends, in a van filled with water (for routine tests of polyethylene pipes) with a specified temperature of 20 or 80 degrees Celsius and a specified time (100 to 10,000 hours). The appearance of any defects in the samples (bursting or leakage) means that the test result is rejected and acceptance is subject to the failure of the sample during the test period. Also, another test called the burst test (burst) is performed by the hydrostatic method. The method of sample preparation and preparation in the Brest test is similar to the Hydro test. The difference is that in the Brust test, the goal is to observe and check the way the pipe bursts. The test method is such that the internal pressure of the sample according to the ASTM 1599D standard increases continuously so that it swells and bursts over time.

According to the standards:

National Standard of Iran (ISIRI): 12181-1 and 12181-2
Reference standard (ISO): 1167-1 and 1167-2
Reference standard (ASTMD): 1599