In not-so-distant future, when water is going to become the most precious commodity in the world, the major challenge will be transport water to consumer without leakage and without affecting the water quality. Specified PE100 pipes have already demonstrated world over that it is the best candidate to accomplish this job at the minimum energy cost and over a minimum lifetime 50-100 years. It is necessary to understand what a specified PE100 material is, in order to ensure that the authorities are using the right material to derive the maximum lifetime benefits.
What are the requirements for a HDPE material to be classified as PE100 ?
As per the international standards ISO/DIS 4427 and EN12201, there are three requirements a HDPE material has to fulfil to be considered as a PE100 material:
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It should have Minimum Required Strength (MRS) of over 10 MPa, extrapolated over 50 years lifetime at 20 degree C.
This is determined by pressure testing of over 30 pipes each at temperatures 20, 60 and 80 degree C for 10000 hours. The failures of pipes at regular intervals are checked whether they are of ductile nature (desirable) or brittle nature and they are plotted on a Hoop Stress (MPa) vs. Time (Hours) plot. It is required that the ductile failure points form a straight line and there is no knee formed due to brittle failures before 5000 hours. The line drawn through the ductile failure points at 20 O C is extrapolated in a log-log plot to 50 years. If the Hoop stress at 50 years is between 10 MPA and 11.19 MPa, the material is classified as PE100.
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It should have resistance to Slow Crack Growth (SCG) of minimum 165 hours tested at 9.2 bar/80 degree C.
This is tested by making four notches of specified depth on the pipe wall in longitudinal direction at 90 O intervals. The pipe is then pressure tested with 9.2 bar internal pressure in a 80 degree C hot water batch. To be classified as a PE100 material, the pipe should not fail before 165 hours.
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Resistance to Rapid Crack propagation of Over 0.42 times of Max. Operating Pressure
Rapid Crack propagation is measured by bringing an internally pressurised pipe to 0 degree C and striking it with a sharp hammer to crack the pipe and see how far the crack is propagated. The crack should not propagate beyond the test length. Here we may either keep the temperature at 0 degree C and increase the internal pressure to determine the Critical Pressure (Pc). Or we may keep the pressure at 0.42 X MOP and reduce the temperature below 0degree C to determine the Critical Temperature (Tc). Following the above quality standards for compounded PE100 defined by international standards alone can guarantee a maintenance free lifetime for 50-100 years for specified pipes.
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Borouge is the leading suppler of specified HDPE PE100 black compounds for water distribution pipes in Asian market and a prominent member of PE100+ Association .Borouge brings the best of European technology to one of the Middle East's most modern plants and is rapidly expanding capacity in the polyolefins industry. For more information, please visit www.borouge.com.
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