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Installation techniques and service environments can be tough on the pipe materials, and as pipes are getting larger in diameter and thicker walled, higher toughness is required – especially in respect of crack growth resistance which safeguards against failures initiating from defects on the pipe surface arising at installation.
Additionally, PE pipes are being used at higher pressures and with a lower design factor, which demands greater consistency of performance from the raw material.
The level of product consistency and quality required can only be achieved by using ready-made fully compounded materials.
Blending of natural polymer with masterbatch in the extruder will fail to ensure good dispersion of pigments and additives and lead to poor long-term reliability. Only ready made compounds are tested by raw material suppliers over a long period of time to demonstrate compliance with the MRS value.
The illustrations below show how coloring with low quality masterbatch leads to pigment agglomeration and consequent premature failure as the agglomerations act as crack initiation sites.
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