HDPE (PE100) has a MRS of 10 MPa. The hydrostatic Design stress for the material is determined by applying a safety factor of 1.25. The design life for the water industry requires a minimum life of 50 years, therefore the design stress for PE 100 is ( 8 MPa ) Polyethylene pipe pressure ratings are generally referred to in bar; 1 bar is approximately equivalent to 10.2 meter head.
Two major factors (working pressure vs. temperature) plays major role in the life span and performance of HDPE Pipes. HDPE can give optimum performance under 20 ̊ C Temperature. However, if an environment where temperature and working pressure both are high, the following reduction factor in the life’s span of HDPE Pipe will apply:
It is necessary to make allowance for this in any design and installation which is exposed to wide variations of temperature. HDPE pipes will expand or contract by 0.2 mm per meter per °C rise or fall in temperature. A 30 °C temperature rise will therefore cause a 36 mm expansion of a 6 meter pipe.