Which is Better-HDPE or MDPE for Gas Pipes?

摘要

The density of the resin is not a propertyrnthat directly determines the performance of arngas pipeline. The important factors are, thernresistance to slow crack growth, SCG, thernmaximum operating pressure and thernresistance to brittle fracture by rapid crackrnpropagation, RCP. The resistance to SCG isrnalready mandated by ISO and ASTMrnspecifications so that the choice of a resinrnbased on SCG is not a significant option.rnThe greater the density the greater thernpossible maximum operating pressure. Thernresistance to RCP tends to increase withrndensity, but the choice of resin with respectrnto RCP should be based on the criticalrntemperature of the resin above which RCP isrnnot possible at any pressure. The criticalrntemperature of the resin should be below thernminimum operating temperature of thernpipeline. It is suggested that the ASTMrndesignation of gas pipe resins be PE06 andrnPE08, which would be consistent with thernISO designations of PE80 and PE100, whichrndo not classify gas pipe resin according torndensity.