Vestman, Andtbacka, Groen
Industrial # 2006 Washington DC
The ability of a solid wall PE pipe (or solid wall pipe of any other material) to support internal pressure is directly related to the pipe’s ‘diameter to wall thickness’ ratio, the DR (dimension ratio) of the pipe. Pipe of a given material type with the same DR, regardless of size, have the same internal pressure rating. When extruding large diameter polyethylene pipe, it is therefore necessary to extrude wall thickness’ that are greater in absolute terms in order to maintain the ‘dimension ratio’. Since there is a practical maximum wall thickness that can be extruded, there is a corresponding decrease in the maximum internal pressure capacity of PE pipe, with an increase in pipe size.
Hydrostatic pressure testing as defined by ISO 9080 or ASTM D2837 indicate clearly that the long term duration under load tensile property of PE is the factor that determines the internal pressure rating (capability) of a solid wall pipe. The largest size PE pipe in the current commercial offering in North America (63” /1600mm ), is limited to continuous service at a pressure of 80 psi., based on the commonly accepted design tensile stress limitation for pipe made with PE 3408 (PE 80) resin and the design factors in common usage in North America ...