New PPI Document Addresses Geothermal Ground Exchanger Piping Longevity

The Plastics Pipe Institute has published a new document to address ground heat exchanger piping longevity. PPI Statement AF: Projected Design Life of Plastic Piping used in Geothermal Ground Heat Exchangers is available here.

The piping material used for the ground heat exchanger is critical to the overall success of the system. It must provide corrosion resistance, flexibility, chemical resistance, resistance to slow crack growth, impact resistance, long-term hydrostatic strength (pressure capability), and temperature resistance.

GSHP pioneers experimented with various types of piping materials starting in the 1970s and 1980s and ultimately found that high-density polyethylene provided the properties needed for the majority of GHX applications. Cross-linked polyethylene was approved for use in geothermal systems in 2008, followed by polyethylene of raised temperature resistance piping, which was recently approved. PPI Statement AF provides detailed information about each of these approved piping materials, as well as the test methods used to predict their long-term hydrostatic strength.