A recent report on a study of the expected lifetime of high-density polyethylene (HDPE) pipes containing chlorinated potable waters adds a new, and perhaps primary, parameter to the conventional parameters of stress-cracking resistance (SCR), oxidative induction time (OIT), and carbonyl index (CI) for the determination of remaining lifetime of HDPE piping. The new parameter is the oxidation-reduction potential (ORP) of the water which seems to be more proportional to HDPE lifetime than any of the other parameters.
Lifetimes in excess of 100 yr in properly designed and installed piping systems are proposed. This ORP approach should also be applicable to HDPEs in contact with landfill leachates and waste waters. It will also most likely be applicable to fPP geomembranes and may, in fact, be the key to understanding the durability problems experienced over the last 10 to 15 years in potable water reservoir fPP liners and floating covers.
The Plastics Pipe Institute (PPI) has issued a press release regarding the report, “Impact of Potable Water Disinfectants on PE Pipe”.
The report is also available for free download online (PDF).
Ian Peggs is the president of I-CORP INTERNATIONAL, Inc. He can be reached at icorp@geosynthetic.com.
