Palermo, Vibien, Oliphant, Kosari
# 2006 Washington DC
The corrugated HDPE pipe industry is considering the responsible use of recycled materials in their pipe production and also in their pipe standards. One of the key requirements for successful use of recycled materials is ensuring performance of the resulting HDPE corrugated pipe. As slow crack growth (SCG) has been identified as a potential key criterion in long-term field performance for HDPE corrugated pipe, research was undertaken to develop a test method for corrugated HDPE pipe samples that results in laboratory SCG failures that test the highest stress riser in the pipe wall geometry. The test method developed utilizes pipe ring segments that are internally pressurized and tested at elevated temperatures, and result in an SCG failure in the liner wall, which is the highest stress area as measured by finite element analysis (FEA). By applying the mathematical modeling techniques of the Rate Process Method (RPM) on laboratory SCG data obtained on pipe ring samples at multiple temperatures and multiple pressures, it is possible to project the difference in SCG resistance between virgin and recycled materials under service conditions. Once the RPM performance of control HDPE corrugated pipe made with virgin resins is determined, it is then possible to determine the effect of recycled materials by conducting a similar RPM experiment on the same pipe produced with recycled materials. This paper will explain the pipe ring test method, compare SCG failure modes of laboratory data with pipe samples exhumed from field service, describe use of RPM methodology on the laboratory SCG data, and detail the proposed next phase in the development of the methodology.