Pressure Testing of CIPP Liners to Failure

Cured in place pipe (CIPP) pressure liner can be designed as fully structural or AWWA type IV liners. This means the liners must carry all soil and live loads, as well as, all internal pressures that act on the pipe over its design life (50 to 100 years). For water pipelines, internal pressures that a liner needs to be designed for are the working pressure and recurring, and occasional surge pressures. These surge pressures can be two to three times greater than the working pressure and as high as 2000 to 2800 kPa (300 to 400 psi). The design of CIPP also has safety factors. This paper reviews typical pressures that occur in water distribution pipelines that need to be considered in CIPP liner designed. It also presents CIPP liner short-term pressure burst pressures for two commonly used CIPP liner systems. It then compares CIPP liner burst pressures with typical design pressures to investigate the design factors and compares these to current practice factors. It also discusses the construction of new liner pressure test facility at the University of Waterloo to advance CIPP pressure liners design, and to better understand CIPP liners’ response to surge and cyclic pressures.