Pipes with nominal diameters 300 mm constructed from GRP or medium density polyethylene (MDPE) have been subject to transient internal pressure loads. generated by ethylene-air detonations. Several GRP sections survived repeated tests, while an MDPE Pipe failed in a catastrophic manner Time resolved strain measurements of the wall responses were obtained and both pre-cursor axial and transverse hoop strains have been resolved. The responses of idealized pipe supports tire also reported.