The effect of loading rate on the production of rapid crack propagation (RCP) was investigated in tensile loaded notched specimens 127 mm long taken from a gas pipe. It was found that the stress intensity to initiate fracture was independent of loading rate, but was slightly greater at 10°C than at 28°C. The initiation of rapid fracture occurred at a critical loading rate and rapid long range fracture (RCP) occurred at a 50% higher loading rate. It was not possible to produce RCP at 28°C with the available equipment. The input energy to initiate rapid fracture was about 10 times the input energy to produce RCP, long range rapid fracture.