Abstract
The paper directs the attention to the detrimental influences exerted by longitudinal notches on the polyethylene pipe surface when subjected under high pressure to long time service. It was shown that the detrimental degree is influenced by the notch depth, working pressure and service duration. Depending on these parameters, researches evinced two types of fracture behaviour: ductile and brittle. The conditions they produce and the transition limits of the ductile – brittle behaviour were demonstrated in two different environments: water and air, at the temperature of 80°C. Keywords: mechanical behaviour, testing duration, environment, PE 80 polyethylene, pressure, longitudinal notches, temperature, pipes