The thermoplastic polymer components are used in new domains and the evaluation of their characteristics in specific conditions represents a new actuality domain. The experimental program realized on polyethylene sample pipes type PE 80, SDR 11 GAS, Æ160x15.5 mm had the objective to present the imperfection noxiousness of the geometric configuration, respectively the different dimensions and to define the influence of those to the safety in exploitation of the transport networks and to the industrial distribution of the fluids under pressure (water, natural gases, etc). A hybrid TT-IRT test method is used, combining the tensile test (TT) and the Infrared Thermography (IRT) method. The temperature distribution of the material is monitored under loading conditions with different rates. The noxiousness of the geometric discontinuity is analyzed by the local losses of resistance following the local heating in the imperfection areas. The results obtained are used in design calculus for the materials quality levels in specified safety conditions for the fluids transport networks.