The need to predict the fracture-mechanical behaviour of polymers is motivated by the increasing use of these materials in structural applications. In order to consider safety in the design of engineering components, it is important to know the behaviour of these materials during operation, their possible degradation mechanisms, and what factors affect the lifetime of the structures and structural elements. Polyethylene pipes have been used in long-term applications, including distribution

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... m for oil, gas, water and chemicals. The most critical location of these pipes is their welded joints. In this paper a short historical overview about the application of PE pipes, their basic matériái structure, characteristics, advantages and disadvantages, as well as their welding technology will be presented. Bevezetés