ABSTRACT
A statistics of fractures of transmission pipelines is presented where the fracture of a large diameter pipeline is regarded as a catastrophe whereas fracture accidents involving smaller diameter pipes are considered to be less dangerous. It is found that hydrogen causes brittleness in the outer layers of the pipes. Therefore, critical crack lengths for pipes have been calculated by means of linear fracture mechanics techniques. It was found that a crack of any length may become critical. The contrary opinion claiming reliable operation of large diameter pipes (larger than 1420 mm in diameter) will be discussed.
