Specifying fracture toughness ranks high in line pipe selection

The selection process requires a knowledge of the characteristics of fracture behavior which relate to toughness, the levels required for various line pipe applications, the factors which influence toughness, the means available in API Specifications 5L to achieve adequate toughness, and some ways in which a pipeline operator can obtain pipe with adequate toughness for various applications. What follows is meant to provide guidance on fracture toughness to purchasers of line pipe materials. It does not take the place of the rigorous analysis that may be necessary in many cases. What follows is meant to provide guidance on fracture toughness to purchasers of line pipe materials. It does not take the place of the rigorous analysis that may be necessary in many cases. Also, the suggested alternatives when impact data are not available are not nearly as dependable as impact tests themselves. Whenever possible, it is both prudent and desirable to know the fracture behavior of a line pipe material and to subject it to service conditions which will be unlikely to induce it to behave in a brittle manner.