[en] During last ten years ENEA funded several research programs with the objective of studying the fracture behavior of cracked pipes. In the framework of national programs almost 100 carbon and stainless steel pipes were tested under quasi-static bending moment. In 1988 ENEA joined the International Piping Integrity Research Group (IPIRG), a consortium of organizations from nine nations: Canada, France, Italy, Japan, Sweden, Switzerland, Taiwan, the United Kingdom and the United States. This 5-year program was conducted at Battelle Laboratories and was completed in June 1991. The scope of this paper is the comparison between Crack Mouth Opening Displacement (CMOD) estimation scheme calculations and IPIRG data relative to displacement controlled tests. Since CMODs are necessary to evaluate the leak area associated to through-wall cracks postulated in Leak Before Break analysis of nuclear power plant pipeline, the accuracy in the prediction of CMODs becomes fundamental. (author)