In this paper, a study on the comparison between the different methodologies for the determination of the safety distances proposed by Standard Organizations and national Regulations is presented. The application of the risk-informed approach is one of the methodologies used for the determination of safety distances together with the risk-based approach. One of the main differences between the various methodologies is the risk criterion chosen. In fact a critical point is which level of risk should be used and then which are the harm events that must be considered. The harm distances are evaluated for a specified leak diameter that is a consequence of some parameters used in the various methodologies. The values of the safety distances proposed by Standard Organizations and national Regulations are a demonstration of the different approaches of the various methodologies, especially in the choice of the leak diameter considered.