[en] Gas Distribution Companies have long paid great attention to improving the quality of gas supply service to the consumer. This has involved them in an on-going attempt to successfully define and establish a clear computer assisted replacement programme which, when drawn up on a reliability basis, may also prove cost effective. The reasons which drive any gas line replacement programme are mainly related to the necessity: to improve the gas network asset so as to face a striking expected growth in gas demand; to refurbish old distribution systems with the purpose not only to increase the reliability and continuity of gas supply but also to reduce the rate of maintenance costs due to frequent repair works; to prevent the possibility of massive replacement works for a progressing ageing of the network. This paper will present the computer assisted procedure being implemented by Italgas. It ranks well defined network areas which urgently need renewal and also have a favourable economic index for action. The results of the analysis performed on a trial model network managed by the Geographic Information System, will also be a topic for discussion. (au)

[en] The effort made by Gas Distribution Companies to improve the quality of services rendered to its customers has resulted in their commitment to carry out feasibility studies, aiming at assessing both economic conditions and reliability of technical renewal programmes concerning gas networks. In this article are described: a) an analysis procedure on economic conditions and reliability, in order to detect and classify 'areas' where interventions take priority; b) the results of analyses carried out on a network prototype described and operated by a local computing system. In the above mentioned analysis reference was made both to test results and criteria currently adopted by international Companies with a long experience in a gas distribution