Replacement Strategies for Ageing Pipelines and the Consequences for Future Investments

Investments in gas distribution networks are very high, exceeding worldwide hundreds of billions of euros. Some of the materials used are already in operation for tens of years and may be replaced/renovated in due time. Too early replacement results in loss of capital. However, by too late replacement safety and security of supply may be in serious danger. An adequate replacement strategy is therefore needed. In this paper a decision tool for strategic replacement decisions is described. This approach is based on academic knowledge as well as practical experience on the various pipeline materials ( steel, cast iron, plastics ) in operation. The methodology described is based on an approach used by life insurance companies. The effects of various ( environmental ) parameters are described by static and dynamic factors. For the methodology a software tool, called Qualital, has been developed. This software tool is based on all the expertise and experiences of the Dutch gas companies and is already used successfully now by a number of companies. By using the methodology decisions on priority replacements can be made as well as insight on future investments be obtained. The system also secures historical knowledge within the company.