The monograph presents a scientific concept, computational technologies and methods of numerical modeling , designed to solve problems of improving the safety and efficiency of main pipeline systems using modern achievements of computational mechanics and mathematical optimization The material presented in the monograph allows the reader to study in detail the proposed basics of numerical modeling of main pipelines . The practical application of these basics is aimed at a comprehensive assessment of the state of pipeline systems of industrial enterprises and the definition of effective safe modes of their operation. They can be used both at the stage of operation of pipeline networks, and in their design. These foundations can be laid as a theoretical foundation in the creation of highly automated hardware and software systems for forecasting, early detection and prevention of dangerous violations in the functioning of pipeline systems. The basics of numerical modeling of trunk pipelines can be useful in the development and analysis of the effectiveness of anti-terrorist measures at highly energy-saturated industrial facilities. The practical application of computational technologies and methods of numerical modeling of main pipelines is illustrated by examples of solving production problems for Russian and foreign enterprises of the gas industry. Also demonstrated the effectiveness of using these technologies and methods to improve the safety of oil pipelines and pipeline networks of thermal power stations. The book may be useful to scientists and engineers , Design and Operation of Pipelines , Management of pipeline networks , Improving industrial and fire safety , as well as environmentally friendly, taking into account a wide range of environmental measures. The material is available to senior students of technical universities . Table. 17. IL. 307.