Summary In this paper, we present a hybrid network model (HY-PIPENET) that uses a minimum cost spanning tree (MCST) network algorithm to determine the optimum path and constrained derivative (CD) method, to select an optimum pipe diameter. The HY-PIPENET has been validated with the published data of a six-node/seven-pipe networking system, and, moreover, this system has been optimized with the MCST-CD method. As a result, it was determined that the gas can be sufficiently supplied at a lower pressure with smaller diameters of pipe, compared to the original system in a six-node/seven-pipe network. Hence, the construction cost was reduced about 40% in the optimized system. The hybrid networking model has also been applied to a complicated domestic gas pipeline network in a metropolitan area of Korea. In this simulation, a parametric study was performed to understand the role of each individual parameter such as the source pressure, flow rate, and pipe diameter on the optimized network. From the results of these simulations, we have proposed that the optimized network is a tree-type structure with an optimum pipe diameter and source pressure, which was used in a Korean metropolitan area. This proposed system however, does not consider potential environmental problems as well as safety concerns.