This study experimentally addresses the pressure evolution during the closed and vented explosion progress of a methane-air mixture ([CH4=10%]) in different vessel-pipeline configurations at ambient initial temperature and different initial pressures. Based on the experimental measurements, it is found that the maximum values of both closed and vented explosion pressure increase linearly with the initial pressure in isolated and linked vessel scenarios. Compared with a vented explosion, the initial pressure has a greater impact on the explosion overpressure in an isolated vessel and a single spherical vessel connected to a pipe during a closed explosion. For the configuration of two spherical vessels connected by a pipe, the explosion overpressure in the primary vessel is always lower than that in the secondary vessel during both closed and vented explosions at each initial pressure. According to Chapman-Jouget Detonation Theory (C-J detonation theory), when the ignition is located in a large vessel, detonation is observed in the secondary vessel at an initial pressure of 0.08 MPa. The vent position and ignition position both have an influence on the extent of variation of the pressure differential between two vessels with a given initial pressure. For the configuration of a single vessel connected to a pipe, the initial pressure influences the maximum explosion pressure and vented explosion overpressure least in a small vessel when the ignition position is located in the small vessel. These conclusions can provide references for the safety design of chemical equipment. (c) 2017 American Institute of Chemical Engineers Process Process Saf Prog 37:86-94, 2018