An explosion venting system is established to examine the influencing factors of the vented explosion position for a single vessel, a single vessel connected by pipes and two vessels connected by pipes during the explosion venting process of a methane‐air mixture. Relative to a single vessel, it is shown that the maximum explosion venting pressure of the lateral vented explosion does not appear to vary greatly from that of a top vented explosion. It appears that as the volume of the spherical vessel increases, the maximum pressure increases. The maximum overpressure for an explosion venting on the top and side does not vary for either a large or small vessel connected by pipes. However, as the maximum explosion overpressure in the pipe increases, the maximum explosion overpressure peak occurs at the end of the pipe, and the explosion flame that propagates in the pipe accelerates and enlarges. Compared with an airtight explosion, an explosion venting on the top and side of a single vessel is more effective for both a large and small vessel connected by pipes. The pressure in the vessel and pipe appears to fluctuate and produces multiple peaks in the explosion venting process. Ignition in a large vessel is more dangerous than ignition in a small vessel under an airtight condition for two vessels connected by pipes. Regardless of the ignition position in the large or small vessel, the explosion venting effect in the small vessel is better than that in the large vessel. © 2017 American Institute of Chemical Engineers Process Saf Prog 37: 248–255, 2018