As the infrastructure for piped hydrogen, including long tube trailers, urban utility tunnels, and hydrogen fuel cell vehicles, expands, the risk of hydrogen explosions increases. To enhance safety technologies and minimize accident risks, this paper presents a study where hydrogen venting tests were conducted with concentrations ranging from 30 % to 60 % in a 2.25-meter-long shock tube with an inner diameter of 70 mm. The effects of different vented areas and different vented shapes on the overpressure propagation law and flame characteristics were investigated. The results indicated that higher hydrogen concentrations increase vent flame temperature, but not pressure proportionally, with 40 % H2 producing the highest pressure peaks under all vented conditions. Smaller vented areas reduce the secondary explosion's impact on internal piping and the sensitivity of venting effectiveness to concentration. The distribution of pressure peaks on the outside of the pipe is highly dependent on the vented area. The vented shape has little effect on pressure, but has a slight effect on flame characteristics at R=2/5 or 1/5. In addition, the mechanism behind pressure peak generation during pipeline venting and a brief consequence analysis of the most hazardous scenario of secondary explosions has been provided.