Nowadays, most part of the Brazilian oil and refined products pipelines employ pressure relief valves in their protection system design. This means that the right sizing and operation of these valves are indispensable to ensure the safety of transport pipelines. These valves work relieving pipeline’s internal pressure, when it exceeds a set-point value. In other words, the role of this type of vale is to relief the pipeline in case of an abnormal condition which could cause overpressures. Hence, pressure relief valves can guarantee the pipeline’s non exposure to pressure higher than the ones specified in some project. It is important to mention that overpressures can lead to mechanical failure of the pipeline and, possibly, a leakage of the transported product to the environment. This project presents a performance study of relief spring-valves to avoid high pressures generated in hydraulic transients due to sudden reduction of flow, i.e, scenarios of accidental blockage of the flow by block valve located upstream of a receiving tank of the product being transported. The flow is determined using the method of characteristics. By this method one can model the flow through the pipe in the presence of relief valve and block valve. The modeling of the dynamic behavior of the relief valve was performed employing the classic formulation of mass-spring-damped system. The model was validated using available experimental data obtained in Department of Mechanical Engineering.