Process risk analysis is used in industrial activities to diminish accident potential by the application of prevention or protection techniques to improve process safety. For this purpose, Preliminary Hazard Analysis and HAZOP have been applied to a hydrogen gaseous effluent treatment and purification plant. This plant recovers contaminated gaseous effluent hydrogen from a metallurgical iron powder reduction furnace. Purified hydrogen is recycled to the process. The process safety studies included hazard identification and consequences to material, equipment and people. The study proposed specific process safety measures and future additional process safety studies.