The offshore exploration, drilling, and production, in O&G industry, are one of the most necessary activities of human Society. However, since its beginning in North America, the process variables - such as temperature, pressure and depth - have increased their operational parameters considerably, leaving the 21 meters deep, on land in 1859, extremely remote from the 6.500 meters in offshore area of Brazil Pre-Salt. To drill a subsea well and raise the crude oil to a platform, by itself, presents a series of risks that compromise the Process Safety of the entire plant. Avoiding a loss of containment, in addition to being inherent to safety itself, is also in the interest of the environment, production control and workers' health. In this sense, understand the safety barriers, as well as comprehend the Human Factors involved in Process Safety, not only brings operational reliability to the plant, but also meets the requirements of the legislation and increases productivity. In this research, a FRAM was developed to analyze a loss of containment of an FPSO storage tank, showing the importance of a systemic understanding of Human Factors in Process Safety, acting as an effective barrier to the security of the entire process.