In Brazil, the Hospital Infections are the main cause of mortality during hospitalization, generating huge financial losses. In 2008, ANVISA issued a warning of epidemiological emergency due to the occurrence of infections by rapidly growing mycobacteria in all regions of the country, strongly related to failures in the processes of cleaning, disinfection and sterilization of medical products. Validation is a metrological tool that allows establishing whether the sterilization process developed is running efficiently and with reproducibility. ISO/TS 17665-2:2009, on validation of sterilization products for health, highlights the need of periodic revalidations, measurements of temperature with sensors distributed throughout the chamber volume, specifies acceptance criteria based on measurements of pressure in the internal volume of the chamber (theoretical temperature) and introduces the measurement uncertainty requirement. In this work, based on the requirements and recommendations outlined in national and international documents, a system and procedure are developed for the metrological reliability evaluation of saturated steam sterilizers. With the developed system, four gravitational autoclaves were evaluated. The results reinforce the importance of revalidation, environmental conditions, and the contribution of temporal stability and spatial uniformity in the overall uncertainty of the cameras. All the autoclave process was carried out by means of superheated steam, which is less efficient and non-conform to ISO 17665. The limitations identified corroborate with the recently published requirements of RDC ANVISA 15:2012, concerning both the need of periodic evaluations of sterilizers and the prohibition of the use of gravitational autoclaves with capacity exceeding 100 L.