Every US OSHA 29 CFR1910.119 Process Safety Management regulated manufacturing facility is populated with equipment that requires appropriate maintenance to fulfill its role in manufacturing and to keep the facility operating in a safe and environmentally sound manner. However, not all equipment poses the same risks at failure when compared to those requirements. Therefore, from a risk perspective, not all equipment deserves the same level of maintenance attention. Proper categorization of risks and appropriate levels of maintenance attention help keep the facility operating safely by better allocating available resources where and when needed. This paper proposes an approach for establishing a hierarchy of maintenance attention based on various equipment failure risks. It does so by helping the reader to understand the difference between "Mechanical Integrity" and "Reliability" and the risks imposed by failure of either. A combination of different maintenance philosophies, such as preventive, predictive, and run-to-failure/breakdown, is discussed as possible approaches for allocating limited resources. (C) 2008 Elsevier Ltd. All rights reserved.