Preventive Maintenance

Within the process safety management system, preventive maintenance (PM) consists of a program of test and inspections conducted on equipment to detect impending or minor failures and to mitigate their potential before they can develop into more serious failures. From a process safety point of view, a PM program consists of a number of activities, including:
    1. Identification of equipment and instrumentation critical to process safety
    2. Determination of required tests or inspections
    3. Determination of test or inspection frequency
    4. Establishment of maintenance procedures
    5. Training of maintenance personnel
    6. Development of acceptable limits or criteria for passing
    7. Documentation of results
    8. Analysis of results
    The first planning step is to compile a list of equipment for which some form of preventive maintenance is desirable .Items may be put on PM because of legal or insurance underwriter requirement, recommended practices by trade organization, manufacturers’ recommendations, company policy or the facility’s determination that the equipment or instrumentation is critical to maintaining the safety of the facility.
    A procedure should also be developed to ensure that new or modified equipment is added to the PM program as appropriate. The next step is to select the required test of inspection method; it can range from a simple visual inspection to use of sophisticated tools. Because selection of a method may involve complex technical issues, appropriate expertise should be employed in program development.
    Testing should be performed at an established frequency based on known failure history, manufacturer’s recommendations, and/or legal requirements. Where data are not available, engineering judgment must be used to set the initial frequency; this rate is adjusted on the basis of actual test data. The management system should also include mechanisms for initiating PM actions at the scheduled frequency and documenting the results.
    Control mechanisms should be established to ensure that the required PM has been properly performed. Appropriate maintenance procedures must be developed and approved to ensure that tests and inspections are carried out properly and consistently between individuals. For detailed procedures, checklists should be developed. At the same time, appropriate training must be provided maintenance personnel, so that they fully understand the PM procedures and are qualified to use any special tools or equipment. Coordination with purchasing personnel is also important to ensure an adequate supply of spare parts and the availability contractors.
    The final steps in a PM program include data review and analysis. For each piece of equipment or instrument undergoing PM, a set of criteria should be established to determine if the component has passed or failed the test. If it fails, then appropriate corrective action needs to be specified, including possible replacement. Finally, based on the results of the PM program, testing and inspection frequencies may need to be adjusted.
    Reference: CCPS(1989) Guidelines for Technical Management of Chemical Process Safety

    Management/Mechanical Integrity/Maintenance Procedures