Failure modes equipment description

What are the proper service descriptions and failure modes of the equipment ... 

The first step in FMECA is to determine a level of resolution. If a system-level liazard is to be addressed, equipment in die system must be studied for a plant-level hazard, individual systems within die plant must be examined. Once the level of resolution luis been determined, a format must be developed-one to be used consistendy tlu oughout die study. A minimal format should include each item, its description, failure modes, effects, and criticality ranking. 

An FMEA table contains a series of columns for the equipment reference number, the name of the piece of equipment, a description of the equipment type, configuration, service characteristics, etc, which may impact the failure modes and/or effects, and a list of the failure modes. Table 2 provides a list of representative failure modes for valves, pumps, and heat exchangers. The last column of the FMEA table is reserved for a description of the immediate and ultimate effects of each of the failure modes on other equipment and the system. 

In the first step a description of the equipment or system is done in a way to imderstand boimdaries and all functional failures that may occur. Here a FMEA could be an interesting tool to look for potential failure modes, causes and their effects. 

Failure Modes and Effects Analysis (FMEA). A failure modes and effects analysis (FMEA) is more structured than a what-if analysis. The teehnique provides for a rigorous analysis of equipment to identify single failure modes that can lead to an effect or incident. The failure mode provides a description of how the equipment failed (e.g., open, closed, stopped, running, on, off). The effects provide a description of the undesired consequence or incident. As a hazard evaluation technique, it may also be used to prioritize the criticality of each effect. 

Fractography is an indispensable tool for extending imderstanding of how and why a material fails. On accoimt of its great depth of field, SEM is an essential item of equipment for fractiu-e siuface analysis. Scanning electron microscopic examination, together with the crack formation concepts (classification into fracture modes and description of their characteristics), provides an opportunity to reconstruct failure processes and to illustrate the limits to loading. 

Failure Mode and Effects Analysis (FEMA)—FEMA is a tabulation of facility equipment items, their potential failure modes, and the effects of these failures on the equipment or facility. Failure mode is simply a description of what caused the equipment to fail. The effect is the incident, consequence, or system response to the failure. It is usually depicted in tabular format and expresses failures in an annual estimation. A FEMA is not useful for identifying combinations of failures that can lead to incidents. It may be used in conjunction with other hazard identification techniques such as HAZOP for special investigations such as critical or complex instrumentation systems. There is also a Failure Modes, Effects, and Criticality Analysis (FMECA), which is a variation of FMEA that includes a quantitative estimate of the significance of the consequence of a failure mode. 

The number and severity of failures experienced by the equipment under study must be related to the operations of the facility. It would be inappropriate to assign the same operating histories to a continuously operating system and a system that operates intermittently. The number of hours in different operating modes (for example, 100% production versus shutdown) affect failure rate calculation and service description for taxonomy definition. 

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