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The Complete Failure Modes, Effects, and Criticality Analysis (FMECA) Course
By Richard Overman, CMRP
This is an introduction into the history and purpose of the Failure Modes, Effects, and Criticality Analysis. During this section, students will provide information about themselves, FMECA experiences, and course expectations. There are various standards and uses for FMECA. A brief description of these standards and uses is included in the introduction.
Purpose of FMECA
Difference between FMEA and FMECA
Standards and uses for FMECAs
Student activity (May vary depending on the course setting. Public courses will have a generic activity. Client courses will have activities applicable to their plant or industry vertical).
In this section the student learns what a function is and how it relates to the FMECA. The student will learn how to define functions, the difference between the primary and secondary functions, and how to appropriately limit functions to what is really needed. This is the foundation of the FMECA and is important to understanding the functional hierarchy.
Appropriate function applications
Functional failures are how the function fails and can be more than just the opposite of the function depending on how the function is written. In this section the student learns how the functional failure relates to the function. Because the next lower level in a functional hierarchy is the functional failure of the level above it, it is important to understand functional failures prior to the learning about the functional hierarchy.
Functional failure definition
Relationship between function and functional failure
The functional hierarchy is the mechanism by which the effects of the functional failures are related up from the point of failure to the product, plant, or organization. The student will learn how to identify functional levels, starting at the organization or plant level, identify the functions at that level, and use the failures of the functions to define the systems of the next lower functional hierarchy level.
Basic functional hierarchy
Top level item and functions
Defining the next level in the hierarchy
Next level item and functions
Defining the next level in the hierarchy
How to know when to stop
FAILURE MODES AND CAUSES
Failure modes are why the function failed. The failure cause is the actual physical cause of the functional failure. In some cases it is appropriate to combine the failure mode and cause while in other cases it is best to split them into two items.
What is a failure mode
What is a failure cause
When should they be combined
How failure modes and causes relate to the functional hierarchy
The failure effects are the impact of the failure at various levels of the functional hierarchy. This section describes how to identify the impact at the point of failure (local effect), the next higher level in the hierarchy (next higher level effect) and the effect on the plant or organization (end effect). Secondary damage can be as much or more important than the other effects.
Importance of identifying the effects
Identifying the local effect
Identifying the next higher level effect
Identifying the end effect
Criticality analysis can take on many forms and be used for many purposes. This section covers the multiple forms of criticality form a simple safety, environmental, operational, non-operational (code I-IV) criticality analysis to a more complex 3 significant figure criticality analysis. The type of criticality analysis used depends on the purpose for performing the criticality ranking. The concept of a Risk Prioritization Number (RPN) is a key concept of criticality and is covered within each appropriate part of this section.
Types of criticality analysis
When to use which type
How to use criticality numbers
EXAMPLE TEAM WORK PROBLEM
An example problem is used to give the students the opportunity to use the information they learned that day. The students will be divided into teams of 4 or 5 depending on the number of students. They will be given a scenario that will vary depending on the audience. In the scenario they will need to build a simple functional hierarchy and perform a FMECA at a specified level of that hierarchy. All of the information will be given to them but they will need to decide what information they need and how to use it.
VARIOUS USES OF FMEA
This section serves as an introduction to advanced FMECA. It expands upon the discussion during the introduction of basic FMECA about the various ways that FMECA are used.
The design FMEA is used to identify inherent design flaws or failures that need to be improved before putting the item into service. The design FMEA is usually performed at the repairable component level and generally does not include human error.
Purpose of design FMEA
Building a design FMEA
Making decisions from a design FMEA
FMEA FOR RCM
The Reliability-Centered Maintenance (RCM) analysis is performed to identify ways to prevent or mitigate the consequences of failure. The FMEA for RCM identifies the failure modes and effects that need to be prevented or mitigated. The FMEA for RCM is best performed at the sub-system or system level. Experience has shown that a design FMEA is not appropriate. The RCM FMEA generally does not but can include human error. This section covers the development of a FMECA that is most useful for an RCM analysis.
Purpose of RCM
Building a FMEA for RCM
Identifying Criticality for RCM
FMEA FOR RCFA
Root cause failure analysis (RCFA) is used to identify why failures occurred. This process begins with a FMEA to identify the failure modes for evaluation. The RCFA FMEA is focused on a specific failure and may include human error depending on the RCFA process being used.
Purpose of RCFA
Building an RCFA FMEA
Using the FMEA in an RCFA
The commissioning FMEA is a relatively new application of the FMEA process and is unique to this course. The commissioning FMEA is used to identify the things that can go wrong while staring equipment or processes. Commissioning FMEAs generally include human error. It identifies the failure modes that cause the commissioning or start-up to fail.
Identifying commission failure modes
Building a commissioning FMEA
As with the commissioning FMEA, the process FMEA is a new application and is unique to this course. The process FMEA identifies ways that a process can fail to fulfill its function. The process FMEA focuses on human error.
Identifying the process function
Human error failure modes
Building the process FMEA