tech article 111

©AV Technology Ltd 02.2012 CM41 Successful FMEA V1.1m

www.avtechnology.co.uk

©AV Technology Ltd 02.2012 CM41 Successful FMEA V1.1m Page 1

Successful Failure Mode and Effect Analysis (FMEA)

Simon Mills– Director of Training Services

– AV Technology Ltd


Introduction

FMEAs and other maintenance optimisation processes can generate huge amounts of data

It’s important to keep these processes manageable, for example:– Ask questions which can easily be answered

– Use engineering approximations where possible

– Limit the depth of investigations

This module outlines how to carry out FMEAs and achieve successful results and real benefits




Contents Objectives

– What you’re responsible for, & what your deliverables are

Pre-Requirements– What information you need up front

Simplified Methodology – Keep it Simple (KISS)– How to make approximations– Easy and hard ways

Practical Processes– Best Practice & Key References– Outputs & Deliverables E.g. Optimised Maintenance Plan– Examples


Objectives

Review design and operation of chosen equipment

Review failure history & failure modes Review current maintenance Agree failure mode criticalities Assign optimised maintenance tasks /

frequencies & owners Produce a revised maintenance plan for the

selected asset(s)




Pre-Requirements

To assist in the FMEA, examples of the following information are useful to support the review on the selected Pilot Area/Equipment:– General layout and schematics

– O&M Manuals for the selected equipment

– Any operator checks for the selected equipment

– List of current maintenance inspections (with history)

– Latest listing of plant breakdown history

– O&M logbooks referring to plant operation

– Listings of spares usage


Simplified FMEA – Best Practice

ISO 17359:2011 Condition monitoring and diagnostics of machines – General guidelines.

New 2nd Edition– Incorporates ISO 13380 – Condition Monitoring

and Diagnostics of Machines using performance parameters

– Adds 9 tables of different machine type FMEAs




ISO 17359:2011 – CM Procedure

The latest issue now has 8 key steps for best-practice implementation of CM:– Cost benefit analysis– Equipment audit– Reliability and criticality audit– Select appropriate maintenance strategy– Select monitoring method– Data acquisition and analysis– Determine maintenance action– Review


Additional Machine Type Examples

ISO 17359:2011 now includes nine different machine types – with typical examples of fault and failure modes – with associated symptoms and measurement parameters.

Examples of fault and symptom diagrams are now included for the following machine types:

– Electric motor– Steam turbine– Aero gas turbine– Industrial gas turbine– Pump– Compressor– Electric generator– Rotary internal combustion engine– Fan




For each of the machine types, the revised ISO 17359 gives a matrix of 27 applicable CM & Performance measurement parameters


For each machine type there is a table with:– A selection of faults and

– A range of measureable symptoms / parameters




Practical FMEA

A full reliability-centred maintenance process can generate huge amounts of data

It’s important to keep the process manageable– Ask questions which can easily be answered

– Use engineering approximations

– Use simple understandable models


KISS Tips FMEAs should be kept as simple as possible.

– Over complication is rarely a good idea so FMEAs should be kept as simple as possible to both evaluate and understand.

FMEAs should be easily carried out. – The easier it is to do, the more likelihood of the

FMEA data being available at timely intervals and on an on-going basis

FMEAs should be quantifiable. – Both Objective and Subjective data must always be

quantified. FMEAs should be done in a short time.

– FMEAs should always be completed in a relatively short time so as to limit the load on personnel.




KISS Tips FMEAs should be understandable by the whole

maintenance team– This ensures engagement of all team members, and

encourages participation FMEAs should be reviewed or subject to

continuous improvement– As business needs and techniques change then so

should the FMEAs which support them FMEAs should be communicated in an

appropriate manner to all sections of the workforce

– A key to driving improvement is the effective communication of progress to the very people who are making it happen


Typical FMECA Tools

Identify process

Itemise components and connections

Produce system level block diagrams

Process Flow Diagram

Reliability Block Diagram

Asset Criticality Pareto

Asset MTTR / Events / MTBF

Availability




Limiting the depth of an FMEA

Keep choices simple at every level– Asset Type– Asset Configuration– Asset Local Performance Requirements– Top 10 faults and failure modes– Preferred maintenance/CM technique– Match frequency to LTTF– Technique fault detectability & confidence– Output is maintenance plan


Making FMEAs Manageable

We should concentrate on:– known facts about the asset

– expected failure modes

Motor Driven Pump No. of rotor bars

Open Drive with Coupling

Rolling element bearings

Coupling No. of teeth or bolts

Bearing make, size and number of balls

Examples of Easy Facts Examples of Difficult Facts

Motor label Speed / Power Pump impeller number of vanes




Example

Estimate of How Many Maintainable Assets?– E.g. Total 2500

Number of Key Asset Types (Variants)– Rotating, Static, Electrical– Typically Max 30 per site

First Estimate Criticality [A, B, C]– A: Important– B: Routine– C: Ad Hoc (As and when)


Simple Criticality Review

Use consequence cards or spreadsheet

Include relevant factors– Operational

– Availability

– Maintainability

– Quality

– Health and Safety

– Environment




Example Asset Types (Typically Max 30)

Motor Driven Fan

Motor Driven Pump

Compressors

Conveyor

Mixer/Blender

Chillers

Tanks

etc


Example Asset Components

Ref Component

11 Pump Impeller

12 Seal

13 Valve

14 etc

15

16

17

18

19

20

Ref Component

1 Bearing

2 Cable

3 Coupling

4 Drive Belt

5 Electric Motor

6 Fan Rotor

7 Filter

8 Gearbox

9 Mount

10 Pulley




Example

Asset Type– Pump – 1430 rpm 18kW

Configuration– Open drive coupled

Local Performance Requirements– Cooling Water 5 Deg C– Downtime < 5%


Example of Top 10 Faults

Top faults and failure modes– Unbalance– Misalignment– Looseness– Lack of Lubrication– Bearing Damage– Leaks– Motor overload– Impeller erosion/damage– Seal Leaks– Corrosion




Workshop Examples of FMEAs


Importance of Local History

Sources– Operator Log Books

– Fault Reporting

– Work Orders

– CMMS

– Local Staff

Actual failure rates, MTBF, MTTR

Actual Lead Time to Failure (LTTF)




Assemble FMEA Data

Assemble the following for the selected asset type– Asset– Components– Failure Modes– Warning Effects– Root Causes– Task, Periodicity, Skill

For example:-


Maintenance Planning & Management

Most tasks can have estimated time & skill– FMEA sets requirements for techniques– CBM / PdM, PPM, Lube, Casual Inspections etc

Needs to be managed and scheduled– Schedule inspections– CBM / PdM Measurements

Feedback needs to be short but useful– Don’t just say “Completed”

• Better to add “Completed – no faults found”• Or “Completed – following faults found …”




Create the Maintenance Plan

Assemble Tasks

Allocate Resources

Carry out Maintenance

Feedback History


Key Points

Important to keep process manageable

Ask questions which can easily be answered

Focus on known failure modes Use approximations Use simple understandable

models




References ISO 17359:2011, Condition monitoring and diagnostics of machines -

General guidelines Developing a Maintenance Strategy and Setting Performance Targets,

Simon Mills– Presented at Maintec 2008– Published in ME Maintenance & Asset Management, Vol 23 no 5, Sept/Oct

2008 Understanding Maintenance Key Performance Indicators, Simon Mills

– Presented at Maintec 2010 Key Steps to Implementing Condition-Based Maintenance, Simon Mills

– Presented at Maintec 2011 Websites

– British Standards web site – www.bsigroup.com– ISO web site – www.iso.org– AV Technology Ltd – www.avtechnology.co.uk

tech article 111

Documents

cm41 successful fmea

successful results

successful failure mode

selected assetsav technology

real benefitsav technology

revised maintenance

failure mode criticalities

different machine types