failure defense planning

7/29/2019 Failure Defense Planning

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Emerson Process Management - CSI

DoctorKnow Application PaperTitle: Failure Defense Planning

Source/

Author:

Bruce Oyler

Product: GeneralTechnology: Vibration

Classification:Abstract

Failure Defense Planning (FDP) is an engineered process to facilitate maintenance planning for

achieving maximum reliability. FDP establishes the significance of systems and equipment to the

overall process, based on cost, production, safety, environment, quality, and other business

concerns.

The goals of Failure Defense Planning are conceptually similar to those of Reliability-Centered

Maintenance (RCM), but more efficient and directed. The process combines comprehensive

system and equipment ranking methods, equipment failure history reviews, personnel knowledge

harvesting and Failure Modes and Effects Analysis (FMEA) to rapidly provide a balanced

selection and prioritization of maintenance tasks for each piece of equipment.

The Failure Defense process is designed to establish the optimum balance of maintenance methods

consistent with the equipment operating context. The multilevel process is flexible and adaptable,

ensuring that maintenance and operations agree on the approach and the priorities. Failure Defense

Planning is readily integrated with a continuing improvement program and provides the foundation

for improving reliability and optimizing maintenance efforts.

Failure Defense Planning

Failure Defense Planning utilizes many of the elements of classical RCM, yet provides an efficient

and streamlined approach to systematically establishing the significance of systems and equipment

to the production process. FDP identifies and ranks the systems and associated assets, provides a

determination of the existing or potential failure modes and assigns the most cost-effectivetechniques for the maintenance of each piece of equipment. FDP provides the necessary support

for work prioritization.

The process is divided into four levels:

Level I: Ranking and Prioritization (SERP)

Level II: Failure Modes and Effects Analysis

Level III: Failure Defense Task Creation

Level IV: Implementation

A full Failure Defense Plan includes levels I, II and III, and IV. It should be noted that in a

practical application, it is not necessary for the levels to be carried out in numerical sequence, as

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the actual sequence will be to some extent dictated by the scope, criticality determination and

selection criteria.

The Results of FDP:

s System definition and ranking of systems by element

s Equipment assignment and ranking

s Ranked equipment list by critically to the systems Maintenance priority for critical equipment

s Failure Modes and Effects Analysis for critical equipment

s Maintenance task analysis for critical equipment

s Maintenance priority for noncritical equipment

s Maintenance task reviews for noncritical equipment

The Benefits of FDP

s An optimum balance of maintenance methods is established consistent with

the equipment operating context and business environment.

s Maintenance and operations are in agreement about the maintenance

approach and priorities.

s The process is dynamic and readily integrated with a continuing improvement

program.

s Equipment criticality is established for prioritizing remedial actions.

s Preventive maintenance activities are refined to ensure that equipment is not

over-maintained.

Preliminaries:

One of the motivating factors for the Failure Defense Planning Process is the desire to foster

communication and cooperation between all departments with an interest in the maintenance of

equipment, and in particular between production/operations and maintenance. It is, therefore, vital

that the process team be selected from a representative cross-section of all interested parties.

The team must include a mix of craft, supervisory and engineering personnel, all of whom have a

direct involvement with and "ownership" of the equipment in question. Seniority is not a

prerequisite for team membership and for effective teamwork, issues of seniority and rank must be

put aside.

The time involved in carrying out the process can be extensive, a commitment which must be

recognized from the beginning and given absolute priority. Typically, the greatest advantage will

be gained by carrying out the initial part of the work, covering the most critical equipment, in a

continuous block of effort. Then, the process for less critical equipment can be staged according to

other priorities, while still allowing for regular, uninterrupted periods of team activity.

Level I - Ranking and Prioritization (SERP)



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A typical plant facility is divided into distinct operational units. The SERP is applied to each

operational unit.

The first stage in the Level I SERP process is to determine the basic systems in the unit, where a

system is a collection of equipment which work together to provide a specific function in support

of the unit=s operation. Once the systems have been determined, each piece of equipment is

assigned to a unique system.

At the second stage, the system's criticality to the unit is gauged with respect to six different

aspects of the unit's operation. The results are combined to provide a system criticality ranking.

Thirdly, the equipment assigned to each system is ranked with respect to its criticality to the

system=s function, giving an operational criticality ranking for each item.

Fourthly, the operational criticality is combined with the system=s own criticality to the unit=s

operation to produce a single ranking of the equipment with respect to its criticality to the unit=s

operation, the asset criticality ranking. The highest ranked equipment forms the basis for a criticalequipment list, usually limited to 25% of the total equipment.

The fifth stage takes the critical equipment list as its starting point. In this stage, the reliability of

the equipment is assessed in broad terms, based upon equipment history, expertise of personnel

and interviews with operations, maintenance and engineering staff, at all levels. Reliability is

assessed on a numerical scale covering the range from highly reliable (requires little or no

attention) to highly unreliable (requires constant attention). This reliability factor (asset failure

probability) is then combined with the equipment asset criticality ranking to determine the

maintenance priority index. The MPI expresses the urgency and level of the demand placed by theequipment on the maintenance organization, if the unit is to operate successfully.

Once critical equipment is complete, at all levels of FDP, noncritical equipment will be assessed.

Level II -Failure Modes and Effects Analysis

In MPI order, the plausible functional failures of each critical piece of equipment are analyzed

using FMEA. The analysis is carried out using the knowledge of equipment experts, experience of

field personnel, maintenance histories, documentation, drawings, and equipment database

information. In conjunction, a series of interviews are usually conducted with all persons involved

with the equipment.

For each plausible functional failure, the possible failure modes, underlying failure causes and the

consequences for the equipment and systems are determined. This enables a suitable maintenance

task to be identified, or for an existing task to be reviewed critically.

Level III - Defense Task Creation

The MPI is used to prioritize the further analysis of appropriate maintenance tasks and the FMEAresults are used to select the optimum, most cost-effective mix of maintenance tools and methods.

The goal of failure defense analysis is to assign tasks which mitigate, warn or defend against



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equipment failures in an appropriate way. For critical equipment, the preference is always for non-

intrusive (operational condition monitoring and inspection), rather than intrusive inspection or

refurbishing actions. It is quite possible that more than one maintenance task will be appropriate,

perhaps of more than one type, for a specific failure mode, even though one or more predictive

tasks will be the first priority. There may also be a question of the extent of a failure to be

considered. At early stages of development, failure may not be obvious or may only degrade

performance, without a serious impairment of function. It may be possible, therefore, to have a

failure-finding task which is intermediate to routine predictive or preventive tasks which maydefend against a serious failure.

Establishing the correct technique or group of techniques will often require a separate predictive

maintenance review. It is important to consider all possibilities for condition monitoring, including

the use of established technologies, innovative technologies and other methods, such as operating

parameter trending.

Preventive maintenance tasks will be sought when a reliable condition monitoring technique is not

available or practicable. Preventive tasks should be subject to regular review for refinement basedupon operating experience and condition monitoring information. Ultimately, usually outside the

FDP process, the task will require clearly defined and detailed procedures, including assembly and

disassembly, specifications, tools and parts required, and so forth.

If a preventive task is not available, then an equipment modification or redesign task may be

considered. If this is not possible or practicable, then a reactive maintenance task will be sought,

including use of shutdown systems and failure-finding actions for early detection and mitigation of

failure consequences. Finally, if no economic or practical alternatives are possible, the risk of

running to failure, without any prior action, must be accepted.

Noncritical Equipment

When the maintenance task analysis is complete for the Critical Equipment, the process will be

continued with the remainder of the equipment list. It may be convenient to break the list down

into smaller sections, for example, every 20%, to make each stage more manageable, but

eventually all equipment should be processed in this way.

Maintenance priority should be established for each part of the list considered, in turn. Thepreferred approach is to follow the same process as for critical equipment, but from a practical

standpoint, owing to the large volume of work involved, the first action should be to review

existing predictive and preventive tasks. Each task should be defending an important functional

failure of the equipment. If it is not, the task should be eliminated, or replaced with a suitable

reactive task. If the task is appropriate, it must be ensured that it is performed at the correct

frequency, with continual review.

Level 4 - Implementation

Failure Defense Planning must be treated as a dynamic, continuous improvement process. Key

systems and assets have been ranked as they contribute to the functionality of the systems and

processes. In addition, the existing and potential failure modes have been established and



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associated with applicable and effective defense tasks. Therefore, appropriate mechanisms must be

put in place to ensure proper focus. Planning and scheduling activities should be based on the

established MPI. The priority of equipment repairs must defer to the asset critically ranking. The

maintenance force must be adequately trained and possess the skill set necessary to address the

identified failure modes. Most importantly, all personnel must be willing to address the critical,

high priority items first.

The failure defense tasks may require the acquisition of specialized equipment; and engineeringmay have to modify or redesign certain systems. Management must be willing to support all the

efforts required to ensure equipment reliability. The bottom line -- in the competitive environment

in which we live, we must eliminate unnecessary costs and focus on the activities that yield the

biggest bang for buck. By applying the right techniques and technologies in a structured approach,

the efforts of improved quality, a safer work environment, less downtime, and cost avoidance all

translate into higher profits.

All contents copyright 1998 - 2006, Computational Systems, Inc.

All Rights Reserved.

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