Define Civil Preventive Maintenance Scenarios (Step 10)

Updated on 09 Aug 2024
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Find below additional details for Step 10 of the Civil RBI Methodology.

Generic maintenance tasks as function of Degradation Mechanism type:

Degradation Mechanism	Revealed	Unrevealed
Age-Related	Time-based tasks are tolerable. Condition-monitoring applied as a means of extending the run length of the asset	Overhaul or replace at the end of design life
Non-Age-Related	Condition-monitoring done to determine the best time for maintenance intervention. Time-based maintenance not appropriate	Test for function

Degradation Mechanism

Revealed

Unrevealed

Age-Related

Time-based tasks are tolerable. Condition-monitoring applied as a means of extending the run length of the asset

Overhaul or replace at the end of design life

Non-Age-Related

Condition-monitoring done to determine the best time for maintenance intervention.

Time-based maintenance not appropriate

Test for function

Generally, RCM recognizes three types of Default Actions:

Failure-finding: This entails checking hidden functions periodically to determine whether they have failed. This is not the same as condition- based monitoring, which entails checking if something is failing.
Redesign: This entails making any once-off change to the built –in capability of a system. This includes modifications to the hardware and once- off changes to procedures.

No scheduled maintenance: This entails making no effort to anticipate or prevent Failure Modes to which it is applied, and so those failures are just allowed to occur and then repaired. This default is also called run- to –failure.

Each category describes a preventive task, except for the Corrective Replacement which is the Base Case Scenario by definition. A PM plan usually comprises a combination of tasks from these categories.

Example: PM plan for steel asset

Task 1 (Lower Cost): 5-yearly coating upkeep, visual inspections

Task 2 (Higher Cost): Grit-blast and re-apply coating after Task 1 is conducted twice

Task 3 (Lower Cost): 5-yearly coating upkeep, after Task 2 is conducted

It is recommended to at least include the Preventive Replacement plan in the evaluation, since this is a final measure that can be taken to prevent the consequences from functional failure.

The figure below gives a simplified presentation of the strength reduction of a steel asset over time due to atmospheric corrosion. It also presents the maintenance intervention options throughout the lifetime of the steel asset. More information about inspection and maintenance practices is given in the Civil, Storage & Marine InfoBase documents.Simplified presentation of aging of a coated steel asset.

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What's Next

Estimate Civil Life Cycle Costs for PM Scenarios (Step 11)