Maintenance Instead of Remediation How Predicitive Maintanance Reduces Both: Risks and Costs

Author / Editor: Hans Christian Schröder* / Anke Geipel-Kern

The reliability of technical test methods and models designed to forecast the behaviour of components under stress has increased over recent years. Nevertheless, insufficient maintenance or unsuitable strategies still sometimes result in failures and significant damage in process plants. The right overall strategy must be customised to each plant, taking individual features into account. This approach helps to reduce both costs and damage.

Downpipe with water leakage below a boiler’s steam drum
Downpipe with water leakage below a boiler’s steam drum
(Source: Tüv Süd)

Many costly defects and unplanned downtime can be avoided if weaknesses, such as leakage, cracks, wear, operational and design faults are detected in time and addressed by taking appropriate measures. Maintenance has come a long way from purely reactive repair and remediation of defects, evolving into today’s future-oriented service.

The objective is to establish a cost-effective, efficient and high level of plant availability and operational safety. One of the requirements for achieving this goal is the right maintenance strategy. As every plant is unique in its performance and behaviour, the maintenance strategy must be tailored to fit the situation in question and the individual operating parameters. Fundamental approaches are preventive, condition-based, predictive and risk-based maintenance.

Deterministic Strategies

Preventive maintenance while covering standardised and anticipatory servicing and maintenance measures at fixed intervals does not have a conceptual framework. It may avoid unplanned downtime but often results in excessive maintenance, i.e. the inspection and replacement of components before wear limits have actually been reached. This goes hand in hand with higher costs caused by unnecessary spare parts and production standstill for maintenance.

Condition-based maintenance monitors the condition of components to ensure prompt identification and assessment of potential defects. This approach allows for timely planning of the necessary maintenance activities. However, monitoring causes higher efforts and costs. Predictive maintenance additionally covers the active search for defects which is time consuming and involves high efforts for personnel.

Deterministic approaches follow the “if-then” principle of cause and effect — if X happens, Y will result. This principles form the basis of Germany’s technology laws. Maintenance strategies based on this principle have proved effective in safety technology. However, they too frequently result in excessive maintenance measures as defined safety factors must be complied with.