AAOM Handbook

• Design - fatigue, chemical action, wear and fouling are all, to some extent, 'designed in' to a process based on the purpose of the process and the choice of technologies for its implementation. • Operation - wear, stress and fouling can be influenced by the age of process elements, operating rates, operating conditions, feed materials, maintenance and process shutdown/start-up cycles etc. • People - the errors, omissions or deliberate actions of people, resulting in changes to operating procedures/limits or material/equipment specifications, can lead to stress, chemical action or wear. • Environment; o Commercial - innovation and competition may lead to obsolescence of product, services or technology. o Natural – e.g. flood, tornado, hurricane, volcanic eruption, earthquake, or landslide can lead to stress, erosion, or silting. o Social – e.g. social unrest or sovereign risk may lead to damage or changes to expectations, standards, laws, etc. The probability of risks can differ significantly, and can also differ significantly over the life of a process. Some hazards and release mechanisms occur frequently, and consequently personal and organisational experience helps us to recognise the potential for them, to understand them and where they are likely to occur, and to identify Service Strategies that can be applied to them. However, some hazard and release mechanisms (for example fatigue, corrosion, fouling, and obsolescence) can develop very slowly, perhaps over decades, and sometimes out of easy view, with the result that; • few of us ever experience such events and hence do not expect them or understand what causes them, • the mechanisms may remain ‘hidden’ from direct observation, • when the mechanisms are visible we tend to become conditioned to slow changes and hence do not recognise the extent of change, and • even when changes are recognised there is a tendency to think that because the process is still functional repairs can be deferred in favour of the frequent, pressing issues that we must deal with. It is therefore important that we understand the probability distribution over time for each probable unwanted event. There are many possible probability distribution shapes for unwanted event, but the following are the most common: • High early risk probability decreasing (either linearly or exponentially) over time or operation to a more constant level (this distribution is referred to as infant mortality). This type of risks probability distribution is typically associated with the period immediately after a change to a process, e.g. a new employee, modification, maintenance, shutdown, start-up. The most common causes of infant mortality relate to design, construction/installation or operating errors that produce overstress or rapid corrosion or fatigue. The best preventive strategy for these threats is to ensure that the Work Management processes for new employees, modification, maintenance, shutdown or start-up delivers the right work, at the right time and in the right way. Any of the Service strategies except

© McAlear Management Consultants 2006

Operational Planning: Set Service Strategy

Updated: August 2018

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