A new approach to achieving effective Contractual Service Agreements

A key variable, “Availability Importance”, creates a higher level of confidence in the Spare Parts List definition

In a typical Contractual Service Agreement (CSA) for a critically important item of equipment – a turbogroup used to drive a production line, for example – the client and the OEM will agree on a minimum level of plant availability. In the client’s interest, this level will be guaranteed. The manufacturer’s motivation is to achieve this threshold level of guaranteed availability at lowest possible cost.

The standard method of predicting future maintenance criticalities is Reliability Centered Maintenance (RCM). It has worked well in many business environments for over 30 years, but because it is largely based on qualitative assessments of key maintenance issues it is insufficiently precise for the development of CSAs.

At GE Energy, we have developed a new approach which is capable of defining the interaction between the three main parameters – reliability of the equipment, the nature of maintenance tasks, and the logistics of spare parts supply. This new approach is called Availability Centered Maintenance (ACM).

There are seven steps in the ACM procedure.

• Analysis of the Process & Instrumentation Diagram and equipment specifications
• Analysis of the operating conditions
• Collection and analysis of reliability data for the equipment
• Definition of the maintenance tasks relating to the equipment
• Random simulation of risks and ranking of Availability Importance (AI) of each component
• Definition of optimum spare parts list and location to achieve the required level of availability

“Availability Importance” in the sixth step is a new parameter, introduced by GE Energy, which defines the relative importance of each component of the equipment. ‘AI’ takes into account the function of the component within the system; the time and expense of replacing it after a failure; the time and expense of bringing the replacement part to the site; the Mean Time Before Failure of the component; and its cost.

Availability Centered Maintenance brings new confidence to the decisions that have to be made when offering a CSA. For more information on the statistical basis of ACM, please contact Giuseppe Ceschini.