MAINTAINABILITY

It is a concept closely related to the characteristics of equipments design and installation.It is defined as the probability that a unit or system will be restored to specified working conditions within a given period when maintenance action is taken in accordance with the prescribed procedures and resources.

Availability

It is the ratio of the time at which the equipment is available for the designated operation service to the total time of operation and maintenance of the equipment. It is also defined as the ration of equipments uptime to the equipment uptime and down time over a specified period of time.

The three types of availability are

⦁ Inherent availability

⦁ Achieved availability

⦁ Operational availability

Inherent availability

It is the probability that a system or equipment shall operate satisfactorily when used under prescribed conditions in a ideal support environment without any scheduled or preventive maintenance at any given time.

Inherent availability = MTBM/ MTBM+MTTR

Achieved availability

It is the probability that a system or equipment shall operate satisfacily when used under prescribed conditions in an ideal support environment with periodic preventive and corrective maintenance at any given time.

Achieved availability = MTBM/ MTBM+M

Operational Availability

In industrial system a certain amount of delay will always caused by time element such as supply downtime and administrative downtime.

Operational availability = MTBM/ MTBM+MDT

Where MOT is the mean downtime is the satisfied mena of the downtimes including the supply downtime and administrative downtime.

Resources

Resources include men, sparks and tools involved in the task of maintenance.

Administration

It include a nearby of authority and responsibility for decision making and plans for the execution of work.

Workplanning and control system

This is the mechanism for planning and scheduling the wok. This also include the feedback of information to drive the maintenance effort to its defined objective.

The basic objective of the maintenance organization is the ensure that the maintenance function ae carried out effectively and hence to minimize the production loss due to maintenance. There has to be a close relationship between the production and maintenance departments to achieve the desired targets of the industry. Continuous monitoring of planned preventive maintenance schedules identififed for the identified for the equipment is required to complete the maintenance tasks in time.

A maintenance organization can be countered as made up of three basic and necessary components.

Resources

Administration

Work planning and control system.

Maintenance of modern equipment and industry requires a healthy, balanced and rationalized organization, devoted to achieve the goals of maintenance task. The organization required for any system can be formed after study of the existing continuous and also the future demands of the industry.

The increasing complexity of present day equipment maintenance management has brought into focus two other aspects known as maintainability and availability, both of them are closely related to reliability.