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Q. In today's tough economy, I wonder what your thoughts are on keeping an extensive supply of spare parts. Can you help me formulate a spare-parts policy?

A. As a design/build contractor of complex operating facilities, it is essential for us to advise the owner of the spare parts recommended to maintain the effective operation of the equipment and systems and minimize the extent of any downtime.

While some owners may consider spare parts uneconomical — because some parts may never be used and there are costs associated with maintaining an appropriate inventory — you need to consider the expense of an extended plant outage which can far exceed the total cost of the spare parts.

Strictly speaking, spares are usually parts needed to replace other parts when they break or wear out. Spare parts management is the main component of a strategic service management process that companies use to ensure that the correct spare part and resources are at the right place at the right time. Controlling the spare parts inventory is paramount to maintaining the costs associated with unanticipated outages caused by equipment failures.

Some considerations in determining the consistency of the inventory include:

• Delays in getting the part from a vendor or a supply warehouse to the facility
• Those parts known to have a high rate of failure and/or wear
• Parts that may not be readily available when needed
• "High ticket" and "long-lead" items
• The proximity of other feed mills in the area with similar equipment and possibly comparable parts inventory

In a typical feed mill, some of the functional components include crushing, screening, and pelletizing equipment; conveyors and bucket elevators; mechanical and hydraulic drives; electrical equipment (primarily motors); computer and control logic hardware; boilers; and liquid-handling equipment, including pumps, valves, filters, and regulators.

The best time to generate a recommended spare parts list is during the design and procurement stage of the project. With the purchase of the original equipment, it is common to request that vendors furnish what they consider the necessary spare parts for their product, broken down by piece mark, description, lead time, and price. With our experience with plant operation and the need for critical components, these lists are reviewed, pared down, and consolidated into a recommended list that can be presented to the owner before startup and commissioning. This list is generally categorized as startup, initial, and long-term spares.

By purchasing a proper inventory of spares before initial plant operation and maintaining this inventory throughout the facility's life, the owner can increase worker productivity, decrease overtime expenses, and mitigate extended downtimes as a direct result of equipment failures.