How reliable are your spare parts for critical equipment at your plant? When a critical piece of equipment comes down for scheduled or unscheduled maintenance, proper organization of your spare parts and related tools can reduce downtime by up to 50%. By setting up a best-in-class spare-parts process, the savings from a single repair job can pay for the entire program within your facility.
Most plants have critical-equipment spare parts, but the overall process of receiving, storage, and replenishment is generally not a priority for the organization. This philosophy results in the organization becoming reactive during both scheduled and unscheduled outages. This article provides a method of gaining control of your critical spare parts. First, this article reviews the costs associated with an inadequate spare-parts system and outlines how to determine which pieces of your equipment are critical in order to define the required spare parts needed in the warehouse to repair the identified items. (It is important to integrate this process into your computerized maintenance management system, or CMMS).
The second part of the article describes the process for kitting the parts, replenishing the kits after use, and returning kits to their proper place in the warehouse, and covers storage of specialty tools and the use and repair of oversize parts.
Note: This article does not cover the process of kitting for routine preventive and corrective maintenance as part of a maintenance management system. Instead, the focus is on critical equipment repairs and how to use a detailed, stringent process to provide faster, better quality, and lower-cost repairs on such equipment.
What parts to stock and how to store them
First, decide which parts, if any, you are going to stock in your warehouse and list them in the CMMS. To do this, you need to have an accurate asset register with a rigorous criticality assessment of each piece of equipment. This will help you focus on the equipment that really matters. You will also need to develop a repair philosophy to determine the following:
- Will the equipment be repaired on-site or off-site using your own personnel?
- Will the equipment be repaired on-site or off-site using a contractor or vendor?
- Who will develop bills of materials (BOMs) for stock and nonstock parts?
- How will quality assurance/quality control (QA/QC) be done on parts?
With the criticality review and repair philosophy in place, you can then inventory the spare parts in the warehouse, including performing a QA/QC assessment of the stocked parts. General issues found in warehouses include:
- Parts are rusted or damaged.
- Used parts are returned to the warehouse to be used as “new” parts.
- Parts are not found in the warehouse or are located elsewhere.
- Parts are not fit for purpose (bar stock passed off as reciprocating compressor connecting rods).
After confirming that the current spare parts are fit for service, review the BOM to ensure there are enough parts to complete a repair under a creditable-failure event. With this “creditable failure” criterion, you don’t have to provide complete spares for every piece of equipment or every machine part, but rather only the parts that will most likely be needed to keep critical equipment running.
Stocking spare parts in a warehouse is not enough, however. If quality parts are purchased and then stored in a warehouse without care, the parts may be hard to find or may not be usable once located, resulting in extended downtime and higher repair costs.
Stocking spare parts is usually contrary to the goals of the accounting department or the warehouse team, who wish to keep their inventory value as low as possible for budgetary and tax purposes. In fact, some warehouses have a policy to delete from stock any inventory that has not been used in three or four years.
Some critical parts and equipment, such as compressors, may not be used for five to 10 years, but when the part is needed, the cost of not having it or having to expedite it can be 10 to 100 times the cost of stocking and paying tax on the part. Among the cost implications:
- Being forced to use non-OEM parts because of the required fast turnaround can lead to potential issues with quality and the ability to meet design conditions.
- Expedited parts have a higher potential for error compared with those sent via standard delivery, potentially resulting in reduced reliability.
- Extended equipment downtimes while searching for parts in the warehouse or other locations or while waiting for parts to be delivered results in lost production, which can be millions of dollars.
- Being unable to locate specialty tools for repairs can cause further delays.
- Being unable to find parts for legacy brand equipment, as no information about these parts is readily available, can drive up costs and delays, as well.
Some equipment repairs require special tools to disassemble the equipment. Examples of specialty tooling include: hydraulic coupling removal tools, seal installation tools, thrust disk removal tools, and rotor positioning tools. If the tool is unique and necessary for repairing the equipment, then it should be made readily available along with the required parts. If these tools are not readily available, then the loss of time and production will be no different than that incurred because of missing parts. Therefore, specialty tools should be treated like spare parts: kitted and included in the equipment BOM.