Food Engineering

Food Safety: In preventive maintenance, little things mean a lot

April 1, 2010
Ignoring small parts such as gaskets, valves, clamps or connections can cause headaches.



For want of a nail the shoe was lost.
For want of a shoe the horse was lost.
For want of a horse the rider was lost.
For want of a rider the battle was lost.
For want of a battle the kingdom was lost.
And all for the want of a horseshoe nail.

This proverb shows how ignoring little things can result in disaster. If the loss of a nail can cause the demise of a kingdom, so too can small parts or components have major effects on process operations.

Preventive maintenance programs and start-up checklists tend to focus on major pieces of equipment, especially those that affect product quality or safety. However, the smallest parts, such as gaskets, valves, clamps or connections, can cause the greatest problems; yet these small parts are often ignored.

Gaskets are used on all kinds of processing equipment. They ensure good seals on fillers, which in turn ensure the fillers are working properly. Choppers and cutters use gaskets to minimize damage to the units and ensure that they seal tightly. Gaskets must be inspected and cleaned on a regular schedule. Even if a filler is cleaned-in-place, the gaskets may not be cleaned properly. Failure to clean (see images below) or replace damaged gaskets has ruined production runs, especially in cold-fill beverage applications.

Product can get trapped between the gasket and sealing surface or in the cracks of damaged gaskets, providing sources for spoilage organisms. As these organisms grow, they can inoculate product as it is filled. In a worst-case scenario, the entrapped residues can support the growth of food pathogens, which can get into product during filling.

Failure to properly inspect gaskets can also result in product adulteration. A damaged gasket may undergo catastrophic failure. It could break up completely and get into product.  

Ideally, gaskets should be replaced before they fail. Processors should also consider the type of product they are packing when selecting gasket colors and materials and choose a contrasting color.

Other seemingly minor parts of equipment can be like the “nail that was lost.” As part of the preventive maintenance program, the engineering group, HACCP team or quality group should conduct a risk assessment on each piece of plant equipment and the maintenance procedures required to keep that unit operational. One goal of the assessment should be to determine the potential risk posed by each “nail” in the piece of equipment and whether current maintenance procedures are adequate.

When conducting the assessment, look at the procedures defined by the equipment manufacturer, those developed by your own staff, and historical records related to the equipment, including maintenance records.

If the equipment manual recommends changing a gasket once a month, but experience shows the potential for failure before the end of that month, the risk assessment should address this. The assessment should also drive changes in procedures to minimize the potential for failure. The result may be a procedure where a gasket is removed daily for inspection and cleaning, and is then replaced every two weeks, whether damaged or not. This is an example of a risk-based maintenance program.

Make a commitment to training your team on the principles of risk assessment and let them know management supports the program. Management must provide training or consultants, time for performing the risk assessments and support to implement any changes that the risk assessment team deems necessary. These are essential steps for a successful preventive maintenance system.