FSMA Standards for Construction and Sanitary Welding of Food-Grade Equipment

When President Obama signed the Food Safety Modernization Act (FSMA) into law on January 4, 2011, the purpose was to make food growers and processors more proactive in food supply contamination prevention as opposed to continuing the reactive practices of relying on recalls. As the deadlines were phased in through the supply chain, the businesses involved in this industry took steps to make certain that both their equipment and practices were in compliance. As with most detailed requirements, it’s easy to get overwhelmed by the specifications and come away unclear about the fundamentals. The most critical point to take away is the mitigation of inadvertent contamination of food processing equipment.

Design to Prevent Contamination

First and foremost, food items should never come in contact with any porous surfaces. Beyond that, the equipment should not have any crevices, cracks or corners where contamination can collect. And, the machinery must be easily cleaned as well as disassembled for cleaning. In and of itself, stainless steel checks the boxes for being easy to clean and non-porous. But the machinery must still be properly designed so that the entire structure is able to be cleaned to a microbiological level. There are regulations and requirements that affect every design aspect, some of which are challenging and require the expertise of a knowledgeable team to navigate.

The Right Stainless Steel

Not every grade of stainless steel meets the standards. For it to obtain Food Contact Substances (FCS) approval, it must have a minimum chromium content of 16%. SAE 200 series (chromium-nickel-manganese alloys), SAE 300 series (chromium-nickel alloys) and SAE 400 series (chromium alloys) meet the FDA, ANSI and NSF standards. In order for stainless steel located in exterior areas to maintain its natural resistance to corrosion, it must be in an environment with good air circulation, low-salinity and normal levels of oxygen.

Constructed of Compatible Materials

It’s not enough that the food contact surfaces are stainless steel, the metal connected to those surfaces has to be compatible. Corrosion from galvanic coupling and heat stress cracking due to differing thermal capacities can lead to liquids and food items getting caught in the corroded surfaces and becoming breeding grounds for bacteria.

Stress-less Surfaces

While heat and galvanic coupling are two sources of surface stress, it can also be induced during the construction process. A poor engineering design, too much stress applied to the metal to get it into place, or too much heat during the welding process can all lead to degradation of the stainless steel’s passive surface, leaving it vulnerable to corrosion.

Clean and Smooth

This is perhaps the biggest and most challenging area of concern. It also is heavily dependent on the skill of the engineers and the welders assembling the equipment. The surface roughness, also known as the roughness average (Ra) of the structure must not exceed .8µm (.008mm) or 30 Ra (micro-inch). Welds must be absolutely smoothed with no sharp edges or burrs – either of which could catch and trap food material, leading to bacterial growth. In fact, FSMA standards repeatedly mention the dangers posed by areas that can serve to promote cross-contamination. Therefore, all edges should be rounded, crevices should be filled and internal angles and corners should be curved, (coved or radiused). Welds themselves should never be made in corners, but rather on completely flat surfaces and each weld must be ground or mechanically polished to ensure a continuous, smooth surface. The end goal is that there should not be an area where material or liquid could get caught nor a section which cannot be as easily cleaned as the rest of the surface. Cracks, seams, lap joints or other gaps and niches serve as areas of entrapment for pathogens and must be avoided.

For that matter, when designing the unit, connectors such as bolts and rivets should be avoided as well since debris can collect under their heads. Instead, brackets, studs, mounting plates and the like should be welded. Ideally, the metal structure should not be pierced by a connector at any point and hollow areas should be hermetically sealed. That includes capping hollow legs, and ensuring that rollers and frames should be similarly sealed. Where parts must thread into each other, those joints must be sealed so that those parts do not become reservoirs of bacterial soup.

Additionally, areas where moisture does collect or condense as part of the food manufacturing process, should be designed to be self-draining so that the liquid is moved away from the product zone.

Sanitary Best Practices

It goes without saying that the machinery should be cleaned according to schedule and that the best practices must be followed stringently. Every part of the equipment must be reachable for maintenance and cleaning. But beyond that, the equipment must be inspected for operational damage that may compromise the safeguards built into its design. Dents or warpage can create low spots or open up gaps where liquids can pool and debris collect. The equipment itself must be easy to disassemble for regular, thorough cleanings. And, when reassembled, it must be done correctly. An improperly installed roller could spray a surface with material it picked up from the food item, or a missing panel can allow material to drip or be thrown into product zones. In terms of cleaning, areas adjacent to product contact surfaces should be treated as if they were product contact surfaces.

Some of these cleaning challenges can be lessened by automated, self-cleaning features and clean-in-place (CIP) systems which offer more efficiency than having to disassemble the unit for clean-out-of-place (COP) processing.

All cleaning protocols should be validated and documented. Any chemicals used for the cleaning and sanitation of the machinery will likewise need to be proven to be compatible with the equipment and the environment it is being operated in.

A Healthy Environment

As was mentioned above, the area that the machinery is to be installed in should have plenty of air circulation (dry) with normal amounts of oxygen and minimal salinity (low in chlorides) to keep the stainless steel’s passive layer – its first line of defense against corrosion – intact. Furthermore, consideration must be given to the rest of the production environment. It must be installed where it can be accessible for inspection, cleaning, sanitation and, of course maintenance. Any subsystems used for cleaning or the like should not provide a hygienic hazard to other systems. The machinery cannot be used for ad hoc storage of material and any maintenance enclosures should also be designed to avoid leaks and product residue accumulation. Similarly, human-machine-interfaces (HMI) such as levers, buttons, knobs and touchscreens need to also be designed with that same consideration. Lastly, the position where the machinery is installed must allow for clearances to ensure that no portion is inaccessible for damage or rodent activity inspection

The Final Word

It is not an overstatement to say that designing and operating food processing machinery in compliance with the FSMA is a complex undertaking. But, by making careful and well thought out decisions in the design and manufacture of the equipment, immeasurable amounts of time and effort can be saved during its operational lifetime.

Blog Posts

Picture of Daryl Roll

Daryl Roll

Astro Pak Consultant, Daryl serves as the primary senior technical advisor for corrosion, surface chemistry and stainless steel Passivation. With over 40 years of experience in chemical processing, Daryl has been published in MICRO, UltraPure Water Journal and Chemical Engineering for his papers on passivation and rouge control. He is a participant on the ASME BPE Subcommittees for Surface Finish and Materials of Construction requirements and a leading contributor for the Rouge and Passivation Task Groups. Daryl holds a B.A. in Chemistry and Earth Science from the California State University of Fullerton and a Professional Engineer's license from the State of California.

Blog Posts