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Cleaning Stainless Steel in the Midst of a Pandemic

  • April 24, 2020

While much is still unknown about the nature of the novel coronavirus, it has been discovered that the virus can survive for many hours on non-porous surfaces such as stainless steel. To be more accurate, the droplets of moisture expelled by an infected person can remain on a non-porous surface for hours or even days, allowing the virus to survive. In mid-March, a study co-published by experts from UCLA, the National Institute for Health (NIH), the Center for Disease Control (CDC) and Princeton University found that the virus can be detectible in the air for up to three hours, up to a day on cardboard and up to three days on plastic or stainless steel.

The virus had a shorter period of transmissibility of four hours when in contact with copper or brass, the latter being an alloy of copper and tin. Given that copper and brass don’t meet the standards for corrosion resistance and durability, industries are not going to switch away from the use of stainless steel. Given the prevalence of stainless steel in the essential food preparation industry, proper sanitizing of work surfaces is absolutely critical.

How COVID-19 is Transmitted

Knowing how COVID-19 is transmitted is essential to being able to prevent its spread. Based on what is currently known of the novel coronavirus formally referred to as COVID-19 (SARS-CoV-2), the primary means of transmission is when a person comes in contact with the droplets expelled by an infected person, primarily by coughing or sneezing. The droplets are inadvertently inhaled, allowing the virus to start an infection in the new host. The risk is especially high if the two people are less than 3 feet (one meter) apart, which is why the CDC recommends a six-foot (2 meter) “social distancing” separation as well as wearing a covering over one’s mouth and nose. The eyes are also a gateway for the virus, whether by coming in contact with the airborne particles, or when a person rubs them after coming in contact with a contaminated surface. The latter being the cause of the popular admonishing of not touching one’s face.

Cleaning Stainless Steel Work Surfaces

While it seems likely that the COVID-19 pandemic will eventually be resolved, it is important to remain vigilant both through its duration as well as going forward because it is only one of millions of viruses and the techniques for preventing its spread also apply to other diseases. The current practice of social distancing will be eased, although it is possible that face masks may become as standard as hair nets in food processing and preparation settings. In addition to preventing an asymptomatic person from spreading a contagion, the mask reminds the wearer to not touch their face.

On the surface cleaning front, the current arsenal of FDA-approved sanitizers for stainless steel is effective in eliminating the coronavirus from those work surfaces. In this time of heightened awareness, most companies are increasing the frequency of cleanings of such work surfaces along with other contact surfaces. While bleach is an effective disinfectant and anti-microbial it should not be used on stainless steel. The sodium hypochlorite (NaOCl) found in household bleach will cause it to corrode over time. This is because the oxy-chloride ions from the bleach will penetrate the passive layer of the stainless steel and interact with the free iron immediately below it. This is especially true of areas under stress, such as cracks, welds and formed areas. The end result will be surface pitting and staining or rouge. The former provides a place for bacteria-laden residue to collect, becoming a source for contamination. The latter is unsightly, but also serves to make it harder to spot areas in need of repair or cleaning.

The Need for Passivating and Cleaning Stainless Steel Goes On

Processing food and manufacturing pharmaceuticals are among the essential industries that are still ongoing during this global crisis. While it is highly unlikely, given what is known today, that COVID-19 could be transmitted through these manufacturing processes, the need to maintain the equipment and facilities has not changed. This will become even more true when a vaccine for COVID-19 is developed. Systems will need to be retooled and sterilized to avoid contamination. If new equipment will have to be added, it must first be properly prepared before it can be commissioned into use. As mentioned earlier, welds are a particular area of risk for contamination due to the damage done by the heat to the metal’s passive layer.

Across the country, Astro Pak has been deemed an essential service and its crews have been hard at work. Many of the normal protocols involved in processing stainless steel are directly applicable to avoiding infection. Astro Pak team members have noted that a cleanroom is possibly the safest place to be during a pandemic. Astro Pak technicians have been on-site at a number of facilities, ensuring that water systems, pharmaceutical production lines and other industries have been able to operate efficiently. And in our cleanroom division, Astro Pak has been supporting this emergent effort as selected customers have been sending ventilators and other medical device components to precision clean prior to assembly in the final product.

Going Forward

Regardless of when this crisis ends, there will be an ongoing need to maintain cleanliness. It’s easy to let one’s guard down after the “all-clear” has been sounded, but even without a future outbreak, there are still other sources of contamination and risks to health. Taking advantage of the current increased awareness to make best practices a habit is key to prevention.