Sterilizer Staining

What to Do About Stained Packs After Autoclaving: Common Causes and Affordable Solutions

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Written by: Scott Mechler

BS Mechanical Engineering, Mechanical Engineer

In the summer of 2016, Windsor Regional Hospital (WRH) in Windsor, Ontario, was forced to cancel hundreds of surgeries at its Ouellette campus due to a “mysterious sterilization scare.”

The strange scare, as reported in numerous media outlets, involved the staining of wrapping materials used to protect sterilized instrument trays during and after autoclaving. Because of the potential risk of contamination, the hospital was forced to suspend all of its surgeries — the impact of which meant the cancellation of 40-50 procedures each day.

Further investigation of the source of the mysterious staining revealed the culprit was the 54-year-old steam lines that run from the hospital’s powerhouse (central steam supply) to the autoclaves that sterilize the instruments.

While the hospital was eventually able to remedy the situation, the problem at WRH points to an incredibly common challenge autoclave users face throughout the world.

Staining of wrapping materials can cause serious disruptions and dollars lost — no matter if you’re in the health care industry or you work in a veterinary clinic, diagnostic lab, research or pharmaceutical facility.

Common Causes of Sterilizer Staining

Sterilizer staining occurs primarily for one reason — it’s almost always contamination of the steam lines.

This contamination can occur for variety of reasons. If you’re attempting to troubleshoot the cause of staining, the answers to the following questions may lead you to a solution:

  • Was your steam boiler serviced shortly before the issues started occurring?

Contamination of the steam lines may have occurred during servicing. During operation of a boiler, contaminants like hardness, suspended solids and dissolved salts precipitate out of solution and collect at the bottom of the boiler. If these contaminants aren’t removed during normal operation through either water filtration or a combination of regular blowdowns and preventative maintenance then an in-service can cause issues.

While the boiler is serviced, contaminants that are collected at the bottom of boiler can get disturbed and loosened enough that they get entrained and carried over in the steam flow to the autoclave. Additionally, sometimes the descaling chemicals used to clean boilers can leave residues behind. To prevent this, it is important to ensure these chemicals are completely neutralized and rinsed out.

If either of these scenarios occur, then the contamination may be brought from the steam boiler and then into contact the wrappings around the instruments or packs. When the steam condenses on the wrappings, then the contamination will be deposited into the fibers of the wrapping resulting in a stain.

  • What materials are the boiler and the piping to your steam sterilizer constructed from?

Typically, in situations where contamination is a concern, sterilizers will use clean steam systems – which means stainless steel boilers with stainless steel piping to the sterilizer chamber and a deionized water feed. If the materials in contact with the water/steam are carbon steel or iron then it is possible for rust to get carried over the steam time into the chamber and onto the packs. If the materials are all stainless steel or copper alloy, then it is best to ensure the water is of appropriate quality.

If recent servicing or materials of construction aren’t the issue, the second cause could be the water source.

  • Is the water source of your sterilizer treated and filtered?

If there are minerals, salts or other contaminating compounds in the water, these will be precipitated out in the boiler and then some of them will be carried into the steam line. Contamination sensitive applications use sterilizers and boilers constructed of all stainless steel. In these applications, the water source should be deionized water with resistivity greater than 1 mega-ohm/cm. This grade of water will typically be pure enough to prevent contamination onto the end product. If the water is treated or filtered in any way, ensure that the filtration system is in good working order with new filters.

  • Is your sterilizer unit being fed from a facility boiler?

If so, ensure that there wasn’t a change in additives to the steam line. Many times, house steam systems will inject chemicals and corrosion inhibitors into the steam lines in order to preserve the piping systems. These chemicals may react with the wrappings and cause stains to appear. Additionally, if the facility steam lines or condensate system was recently serviced, this could have loosened contaminants that were clinging to the pipe walls.

The last thing to examine is the dryness of the steam.

  • Are the steam lines to your autoclave insulated and trapped properly?

If not, then too much moisture may be entrained in the steam line. This moisture will pick up contamination as it travels though the steam pipes. It is recommended that you check all the steam traps and pressure regulators to ensure proper operation. Additionally, you can perform a steam dryness test to determine if the steam is at least 97% dry vapor.

How to Solve a Sterilizer Staining Problem

In the case of Windsor Regional Hospital, the solution was a new $500,000 steam-to-steam generator, not to mention the installation of new piping in the facility. This solution equated to a nearly $1.5 million investment.

Luckily, there is a more cost-effective way.

One way to capture impurities that typically cause steam staining is to use an appropriately designed steam filter with submicron level filtration and chemical absorbency capacity. Not all steam filters are made equal though, therefore it is important to employ a filter specifically designed to help address steam staining issues.

Steam filters should be installed on the incoming steam lines directly before the valves that feed the steam into the chamber. This approach is not only far more affordable (typically around $5,000-$10,000 including installation), but it is also easier and faster to implement while yielding similar results to a full system overhaul. Furthermore, a steam filter approach yields significantly lower facility downtime and interruption.

As a further benefit, a steam filter can act as a condensate trap and separator to help remove moisture from the steam line. An appropriately specified filter will also remove particulate impurities such as minerals, salts and rust that may be entrained in the steam line as well as reduce certain chemical loads.

Talk to the Experts

As the autoclave infrastructure in the world’s many healthcare institutions, learning laboratories and research facilities continue to age — the issue of sterilizing staining will undoubtedly continue to arise.

Contact CSS if you’re experiencing staining issues and we’ll put you in touch with one of our autoclave experts.

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