Guide to Steam Sterilizer Stainless Steel Corrosion Removal in Sterile Processing

Sterile Processing Departments (SPDs) inevitably must deal with stainless steel corrosion, also called rouge. Corrosion on steam sterilizers is caused by a chemical reaction between moisture and stainless steel. While corrosion is often an issue many know little about on autoclaves, it is important to remove to prevent costly repairs.

If left unaddressed steam sterilizer corrosion can:

• Cause contamination, resulting in failed loads
• Increase equipment downtime and with unexpected repairs
• Require costly replacements earlier than planned

What is Stainless Steel Corrosion (Rouge)?

Did you know? Stainless steel can, in fact, still get stained. It would be truer to its name if it was called stain-resistant steel. When the passive layer on its surface is destroyed, eroded, or interrupted the iron underneath may begin to oxidize causing staining.

Stainless steel corrosion, also known as “rouge,” describes a variety of discolorations to the surface. The color depends on the amount of oxygen to which the surface is exposed. Inside steam lines corrosion will typically be black, while corrosion on an autoclave chamber is more commonly a red-brown color on the walls. Rouging can take place because of any water or moisture that builds up on the surface, regardless of whether it is pure water, ultra-pure water, steam, or simply tap water.

Since corrosion is caused by a chemical reaction between moisture and stainless steel, it is an unavoidable effect. Enhancing the corrosion resistance of stainless-steel equipment and removing rouge once it begins should be an essential part of your preventative maintenance schedule for any Sterile Processing Department.

What is the best way to minimize rouge formation on stainless steel?

• Minimize contact with water and moisture. While this may sound difficult, remember that steam sterilizers use dry steam in their cycles. "Wet steam" can indicate a problem with your equipment and if not addressed may lead to failed loads.
• Avoiding chemicals which may affect the passive film layer on stainless steel. Abrasive chemicals can scratch the surface, while harsh cleaning products such as bleach can break down the protective layer
• Implement a routine maintenance procedure for rouge removal and passivation of steam generation system components. Regularly removing and protecting against corrosion can ensure equipment downtime is minimalized.

How to Address Stainless Steel Corrosion

Since corrosion over time is inevitable, once it does occur it should be addressed quickly to prevent further corrosion and to keep your equipment operating efficiently. A typical procedure for derouging and passivation of stainless-steel equipment includes:

• Determining the cause of corrosion by obtaining a laboratory-based assessment. Depending on the cause, a water quality analysis can give insight on how to prevent corrosion in the future. STERIS offers a complete Diagnostic Solutions Service to provide full-service laboratory testing/analysis service of water and substrates
• Perform cleaning with an alkaline solution to remove organic residues. An acid treatment can be used to remove iron oxides (also known as derouging)
• Add a protective layer against further corrosion

Rouge & Rust Removal
from Stainless Steel

Since rouge is an iron oxide, chemicals that will break down iron oxides will remove the rouge. The process, known as derouging, should be tailored to the specific type of corrosion and can involve chemicals that require personal protective equipment therefore a proven professional method for successful derouging is recommended.

Adding a Protective Layer –
Tank Passivation

STERIS's Autoclave Chamber Cleaning Service is designed to maximize your steam sterilizer's performance and help you meet regulatory requirements. The proprietary STERIS Service process for autoclave chamber cleaning is performed by Medical Equipment Technicians who specialize in this service. Appointments are scheduled for your convenience – including off-hours and weekends to minimize disruption to your Sterile Processing Department (SPD).

The process of STERIS Autoclave Chamber Cleaning includes:

1. Manual preparation including chamber scrubbing
2. Cleaning process using Automated-Descaling and Tank Passivation
3. Documented environmentally-friendly chemical process using alkaline and acidic autoclave cleaning solutions which are carefully neutralized prior to disposal to avoid damage to plumbing

An industry-recognized team of chemists, engineers, and service professionals is available to offer product and process consultation for your derouging and passivation application. Only STERIS can provide solutions designed to work in concert to help you get the results you need, time and time again. Contact your STERIS Representative or call 1-800-548-4873.

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