Modern laboratory autoclave chambers are typically constructed from stainless steel, particularly 316L stainless, due to its durability and cost-effectiveness. In the past, however, many sterilizers were made using nickel-clad steel materials, prized for their exceptional corrosion resistance. Over the past 10–15 years, the industry has largely transitioned away from nickel cladding, driven by the increasing costs associated with its production.
Because while stainless steel offers many advantages, misconceptions about its resistance to all forms of corrosion can result in premature material failure. In certain environments, investing in a nickel-clad chamber remains the smarter, longer-lasting choice.
Stainless steel is a highly versatile material used across numerous industries, from food processing and medical devices to manufacturing equipment and semiconductors. In the medical and laboratory fields, the most widely used grade is type 316L stainless steel. This particular alloy is favored for its strength, chemical resistance, and ease of cleaning.
However, while stainless steel is the standard choice for autoclave construction, there are situations where nickel-clad materials warrant consideration. Despite its name, stainless steel is not entirely impervious to staining or corrosion—it is simply more resistant than ordinary steel. Understanding these limitations is essential when selecting the right material for your application. Let's take a closer look.
Stainless steel autoclave chambers are susceptible to corrosion from various sources, including poor-quality steam, contaminated water, and exposure to harsh chemicals. Below are some of the most common causes:
Chemical Exposure: Substances such as chlorides, sulfates, chlorine, hypochlorites, bleach, and acids are highly aggressive and can severely damage both the autoclave chamber and its plumbing.
Improper Cleaning Agents: Hypochlorites, acids, and bleach are especially corrosive and should never be used for cleaning or sterilization in an autoclave. The combination of high-temperature steam and these chemicals significantly accelerates corrosion.
Salt Solutions: High-concentration salt solutions, such as seawater, contain elevated levels of chlorides and are not suitable for sterilization in stainless steel autoclaves.
Water Quality: Tap water with high chlorine or chloride content should be avoided when generating steam, as it can contribute to long-term corrosion of the chamber.
Understanding and controlling these factors is key to maintaining the longevity and performance of stainless steel autoclave systems.
When sterilizing high-concentration salt solutions or using feedwater with elevated chloride levels for steam generation, a nickel-clad autoclave chamber is strongly recommended over standard stainless steel. While stainless steel offers many advantages, nickel-clad construction provides superior resistance in environments with high chloride content, significantly reducing the risk of corrosion.
The term nickel-clad refers to a manufacturing process known as cladding, in which a layer of nickel is metallurgically bonded to a carbon steel base. This results in a composite material that combines the structural strength of carbon steel with the exceptional corrosion resistance of nickel. Nickel-clad steel is commonly used in harsh, corrosive environments where traditional materials or coatings may fail.
To extend the lifespan of an autoclave and prevent damage, it's essential to clean the chamber immediately after each use. Use only cleaning solutions specifically designed for stainless steel surfaces, as improper agents—especially those containing harsh chemicals—can cause corrosion and compromise the chamber's integrity.
If the autoclave will be used to sterilize solutions with mild chloride content, passivation is strongly recommended. This factory-applied process enhances the corrosion resistance of stainless steel by restoring its protective oxide layer. When combined with routine, proper cleaning, passivation significantly improves the chamber's durability and long-term performance.
