Citric Acid Passivation for Underwater Load Cells and Torque Sensors

What Is Citric Acid Passivation?

Citric acid passivation is a chemical treatment process that removes free iron and other contaminants from the surface of stainless steel, enhancing its ability to form a passive oxide layer. Unlike older methods that rely on nitric acid—an aggressive, hazardous chemical—citric acid is safer, environmentally friendly, and equally effective when applied with proper controls and techniques.

This method is particularly well-suited for precision components, including those used in sensitive, high-value applications like load sensing and torque measurement under water.

Why Citric Acid Passivation Matters for Subsea Equipment

Both underwater load cells and underwater torque sensors require stainless steel surfaces that can endure the harsh realities of subsea use. These devices are often exposed to:

• Saltwater, a highly corrosive environment

• Varying pressures and temperatures

• Long periods of deployment with limited maintenance access

Citric acid passivation of these components ensures a clean, passive surface that resists corrosion and preserves the integrity of tight tolerances and measurement accuracy over time.

Key Benefits for Underwater Sensors

Enhanced Corrosion Resistance
Citric acid passivation eliminates surface contaminants that can lead to pitting or localized corrosion, especially critical for sensor housings and internal components exposed to saltwater.

Material Compatibility
Citric acid is effective on a wide range of stainless steel grades commonly used in sensor manufacturing, such as 17-4PH, 316, and 304, without compromising mechanical properties.

Eco-Friendly and Safe
Compared to nitric acid passivation, citric acid offers a safer, greener solution with fewer environmental disposal concerns—ideal for manufacturers adhering to strict compliance standards.

Improved Performance and Longevity
With a properly passivated surface, underwater sensors maintain their reliability and precision, even after prolonged exposure to extreme marine conditions.

Why Choose New England Electropolishing?

New England Electropolishing (NEE) is a recognized leader in citric acid passivation, offering tightly controlled, validated processes tailored to the needs of critical industries. Our expertise supports manufacturers of underwater load cells and underwater torque sensors with consistent, high-purity surface treatments that meet or exceed industry specifications.

Whether you’re developing next-generation subsea sensing equipment or looking to extend the lifespan of your current components, NEE delivers corrosion resistance you can trust.