Vapor & Soluble Corrosion Inhibitors (VCI & SCI)

 

What is a Vapor Corrosion Inhibitor (VCI)?

Vapor Corrosion Inhibitors (VCIs) are corrosion-inhibiting compounds that volatilize and diffuse through an enclosed environment to reach exposed metal surfaces. VCI technology can be incorporated into a variety of delivery systems, including powders, liquids, films, emitters, oils, and other formulations depending on the application.

VCI technology is used across numerous industries to protect metal components, equipment, and infrastructure during operation, storage, shipment, preservation, and periods of inactivity.

 

How do Vapor Corrosion Inhibitors (VCIs) Work?

VCI molecules volatilize from their source and migrate throughout the enclosed environment. When these molecules reach the metal surface, they adsorb onto it and form a protective molecular layer.

This protective layer helps interfere with the electrochemical reactions that cause corrosion, reducing the interaction of the metal surface with corrosive elements such as moisture and oxygen.

Because VCI molecules can migrate through an enclosed environment, the technology can provide protection to recessed, internal, and difficult-to-access metal surfaces that may be challenging to protect using conventional coatings or other direct-contact methods.

 

VCI Protection for Hard-to-Reach Areas

Corrosion frequently develops in locations that are difficult to inspect, access, or protect using conventional methods. One of the advantages of VCI technology is its ability to migrate through an enclosed environment and reach metal surfaces beyond the immediate point where the inhibitor is introduced.

This makes VCI technology particularly useful for complex geometries, enclosed spaces, internal surfaces, and other areas where direct application of a traditional protective coating may be difficult.

 

Regulations for VCI Use

API TR 655 was published by the American Petroleum Institute (API) to provide information detailing the use of Vapor Corrosion Inhibitors (VCIs) for protection of the soil-side of tank bottoms from corrosion.

 

What is a Soluble Corrosion Inhibitor (SCI)?

Soluble Corrosion Inhibitors (SCIs) are corrosion-inhibiting compounds designed to dissolve in a liquid carrier, typically water, and provide protection when the inhibitor-containing solution contacts a metal surface.

SCI technologies can be used in applications where aqueous solutions are introduced into or circulated through equipment, piping, tanks, or other systems. Depending on the formulation and application, SCIs can help reduce corrosion during activities such as hydrotesting, wet lay-up, cleaning, preservation, and other temporary or operational conditions.

VCI and SCI technologies may also be used together when an application requires protection of both wetted metal surfaces and other exposed metal surfaces within the enclosed environment.

 

VCI & SCI Applications

VCI and SCI technologies can support corrosion mitigation and preservation across a variety of applications, including:

• Aboveground storage tank bottoms
• Pipeline preservation
• Pipe casing protection
• Hydrotesting and hydrotest water treatment
• Internal equipment preservation
• Piping and pipe segments
• Enclosed void spaces
• Spare parts and equipment storage
• Temporary and long-term preservation
• Other difficult-to-access metal surfaces

 

ZERUST Integrity Solutions^® evaluates the asset, environment, operating conditions, and corrosion risks to determine an appropriate corrosion mitigation approach for each application.

 

Corrosion Inhibitor Expertise

ZERUST^® has decades of experience developing and applying corrosion inhibitor technologies for the protection of metals. Through ongoing research, laboratory testing, field validation, and application expertise, ZERUST Integrity Solutions^® applies VCI and SCI technologies to address complex corrosion challenges across critical infrastructure and industrial assets.

The appropriate corrosion inhibitor technology and delivery method depend on the asset, environment, operating conditions, and project objectives. Our team works with clients to evaluate these factors and develop corrosion mitigation and preservation strategies suited to their specific applications.