Vapor Corrosion Inhibitors for Storage Tanks

API Technical Report 655: Vapor Corrosion Inhibitors for Storage Tanks

Protecting critical assets like storage tanks from corrosion is paramount in the oil, gas, and chemical industries. API Technical Report 655 (API TR 655) provides essential guidance for implementing vapor corrosion inhibitors (VCIs), a proven method to safeguard tank integrity and extend operational life. This authoritative document offers engineers and designers the knowledge needed to effectively deploy VCIs, ensuring the long-term reliability of storage infrastructure.

What is API TR 655?

API TR 655 is an industry-leading technical report developed by the American Petroleum Institute. It details the application and effectiveness of vapor corrosion inhibitors specifically for storage tank foundations. The primary purpose is to provide best practices for utilizing VCIs to mitigate corrosion, particularly in the under-tank environment where moisture and corrosive substances can accumulate.

Scope & Purpose

This comprehensive standard governs the selection and application methods for vapor corrosion inhibitors in storage tank foundation designs. It addresses various foundation types, including single and double-bottom configurations, and discusses materials and environmental factors that influence VCI performance. While focusing on VCI application, it does not dictate specific VCI product formulations or comprehensive tank maintenance schedules beyond the scope of foundation protection.

Who Must Comply?

• • Primary audience: Corrosion Engineers, Materials Engineers, Process Engineers, Maintenance Managers, and Operations Supervisors involved in the design, construction, and maintenance of storage tanks.
• • Industries affected: Oil and Gas, Refining, Petrochemical, and Chemical Manufacturing.
• • Compliance nature: The use of API standards is voluntary. However, regulatory bodies or third parties may incorporate this report by reference, making compliance mandatory in specific jurisdictions or projects.
• • Enforcement: Primarily through internal company policies, project specifications, and by authorities having jurisdiction when the standard is referenced in regulations.

Key Requirements Overview

API TR 655 outlines several key provisions for effective VCI implementation:

• • The standard requires careful consideration of various foundation designs, including those with release prevention barriers, sand pads, and concrete structures, when planning VCI application.
• • Professionals must ensure that environmental factors such as moisture, contaminants, and the potential for oxygen concentration cells or microbially induced corrosion (MIC) are evaluated to optimize VCI effectiveness.
• • Key provisions include guidance on the proper installation and maintenance of VCI systems within the tank foundation to achieve sustained protection.
• • The report emphasizes understanding how different foundation materials, like sand, concrete, and asphalt, interact with VCIs and the environment.

Related Standards & References

API TR 655 complements other essential API standards related to tank integrity and design. For instance, it works in conjunction with API 650 (Welded Tanks for Oil Storage) for overall tank construction requirements and API 653 (Tank Inspection, Repair, Alteration, and Reconstruction) for ongoing integrity management, ensuring a holistic approach to tank protection.