API 653 RESOURCES
Storage Tank
Integrity
Resources supporting tank inspection,
maintenance planning,& compliance activities.stewardship.

Inspection Beyond Compliance

API 653 provides the framework for the inspection, repair, alteration, reconstruction, and fitness-for-service evaluation of aboveground storage tanks.

Successful tank integrity programs require more than scheduled inspections—they require understanding degradation mechanisms, operating conditions, inspection history, and long-term risk exposure.

At Advanced Inspection Solutions, tank inspections are built around understanding:

  • How tanks deteriorate
  • Where damage develops
  • Why failures occur
  • Which areas present the highest risk
  • How inspection resources can be optimized

The AIS
Approach

AIS develops inspection strategies that combine:

  • API 653 Tank Inspection Practices
  • API 571 Damage Mechanism Reviews
  • API 580 Risk-Based Inspection Principles
  • Corrosion Mechanism Analysis
  • Tank Component Classification
  • Integrity Operating Window (IOW) Reviews
  • Corrosion Circuit Evaluation
  • Asset History Reviews

The objective is simple:
Focus inspections where risk and degradation are most likely to exist.

API 571: Understanding Tank Damage Mechanisms

Effective tank inspections begin with understanding how degradation occurs.

AIS utilizes API 571 principles to identify damage mechanisms that may affect tank floors, shells, roofs, nozzles, and associated components.

Potential degradation mechanisms may include:

  • General corrosion
  • Localized corrosion
  • Soil-side floor corrosion
  • Product-side corrosion
  • Water bottom corrosion
  • MIC (Microbiologically Influenced Corrosion)
  • Corrosion under insulation (CUI)
  • Atmospheric corrosion
  • Erosion-corrosion
  • Cracking mechanisms
  • Settlement-related damage

Understanding the active damage mechanisms allows inspections to focus on areas most susceptible to deterioration.

Tank System Classification

Every storage tank is different.

AIS evaluates tank inspection requirements based on:

Stored Product

  • Crude oil
  • Produced water
  • Hydrocarbons
  • Refined products
  • Chemicals
  • Specialty products

Operating Conditions

  • Temperature
  • Water content
  • Water content
  • Product composition
  • Fill and withdrawal cycles
  • Operating history

Consequence Factors

  • Environmental exposure
  • Spill potential
  • Production impact
  • Personnel exposure
  • Regulatory considerations

This classification process helps determine inspection priorities and mechanical integrity risk.

Critical Tank Components

AIS inspection planning focuses on the areas where tank failures most commonly occur.

Tank Bottoms

Often represent the highest corrosion risk within the tank system.

Evaluation may include:

  • Product-side corrosion
  • Soil-side corrosion
  • Water bottoms
  • Settlement effects
  • Coating condition
  • Leak potential

Tank Shells

Assessment focuses on:

  • Corrosion rates
  • Localized thinning
  • Weld condition
  • Settlement impacts
  • Structural integrity

Roof Systems

Inspection considerations include:

  • Roof corrosion
  • Drainage issues
  • Structural deterioration
  • Penetration integrity
  • Weather exposure

Nozzles & Appurtenances
Including:

  • Nozzle reinforcement
  • Weld condition
  • Flanges
  • Piping connections
  • External corrosion

Asset-Specific Inspection
Test Plans
(ITPs)

AIS develops inspection strategies specific to each tank and service.
Inspection planning considers:

Product Characteristics

  • Corrosivity
  • Water content
  • Contaminants
  • Chemical composition

Environmental Conditions

  • Temperature cycling
  • Moisture exposure
  • Atmospheric conditions
  • Foundation conditions

Historical Inspection Data

  • Thickness trends
  • Previous repairs
  • Corrosion rates
  • Settlement history
  • RBI assessments

Tank Design Features

  • Fixed roof
  • Floating roof
  • Cone roof
  • Internal floating roof
  • Foundation type

This approach maximizes inspection effectiveness while targeting the areas most susceptible to degradation.

Applying
API 580 to
API 653 Programs

AIS integrates Risk-Based Inspection principles to enhance tank integrity management.

Probability of Failure

Evaluating:

  • Corrosion activity
  • Tank age
  • Inspection findings
  • Coating condition
  • Settlement history
  • Damage mechanisms

Consequence of Failure

Evaluating:

  • Environmental impact
  • Product release potential
  • Personnel exposure
  • Production interruption
  • Regulatory risk

Risk-based methodologies help prioritize inspection resources on the tanks presenting the greatest integrity exposure.

Integrity Operating Windows
(IOWs)

Tank integrity is directly influenced by operating conditions.

AIS encourages owner-operators to establish operating limits that may affect degradation rates, including:

  • Water content
  • Product composition
  • Temperature
  • Corrosive constituents
  • Operating cycles
  • Treatment programs

Monitoring these variables can provide early indication of changing damage rates and mechanical integrity concerns.

AIS
Philosophy

Many tank inspection programs focus primarily on regulatory intervals.
AIS focuses on:

  • Damage mechanisms
  • Failure locations
  • Corrosion drivers
  • Inspection effectiveness
  • Mechanical integrity risk

By combining API 653 inspection practices with API 571 damage mechanism identification and API 580 risk-based methodologies.

AIS develops inspection strategies designed to support safer operations, improved reliability, and informed asset management decisions.

Stewardship Quote

"Tank integrity is preserved when degradation is understood, risk is managed, and critical assets are inspected before loss occurs."

— Kevin B. Hudgens
Founder & Principal Inspector
Advanced Inspection Solutions
API INSPECTION RESOURCES

API 653 Resources

Technical resources supporting storage tank inspection, condition assessment, repair planning, remaining life evaluation, and mechanical integrity compliance.