Free storage tank inspection checklist

• The MapTrack storage tank inspection checklist contains 22 checks across 8 sections. Sections covered: Shell & Bottom Plates, Roof, Foundation & Settlement, Vents & Valves, Cathodic Protection, Coatings, Bunding & Secondary Containment, Documentation.
• Tank identification: tank number, product stored, capacity, design code, construction date, last internal inspection date, shell material and design thickness.
• External shell: visual inspection for corrosion, pitting, dents, bulging, weld defects, staining (indicating seepage), coating and paint condition, shell-to-bottom weld condition.
• Tank floor: floor plate condition from external observation (settlement patterns, staining at shell-to-bottom junction), underside corrosion assessment from internal inspection or floor scan if tank is out of service.

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• Structural integrity: systematic inspection of shell, floor and roof components identifies corrosion, cracking and mechanical damage before they progress to leaks or catastrophic tank failure.
• API 653 compliance: documented inspection records with shell thickness measurements and corrosion rate calculations demonstrate compliance with API 653 in-service inspection requirements.
• AS 1940 compliance: verifying bunding, venting, overfill prevention and separation distances satisfies Australian regulatory requirements for flammable and combustible liquid storage.
• Environmental protection: detecting corrosion, seal leaks and bund defects before product escapes the primary containment prevents soil contamination, groundwater pollution and costly remediation.
• Optimised inspection intervals: API 653 allows inspection intervals to be extended based on documented corrosion rates, meaning thorough inspections with accurate thickness measurements can reduce the frequency and cost of future inspections.
• Insurance and regulatory readiness: complete tank inspection records are required for insurance renewals, environmental licence conditions and regulatory audits conducted by state environment protection authorities.

• Tank identification: tank number, product stored, capacity, design code, construction date, last internal inspection date, shell material and design thickness.
• External shell: visual inspection for corrosion, pitting, dents, bulging, weld defects, staining (indicating seepage), coating and paint condition, shell-to-bottom weld condition.
• Tank floor: floor plate condition from external observation (settlement patterns, staining at shell-to-bottom junction), underside corrosion assessment from internal inspection or floor scan if tank is out of service.
• Roof: fixed roof condition (corrosion, vent screens, pressure-vacuum valve operation), floating roof condition (seal condition, drainage, pontoon or deck plate integrity, guide pole and anti-rotation device).
• Foundation: ring wall or slab condition, evidence of settlement (differential or uniform), erosion under the tank edge, drainage adequacy around the foundation.
• Appurtenances: inspect all nozzles, manways, clean-out doors, drain valves, sampling points and instrumentation connections for leaks, corrosion and gasket condition.
• Secondary containment: bund wall condition (cracks, vegetation penetration, drain valve closed and locked), bund capacity verification, liner condition if applicable.
• Safety systems: tank gauging system operation, overfill prevention system test, pressure-vacuum relief valve condition, fire protection system condition (foam chambers, cooling ring if fitted).
• Cathodic protection: check cathodic protection system readings if installed (impressed current or sacrificial anode), verify protection potential meets the criteria.

1. Review the tank records including the design data sheet, previous inspection reports, thickness survey data and corrosion rate history. Identify any areas of concern from prior inspections.

   Obtain the tank data sheet showing design code, shell and floor plate thicknesses, material specification, capacity and product service. Review the previous internal and external inspection reports and any thickness surveys. Calculate the elapsed time since the last internal inspection and compare against the API 653 interval. Identify areas flagged for monitoring in prior reports. Prepare the inspection checklist with the tank-specific data pre-populated.

2. Conduct an external visual inspection of the entire tank: walk around the full circumference inspecting the shell, shell-to-bottom junction, roof, foundation, appurtenances and coating condition.

   Walk around the tank at ground level, inspecting the lower shell courses for corrosion, pitting, dents, bulging, staining (rust streaks or product staining indicating seepage) and coating deterioration. Inspect the shell-to-bottom weld area closely, as this is a common location for corrosion breakthrough. Check the foundation ring wall or slab for cracking, settlement or erosion. Inspect the roof from ground level (and from the roof if safe access is available) for corrosion, damaged vents, leaking seals and drainage condition. Inspect every nozzle, manway, valve and instrumentation connection for leaks and corrosion.

3. Inspect the secondary containment: check bund walls for cracks, deterioration and vegetation penetration. Verify the bund drain valve is closed and locked. Confirm bund capacity meets the requirement.

   Walk the full perimeter of the bund (containment wall). Inspect for cracks, spalling, tree root penetration, rodent holes and any damage that could compromise containment capacity. Verify the bund drain valve is closed and padlocked to prevent accidental drainage of contained product to the environment. Confirm the bund capacity meets the AS 1940 requirement (typically 110 per cent of the largest tank within the bund). Check the bund floor for product staining or ponded water that may indicate a slow leak. Inspect bund liners where installed for tears, UV degradation or chemical damage.

4. Test safety systems: verify tank gauging, overfill prevention, pressure-vacuum relief valves and fire protection equipment are functional.

   Check the tank level gauging system (float gauge, radar, or servo) for correct operation by comparing the indicated level to a manual tape gauge reading. Test the overfill prevention system by verifying the high-level alarm activates at the correct set point and triggers the correct response (alarm, pump shutdown). Inspect pressure-vacuum relief valves for corrosion, debris in screens and correct operation. Check fire protection equipment (foam chambers, cooling water ring, fixed monitors) for physical condition, valve operability and foam concentrate expiry date.

5. Perform ultrasonic thickness measurements on representative shell and floor locations if the inspection scope includes thickness surveying. Calculate corrosion rates and remaining life.

   If the inspection scope includes thickness measurements, use a calibrated ultrasonic thickness gauge to measure shell plate thickness at representative locations on each shell course, focusing on areas of visible corrosion, the shell-to-bottom junction and windward faces exposed to weather. Measure floor plate thickness at accessible locations. Compare measurements against previous surveys to calculate the corrosion rate (mm per year). Use the API 653 formulas to determine the minimum acceptable thickness and the estimated remaining life of each component. These calculations determine the next inspection interval.

6. Document all findings with photographs, record thickness measurements, calculate corrosion rates and create corrective action items. Determine the next inspection due date per API 653.

   Record all visual findings with descriptions, locations and severity ratings. Photograph all defects and areas of concern. Record thickness measurements in a tabular format with location identifiers. Calculate corrosion rates and remaining life for each measured area. Determine the next internal and external inspection due dates per API 653 interval calculations. Create corrective action items for all defects with assigned responsibility and due dates. Attach the completed checklist and all supporting documentation to the tank inspection file.

Practical answers about the form, record keeping and using MapTrack.

This form is a starting point. Check the current requirements that apply to your equipment, work and location. The form alone does not establish compliance.

• API 653 (Tank Inspection, Repair, Alteration, and Reconstruction)
• AS 1940 (The Storage and Handling of Flammable and Combustible Liquids)
• API 650 (Welded Tanks for Oil Storage - design standard)
• State EPA licence conditions for bulk liquid storage

MapTrack publishes this template. The linked authorities publish their own guidance; they haven't endorsed this form.

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