Common Integrity Issues Discovered During Tank Inspections — And How to Fix Them?
If you’ve ever been part of a tank inspection companies, you already know this: tanks rarely fail out of nowhere.
They whisper first.
A little corrosion here. Slight settlement there. Maybe a roof that doesn’t sit quite right anymore.
And if you catch those whispers early? You save money. You avoid environmental incidents. You sleep better at night.
Let’s talk about the most common integrity issues inspectors find in aboveground storage tanks — and what actually fixes them.
1. Corrosion
Corrosion is, without exaggeration, the number one issue discovered during inspections governed by standards like API 653.
You’ll typically see it in:
There are two main types:
Why It Happens
Moisture. Product chemistry. Poor coatings. Trapped water under the bottom. Time.
Tanks don’t care about your maintenance budget.
How It’s Fixed
It depends on severity.
Here’s the thing people forget: fixing corrosion isn’t just welding steel. It’s correcting the environment that caused it.
Otherwise? It’s coming back.
2. Tank Settlement
Settlement is one of those issues that doesn’t look dramatic at first — until it is.
You’ll hear inspectors talk about:
Uniform settlement is usually manageable. Differential settlement? That’s where shell distortion and bottom stress start creeping in.
And once your shell starts going out-of-round, repairs get complicated fast.
How It’s Fixed
Sometimes the fix isn’t even in the steel. It’s in the soil.
And yes, that’s expensive. But ignoring settlement is worse.
3. Roof Integrity Problems
Roofs don’t get enough attention — until they leak.
Common roof issues include:
Floating roofs especially can develop seal gaps that increase vapor emissions and environmental exposure.
How It’s Fixed
Roof integrity isn’t just structural — it’s environmental compliance.
And regulators are paying attention.
4. Bottom Plate Deterioration
Tank bottoms take the worst beating. They’re in constant contact with:
Internal corrosion often occurs near the product-water interface. Externally, moisture trapped under the bottom creates underside corrosion.
It’s not visible from outside. That’s what makes it dangerous.
How It’s Fixed
And this is where proper thickness mapping during inspection really pays off.
Guessing doesn’t work here.
5. Shell Distortion and Buckling
Shell distortion can result from:
You might notice ripples, flat spots, or buckling between stiffeners.
Sometimes it’s cosmetic. Sometimes it’s structural.
An experienced API-certified inspector for fiberglass tank inspection — typically credentialed through the American Petroleum Institute — evaluates whether the distortion exceeds allowable tolerances.
How It’s Fixed
Never ignore buckling. Steel doesn’t “self-correct.”
6. Nozzle and Weld Defects
Weld cracks, nozzle misalignment, and reinforcement pad issues are also commonly found.
They’re not always obvious. Many are discovered during non-destructive testing.
Cracks around nozzles are particularly concerning because they’re stress concentration points.
How It’s Fixed
And importantly — identifying root cause. Was it stress? Corrosion fatigue? Poor fabrication?
If you don’t answer that, you’re just treating symptoms.
The Bigger Picture
Here’s what most facility owners eventually realize:
Inspection findings aren’t bad news.
They’re early warnings.
A well-documented inspection gives you:
It turns surprises into manageable projects.
And honestly? That’s the whole point.
FAQs
1. What is the most common defect found during tank inspections?
Corrosion — particularly bottom plate corrosion — is the most common issue identified in aboveground storage tanks.
2. How serious is tank settlement?
It depends on type and magnitude. Uniform settlement may be manageable, but differential settlement can cause shell sss and structural distortion.
3. Can corroded tank bottoms be repaired without full replacement?
Yes, localized damage can be addressed with patch plates. However, widespread thinning often requires full bottom replacement.
4. Are roof issues considered structural problems?
They can be. Roof failures may affect emissions control, environmental compliance, and overall tank safety.
5. How often should tanks be inspected?
Inspection frequency depends on corrosion rates, operating conditions, and regulatory requirements. Standards like API 653 provide structured interval guidance.
If there’s one takeaway here, it’s this:
Tanks don’t usually fail because no one inspected them.
They fail because warning signs were underestimated.
And catching corrosion, settlement, or roof issues early isn’t just maintenance — it’s asset protection.
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