Corrosion Rate & Remaining Life Calculator
Two thickness readings in, a full engineering breakdown out: corrosion rate, remaining allowance, projected remaining life, and a suggested next-inspection interval - with every step of the arithmetic shown.
Thickness readings
Result
Linear projection from two thickness readings. Not a substitute for a fitness-for-service assessment (e.g. API 579-1/ASME FFS-1) or your governing code’s retirement calculation.
- 01Metal loss since baseline
12.70 mm original − 11.40 mm current = 1.30 mm lost over 8 years in service.
- 02Corrosion rate
1.30 mm ÷ 8 years = 0.162 mm/year, assuming a linear rate. General (uniform) corrosion loses metal roughly evenly across a surface, which is what makes a simple linear rate a reasonable first approximation.
- 03Remaining corrosion allowance
11.40 mm current − 7.90 mm minimum required = 3.50 mm of metal remaining before the asset reaches its retirement thickness.
- 04Projected remaining life
3.50 mm ÷ 0.162 mm/year = 21.5 years before this asset is projected to reach minimum required thickness, holding the current rate constant.
- 05Suggested next-inspection interval
Using the "half of remaining life" convention common in API 510/570/653-style inspection intervals, capped at your stated maximum of 10 years: min(10.8, 10) = 10.0 years. Your actual code-compliant interval also depends on requirements this tool does not check.
- How this remaining-life engine works (this tool, explained)
LeakSonic blog - full methodology write-up for this calculator.
- External corrosion on buried pipelines: causes, warning signs, and controls
LeakSonic blog - background on the general corrosion mechanism this tool assumes by default.
- Corrosion under insulation (CUI): why insulated pipe is a blind spot
LeakSonic blog - a localized mechanism that can invalidate a simple linear-rate projection.
- Microbiologically influenced corrosion (MIC): why bacteria are a threat
LeakSonic blog - another localized mechanism worth ruling out before trusting a linear rate.
- Risk-based inspection: how operators prioritise pipeline segments
LeakSonic blog - how a remaining-life estimate typically feeds a prioritisation decision.
- API - American Petroleum Institute
Publisher of API 510, 570, 653 (in-service inspection codes) and API 579-1/ASME FFS-1 (fitness-for-service), which govern real retirement-thickness and interval decisions.
Copy this snippet to credit and link back to the tool.
<a href="https://leaksonic.com/tools/corrosion-remaining-life-calculator" target="_blank" rel="noopener">Calculated with LeakSonic's Corrosion Rate & Remaining Life Calculator ↗</a>
Methodology & limits
Corrosion rate is computed as (original thickness − current thickness) ÷ years in service - a linear approximation. Remaining allowance is current thickness minus your stated minimum required thickness; remaining life is that allowance divided by the corrosion rate. The suggested next-inspection interval applies the widely used 'half of remaining life' convention from API 510/570/653-style programmes, capped at whatever maximum interval you set. This tool does not calculate your minimum required thickness, does not account for localized corrosion mechanisms unless you factor that in yourself, and is not a substitute for a real fitness-for-service assessment under API 579-1/ASME FFS-1 or your governing code.
Frequently asked
What does the Corrosion Rate & Remaining Life Calculator compute?
From an original thickness, a current measured thickness, and the years between readings, it computes a linear corrosion rate, the remaining corrosion allowance down to your stated minimum required thickness, a projected remaining life in years, and a suggested next-inspection interval using the "half of remaining life" convention common in API 510/570/653-style in-service inspection programmes.
Does this replace a fitness-for-service assessment?
No. A real retirement-thickness or fitness-for-service determination follows your governing code - commonly API 579-1/ASME FFS-1 for fitness-for-service, or API 510/570/653 for the applicable asset type - and accounts for factors this tool does not, including flaw geometry, remaining strength, and applicable safety factors. This tool is a fast, linear approximation for reasoning about a known corrosion trend, not a substitute for that assessment.
Why does the tool ask about general versus localized corrosion?
A linear rate is a reasonable approximation for general (uniform) corrosion but can be dangerously optimistic for localized mechanisms - pitting, corrosion under insulation, or microbiologically influenced corrosion - which can progress far faster at specific points than a uniform average suggests. The tool flags this explicitly rather than presenting one projection as universally valid.
Where does the minimum required thickness value come from?
You supply it - this tool does not calculate a code-minimum thickness itself. That figure should come from your own governing-code calculation (for example ASME B31G for pipelines, or the applicable API code for your asset type), since it depends on design pressure, material properties, and safety factors this tool does not model.
Want this done properly, on your real network or site?
This tool gives you a fast, illustrative estimate. Sentrix gives you a defensible, evidence-backed answer, built on your actual data. Tell us about your network or site and we'll walk you through it.