.corrosion-calculator-container {
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margin: 20px auto;
padding: 30px;
background: #f9fbfd;
border: 1px solid #e1e4e8;
border-radius: 8px;
box-shadow: 0 4px 6px rgba(0,0,0,0.05);
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.severity-low { background-color: #27ae60; }
.severity-moderate { background-color: #f39c12; }
.severity-high { background-color: #c0392b; }
.severity-extreme { background-color: #8e44ad; }
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Corrosion Rate Calculator (Weight Loss Method)
Calculate the corrosion rate of metals using the standard mass loss formula (ASTM G1). Select a material to auto-fill density or enter custom values.
Select Material (Optional Helper)
— Select a Metal —
Carbon Steel (7.85 g/cm³)
Stainless Steel 304 (7.90 g/cm³)
Stainless Steel 316 (8.00 g/cm³)
Aluminum (2.70 g/cm³)
Copper (8.96 g/cm³)
Brass (8.50 g/cm³)
Zinc (7.14 g/cm³)
Titanium (4.51 g/cm³)
Lead (11.34 g/cm³)
Material Density (g/cm³)
Weight Loss (grams)
Exposed Surface Area (cm²)
Exposure Time (hours)
Calculate Corrosion Rate
Corrosion Rate (mpy):
0.0000 mpy
Corrosion Rate (mm/year):
0.0000 mm/y
Weight Loss Rate:
0.0000 g/hr
Understanding the Corrosion Rate Calculation Formula
Corrosion rate is a fundamental metric in materials science and engineering, used to determine the lifespan of metal structures, pipelines, and equipment. The most common method for calculating this rate is the Weight Loss Method (based on ASTM G1 standards).
The Formula
To calculate the average corrosion rate, we use the following equation:
CR = (K × W) / (D × A × T)
Where:
CR = Corrosion RateK = A constant defining the units of the corrosion rate (87,600 for mm/year or 3,450,000 for mpy if using grams and cm²).W = Weight loss (mass change) in grams (g).D = Density of the material in grams per cubic centimeter (g/cm³).A = Exposed surface area in square centimeters (cm²).T = Time of exposure in hours (h).
Interpreting the Results (mpy)
The unit mpy stands for "mils per year," where 1 mil = 0.001 inches. It is the standard unit for corrosion rates in the United States oil and gas industry.
< 1 mpy: Outstanding (Low corrosion)1 – 5 mpy: Good / Acceptable5 – 10 mpy: Moderate (Caution required)> 10 mpy: Severe / High (Material may fail prematurely)
Why is Density Important?
Density converts the weight loss (mass) into volume loss. A lighter metal (like Aluminum) losing 10 grams represents a much larger volume of metal lost—and therefore deeper pits or thinning—than a heavy metal (like Lead) losing the same 10 grams. This is why accurate density input is critical for determining the actual penetration rate.
Example Calculation
Imagine a Carbon Steel coupon (Density: 7.85 g/cm³) with a surface area of 20 cm² is exposed to seawater for 24 hours. After cleaning, the weight loss is measured at 0.05 grams.
Using the formula for mm/year (K = 87,600):
CR = (87,600 × 0.05) / (7.85 × 20 × 24) = 4,380 / 3,768 ≈ 1.16 mm/y
Converted to mpy (× 39.37): 45.7 mpy (Severe corrosion).
function updateDensity() {
var select = document.getElementById('material_select');
var densityInput = document.getElementById('density');
if (select.value) {
densityInput.value = select.value;
}
}
function calculateCorrosion() {
// Get input values
var density = parseFloat(document.getElementById('density').value);
var weightLoss = parseFloat(document.getElementById('weight_loss').value);
var area = parseFloat(document.getElementById('surface_area').value);
var time = parseFloat(document.getElementById('exposure_time').value);
// Validation
if (isNaN(density) || density <= 0) {
alert("Please enter a valid positive Material Density.");
return;
}
if (isNaN(weightLoss) || weightLoss < 0) {
alert("Please enter a valid Weight Loss.");
return;
}
if (isNaN(area) || area <= 0) {
alert("Please enter a valid Surface Area.");
return;
}
if (isNaN(time) || time <= 0) {
alert("Please enter a valid Exposure Time.");
return;
}
// Calculation Logic
// Formula: CR = (K * W) / (D * A * T)
// Constant K for mm/year when:
// W is in grams
// D is in g/cm3
// A is in cm2
// T is in hours
// Metric derivation:
// 1 hr = 1/8760 year. 1 cm = 10 mm.
// Factor = 8760 * 10 = 87,600
var k_metric = 87600;
var mmYear = (k_metric * weightLoss) / (density * area * time);
// Convert mm/y to mpy (mils per year)
// 1 mm = 39.3701 mils
var mpy = mmYear * 39.3701;
// Weight loss rate (g/hr)
var lossRate = weightLoss / time;
// Determine Severity
var severityText = "";
var severityClass = "";
// General industry guidelines for Carbon Steel (approximate)
if (mpy < 1) {
severityText = "Outstanding Resistance";
severityClass = "severity-low";
} else if (mpy < 5) {
severityText = "Good / Acceptable";
severityClass = "severity-low";
} else if (mpy < 10) {
severityText = "Moderate Corrosion";
severityClass = "severity-moderate";
} else if (mpy < 20) {
severityText = "High Corrosion";
severityClass = "severity-high";
} else {
severityText = "Severe / Extreme";
severityClass = "severity-extreme";
}
// Display Results
document.getElementById('result_mpy').innerText = mpy.toFixed(2) + " mpy";
document.getElementById('result_mmy').innerText = mmYear.toFixed(4) + " mm/y";
document.getElementById('result_rate').innerText = lossRate.toFixed(5) + " g/hr";
var badge = document.getElementById('severity_badge');
badge.className = "severity-badge " + severityClass;
badge.innerText = severityText;
document.getElementById('result-area').style.display = "block";
}