Corrosion Rate Calculation from Weight Loss

by
Corrosion Rate Calculator (Weight Loss Method) .corrosion-calculator-container { font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif; max-width: 800px; margin: 0 auto; padding: 20px; background: #f9f9f9; border: 1px solid #e0e0e0; border-radius: 8px; color: #333; } .calc-header { text-align: center; margin-bottom: 25px; } .calc-header h2 { color: #2c3e50; margin: 0; } .calc-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 20px; } @media (max-width: 600px) { .calc-grid { grid-template-columns: 1fr; } } .input-group { display: flex; flex-direction: column; } .input-group label { font-weight: 600; margin-bottom: 5px; font-size: 0.95em; color: #444; } .input-group input, .input-group select { padding: 10px; border: 1px solid #ccc; border-radius: 4px; font-size: 16px; } .input-group input:focus { border-color: #3498db; outline: none; } .input-hint { font-size: 0.8em; color: #666; margin-top: 3px; } .btn-container { grid-column: 1 / -1; text-align: center; margin-top: 15px; } button.calc-btn { background-color: #e67e22; color: white; border: none; padding: 12px 30px; font-size: 18px; font-weight: bold; border-radius: 5px; cursor: pointer; transition: background 0.3s; } button.calc-btn:hover { background-color: #d35400; } .results-area { grid-column: 1 / -1; background: #fff; border: 1px solid #ddd; border-radius: 6px; padding: 20px; margin-top: 20px; display: none; /* Hidden by default */ } .result-row { display: flex; justify-content: space-between; align-items: center; padding: 10px 0; border-bottom: 1px solid #eee; } .result-row:last-child { border-bottom: none; } .result-label { font-weight: 500; color: #555; } .result-value { font-weight: bold; font-size: 1.2em; color: #2c3e50; } .primary-result { color: #c0392b; font-size: 1.5em; } .article-content { margin-top: 40px; line-height: 1.6; color: #333; } .article-content h3 { color: #2c3e50; margin-top: 25px; } .article-content ul { margin-bottom: 20px; } .formula-box { background: #eee; padding: 15px; border-left: 4px solid #3498db; font-family: monospace; margin: 15px 0; }

Corrosion Rate Calculator

Calculate corrosion rate (mpy & mm/y) using the weight loss method.

Unit: grams (g)
Unit: grams (g)
Unit: square centimeters (cm²)
Unit: hours (h)
Custom Density Carbon Steel (7.87 g/cm³) Aluminum (2.70 g/cm³) Copper (8.96 g/cm³) Stainless Steel 304 (7.93 g/cm³) Stainless Steel 316 (8.00 g/cm³) Zinc (7.14 g/cm³) Lead (11.34 g/cm³)
Unit: grams per cubic centimeter (g/cm³)
Weight Loss: –
Corrosion Rate (mpy): –
Corrosion Rate (mm/y): –
Classification: –

About the Corrosion Rate Calculation

This calculator uses the standard weight loss method (often referenced in ASTM G1) to determine the average corrosion rate of a metal specimen. This is one of the most reliable and widely used methods in corrosion engineering to assess material performance in specific environments.

The Formula

The corrosion rate is calculated using the following equation:

CR = (K × W) / (A × T × D)

Where:

  • CR: Corrosion Rate
  • K: A constant determining the units of the result (3.45 × 106 for mpy, 8.76 × 104 for mm/y)
  • W: Weight loss in grams (Initial Weight – Final Weight)
  • A: Surface area in cm²
  • T: Exposure time in hours
  • D: Density of the material in g/cm³

Understanding the Results

MPY (Mils Per Year): This is the standard Imperial unit used in the oil, gas, and chemical industries. One mil is one thousandth of an inch (0.001″).

mm/y (Millimeters Per Year): This is the standard Metric unit for corrosion rates.

Typical Corrosion Rate Categories

While acceptable rates vary by industry and application, a general guide for carbon steel follows:

  • < 1 mpy: Outstanding (No concern)
  • 1 – 5 mpy: Good (Suitable for most applications)
  • 5 – 10 mpy: Fair (May require monitoring)
  • > 10 mpy: Poor (Action usually required)
function updateDensityInput() { var select = document.getElementById('densitySelect'); var input = document.getElementById('densityValue'); if (select.value !== 'custom') { input.value = select.value; } } function calculateCorrosion() { // Get input values var initW = parseFloat(document.getElementById('initialWeight').value); var finalW = parseFloat(document.getElementById('finalWeight').value); var area = parseFloat(document.getElementById('surfaceArea').value); var time = parseFloat(document.getElementById('exposureTime').value); var density = parseFloat(document.getElementById('densityValue').value); // Validation if (isNaN(initW) || isNaN(finalW) || isNaN(area) || isNaN(time) || isNaN(density)) { alert("Please fill in all fields with valid numbers."); return; } if (time <= 0 || area <= 0 || density initW) { alert("Final weight cannot be greater than initial weight. This implies weight gain (deposition/oxidation product accumulation) rather than pure weight loss, or a measurement error."); return; } // Calculation Logic var weightLoss = initW – finalW; // in grams // Constants per ASTM G1 // For mpy (Mils per year): K = 3.45 x 10^6 // For mm/y (Millimeters per year): K = 8.76 x 10^4 var K_mpy = 3.45 * Math.pow(10, 6); var K_mmy = 8.76 * Math.pow(10, 4); var rate_mpy = (K_mpy * weightLoss) / (density * area * time); var rate_mmy = (K_mmy * weightLoss) / (density * area * time); // Determine Classification (General guidelines for Steel) var classification = ""; if (rate_mpy < 1) { classification = "Outstanding"; } else if (rate_mpy < 5) { classification = "Good"; } else if (rate_mpy < 10) { classification = "Fair"; } else { classification = "Poor / Severe"; } // Display Results document.getElementById('resWeightLoss').innerText = weightLoss.toFixed(4) + " g"; document.getElementById('resMpy').innerText = rate_mpy.toFixed(2) + " mpy"; document.getElementById('resMmy').innerText = rate_mmy.toFixed(3) + " mm/y"; document.getElementById('resClass').innerText = classification; // Show the results div document.getElementById('results').style.display = "block"; }

Leave a Comment