Pipe Repair Clamp Size Calculator

ANA›Life Services Authority›National Calculator Authority›Pipe Repair Clamp Size Calculator

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Pipe Repair Clamp Size Calculator

Determine the appropriate repair clamp length, width, and pressure class for a damaged pipe section based on pipe outer diameter, damage zone length, operating pressure, and pipe material.

Pipe Outer Diameter (mm)

Damage / Defect Length (mm)

Operating Pressure (bar)

Pipe Wall Thickness (mm)

Pipe Material

Carbon Steel (SMYS 245 MPa) Stainless Steel 316 (SMYS 170 MPa) Ductile Iron (SMYS 290 MPa) PVC (SMYS 48 MPa) HDPE (SMYS 20 MPa) Copper (SMYS 69 MPa)

Fluid Type

Water / Non-Hazardous Liquid Gas / Vapour Hazardous / Flammable Liquid

Operating Temperature (°C)

Calculate Clamp Size

function pipCalc() { // --- Read inputs --- var od = parseFloat(document.getElementById('pip-od').value); var damageLen = parseFloat(document.getElementById('pip-damage-len').value); var opPres = parseFloat(document.getElementById('pip-op-pressure').value); var wall = parseFloat(document.getElementById('pip-wall').value); var material = document.getElementById('pip-material').value; var fluid = document.getElementById('pip-fluid').value; var temp = parseFloat(document.getElementById('pip-temp').value);

var resultDiv = document.getElementById('pip-result'); resultDiv.style.display = 'block';

// --- Validation --- var errors = []; if (isNaN(od) || od = od / 2) errors.push("Wall Thickness cannot be >= pipe radius (OD/2)."); if (!isNaN(od) && !isNaN(wall) && od > 0 && wall / (od / 2) > 0.5) errors.push("Wall Thickness seems unrealistically large relative to OD.");

if (errors.length > 0) { resultDiv.className = 'calc-result calc-error'; resultDiv.innerHTML = 'Input Errors:' + errors.map(function(e){ return ''; }).join('') + ''; return; }

// --- Material SMYS (MPa) --- var smysMap = { carbon_steel: 245, stainless_316: 170, ductile_iron: 290, pvc: 48, hdpe: 20, copper: 69 }; var smys = smysMap[material]; // MPa

// --- Temperature de-rating factor (simplified linear) --- // Above 100°C reduce allowable stress by 0.5% per °C above 100°C (max 30% reduction) var tempFactor = 1.0; if (temp > 100) { tempFactor = Math.max(0.70, 1.0 - 0.005 * (temp - 100)); } if (temp = designPressure) { clampPressureClass = pressureClasses[i]; break; } } if (clampPressureClass === null) { resultDiv.className = 'calc-result calc-error'; resultDiv.innerHTML = 'Error: Operating pressure exceeds standard clamp pressure classes (max 256 bar design). Consult a specialist.'; return; }

// --- Clamp length calculation (ISO 24817 / ASME PCC-2 Article 2.1) --- // Minimum clamp length = damage length + 2 × overlap // Overlap each side = max(50 mm, 0.5 × OD, 1.5 × wall thickness × 10) // Additional length for high-pressure gas service var minOverlap = Math.max(50, 0.5 * od, 1.5 * wall * 10); if (fluid === 'gas' || fluid === 'hazardous') { minOverlap = Math.max(minOverlap, 75); // extra margin for gas/hazardous } var clampLength = damageLen + 2 * minOverlap; // mm

// Round up to nearest 50 mm for standard sizing clampLength = Math.ceil(clampLength / 50) * 50;

// --- Clamp width (axial band width) --- // Each band width ≈ max(40 mm, 0.15 × OD) for structural integrity var bandWidth = Math.max(40, 0.15 * od); bandWidth = Math.ceil(bandWidth / 5) * 5; // round to nearest 5 mm

// Number of bands = clamp length / (band width + gap) // Typical gap between bands = 20 mm var gap = 20; var numBands = Math.max(2, Math.ceil(clampLength / (bandWidth + gap)));

// --- Clamp bolt torque (simplified) --- // Gasket seating stress ≈ 14 MPa (soft gasket) to 28 MPa (semi-metallic) // Contact area per bolt ≈ π/4 × bolt_dia² × num_bolts_per_band // Simplified: bolt torque T = K × d × F (K=0.2 nut factor, d=bolt dia, F=bolt load) // Bolt diameter selection based on OD var boltDia_mm; if (od = clampAllowable_MPa) { clampThickness_mm = NaN; } else { clampThickness_mm = (od / 2) * (Math.sqrt((clampAllowable_MPa + designPres_MPa) / (clampAllowable_MPa - designPres_MPa)) - 1); clampThickness_mm = Math.max(6, Math.ceil(clampThickness_mm * 10) / 10); // min 6 mm }

// --- Pipe ID and flow area --- var id = od - 2 * wall; var flowArea_mm2 = Math.PI / 4 * id * id; var flowArea_cm2 = flowArea_mm2 / 100;

// --- Condition assessment --- var condition, condClass; if (pressureRatio ';

function row(label, value, unit, note) { return '' + '' + label + '' + '' + value + (unit ? ' ' + unit + '' : '') + '' + (note ? '' + note + '' : '') + ''; }

html += row('Pipe Inner Diameter', id.toFixed(2), 'mm', ''); html += row('Pipe Flow Area', flowArea_cm2.toFixed(2), 'cm²', ''); html += row('Hoop Stress (Barlow)', hoopStress.toFixed(2), 'MPa', 'σ = P·OD / (2t)'); html += row('MAOP (intact pipe)', maop_bar.toFixed(2), 'bar', 'Barlow × SF × temp factor'); html += row('Pressure Ratio (P/MAOP)', (pressureRatio * 100).toFixed(1), '%', ''); html += row('Design Pressure (1.25×OP)', designPressure.toFixed(2), 'bar', 'ISO 24817 §6.3'); html += '► Recommended Clamp Specification'; html += row('Clamp Pressure Class', clampPressureClass, 'bar', 'Next standard class ≥ design pressure'); html += row('Minimum Clamp Length', clampLength, 'mm', 'Damage + 2 × ' + minOverlap.toFixed(0) + ' mm overlap, rounded to 50 mm'); html += row('Overlap Each Side', minOverlap.toFixed(0), 'mm', 'max(50, 0.5·OD, 15·t)'); html += row('Number of Bands', numBands, '', 'Bands across clamp length'); html += row('Band Width', bandWidth.toFixed(0), 'mm', 'max(40, 0.15·OD)'); html += row('Bolt Diameter', 'M' + boltDia_mm, '', 'Based on pipe OD'); html += row('Number of Bolts', numBolts, '', numBands + ' bands × 2 bolts'); html += row('Bolt Torque (target)', torque_Nm.toFixed(0), 'N·m', 'T = K·d·F, K=0.2'); if (!isNaN(clampThickness_mm)) { html += row('Clamp Shell Thickness', clampThickness_mm.toFixed(1), 'mm', 'Thick-wall cylinder, min 6 mm'); } else { html += row('Clamp Shell Thickness', 'N/A', '', 'Pressure exceeds clamp material limit'); } html += row('Temperature De-rating', (tempFactor * 100).toFixed(0), '%', temp + '°C applied'); html += '';

html += ''; html += 'Condition Assessment: ' + condition + ''; html += '';

if (pressureRatio > 1.0) { html += ''; html += '⚠ Warning: Operating pressure exceeds the calculated MAOP of the pipe. Immediate pressure reduction and engineering review required before any repair attempt.'; html += ''; }

resultDiv.className = 'calc-result calc-success'; resultDiv.innerHTML = html; }

#### Formulas Used

Hoop Stress (Barlow's Formula): σhoop = (P × OD) / (2 × t)

Maximum Allowable Operating Pressure: MAOP = (2 × t × SMYS × SF × TF) / OD where SF = safety factor (0.72 water, 0.60 gas/hazardous), TF = temperature de-rating factor

Design Pressure (ISO 24817): Pdesign = 1.25 × Poperating

Minimum Clamp Length: Lclamp = Ldamage + 2 × Loverlap Loverlap = max(50 mm, 0.5 × OD, 15 × t)

Clamp Shell Thickness (Thick-Wall Cylinder — Lamé): tclamp = (OD/2) × (√((σallow + P) / (σallow − P)) − 1)

Bolt Torque: T = K × d × F   (K = 0.2 nut factor, d = bolt diameter, F = bolt load per bolt)

#### Assumptions & References

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References

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