Pipe Bend Radius Calculator

Pipe Bend Radius Calculator

Calculate Centerline, Outer, and Inner Radius for Piping Engineering

Calculation Results:

Outer Radius: 0

Inner Radius: 0

Arc Length: 0

Thinning Factor: 0%

Radius Type: Short Radius

Min Straight Leg Req: 0

function calculatePipeBend() { var od = parseFloat(document.getElementById("pipeOD").value); var wall = parseFloat(document.getElementById("wallThickness").value); var clr = parseFloat(document.getElementById("bendRadius").value); var angle = parseFloat(document.getElementById("bendAngle").value); if (isNaN(od) || isNaN(clr) || isNaN(angle) || od <= 0 || clr <= 0) { alert("Please enter valid positive numbers for Diameter, Radius, and Angle."); return; } // Calculation Logic var outerR = clr + (od / 2); var innerR = clr – (od / 2); var arcLength = (Math.PI / 180) * angle * clr; // Wall thinning approximation formula var thinning = (od / (2 * clr + od)) * 100; // Determine Bend Type (Short Radius vs Long Radius) var ratio = clr / od; var typeStr = ""; if (ratio = 1.5 && ratio = 3) { typeStr = "3D or 5D Bend"; } else { typeStr = "Standard Bend"; } // Minimum straight leg (General rule: 2x OD) var leg = od * 2; document.getElementById("resOuterR").innerText = outerR.toFixed(3); document.getElementById("resInnerR").innerText = innerR.toFixed(3); document.getElementById("resArc").innerText = arcLength.toFixed(3); document.getElementById("resThinning").innerText = thinning.toFixed(2); document.getElementById("resType").innerText = typeStr; document.getElementById("resLeg").innerText = leg.toFixed(3); document.getElementById("resultsArea").style.display = "block"; }

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How to Use the Pipe Bend Radius Calculator

In piping engineering, the bend radius is the distance from the center of the bend to the centerline of the pipe. Determining the correct radius is vital for maintaining fluid flow efficiency and the structural integrity of the pipe wall.

Core Formulas

• Outer Radius (Ro): CLR + (Outside Diameter / 2)
• Inner Radius (Ri): CLR – (Outside Diameter / 2)
• Arc Length: (Angle × π / 180) × CLR
• Wall Thinning %: (OD / (2 × CLR + OD)) × 100

Standard Pipe Bend Classifications

Bend Type	Centerline Radius (CLR)
Short Radius (SR)	1.0 × Nominal Pipe Size
Long Radius (LR)	1.5 × Nominal Pipe Size
3D Bend	3.0 × Nominal Pipe Size
5D Bend	5.0 × Nominal Pipe Size

Why Bend Radius Matters

Choosing a bend radius that is too tight can lead to several engineering failures:

1. Wall Thinning: The outer wall of the pipe stretches and thins during the bending process, potentially falling below the minimum required thickness for the internal pressure rating.
2. Ovality: Tighter bends often result in the pipe cross-section becoming elliptical (flattening), which restricts flow.
3. Flow Resistance: Smaller radii increase turbulence and pressure drop across the fitting.

Example Calculation

If you have a 4-inch pipe (Actual OD = 4.5 inches) and you want a 3D bend:

• CLR: 4.5 × 3 = 13.5 inches.
• Outer Radius: 13.5 + 2.25 = 15.75 inches.
• Inner Radius: 13.5 – 2.25 = 11.25 inches.
• Theoretical Wall Thinning: (4.5 / (2 × 13.5 + 4.5)) × 100 &approx; 14.28%.

Note: This calculator provides theoretical values based on standard geometric formulas. Always consult specific piping codes (like ASME B31.3) and material data sheets for critical engineering applications.