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Thermal Engineering2D

Heat Loss Calculator - Pipe & Tank Insulation

Calculate heat loss from insulated or uninsulated pipes and tanks to ambient air, with economic insulation thickness.

Inputs
Enter your values below

Mineral wool ≈ 0.04 W/mK, foam ≈ 0.025 W/mK

Still air ≈ 10, windy outside ≈ 25 W/m²K

Result
Heat Loss
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Enter values and click Calculate
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Formula
(t_surface − t_ambient) ÷ (1 ÷ (h × π × diameter) + log((diameter+2 × thickness) ÷ diameter) ÷ (2 × π × k)) × length
Result unit: W

Cylindrical heat loss with insulation. R_total = R_outside + R_insulation. R_outside = 1/(hπD), R_insulation = ln((D+2t)/D)/(2πk). h = outside convection coefficient.

Introduction

Calculate conductive and convective heat loss from insulated or bare pipes and cylindrical equipment. Essential for energy audits, insulation specification, and tracing/heat-up calculations.

How This Calculator Works

Cylindrical heat loss with insulation. R_total = R_outside + R_insulation. R_outside = 1/(hπD), R_insulation = ln((D+2t)/D)/(2πk). h = outside convection coefficient.

Step-by-step process:

  1. Enter your input values in the calculator above
  2. The engine converts all inputs to SI base units (meters, kg, Pa)
  3. The formula is evaluated: (t_surface - t_ambient) / (1/(h * pi * diameter) + log((diameter+2*thickness)/diameter)/(2*pi*k)) * length
  4. Result is formatted with the appropriate unit and precision

Calculation Example

114mm pipe at 150°C with 50mm mineral wool insulation, 100m long: ~4.7 kW heat loss.

Inputs: t_surface=150, t_ambient=20, diameter=114, thickness=50, k=0.04, h=10, length=100
Result: 4668 W

Unit Conversion for Heat Loss

**Heat rate units**

- 1 W = 3.412 BTU/hr

- 1 kW = 3412 BTU/hr

- 1 BTU/hr = 0.2931 W

**Temperature units**

- °F = °C × 9/5 + 32

- ΔT in °C = ΔT in K

**Area units**

- 1 m² = 10.764 ft²

**Conductivity units**

- 1 W/m·K = 0.578 BTU/hr·ft·°F

Heat loss Q = U × A × ΔT. Convert all inputs to one consistent unit system before computing, then convert the result to W or BTU/hr as needed.

Engineering Applications

  • •Energy audits
  • •Insulation specification
  • •Steam tracing design
  • •Heat-up calculations

Frequently Asked Questions

What is a typical insulation k-value?

Mineral wool: 0.035-0.045; polyurethane foam: 0.022-0.030; calcium silicate: 0.055-0.070; fiberglass: 0.034-0.045 W/mK.

How much energy does insulation save?

Uninsulated 150°C pipes lose ~20x more heat than well-insulated ones. Insulation typically pays back in under a year on hot pipes.

How do I convert heat loss between W and BTU/hr?

1 W = 3.412 BTU/hr. For example, 500 W = 1706 BTU/hr. Convert to consistent units when comparing insulation options.

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Engineering Disclaimer: Calculations are for reference and educational purposes only. Always verify results independently for engineering design. See full disclaimer.
Reviewed by: Industrial Engineering Team
References: ASME B31.3, ASTM A36, Perry's Chemical Engineers' Handbook