Mechanical Insulation Design Guide: A User’s Guide

March 1, 2009

Whether you are looking for basic insulation information or need to design a complex insulation system, the Mechanical Insulation Design Guide (MIDG), available at, is the best resource. Designed to assist the novice or the knowledgeable user alike in the design, selection, specification, installation, and maintenance of mechanical insulation, the MIDG is continually updated with the most current and complete information.

An insulation designer’s basic questions can be summed up as follows:

  • Why am I insulating this?
  • What am I insulating?
  • Where am I insulating and what are the ambient design conditions?
  • What materials and systems are best for this job?
  • How much will this cost and what is the best way to implement this solution?

The MIDG is divided into sections that answer each of these questions.

Design Objectives. This section helps answer the questions why, what, and where. It discusses the potential design objectives and considerations for mechanical insulation systems. An insulation system can be designed for specific objectives, such as energy conservation or condensation control, or for multiple objectives. To select the right insulation system, you need a clear understanding of the finished system’s objectives.

The most familiar uses of insulation are to reduce heating and cooling loads, and to control noise in building envelopes. However, mechanical insulation is primarily used to limit either heat gain or heat loss from surfaces operating at temperatures above or below ambient temperature. It also may be used for the following design objectives:

  • Condensation Control
  • Energy Conservation
  • Return on Investment
  • Sustainability
  • Fire Safety
  • Freeze Protection
  • Safety
  • Process Control
  • Noise Control

Other factors to consider when designing a mechanical insulation system include:

  • Abuse Resistance
  • Corrosion Under Insulation (CUI)
  • Indoor Air Quality
  • Maintainability
  • Regulatory Considerations
  • Service and Location
  • Service Life

Materials and Systems. In most cases, one can choose from multiple types of mechanical insulation materials for any given application. The Materials and Systems section discusses material categories and provides links to additional information and to the material manufacturers. The list changes continually as existing products are modified, some products are phased out, and new products are developed. In addition to commonly used materials, this section also describes important performance or physical properties for insulation materials and associated weather barriers, vapor retarders, and finishes.

The MIDG categorizes mechanical insulation materials into the following major types, listed alphabetically:

  • Cellular
  • Fibrous
  • Flake
  • Granular
  • Reflective

The MIDG provides immediate links to specific material data, including submittal sheets, and further links to insulation manufacturers through the MTL Product Catalog (see sidebar).

Design Data. This section contains information on estimating heat loss and heat gain, controlling surface temperature, determining dimensions of standard pipe and tubing insulation, and estimating heat loss from bare pipe and tubing. Users also will find a product selection chart, searchable by temperature, and some simple tools for calculation of heat flow and surface temperatures.

  • Simple Payback, Rate of Return, and Emissions Calculator: estimates the benefits of insulation for particular applications.
  • Time to Freezing for Fluid in an Insulated Pipe Calculator: estimates the time for a fluid-filled pipe (no flow) to reach a freezing temperature.
  • Temperature Drop Calculator: calculates temperature drop of a fluid flowing in a duct or pipe.
  • Simple Thickness Calculator: estimates the thickness of insulation required to obtain a specified surface temperature given the boundary temperatures, conductivity of the insulation material, and surface coefficient.
  • Simple Heat-flow Calculator: estimates heat flow through insulation for flat and cylindrical systems given the temperature on each side and the effective conductivity of the insulation material.

Resources and Case Studies. The MIDG links to resources from the National Insulation Association; American Society of Heating, Refrigerating and Air-Conditioning Engineers; American Society for Testing and Materials; National Fire Protection Association; Underwriters Laboratories; and many more sources for information. Case studies and a glossary also are included.

Update Summary. This page notes new features and where to find them.

The MIDG is available online at Suggestions to improve the MIDG can be submitted through a handy “Comment on this page” link on each of its pages.