Steam System Insulation
The effectiveness of insulation is tested by measuring the base pipe temperature and insulation surface temperature with a thermocouple. A steady flow of heat through any medium of transmission is directly proportional to the temperature differential causing the flow, and inversely proportional to the resistance to heat flow of the bodies and the heat transfer medium. Insulation is used to increase the resistance to heat flow.
Basic Types of Insulating Materials
There are five basic types of thermal insulation, which may be used alone or in combination.
Flake insulation, such as vermiculite or expanded micra, is composed of small particles that finely divide the air space.
Fibrous insulation, such as glass or Rockwool, is composed of small-diameter fibers.
Granular insulation, such as magnesia, calcium silicate, or diatomaceous earth, is composed of small granules that contain voids.
Cellular insulations generally made from glass, rubber, or plastic, is composed of small individual cells that finely divide the air space.
Reflective insulation, such as aluminum or stainless-steel foil, is composed of parallel thin sheets of foil having high thermal reflectance to restrict radiant heat transfer; the spacing is designed to reduce conductive or convective heat transfer.
Insulation is available in many different forms, including blankets, boards, and blocks. Different insulation materials have other properties that must be considered in selecting insulation: temperature limits, fire hazard classification, dimensional stability, and moisture absorption.
Insulation Selection Criterion
Thermal properties at the operating temperature (i.e., thermal conductivity, thermal use range,…etc.), mechanical properties, fire resistance, forms (blanket, pipe covering, board, blocks, loose), resistance to water, chemicals, oil and other agents and of-course last but not least is cost.
Tip for Steam System Improvement
Repairing steam leaks, installing or replacing insulation, and repairing or replacing steam traps
(All losses will be saved when leaks are fixed. Leakage rate in kg/hr = 0.4 D^2 (P+1)
Where D = diameter (mm), and p = pressure (bar))