Cellular glass insulation (or foam glass) is an inorganic insulation material that is composed of millions of completely sealed glass cells. It is comprised of recycled glass and sand as base materials, supplemented by mineral substances and other natural materials.
It is made by heating crushed or granulated glass with a chemical foaming agent such as carbon or limestone. The foaming agent will release a gas producing a foaming effect. When the mixture cools, it hardens into a rigid, lightweight material of mostly gas-filled closed-cell pores.
Foam glass is first seen when Saint-Gobain of France applied for a patent after doing the process using calcium carbonate as the foaming agent. It was first claimed to be used as a construction material by Soviet scientist Professor I.I. Kitaygorodskiy at the All-Union Conference on Standardization and Manufacture of New Construction Materials in Moscow in 1932. Then in 1939 the Soviet Union experimented with glass powder screened through 0.09 mm mesh and mixed with limestone as the foaming agent (later using anthracite and coal) at the intermediate pilot plant of the Mendeleev Institute of Chemical Technology.
As we know it today, Foamglas cellular glass insulation was developed by Pittsburg Corning then acquired by Owens Corning. The crushed glass and foaming agent used is melted at a high temperature, foamed, and cooled slowly. It is made of many uniform bubbles with a diameter of 1 to 2 mm. The ratio of open cell bubbles and closed cell bubbles can be adjusted through changes in the production techniques to accommodate different requirements.
As one of several insulated products available from Insulation Components Inc. Cellular Glass Insulated iShields prevent pipe insulation crushing and maintain insulation integrity at pipe hanger locations.
Some product data; Used on low to high temperature plumbing and HVAC piping. Provides a full 360 degrees of high-density insulation and ASJ (All Service Jacket) vapor barrier. – Commonly installed on lines such as: domestic hot and cold water, chilled water, heating hot water, condenser water, and steam. – ASJ with SSL for quick and positive installation on piping. – Available in standard lengths from 6“to 36″ long to meet MSS SP-58 point load requirements for a wide range of hanger types and spans
Sources: Wikipedia, Owens Corning, Insulation Components data sheet