MI Spec > Appendices > Appendix B

Polyiso -cyanurate Insulation with All Service Jacket (ASJ)


Polyisocyanurate is often referred to as “polyiso” by industry. It is a closed cell, high performance insulation for pipe, vessels, and equipment. It has a very low thermal conductivity and dimensional stability over a broad temperature range and it is a cost-effective choice for chilled water, hot water and other pipe insulation systems with service temperatures from -183°C to 149°C. It is available in a variety of densities and compressive strengths.

It is shown in the picture above with an ASJ cover, however it is commonly supplied to the distributor in billet form. The distributor must have special equipment to prepare pipe insulation in the form shown above; this would contribute to the finished product lead time. The material requires a vapour barrier when used in low ambient temperature applications. Further, off-gassing is an issue throughout the early service life of the material. Care must be taken to protect this material from UV, to avoid shortening the service life.

Physical Properties

Installed Cost Ref Density Temperature Range Thermal Conductivity
Low  26 kg/m3  -183°C to 149°C  0.023 W/mºK
UV Resistance Flame Spread Smoke Developed Compressive Strength
 Medium  25 130 (It is available in smaller thicknesses with a 50 smoke developed rating.) 860 kPa (or 125 PSI)

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