Tolerances of Closed Cell Elastomeric Insulation
Unlike traditional mechanical insulation materials, such as open-cell fibrous (fiberglass) and rigid closed-cell (cellular glass, phenolic, polyisocyanurate), closed cell elastomeric foam insulation is flexible and comprised of many encapsulated spheres of air within a synthetic rubber base.
The manufacture of flexible elastomeric foam insulation (also known as rubber) must comply with ASTM C534 Standard Specification for Preformed Flexible Elastomeric Cellular Thermal Insulation in Sheet and Tubular Form.
ASTM C534 specifies “dimensional tolerances” for Type I Tubular and Type II Sheet materials. For tubes, tolerances are published for the inside diameter (ID), wall thickness, and length; for sheets, length, width, and thickness.
The manufacturing process for closed cell elastomeric insulation must be incredibly precise to meet ASTM’s tight tolerances. Producing a rubber-based product to specification, which is full of air, has been a challenge for rubber manufacturers since the 1950’s. However, due to technological advances and manufacturer subject matter experts fine-tuning their production processes, ASTM’s specifications can be achieved.
Aeroflex USA manufactures the AEROFLEX® brand of EPDM closed cell elastomeric insulation with a strict quality assurance process plus quality control procedures. All AEROFLEX product tolerances are manufactured and inspected based on a minimum (MIN), target, and maximum (MAX) tolerance range.
Since AEROFLEX tubes should never be stretched over a pipe, we strive to manufacture in the target to MAX range for both ID and wall thickness.
It’s important to note that even though C534 allows up to -1” tolerance on a 72” tube length (71” actual), AEROFLEX delivers 6-foot tubes to our customers so they can count on consistent coverage and value for their insulation projects.
When an insulation jacket is specified to be installed over AEROFLEX EPDMTM pipe insulation, we offer the following technical resources to assist with the accurate estimation and fabrication of jacketing materials:
Outside Diameters for Jacketing AEROFLEX EPDM Pipe Insulation