The purpose of this practice is to ensure satisfactory fit on standard sizes, to accommodate radial expansion of pipes and tubes which are heated after being insulated, and to minimize the number of insulation sizes and thicknesses to be manufactured and stocked.

While insulation may be manufactured to these recommended dimensions, care should be exercised in attempting to nest layers of different materials, or layers supplied by different manufacturers. Individual manufacturing processes may operate at slightly different tolerances. While the product will fit the pipe, it may not readily nest as the outer layer between the different materials or with different manufacturers. Care should be exercised to determine these differences before specifying or ordering nesting sizes.

Dimensions in accordance with this practice permit application of one thickness of pipe insulation over another (Nesting or Simplified Dimensional System), to obtain total thicknesses greater than those manufactured as single layer, or for multilayer application when desired.

1.1 This practice is intended as a dimensional standard for preformed rigid thermal insulation for pipes and tubing.

1.2 This practice covers insulation supplied in cylindrical sections, usually split into half-sections, and lists recommended inner and outer diameters of insulation having nominal wall thicknesses from 1 to 5 in. (25 to 127 mm) to fit over standard sizes of pipe and tubing.

1.3 The values stated in inch-pound units are to be regarded as the standard. The values stated in SI units are provided for information only.

This standard does not purport to address the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.