ASTM C335/C335M-17,Standard Test Method for Steady-State Heat Transfer Properties of Pipe Insulation.
ASTM C335/C335M-17 covers the measurement of the steady-state heat transfer properties of pipe insulations. Specimen types include rigid, flexible, and loose fill; homogeneous and nonhomogeneous; isotropic and nonisotropic; circular or non-circular cross section.
The test apparatus for this purpose is a guarded-end or calibrated-end pipe apparatus. The guarded-end apparatus is a primary (or absolute) method. The guarded-end method is comparable, but not identical to ISO 8497.
ASTM C335/C335M-17 allows for operation over a wide range of temperatures. The upper and lower limit of the pipe surface temperature is determined by the maximum and minimum service temperature of the specimen or of the materials used in constructing the apparatus.
6. Test Specimen
6. 1 Specimens types include rigid, semi-rigid, or fexible (blanket-type),or loose-fill, suitably contained. Specimens shall be uniform in size and shape throughout their length (except for any intentional irregularities that occur well withinthe test section) and shall be designed for use on pipes of the same size and shape as the available test apparatus.