View Historical Standards for C421:

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Document Designation and Title Year Select Item(s) C421 Standard Test Method for Tumbling Friability of Preformed Block-Type Thermal Insulation 05 C421 Standard Test Method for Tumbling Friability of Preformed Block-Type Thermal Insulation 00 C421 Standard Test Method for Tumbling Friability of Preformed Block-Type Thermal Insulation 95