Joints of duct programs shall be built substantially airtight via tapes, mastics, liquid sealants, gasketing or other permitted closure units. Closure systems applied with rigid fibrous glass ducts shall comply with UL181A and shall be marked181A-P for strain-sensitive tape, 181A-M for mastic or 181 A-H for warmth-sensitive tape. Closure systems https://ermas999rkd2.wikilinksnews.com/user