Joints of duct techniques shall be manufactured substantially airtight by means of tapes, mastics, liquid sealants, gasketing or other authorised closure methods. Closure methods employed with rigid fibrous glass ducts shall comply with UL181A and shall be marked181A-P for pressure-delicate tape, 181A-M for mastic or 181 A-H for heat-sensitive tape. https://francesa467sqp8.wikipublicity.com/user