Law Department notice on WTC document preservation, Oct 2001

NYC 9/11 Public Portal Document

APPENDIX B INSTALLATION OF SERVICE OPENINGS IN AIR HANDLING SYSTEMS

[B. 1] Service openings in Sheet Metal Ventilation System Components: Any Service openings shall be made in such a way as to not significantly weaken the structural integrity of the metal ventilation system component and provide an air tight seal once secured. Ventilation system/duct cleaning firm must provide a finished surface deemed visually acceptable by the Client and in the opinion of the Client, not reduce the building's aesthetic qualities. Work cut and patched in an unsatisfactory manner shall be removed and replaced by the Ventilation system/duct cleaning firm at no additional cost to the Client. Upon completion of inspection and/or cleaning services, the Service openings shall be sealed in accordance with job specifications, with one of the following closure techniques:

(1) Install gasketed removable Access Doors.

(2) Install sheet metal panels fastened with sheet metal screws and sealed with silicone chalk, mastic or duct sealant.

[B.2] Service openings in Externally Insulated Sheet Metal Ventilation System Components; (See [C.l] Service openings in Sheet Metal Ventilation System Components) Upon closure of Access Hole, external insulation must be replaced as necessary and the edges secured with either an approved water-based bridging encapsulant for canvas-wrapped insulated duct exteriors or reinforced 4” wide foil tape on foil-faced insulated duct exteriors.

[B.3] Service openings in Fibrous Lined Sheet Metal Ventilation System Components: Any Service openings shall be made in such a way as to not significantly weaken the structural integrity of the metal ventilation system component or create fiber shed from the internal insulation at the cut area once the Access Hole is closed. Upon completion of inspection and/or cleaning services, the Service openings shall be sealed in accordance with the following closure techniques:

(1) Install gasketed, insulated Access Doors. The cut edge of the internal insulation lining at the Access Hole must be sealed with an approved Bridging Encapsulant to prevent fiber shed, and the insulation on the cover plate should fit securely in the cut-out area.

(2) Pressure fitting round hole plugs (for Service openings 3" diameter or smaller in low/medium positive air pressure applications) after an approved ventilation system Bridging Encapsulant has been applied to the cut edge of the internal insulation to prevent fibershed. (3) Install sheet metal panels affixed with similar insulation to match the removed portion of insulation from the service opening, fastened with sheet metal screws and sealed with silicone chalk, mastic or duct sealant. The cut edge of the internal insulation lining at the Access Hole must be sealed with an approved bridging encapsulant to prevent fiber shed, and the insulation on the cover plate should fit securely in the cut-out area.

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NYC-WTC_000145225