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Oklahoma Administrative Code (Last Updated: March 11, 2021) |
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TITLE 748. Oklahoma Uniform Building Code Commission |
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Chapter 20. Adopted Codes |
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Subchapter 5. IRC® 2015 |
SECTION 748:20-5-13.1. IRC® 2015 Chapter 16 Duct Systems
Latest version.
- (1) Table M1601.1.1 Duct construction minimum sheet metal thickness for single dwelling units has been stricken from the code and replaced with a newly created table with the same table heading. The newly created table contains three columns and three rows and a footnote. The description of the newly created table is listed below:(A) Row 1: Contains the three column headings as follows:(i) Column 1 heading is entitled "Duct Size"(ii) Column 2 heading is entitled "Galvanized" with two sub-columns; the first sub-column is entitled "Minimum Thickness (inches)" and the second sub-column is entitled Equivalent Galvanized Gage No."(iii) Column 3 heading is "Approximate Aluminum B and S Gage."(B) Row 2: Under the first column entitled "Duct Size" are four sub-rows with corresponding dashes or figures that match to each sub-row in the second (including sub-columns) and third columns. Those sub-rows and figures are as follows:(i) Sub-row 1 in column 1 lists "Round ducts and enclosed" and in column 2 entitled, "Galvanized," (sub-column "Minimum Thickness (inches) and sub-column "Equivalent Galvanized Gage No." and in column 3 entitled "Approximate Aluminum B and S Gage" a "dash" is listed instead of a figure.(ii) Sub-row 2 in column 1 lists "Rectangular ducts" and in column 2, entitled "Galvanized" (sub- column "Minimum Thickness (inches)" and sub-column "Equivalent Galvanized Gage No." and in column 3, entitled "Approximate Aluminum B and S Gage" a "dash" is listed instead of a figure.(iii) Sub-row 3 in column 1 lists "14 inches or less" and in column 2, entitled "Galvanized," sub- column "Minimum Thickness (inches)" lists the figure "0.013", sub-column "Equivalent Galvanized Gage No." lists the figure "30," and column 3 entitled "Approximate Aluminum B and S Gage" lists the figure "26."(iv) Sub-row 4 in column 1 lists "Over 14 inches" and in column 2, sub-column "Minimum Thickness (inches)" lists the figure "0.016", sub-column "Equivalent Galvanized Gage No." lists the figure "28" and column 3 entitled "Approximate Aluminum B and S Gage" lists the figure "24."(C) Row 3: Under the first column entitled "Duct Size" are three sub-rows with corresponding dashes or figures that match to each sub-row in the second column and the third column. Those sub-rows and figures are as follows:(i) Sub-row 1 in column 1 lists "Exposed rectangular ducts" and in column 2, entitled, "Galvanized," (sub-column "Minimum Thickness (inches) and sub-column "Equivalent Galvanized Gage No." and in column 3 entitled "Approximate Aluminum B and S Gage" a "dash" is listed instead of a figure.(ii) Sub-row 2 in column 1 lists "14 inches or less" and in column 2, sub-column "Minimum Thickness (inches)" lists the figure "0.016", sub-column "Equivalent Galvanized Gage No." lists the figure "28" and column 3 entitled "Approximate Aluminum B and S Gage" lists the figure "24."(iii) Sub-row 3 in column 1 lists "Over 14 inches" and has a superscript "a" to indicate an associated footnote. In column 2, sub-column "Minimum Thickness (inches)" lists the figure "0.19", sub-column "Equivalent Galvanized Gage No." lists the figure "26" and column 3 entitled "Approximate Aluminum B and S Gage" lists the figure "22."(D) Between the end of the table and Footnote "a" is the wording "For SI: 1 inch is equal to 25.4 mm."(E) Footnote "a" has been added to read: a. Ductwork that exceeds 20 inches by dimension or exceeds a pressure of 1 inch water gage (250 pa) shall be constructed in accordance with SMACNA HVAC Duct Construction Standards Metal and Flexible.(2) Section M1601.4.1 Joints, seams, and connections. This section has been modified to add a fourth exception for duct systems with sheet metal plenums, Y's and supply boots with liquid applied sealants. This section has been modified to read: M1601.4.1 Joints, seams and connections.(A) Longitudinal and transverse joints, seams and connections in metallic and nonmetallic ducts shall be constructed as specified in SMACNA HVAC Duct Construction Standards-Metal and Flexible and NAIMA Fibrous Glass Duct Construction Standards. Joints, longitudinal and transverse seams, and connection in ductwork shall be securely fastened and sealed with welds, gaskets, mastics (adhesive), mastic-plus-embedded-fabric systems, liquid sealants or tapes. Tapes and mastics used to seal fibrous glass ductwork shall be listed and labeled in accordance with UL 181A and shall be marked "181A-P" for pressure-sensitive tape, "181 A-M" for mastic or "181 A-H" for heat sensitive tape.(B) Tapes and mastics used to seal metallic and flexible air ducts and flexible air connectors shall comply with UL 181B and shall be marked "181 B-FX" for pressure-sensitive tape or "181 BM" for mastic. Duct connections to flanges of air distribution system equipment shall be sealed and mechanically fastened. Mechanical fasteners for use with flexible nonmetallic air ducts shall comply with UL 181B and shall be marked 181B-C. Crimps joints for round metallic ducts shall have a contact lap of not less than 1 inch (25 mm) and shall be mechanically fastened by means of not less than three sheet-metal screws or rivets equally spaced around the joint.(C) Closure systems used to seal all ductwork shall be installed in accordance with the manufacturers' instructions.(D) Exceptions:(i) Spray polyurethane foam shall be permitted to be applied without additional joint seals.(ii) Where a duct connection is made that is partially inaccessible, three screws or rivets shall be equally spaced on the exposed portion of the joint so as to prevent a hinge effect.(iii) For ducts having a static pressure classification of less than 2 inches of water column (500 Pa), additional closure systems shall not be required for continuously welded joints and seams and locking-type joints and seams of other than the snap-lock and button-lock types.(iv) For duct systems with sheet metal plenums, Y's and supply boots, only liquid applied sealants complying with UL 181 BM (Mastic or similar) or equivalent method, shall be used to seal inner liners and start collars to plenum and any other seams in system.