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Fiberglass Reinforced Plastic Duct Specifications
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UnderDuct Sample Specification:
QUALIFIED ENGINEERING ASSISTANCE IS AVAILABLE TO COMPOSE SPECIFICATIONS FOR EACH INDIVIDUAL PROJECT.
SECTION XXXXX – FIBERGLASS REINFORCED PLASTIC DUCTWORK (FRP)
Part 1 General
1.1 Summary:
A. Section includes:
a. Thermoset FRP ducts and fittings
B. Related Sections:
a. Section XXXXX “Testing, Adjusting and Balancing for HVAC” for testing, adjusting and balancing requirements for nonmetal ducts.
b. Section XXXXX “Metal Ducts” for single and double wall, rectangular and round ducts.
c. Section XXXXX “Air Design Accessories” for dampers, duct-mounting access doors and panels, turning vanes and flexible ducts.
1.2 References:
A. Comply with the latest revision of the following codes, standards and specifications, except where more stringent requirements have been specified herein:
a. American Society for Testing Materials (ASTM0:
i. C 582 Contact-Molded reinforced Thermosetting Plastic (RTP)
Laminated for Corrosion-Residence Equipment
ii. D 2412
iii. D 2996 Filament-Wound “Fiberglass” (Glass Fiber Reinforced Thermosetting Resin) Pipe and Fittings.
iv. D 3982 Contact-Molded “Fiberglass” (Glass Fiber Reinforced Thermosetting Resin) Duct and Hoods
v. E 84 Standard Test Method for Surface Burning Characteristic of Building Materials
b. Sheet Metal and Air Conditioning Contractors National Association, Inc. (SMACNA)
i. Thermoset FRP Duct Construction Manual
c. United States Department of Commerce:
i. NPS 15-69
d. Underwriters Laboratories (UL181)
i. UL 181
1.3 Submittals
A. Product Data:
a. Resin
b. Glass
c. Gel Coat
B. Coordination Drawings: Plans drawn to scale, on which the following items are shown and coordinated with each other, using input from installers of the items involved:
a. Duct installation in congested spaces, indicating coordination with general construction, building components and other building services. Indicated proposed changes to duct layout.
b. Suspended ceiling components.
c. Structural members to which duct will be attached.
d. Penetrations of smoke barriers and fire-rated construction.
C. Verification that the resin to be supplied has been tested by an ASTM E84 Nationally Recognized Testing Laboratory to comply with UL 181 Class 1 standards of low smoke and low flame. Certification shall be current within ten (10) years of project start date.
Part 2-Products
2.1 Thermoset FRP Ducts and Fittings
A. Resin:
a. Thermoset FRP Resin: Manufacture duct with Monoxivent 824 modified acrylic resin that complies with UL 181, Class 1, maximum flame-spread index of 25 and maximum smoke-developed index of 50 when tested by an NRTL according to ASTM E 84.
b. The use of liners to achieve the indicated smoke and flame spread development will not be accepted.
B. Insulation:
a. Double-Wall Insulated Duct: Inner and outer duct complying with requirements for “Round Duct” description. Closed Cell Polyurethane Foam insulation with maximum thermal conductivity of 0.14 BTU x in. / h x sq. ft. x deg F at 75 deg. F mean temperature
R7 1” THK
R10 1.5” THK
C. Reinforcement:
a. Surfacing Veil shall be “C” glass veil with a silane finish and a styrene soluble binder.
b. Chopped Strand Mat shall be Type E Glass with a minimum 1-1/2 ounce per square foot with silane finish and styrene soluble binder.
c. Woven Roving shall be Type E glass minimum 24 ounces per square yard.
d. Continuous Roving for a filament binding shall be Type E glass with a silane finish.
D. Construction:
a. Fabricate joints, seams, transitions, reinforcement, elbows, branch connections, and access doors and panels, according to SMACNA’s “Thermoset FRP Duct Construction Manual” Chapter 7, “Requirements”.
b. FRP ductwork shall be design safety factor of 10 to 1 for pressure and 5 to 1 for vacuum
c. Out of roundness of duct shall be limited to ±1/4”
d. Round Duct: Filament wound minimum Thickness:
2” to 20” diameter 0.125” THK
22” to 36” diameter 0.1875” THK
38” to 96” diameter 0.25” THK
E. Lamination:
a. All ductwork shall have any interior and exterior “C” veil liner 10 mil thick.
b. Structural layer shall be fabricated toward Winding or Hand lay-up Standard.
c. Exterior:
i. Below ground to have a “C” veil layer.
ii. Above ground to have a “C” veil layer and White paraffinated gel coat with UV inhibitors
F. Fittings:
a. All fittings shall be made out of the same resin and having the same strength as the FRP ductwork
b. The internal diameter of all fittings shall be equal to the adjacent duct
c. The tolerance on angles of all fittings shall be ± 1o up to and including 24” diameter and ± ½o for 30” diameter and above.
G. Elbows:
a. Elbows Centerline radius shall be 1-1/2 times the diameter.
b. Fabricate 45-degree elbows with a minimum of two (2) segments and 90-degree round elbows with a minimum of three (3) segments.
H. Drains:
a. When required, formed drain pockets with a minimum of NPS 1” threaded pipe connections
I. Joints:
a. Field Joints to be Butt & Wrap type for wet lay-up method.
b. Field joint kits sent out in bulk form with an extra 20% material for waste
c. Resin to be same as duct
Part 3-Execution
3.1 Duct Installation
A. General
a. Store Resin, glass reinforcing and curing agent in a cool, dry area to maximize shelf life.
b. Upon arrival at the installation site the customer shall examine the duct for any damage that may have occurred in transit.
c. Follow ASTM D 3982 Table 1 for recommended hanger spacing.
d. Use flexible connections to isolate ductwork from vibration caused by air-moving equipment (By Others).
e. Unload the duct system with care and store in a location where it will be free of damage. Impact of a tool or other heavy object may result in a fracture of the inner lining and may affect the service life of the duct.
f. Support large sub-assemblies during unloading and transportation to prevent excessive deflection and over stressing.
g. Use full-face gaskets to eliminate any cantilever effect caused from bolting.
h. Tighten bolts on flange connections following torque values given in Table1 per ASTM D 3982.
i. Follow manufactures Field Jointing instructions for bonding ductwork together.
B. Burial
a. Ductwork Trench shall be dug so that it will be 1.5 times wider than then diameter of the duct.
b. Fill bottom of trench with a minimum of 6” of back fill (sand or pea gravel) compacted to 80%-90%.
c. Grade Trench with a 1% pitch back to the largest diameter duct.
d. Backfill in 6” lift increments compacting 80%90%.
e. A minimum of 4” of backfill overtop the duct system is required.
3.2 Field Quality Control
A. Leakage Test:
a. Comply with SMACNA’s “HVAC Air Duct Leakage Test Manual”. Submit a test report for each test.
b. Test the following systems:
i. Supply Ducts with a Pressure Class of 2-inch w.g. or higher: Test representative duct sections totaling no less than 100 percent of total installed duct area for each designated pressure class.
ii. Return Ducts with a Pressure Class of 2-inch w.g. or higher: Test representative duct sections totaling no less than 100 percent of total installed duct area for each designated pressure class.
c. Disassemble, reassemble and seal segments of systems to accommodate leakage testing and for compliance with test requirements.
d. Test for leaks before burial of ducts.
e. Conduct tests at static pressures equal to maximum design pressure of system or section being tested. If static-pressure classes are not indicated, test entire system at maximum system design pressure. Do not pressurize systems above maximum design operating pressure.
END OF SECTION XXXXX