from formed welded or seamless tubing to a minimum centerline radius of
[2.0] [_____] diameters and preferably 2.5 times the duct diameter.
Assemble, weld, and finish ground gore sections to prevent internal
crevices and projections. Construct gored elbow in accordance with the
following:
400 mm diameter and less
Over 400 mm diameter
16 inches diameter and less
Over 16 inches diameter
90 degree - 5 piece minimum
90 degree - 6 piece minimum
60 degree - 4 piece minimum
60 degree - 5 piece minimum
45 degree - 3 piece minimum
45 degree - 4 piece minimum
30 degree - 3 piece minimum
30 degree - 3 piece minimum
15 degree - 2 piece minimum
15 degree - 2 piece minimum
2.10.5
Gasketed with full-face gaskets which are one-piece, heat, adhesive or
solvent vulcanized, or bonded and assembled to prevent drainage and limit
extrusion or cavity at joint.
2.10.6
Access and Cleanout Door Openings
Provide access plates upstream and downstream of equipment installed in
ductwork, at locations to facilitate duct cleaning (such as in horizontal
runs, near elbow junctions, and vertical runs), and where indicated. For
ducts 300 mm 12 inches diameter or less, locate cleanout or access openings
a minimum of 3.70 meters 12 feet apart. Provide 250 by 300 mm 10 by 12
inches minimum size access opening; unless otherwise indicated or prevented
by duct dimension. Locate opening a minimum of 80 mm 3 inches from bottom
of duct. Frame access openings by welded and ground miter joint 5 mm 3/16
inch thick strap iron, or angle iron, with 6 mm 1/4 inch stainless steel
bolt or stud assembly to duct on 100 mm 4 inch centers. Fabricate plates
out of 300 series corrosion-resistant steel or polyvinyl chloride faced
sheet backed by 16 gage sheet metal, reinforced as required for larger
sizes, or constructed of heavier gage metal. Ensure only corrosion
resistant materials are expose to duct interior. Provide one "U" handle on
access plates through 250 by 300 mm 10 by 12 inches and two "U" handles on
larger sizes. Locate access openings at points which will permit ready
access to duct internals with no duct cutting. Where access through
equipment or access doors specified herein is not available at a specific
point, provide 200 mm 8 inch diameter gasketed access plates spaced on
maximum 3 meters 10 foot centers. Where penetration of duct surfaces is
approved or specified, provide 300 series corrosion resistant steel
fastener assemblies. Provide hex type, cadmium plated flange fastener
bolts and nuts and [3 mm 1/8 inch thick acid resistant chloroprene] [3 mm
1/8 inch thick Buna N] joint gaskets.
2.11
THERMOPLASTIC DUCTWORK
**************************************************************************
NOTE: Duct systems of plastic material may be used
to handle only nonflammable corrosive fumes and
vapor when conventional metal duct systems will not
be adequate.
SECTION 15801N
Page 29
Previous Page
