pin.
Anchor bolts shall be 303 stainless steel.
b.
Galvanized Steel Systems: The removable header assembly shall be
fabricated from Schedule 40 steel pipe conforming to ASTM A 53/A
53M. All welding shall be performed in the shop. Butt welds
shall be full penetration welds with an interior projection not
exceeding 2 mm 1/16 inch. Welding shall conform to AWS D1.1/D1.1M.
The assembly shall be hot-dip galvanized after fabrication.
Anchor bolts shall be 303 stainless steel. The quick-coupling
flange shall be nickel plated ductile iron with a stainless steel
hinge pin.
2.4.2.4
Supports and Guides
Each removable header shall be supported by two adjustable supports with
vee-shaped guides. Supports shall be fabricated from 6 mm 1/4 inch steel
plate and shall have at least 25 mm 1 inch vertical adjustment. The
supports shall support the weight of the assembly so that the
quick-coupling can be easily disconnected.
2.4.3
Rotary or Swing Header Air Distribution System
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NOTE: Delete inapplicable header types and
materials of construction.
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Rotary or swing header air distribution systems shall be provided as
indicated and shall consist of an air supply assembly, rotary or swing-type
air header assembly, and supports. The system shall be compatible with the
air main and the specified diffusers.
2.4.3.1
Air Supply Assembly
An air supply assembly shall be provided for each rotary or swing header to
connect the upper swing joint to the air main. The assembly shall consist
of the required pipe and fittings, a butterfly valve, and a combination
connector and support for the upper swing joint.
2.4.3.2
Rotary or Swing Header Assembly
The rotary or swing header assembly shall consist of an upper swing joint,
a knee joint, hanger pipes, and a header. The upper swing joint shall
connect to the air supply assembly and shall include connectors for field
installation of diffusers. The rotary or swing header assembly shall be
designed to withstand a vertical load that results in a moment of 56.5 N m
500 in-lb at the diffuser connection without permanent deformation.
Lifting lugs shall be provided on the assembly as required to lift the
header assembly out of the tank. Rotary or swing header assembly shall be
stainless steel systems, carbon steel systems, galvanized steel systems, or
fiberglass systems as follows:
a.
Stainless Steel Systems: The upper swing joint and knee joint
shall be cast stainless steel. Connection between the two
sections shall be by means of a stainless steel pin working in a
graphite bronze bushing. Bearings shall be graphite impregnated
cast bronze complying with ASTM B 584. Brass seal rings with
labyrinth grooves between the two joint sections shall be
provided. A grease fitting to lubricate the seal rings shall be
SECTION 11375A
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