2.3.6
Breaching
Breaching shall be constructed of not less than 3.416 mm 10 gauge steel
sheets conforming to ASTM A 36/A 36M. Breaching shall be adequately
reinforced and braced with structural steel angles not smaller than 50.8 x
50.8 x 6.4 mm 2 x 2 x 1/4 inch and all joints and seams in the sheets and
angles shall be welded. Expansion joints shall be installed as indicated
and as required to suit the installation and shall be flexible type
requiring no packing. Breaching shall have angle flanges and gaskets for
connection to boilers, fans, equipment, or stacks with breaching to be the
full size of the opening. Breaching shall be lined with a minimum of 76.2
mm 3 inch thick refractory. Breaching connections shall be gas-tight,
caulked tight all around and sealed with cement to form an air-tight joint.
Clean-out openings of suitable size and at approved locations shall be
provided for access to all sections of the breaching and shall have
tight-fitting hinged doors with frames. One 400 x 400 mm 16 x 16 inch
inspection door shall be located in the side of the breaching just
preceding the boiler unit. A similar inspection door shall be located just
following the boiler unit. Breaching may be supplied in bolted or welded
sections for ease of handling and erection and shall be constructed per
SMACNA HVAC Duct Const Stds. Connectors shall be in accordance with NFPA
211. Plastic materials polyetherimide (PEI) and polyethersulfone (PES) are
forbidden to be used for vent piping of combustion gases.
2.3.7
Flue Gas Inlet Damper
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NOTE: Optional wording is applicable to
guillotine-type dampers.
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A [guillotine] [butterfly] [shutter] damper [of the thickness indicated]
[at least 63 mm 2-1/2 inches thick] and consisting of refractory material
enclosed in a steel frame shall be installed at the entrance of the waste
heat recovery boiler to isolate it from the combustion equipment during
emergency boiler repairs. A [chain hoist] [manual lever] [electrical
control] for raising and lowering the damper shall be furnished and shall
be of a size and design to ensure free movement by the damper. [The hoist
cable shall be secured to the damper frame by shackles and bolts. The
damper slot shall have a steel plate cover 6.4 mm 1/4 inch thick and of the
proper length and width. The cover shall have a slot to permit passage of
the damper cable, and for easy removal of the damper. The hoist shall be a
product of a manufacturer regularly engaged in the manufacture of hoists.
Hoist shall be spur geared. Unit shall be designed for high-speed lifting,
have high mechanical efficiency, an automatic load brake, and a built-in
load limit.] The operator shall be able to move the required load freely
and maintain the damper in any desired position within the limits of the
flue opening. Maximum pull to operate the unit shall not exceed 310
Newtons 70 pounds.
2.3.8
Flue Gas Discharge Dampers
A controller-actuated, refractory-lined damper shall be installed at the
boiler exit. Another damper shall be installed in the dump stack and shall
open if any of the following conditions occur:
a.
Excess boiler steam pressure.
b.
Induced draft fan failure.
SECTION 15846A
Page 34
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