with an allowable rope pull of 45 kN 10,000 pounds, so fabricated as to be
readily attachable to, and removable from, the car frames.
2.29.13
Coal Bunkers
Suspension coal bunkers of size and capacity indicated shall be constructed
of ASTM A 36/A 36M steel plate reinforced and braced as required and
installed dust-tight. Bunkers shall be provided of a design optimized for
coal flow, not susceptible to rat-holing or hangups. Cylindrical or silo
type bunkers to reduce stagnation shall be provided for each boiler, each
with conical discharge hoppers and slopes not less than 70 degrees. The
outlet cone shall be manufactured of, or lined with, ASTM A 167, Type 304
stainless steel. Bunkers shall be provided with rack and pinion type coal
shutoff valves, self-cleaning, and dust tight. Valve materials exposed to
flowing-coal shall be of corrosion resistant steel. An emergency diverter
shall be provided for emptying the bunker.
2.29.14
Coal Storage Silos
2.29.14.1
Silo Design
Silo walls may be slip-formed, cast-in-place reinforced concrete, precast
concrete, or other approved construction materials. Concrete shall have a
28-day compressive strength in accordance with Section 03300A CAST-IN-PLACE
STRUCTURAL CONCRETE. Silo roof shall be reinforced concrete complete with
600 mm 24 inch square, weatherproof, hinged access door. Handrail and
steel toe-board shall be provided all around the roof of the silo. Live
storage shelf for the silo shall be reinforced concrete, sloped not less
than 60 degrees from horizontal and supported by steel beams corbelled from
the inside walls of the silo. Live storage outlet hopper to chute and
feeders shall be built of not lighter than 9.5 mm 3/8 inch steel. Silo
reserve storage floor shall be reinforced concrete, sloped not less than 60
degrees and laid on well-tamped fill material. Reclaim outlet hopper to
the chute feeding the flight feeder shall be built of not lighter than 9.5
mm 3/8 inch steel.
2.29.14.2
Silo Interior Finish
In a concrete stave silo, the interior finish shall consist of a three-coat
concrete parget. A brush coat, scratch coat, and a finish trowel coat
shall be applied, one after the other, to produce a smooth monolithic
finish. The parget shall be worked into the vertical and horizontal
grooves to permanently interlock the concrete staves.
2.29.14.3
Silo Exterior Finish
The exteriors of stave and concrete silos shall be covered with a brush
coat of gray cement. This coating shall be applied over all hoops, lugs,
and staves to produce a homogeneous finish.
2.29.14.4
Silo Level Controls
A normal high-level and emergency high-level control switch shall be
mounted at the top of the silo to shut off the feeding system when the silo
is full of coal. A low-level switch shall be furnished at the low level of
the silo's live storage shelf, as indicated, to signal by light that coal
is at a low level in the live storage compartment. Switches shall also be
furnished near the bottom of the silo, as indicated, to signal by light
that coal is at a low level in the reserve storage compartment. Switches
SECTION 15559A
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