prevent access when the nuclear level detectors are operational. Doors
shall be in accordance with the requirements specified in paragraph
entitled "Structural and Miscellaneous Steel." Each hopper shall be
furnished with provisions for attachment of vibrators. Hoppers shall have
adequate flexibility for vibrating. Each hopper shall be provided with two
100 mm 4 inch poke holes with a tee wash connection and screw caps. Poke
holes shall be positioned to permit downward thrusts into the hopper. A
special plate reinforced "pounding area" shall be furnished on each hopper
face for external manual vibrating. Each pounding plate shall be 300 by
300 by 25 mm 12 by 12 inches by 1 inch thick plate steel ASTM A 36/A 36M.
A work platform with stairs shall be provided to each pounding area for
units with pounding areas more than 1 1/2 meters five feet above ground.
Approve location and arrangement of poke holes and pounding areas by the
Contracting Officer. Pounding plate shall not be insulated. Insulation
shall be neatly finished at this discontinuity. Each hopper shall include a
300 mm 12 inch diameter 57 kg 125 pound flat face flanged outlet
connection to match ash conveying system to be provided by the Contractor.
Provide access hatch not less than 200 by 200 mm 8 by 8 inch for cleanout
within 200 mm 8 inches above the flange. Ash valve shall be a minimum of
150 mm 6 inch diameter. Bolt-down type hatch is acceptable for clean-out
hatch. Provide each hopper with two mechanical vibrators, to be located at
mid-height on opposite sides. Vibrator controls shall be interfaced with
ash collection system to provide vibrator operation only at the inception
and during an evacuation cycle. Operation shall be automatic. Manual
override control for hopper vibrators and evacuation system shall be
provided in hopper area and shall be enclosed in cases to prevent
accidental energization of systems. A warning shall be placed over the
vibrator manual control with the following inscription: "Warning:
Vibrator Control. Do not activate unless hopper evacuation system is
operating." Provide nuclear hopper level switches as specified in
paragraph entitled "Instrumentation and Controls." Provide a hopper heater
system for each fabric filter baghouse. Each system shall be as specified
herein. Hopper heaters for each hopper shall be furnished by the collector
manufacturer and shall include material required for mounting. The system
shall be designed to provide a 93 degrees C 200 degrees F rise in
temperature in the hopper, in the vicinity of the heaters, during offline
and startup conditions. The system shall be designed to provide maximum
heater coverage between hopper stiffeners. The system shall be designed
with a minimum heating safety factor of 1.1 and a minimum wind heat loss
factor of 1.12. The system shall include a flexible throat heater for each
hopper. Heaters shall be of modular design except for throat heaters.
Flexible electric heating blankets or tapes, capable of withstanding 454
degrees C 850 degrees F, shall be used for areas where modular equipment
will not fit. Heater modules shall be designed for easy installation.
Heater modules shall cover at least 20 percent of the hopper area (covered
hopper area not to include exposed areas of poke holes, level detectors,
strike plates, stiffeners, access doors, etc.), shall cover the bottom
portion of the hopper to the maximum extent possible, and shall extend at
least 50 percent up the hopper height. Hopper throats shall be heated with
blanket or tape heaters. Equipment furnished shall be designed and tested
to withstand natural and induced vibrations including manual rapping of the
strike plates. The hopper heater system shall be individually
thermostatically controlled with adjustable setpoint between 66 to 121
degrees C 150 to 250 degrees F internal skin temperature, the minimum
specified ambient temperature, and shall be furnished and installed
complete including power, control, and alarm components. Heater voltage
shall be [_____] volts AC. Control voltage shall be 120 volts AC. Modular
heaters shall be furnished complete. Heater modules shall be
self-contained. The modules shall have a flexible heating face to conform
SECTION 15864N
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