mineral fiber block or ASTM C 59/C 59M2 mineral fiber blanket insulation.
Insulate the roof with ASTM C 533 calcium silicate block. Minimum
insulation thicknesses shall be as follows:
a.
Housing [_____] mm inches
b.
Hoppers [_____] mm inches
c.
Hot Roof [_____] mm inches
d.
Penthouse [_____] mm inches.
2.4.3
Casing Materials
Casing except top surface casing, which might serve as personnel walking
surface, shall be 1.27 mm 0.050 inch thick stucco embossed, 100 mm 4 inch
rib, unpainted aluminum panel. Aluminum casing shall be ASTM B 209M ASTM
B 209.
2.5
HOPPERS
Construct hopper plate of [Type 316 stainless steel conforming to ASTM A 276
] [structural steel conforming to ASTM A 242/A 242M Type 1] and a minimum 6
mm 1/4 inch thick. Provide hoppers with ASTM A 242/A 242M baffles to
prevent flue gas from bypassing the electrostatic field. Hoppers shall
span no more than one electrical field. Provide hoppers with untapered
fillet plates, constructed of cold rolled minimum 10-gage ASTM A 276 Type
316 stainless steel, in each corner. Extend the fillet plates the full
length of the corner. Seal weld the fillet plates to the hopper walls.
Provide closure plates at the top of the hopper at each corner to prevent
flow into the area between the fillet plate and the hopper corner. Steel
reinforcements not in contact with the gas or ash may be either ASTM A 276
Type 316 stainless steel or ASTM A 242/A 242M structural steel. If the
latter is used, select welding rods specifically for the service and submit
to the Contracting Officer for approval. Provide protection of rods
against moisture.
2.5.1
Hopper Accessories
Provide key interlocked access doors on each hopper on both sides of any
hopper baffle. Doors shall be in accordance with the requirements
specified herein. Hoppers shall have adequate flexibility for vibrators.
Provide each hopper with two 100 mm 4 inch poke holes with a tee wash
connection and screwed caps. Position poke holes to permit downward
thrusts into the hopper. Provide a special plate reinforced "pounding
area" on each hopper face for external manual vibrating. Each pounding
plate shall be 300 by 300 by 25 mm 12 by 12 by 1 inch thick ASTM A 36/A 36M
plate steel. Provide a work platform with stairs to each pounding area for
units with pounding areas more than 1.50 meters five feet above ground. Do
not insulate pounding plate. Finish insulation at this discontinuity.
Provide a minimum 200 mm 8 inchdiameter flanged fly ash outlet connection
on each hopper to accept the fly ash transportation system equipment.
Provide access hatch not less than 200 by 200 mm 8 by 8 inches for
cleanout within 200 mm 8 inches above flange.
2.5.2
Hopper Vibrators
Provide each hopper with two vibrators set at the mid-height and on
opposite sides. Interface vibrator controls with ash collection system to
SECTION 15862N
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