air passages in insulated walls or brick work required for the
stoker.
2.2.3.5
Baffles
When provided, baffles shall be properly located and practically gastight.
Maximum velocity at end of baffle where gas turns shall be 17 meter 55
feet per second, except at baffle above rear pass hopper where maximum
velocity shall not exceed 12 meter 40 feet per second.
2.2.3.6
Casing
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NOTE: Designer shall fill in this blank depending
on type of air pollution equipment and maximum
pressure possible to be exerted on boiler casing by
induced draft fan. Do no use less than 4980 Pa 20
inches of water gage.
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Provide the entire setting, other than the top half of the steam drum with
a continuously welded tight skin steel casing of not less than 10 gage, or
an integral wall construction with outer casing of not less than 12 gage
construction. Weld other steel casing joints where practicable, and reduce
the number of bolted joints to a minimum. In places where sections of the
casing are subject to removal periodically for inspection and maintenance,
the casing shall be bolted using 18 mm 5/8 inch bolts on not more than 76 mm
3 inch centers with joints gasketed. Design the steel cased settings to
withstand an internal negative or positive pressure of not less than the
maximum static pressure generated by the boiler fans at shutoff and test
block, plus a 25 percent safety factor without objectionable deflection of
sides, or damage to side walls, casing, or refractory materials, or other
parts of the unit. The minimum design pressure shall be a [_____] Pa inch
water column. Make proper provisions for expansion and contraction of the
casing without creating breakage or air leaks. With a surface wind
velocity of 0.07 meter 2 feet per second, the average surface temperature
of the casing shall not exceed 66 degrees C 150 degrees F while the boiler
is operated at full rated load in an ambient temperature of 38 degrees C
100 degrees F. Finish the top half of the steam drum with 16 gage welded
steel casing, as previously specified for the setting.
2.2.3.7
Access and Observation Doors
a.
General: Provide boiler with a sufficient number of access and
observation doors, to give free and easy access and observation to
parts of the interior of the boiler.
b.
Access and Cleaning Doors: Provide a minimum of [_____] by 450 mm
18 inch access and cleaning doors to give free and easy access to
parts of the interior of the setting and the convection section of
boiler. Brick up the furnace access door openings with No. 1
firebrick or firebrick tile properly held in place, between door
and furnace.
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NOTE: At the text below, consider that access is
essential to all spaces between boiler tube banks,
the convection section, and on both sides of baffles
within these spaces. Consider access door under
SECTION 15502N
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