minimized. Adequate superheater piping to mount the safety valves shall be
provided. The design shall be such as to minimize external corrosion on
the superheater and reheater due to molten slag or fouling. The location
of headers in the gas stream shall be minimized. Spray desuperheaters
shall be complete with thermal sleeves of sufficient length to prevent
droplets of water from coming in contact with the hot wall of the pipe.
The sleeves shall be arranged for attaching securely to the pipe, but in a
manner that will permit differential expansion.
2.2.2.7
Boilers and Firing Equipment
Boilers and firing equipment shall be supported from the foundations with
structural steel independent of all brickwork. Boiler supports shall
permit free expansion and contraction of each portion of the boiler without
placing undue stress of any part of the boiler or setting.
2.2.3
Boiler Settings
2.2.3.1
Boiler Material
Materials shall conform to the following:
a.
Firebrick: ASTM C 27, class as recommended by the boiler
manufacturer.
b.
Insulating Brick:
ASTM C 155.
c.
Castable Refractory: ASTM C 401. The minimum modulus of rupture
for transverse strength shall not be less than 4.1 MPa 600 psi
after being heat-soaked for 5 hours or more at a temperature in
excess of 1371 degrees C 2,500 degrees F.
d.
Mortar, Air-Setting, Refractory:
As recommended by the boiler
manufacturer.
e.
Brick, Common:
ASTM C 62.
f.
Galvanized Steel Sheets: ASTM A 659/A 659M, ASTM A 653/A 653M.
Gauges specified are manufacturer's standard gauge.
g.
Uncoated Steel Sheets and Strips, Low Carbon: ASTM A 36/A 36M.
Gauges specified are manufacturer's standard gauge.
2.2.3.2
Firebox, Packaged Type
Boiler refractories and insulation shall be installed to permit free
expansion without placing undue stress on the boiler or refractory.
Insulation and jacket shall provide a casing temperature not exceeding 77
degrees C 170 degrees F in an ambient temperature of 38 degrees C 100
degrees F with a surface wind velocity not exceeding 254.0 mm/second 50 fpm
while operating at full load.
2.2.3.3
Watertube, Waterwall Type
**************************************************************************
NOTE: On watertube type boilers that will be used
intermittently, welded wall construction is
recommended to minimize corrosion. In other
applications or with fuels containing not more than
SECTION 15559A
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