to provide an adequate and firm installation to the foundation structure.
Supports are to provide for free expansion and contraction of each part of
the boiler without placing undue stress on any part of the boiler or
setting.
2.2.12.3
Shell
Casing or shell sides shall be constructed of carbon steel materials not
lighter than 3.416 mm 0.1345 inch thick, either bolted or welded. Casing
shall be gas-tight and shall be reinforced with steel ribs or stiffeners to
provide rigidity and prevent buckling. Boiler casing shall be fully
insulated with sufficient thickness to limit the casing temperature as
specified. Boiler shell shall be equipped with all necessary connections
including outlet nozzles, return connections, and connections for pressure
relief valves, water level controls, and other required trim. Manholes,
handholes, and observation ports shall be provided in accordance with ASME
BPVC SEC I. Boilers shall be equipped with gas-tight observation ports.
2.2.12.4
Expansion and Contraction
Adequate provisions shall be made for expansion and contraction of the
boiler unit and associated breaching to prevent damage to the support
structure or the equipment and associated ductwork. Provisions shall be
made for expansion and contraction between boiler foundation and floor.
Joints shall be packed with oakum and filled with a suitable compound that
will not become soft at temperatures of 49 degrees C 120 degrees F.
2.2.13
Water-Tube Boiler
Boiler shall be a shop fabricated and field erected or a packaged unit.
Boiler shall include water walls, soot-blowers, [economizer,] [super
heater,] and steam drums to withstand temperatures existing under maximum
load conditions to ensure production of the steam as specified. Boiler
shall include setting refractory, insulation to maintain a casing
temperature of not greater than 55 degrees C 130 degrees F with a surface
air velocity at 5.4 km/hour 5 feet/second and an ambient temperature of 26
degrees C 80 degrees F while boiler is operating at maximum capacity (no
asbestos material shall be used), and welded or doubled wall casing.
Access opening covers shall be hinged.
2.2.13.1
Drums or Dome Space
For water-tube boilers, each drum or dome space shall be steel plate,
fusion welded in conformance with ASME BPVC SEC I, including stress
relieving and x-raying of welded seams. The main steam drums shall be of
sufficient size to accommodate steam separators and drum internals with
provisions and space for accomplishment of maintenance. Baffling shall be
provided to separate the steam from the water in the drum and to maintain a
stable water level under a fluctuating load. Variations in normal water
level shall not exceed 50 mm 2 inches with an increasing load change of 20
percent of rated capacity per minute. Steam separators shall be provided
to deliver saturated steam with a maximum specified moisture content. Each
drum shall have two 300 x 400 mm 12 x 16 inch elliptical manholes, with the
exception of the mud drum which shall have at least one 300 x 400 mm 12 x
16 inch elliptical manhole. Each manhole shall have a cover, yoke, and
gaskets.
SECTION 15846A
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