Provide a flexible mechanical coupling, Dresser style or equal, to connect
pump discharge elbow to [transition section][wall thimble][discharge
piping].
2.2.7.10
Wall Thimble
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NOTE: This alternative is used when the discharge
piping includes the piece that will be embedded in
the wall of the station. The size of vent to be
used is determined from information in EM
1110-2-3105.
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Wall thimble shall have one plain end to accommodate flexible mechanical
coupling and one flanged end to mate with [flap valve][multiple shutter
gate][discharge piping]. Plain end shall match pump discharge elbow in
thickness and diameter and flanged end shall be drilled to match, and shall
be capable of supporting without distortion, the [flap valve][multiple
shutter gate]. Provide seal ring on wall thimble located so that it is
centered in the wall when embedded. In addition, furnish a [_____] mm inch
flanged vent nozzle equipped with an ASME B16.5 Standard 125 pound flange
and locate where shown. Fabricate wall thimble from steel plates.
2.2.7.11
Discharge Piping
Discharge piping shall consist of a transition section and a wall thimble.
Transition section shall have one plain end and one flanged end, and shall
provide a change in cross section from round to [square][rectangular]. The
plain end shall match pump discharge elbow in thickness and diameter.
Arrange wall thimble for embedment and with flanges on each end. One end
shall mate with flange on transition section and the other end shall mate
with flap gate. Fabricate discharge flange with a minimum dimension of
AWWA C207, Class D, drill to match. Discharge flange shall be capable of
supporting without distortion the multiple shutter gate. Provide seal ring
on wall thimble and located so that it is centered in the wall when
embedded. In addition, furnish a [_____] mm inch flanged vent nozzle
equipped with an ASME B16.5 Standard 125 pound flange and locate where
shown. Discharge piping shall be fabricated from steel plate.
2.2.8
Impeller
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NOTE: Cast steel and aluminum bronze are normally
used when pumps are less than 2100 mm (84 in.).
Fabricated steel impellers are used with pumps
having discharge diameters 2100 mm (84 in.) or
greater. Cast stainless steel is used for pumps
where the difference between pump NPSHA and NPSHR is
small (less than 600 mm (2 ft)) or, when severe
corrosion is expected.
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Make impeller of [cast steel, ][cast stainless steel, ][aluminum bronze] or
[fabricated of welded steel plate].
SECTION 15131A
Page 30
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