flanges shall not be less than 40 mm 1 1/2 in. thick after machining.
Flange machining shall not vary more than 10 percent of the greatest flange
thickness. Fabricated flanges, as a minimum, shall be constructed to the
dimensions of AWWA C207, Class B. Flanges shall be connected to the column
tube [and discharge elbow] with two continuous fillet welds, one at the
inside diameter of flange-to-pump-tube and the other at the outside
diameter of pump-tube-to-flange. Weld design is the pump manufacturer's
responsibility. Mating flanges shall be machined parallel to a tolerance of
0.05 mm. 0.002 in. The machine mating flange surface shall be finished to
125 microns or better.
2.3.3
Nuts and Bolts
Nuts and bolts shall be of the hexagonal type. Bolts, including assembly,
anchor, harness, and dowels, shall be 300 stainless steel. Nuts shall be
bronze; washers shall be 300 series stainless steel.
2.3.4
[Bolted Lid
A watertight lid shall be provided, hinged and bolted to the top of the
discharge tube.]
2.3.5
[Harnessed Coupling
Flexible mechanical coupling shall be provided connecting the pumping unit
discharge elbow to the wall thimble and the discharge piping equal to
Dresser style 38 coupling or approved equal. The middle ring shall be
finished without pipe stop to facilitate the installation and removal of
coupling.]
2.3.6
[Wall Thimble
The wall thimble shall have one plain end to accommodate flexible
mechanical coupling and one flanged end to mate with the flap gate. The
plain end shall match the discharge elbow in thickness and diameter, and
the flanged end shall be drilled to match and shall be capable of
supporting, without distortion, the flap gate. A seal ring will be
provided on the wall thimble, located so that it is centered in the wall
when embedded. The wall thimble shall be fabricated from steel plates.]
2.3.7
Dissimilar Metals
When dissimilar metals are used in intimate contact, suitable protection
against galvanic corrosion shall be applied. The anodic member shall be
protected by proper electrical insulation of the joint.
2.4
INTAKE DESIGN
**************************************************************************
NOTE: Information on intake design is available in
EM 1110-2-3105, Hydraulic Institute standards,
manufacturers' catalogs, and model tests from the
U.S. Army Engineer Waterways Experiment Station
(WES). The designer should be aware of net positive
suction head available (NPSHA) and NPSHR from pump
performance curves and the plant design operation.
If the approach inlet conditions to the pumping
station are unique or unusual, the designer should
consult WES about the need for a model test or to
SECTION 15132A
Page 24
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