2.
The piping, both suction and discharge, should be as short and direct as possible. Avoid all un-
necessary elbows, bends, and fittings, as they increase the friction losses in the piping. The size
of pipe and fittings should be carefully selected and of sufficient size to keep the friction losses as
low as practical.
3.
Piping must not be connected to the pump until the grout has thoroughly hardened and the foun-
dation bolts, as well as driver and pump hold down bolts have been tightened.
4.
When handling liquids at elevated temperatures, it is suggested that expansion loops or joints be
properly installed in suction and/or discharge lines so that linear expansion of the piping will not
draw the pump out of alignment.
If such expansion loops or joints are not used, the forces and moments, due to thermal expan-
sion of the piping system, that can act upon the pump inlet and discharge flanges must be deter-
mined and must not exceed the limits permissible for the specific pump in question.
Such installations require extremely careful and precise attention to hot alignment procedures.
See
5.18 Final Alignment on page 45
5.
On units handling corrosives, the piping can be arranged so that corrosives can be flushed from
pump prior to opening unit for service. See image below. During operation, valves "1" and "3"
would be closed, "2" and "4" open. Prior to dismantling, close valves "2'' and "4", open "1" and
"3". Introducing water at valve "3" will allow water to flush pump and drain at valve "1".
1. Tee
6. Suction
2. Valve "A"
7. Tee
3. Flush water
8. Valve "2"
4. Valve "3"
9. Valve "1"
5. Discharge
10. To waste
Figure 21: Piping
4.7 General Suction Piping
Properly installed suction piping is of extreme importance for trouble-free centrifugal pump operation.
1.
Use of elbows close to the pump suction flange should be avoided. Where used, elbows should
be long radius.
On double suction pumps, if an elbow must be used at the pump suction flange, it must be in a
vertical position only. If an elbow must be used in other than a vertical position, it is permissible
4.7 General Suction Piping
24
3175 Installation, Operation and Maintenance Instructions
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