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Pump Installation 8 Piping

effective way to prevent pipe strain during initial installation, which is
exactly the right time to stop it.
The effects of pipe strain in a conventional process pump can also be
transmitted to the shaft coupling. With the accuracy of laser alignment
technology, pipe strain can be measured much in the same way as soft
foot and should be integrated into the shaft alignment program. By
loosening the pipe connection after a correct shaft alignment has been
performed, any movement at the coupling will indicate the existence of
pipe strain and can therefore be corrected.

As there is an exception to almost every rule, the A.P.I. 610 Pump
Specification used in the petroleum industry identifies a maximum level
of forces and moments that may be imposed on the pump flanges.
These must be acceptable to any pump being sold into that, or a
related, industry using that specification. As a consequence, all API
pumps are of a much more robust and heavier design than their ANSI
size equivalents.
In high temperature applications, some piping misalignment is
inevitable owing to thermal growth during the operating cycle. Under
these conditions thermal expansion joints are often introduced to avoid
transmitting any piping strains to the pump. However, if the end of the
expansion joint closest to the pump is not anchored securely, the pipe
strain is passed through to the pump, thus defeating the objective of the
expansion joint.
To ensure even gasket compression when tightening up the flange nuts
and bolts, always tighten the bolts diametrally opposed to each other in
an alternating pattern.

10.2.1.7 Pipe fittings
The Suction VaNe has only one function, and that is to isolate the
pump from the system during maintenance. It should never be used to
throttle the flow rate as this will cause cavitation and suction
recirculation in the eye of the impeller.
The Suction Strainer may be required during the commissioning stage,
or other emergency conditions. In such cases, a strainer with a net area
of at least 5 to 6 times the size of the suction line is usually
recommended. However, in view of their function, they will gradually
build up an increased resistance to an even flow to the pump.
Consequently, they should be avoided whenever possible during normal
system operation. Any straining of particles from the pumpage should
be carried out downstream of the pumps, and the pumps selected to be
able to pass such particles.
The Discharge Valves usually constitute a non-return check valve and

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