PUMP PIPING

Pump Piping

Permanent strainers should be provided upstream of pumps handling streams which
are likely to contain foreign material such as sand and scale. Temporary strainers,
preferably of the cone type, should be provided for initial unit start-up where
permanent strainers are not provided, and should be located as close as possible
to the pump suction nozzle. A block valve should be provided in the suction line
of each pump and located upstream of the strainer. For dirty streams, where two
or more pumps take suction from a single header, the block valves should be located
as close as is practical to the header to minimize the collection of dirt upstream of
the valve.
A block valve should be provided in the discharge line of each pump. A check
valve should be installed in the discharge line of each centrifugal or rotary pump
unless there is no possibility of a reversal of flow or pressure surge under any
condition. The check valve should be located between the pump and the block
valve with a drain between the block and the check valve.

Pump location will affect the piping routing and supporting. Pumps carrying hydrocarbons and materials above 230 degree C shall not be located below pipe racks, structures, air fin coolers and vessels. Those in non-flammable service may be located beneath the pipe rack without obstructing the access bay, other maintenance requirements of the respective process unit.

Pumps shall be located as close to the source of suction in order to minimize pressure drop in the system. The line size and temperature will be the determining factors in piping layout.

A preliminary piping layout ( study layout ) shall be made to determine the requirement of spacing between pumps especially in case of side suction/ side discharge, top suction/ top discharge pumps where straight length requirement / platform / CPS requirement etc have to be considered.

Reducers in pump suction lines shall be as close as possible to the pump suction/discharge nozzles. Eccentric reducers in pump suction lines shall be flat on top in order to prevent any entrained vapours in the liquid from accumulating in the high point ( if installed bottom flat ) and thus causing cavitation in the pump. Pumps in boiler feed water service operating close to vapour pressure of the liquid are susceptible to this type of problems.

Reducers in pump discharge should be concentric in most cases. Eccentric reducers may be used in both suction and discharge piping for top suction/ top discharge pumps in order to obtain clearance between suction and discharge piping. prevent any entrained vapours in the liquid from accumulating in the high point ( if installed bottom flat ) and thus causing cavitation in the pump. Pumps in boiler feed water service operating close to vapour pressure of the liquid are susceptible to this type of problems.

Reducers in pump discharge should be concentric in most cases. Eccentric reducers may be used in both suction and discharge piping for top suction/ top discharge pumps in order to obtain clearance between suction and discharge piping.

When flexibility loops are required between pumps, it is necessary to
partially run the lines over the pump and driver. Every effort must be
made to minimize maintenance obstructions by running the piping either
outside the area directly over the pumps or at a high enough elevation to
permit the removal of the pump or driver.

Some of the Pump Piping layouts generally used are represented in the
following pages. It shall be noted that even if the type of pump is same,
different piping layouts may be followed. So it is not always necessary
that same layout shall be followed for same type of pumps, but is
governed by various factors such as temperature, requirement of vertical
strainers etc.

Centrifugal Pumps.