Layout Arrangement for Centrifugal Pump Piping By A JAD Layout arrangement for Centri fugal Pump Piping 1. GENERAL The design of a piping system can have an important effect on the successful operation of a centrifugal pump. Such items as pump design, suction piping design, suction and discharge pipe size and pipe supports must all be carefully considered. A typical horizontal centrifugal pumpinstallation is illustrated in Fig.CPP1, CPP2, CPP3. Selection of the discharge pipe size is primarily a matter of economics. The cost of various pipe sizes must be compared to the pump size and power cost required to overco me the resulti ng friction head. 1.1 The suction piping size and design is far m ore important . Many centrifugal pumptroubles are caused by poor suction conditions. 1.2 The suction pipe should never be smaller than the suction nozzle of the pump and in mo st cases it should be at least one size larger. Suction pipes should be as short and as straight as possible. Suction pipe velocities should be in the 1.0 – 1.5 metre per second range, unless suction conditions are unusually good. Higher velocities will increase the friction loss and c an result in trouble some a ir and vapour separation. This is further complicated when elbows or tees are located adjacent to the pump suction nozzle. In that case uneven flow patterns or vapour separation keeps the liquid from evenly filling the impeller. This upsets hydraulic balance leading to noise, vibration, possible cavitation and excessive shaft deflection. Cavitation, erosion damage, shaft breakage or permature bearing failure etc. may result. 1.3 On pump installations inv olving suction lift, air pockets in the suc tion line can be a source of trouble. The suction pipe should be exactly horizontal or with a uniform slope upward from the sump to the pump as illustrated in Fig.CPP7. There should be no high spots where air can collect and cause the pump to lose its prime. Eccentric rather than concentri c reducer s with flat side top shoul d always be used. 1.4 If an elbow is required at the suction of a double suction pump, it should be in a vertical position if at all possible. Where it is necessary for some reason to use a horizontal elbow, it should be a long radius elbow and there should be a minimum of five diameters of straight pipe between elbow and the pump suction as illustrated in Fig.CPP9. 2. LOCATION 2.1 Common location of pumps in chemical and petrochemical plant is under the piperack at grade. Pumps are to be placed close to and below the vessels from which they take thei r suc tion in order to have net-positive suction head (NPSH) required by the pump.
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7/27/2019 Layout Arrangement for Centrifugal Pump Piping
The design of a piping system can have an important effect on the successful operation of acentrifugal
pump. Such items as pump design, suction piping design, suction and discharge pipe size and pipe
supports must all be carefully considered. A typical horizontal centrifugal pump installation is illustrated
in Fig.CPP1, CPP2, CPP3.
Selection of the discharge pipe size is primarily a matter of economics. The cost of various pipe sizes
must be compared to the pump size and power cost required to overcome the resulting friction head.
1.1 The suction piping size and design is far more important. Many centrifugal pump troubles are
caused by poor suction conditions.
1.2 The suction pipe should never be smaller than the suction nozzle of the pump and in most cases it
should be at least one size larger. Suction pipes should be as short and as straight as possible.
Suction pipe velocities should be in the 1.0 – 1.5 metre per second range, unless suction conditions are
unusually good. Higher velocities will increase the friction loss and can result in trouble some air and
vapour separation. This is further complicated when elbows or tees are located adjacent to the pump
suction nozzle. In that case uneven flow patterns or vapour separation keeps the liquid from evenly filling
the impeller. This upsets hydraulic balance leading to noise, vibration, possible
cavitation and excessive shaft deflection. Cavitation, erosion damage, shaft breakage or
permature bearing failure etc. may result.
1.3 On pump installations involving suction lift, air pockets in the suction line can be a source of trouble.
The suction pipe should be exactly horizontal or with a uniform slope upward from the sump to the pump
as illustrated in Fig.CPP7. There should be no high spots where air can collect and cause the pump to
lose its prime. Eccentric rather than concentric reducers with flat side top should always be used.
1.4 If an elbow is required at the suction of a double suction pump, it should be in a vertical position if at
all possible. Where it is necessary for some reason to use a horizontal elbow, it should be a long radiuselbow and there should be a minimum of five diameters of straight pipe between elbow and the pump
suction as illustrated in Fig.CPP9.2. LOCATION
2.1 Common location of pumps in chemical and petrochemical plant is under the piperack at grade.
Pumps are to be placed close to and below the vessels from which they take their suction in order to have
net-positive suction head (NPSH) required by the pump.
7/27/2019 Layout Arrangement for Centrifugal Pump Piping
Various Auxiliary piping plan is recommended in API 610 for proper selection according to design
requirements.
4.12 Pump vendors usually supply the Auxiliary piping and the neat arrangements of these piping
and its support are to be ensured by the designer while reviewing the vendor document. Fig.CPP10
illustrates one typical Auxiliary piping arrangement on the pump base plate.
4.13 A typical arrangement for piping and valves operation is illustrated in Fig.CPP11 with
maintenance and operation access.
4.14 A typical suction and discharge piping arrangement with common platform for operation of
valves connected to two adjacent pumps is illustrated in Fig.CPP12 and CPP13.5. SUCTION BASIN OF PUMP
5.1 The basin for the intake of centrifugal pump shall be designed and sized properly for smooth function
of the pump. The recommendations of hydraulic institute are illustrated in Fig.CPP14.5.2 The flow of fluid to the suction bell should be even, smooth and stream lined without any vortices.
5.3 A typical sump with the components and relative dimensions of clearance and submergence is
illustrated in Fig.CPP15.
5.4 For multiple pump installations with high capacity pumps, the analysis of a proposed intake design
are often made by use of a scale model of the intake basin with all parts such as baffles, screens, gates,
separating walls etc.
The large basin is required to ensure low inlet velocity (approx. 2 ft. per sec.) and to eliminate vortexing at
the bell mouth.
5.5 A typical sump pit with pump is illustrated in Fig CPP16. This sump is the collection pit of wastematerial coming thru a pipeline. A screen at the mouth of the pump avoids choking / fouling of the pump
during operation. The discharge of the pump may go to a slope tank / pond / waste-removal tanker.
7/27/2019 Layout Arrangement for Centrifugal Pump Piping