Witness Testing of Api 610 Centrifugal Pumps
Witness Testing of Api 610 Centrifugal Pumps
Witness Testing of Api 610 Centrifugal Pumps
R. C. Patel
Lead Pump Engineer
Bechtel Oil, Gas & Chemicals, Inc.
Houston, Texas, USA
INTRODUCTION
ABSTRACT
The tutorial outlines the basic concepts and offers some
tips on witness testing of API 610 centrifugal pumps and API
611 steam turbines. The section on API 610 pump testing
discusses performance, NPSH and mechanical run tests of API
610 centrifugal pumps that are often specified with witness
testing. Various parameters that are measured during testing
and the related instrumentation are introduced. This section
references related paragraphs and tables from ANSI/API
Standard 610 (2010). The section on API 611 steam turbine
testing covers the mechanical run test and cites the related
paragraphs of API Standard 611 (2008). The same section also
recommends a few additional tests that could be performed on
general purpose steam turbines, if feasible and applicable.
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73
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VACUUM
PUMP
PRESSURIZED AIR
VENT
ELECTRICAL
POWER
SUPPLY
ELECTRICAL
POWER
MEASUREMENT
MOTOR
DISCHARGE
PRESSURE
PI
PI
TEST PUMP
SUPPRESSION
TANK
TI
FILL
DRAIN
SUCTION
VALVE
FM
FLOW
METER
DISCHARGE
CONTROL VALVE
HEAT
EXCHANGER
(OPTONAL)
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Vibration
Probes
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NPSH Test
If an NPSH test has been specified, it will generally be
conducted simultaneously with the performance test. This test
is conducted by gradually reducing the pump suction pressure
by drawing vacuum on the suppression tank or by throttling the
suction valve until the differential head developed (first-stage
head in a multistage pump) drops by 3 percent at every flowrate
(except shutoff).
The vacuum suppression method employs reduction of the
suction pressure by creating a partial vacuum in the suppression
tank with the use of a vacuum pump. On the other hand, the
valve throttling method utilizes reduction of the suction
pressure by throttling the suction valve. The vacuum
suppression method is more common since the throttling action
on the suction valve may cause disturbance in the flow, thus
affecting the accuracy of the results.
It should be noted that ANSI/API Standard 610 (2010)
Copyright 2011 by Turbomachinery Laboratory, Texas A&M University