Page 235 - Subyek Teknik Mesin - Forsthoffers Best Practice Handbook for Rotating Machinery by William E Forsthoffer

Compressor Best Practices Best Practice 3 .24
from the improper design of the lube system, seal system the operating discharge pressure is above 3,450 kPa (500 psi))
separation labyrinth. In addition to the above considerations, should always be conducted when retrofitting from liquid to
a critical speed analysis, rotor response and stability analysis (if dry gas seals.

Best
Best Practice 3.24Practice 3.24Practice 3.24
Best
For operating pressures above 13,800 kPa (2,000 psi), re- Lessons Learned
quire full pressure and full load centrifugal compressor Correcting a gas disturbance problem in the field can
shop testing only if the vendor does not have 2 years’ op- result in long operational delays (weeks), losses of millions
erating field experience on similar gases at the pressure of dollars of revenue and may require multiple field
levels specified. modifications.
At high field operating pressures >13,800 kPa (2,000 psi), gas
disturbances can result in serious operational problems and prevent Benchmarks
continued operation. This best practice has been used since 1990. Very few full pressure and
Since high pressure gas densities will cause these issues, be sure full load tests are necessary today if vendors are selected who have
to specify a full pressure and load shop test and not only a full load test high pressure field operating experience.
which may not match field pressure levels, if the vendor cannot show
field operating experience at the specified pressure levels.

B.P. 3.24. Supporting Material there certainly are many opportunities to ensure equipment re-
liability during shop test, but there are also a lot of potential lost
If a full pressure and load test is required, justify the full pres- opportunities if they are not justified to the project team early,
sure test on the basis of a minimum of two weeks of lost pro- during the pre-FEED phase of the project. The potential lost shop
duction in the first year of plant operation. test phase opportunities are noted in Figure 3.24.2.

Testing phase
The following opportunities will be lost if they are not justified at
project inception:
The testing phase is the last phase in terms of vendor and sub- Possible full load test
supplier design and manufacturing involvement in the project; Unproven component tests
and it is the last chance to ensure the optimum availability of the Attendance at test by plant personnel
finished product. Use of special tools
Remember that all of the equipment addressed in this section Vendor permission for pictures
is most likely custom designed, and no matter how much ac- Agreement that assigned vendor field service specialists will be
crued design and manufacturing experience is present, the present for tests
Agreement that the instruction book is reviewed
possibility of some abnormality, hopefully minor, is high. Agreement for formal field construction meeting to clearly
Therefore, it is imperative that this phase be carefully observed define all vendor procedures from receipt of equipment on site
and witnessed by the end user team. Figure 3.24.1 lists impor- to initial run in of equipment
tant facts surrounding this phase of the project.
Fig 3.24.2 Potential lost test opportunities
The shop test is an opportunity to:
The success of the shop test depends on a good test plan that
Confirm vendor proper design and manufacture
is reviewed by the end user and contractor and modified as
To match field conditions
requested, well in advance of the test. Figure 3.24.3 presents
To witness assembly and disassembly using job special tools
To have plant personnel observe test, assembly, etc. and take these facts.
pictures for purposes of emergency field maintenance
excellence
Review the instruction book The agenda is issued for review 2 months prior to test
Have the assigned vendor service engineer observe the It incorporates agreed VCM scope
equipment he will install Compressor performance test conditions are per ASME PTC-
Review all vendor field procedures 10 requirements
A sample of test calculations and report format is included
Vendor concurs with all end user and contractor comments
Fig 3.24.1 The shop test prior to test
A shop test checklist is included at the end of this B.P. that will
be valuable for planning and executing the shop test phase. Yes e Fig 3.24.3 Shop test agenda review e key facts

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