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Fig. 5 - On-line compressor
train configuration
Fig. 6 – Summary of the gui- injection at high-pressure.
delines and criteria for the • compressor train of innovative design and
tests selection
technology, for severe service (high pressure,
side streams, sour service);
• train composed by elements without a
proven track record by the Manufacturer.
If the Manufacturer does not have specific
experience about the given configuration, it
is advisable to test the train at factory. If the
Client, in order to reduce the cost and schedule
impact imperatively non-expandable, decides
to exclude the Complete unit test at factory,
he shall be aware that this could lead to a
possible failure in production;
• subsea compressors.
3. Operating issues that may
occur at field after train’s
installation
This information is needed to answer the question:
what does the Client risk by avoiding the Complete
unit test in closed loop at factory?
The most common issues in operation can be
summarized as follows:
(*) The selection of test type depends on the level of criticality of the package and on manufacture’s experience
44 Impiantistica Italiana - Luglio-Agosto 2015
• characteristic curve of the compressors “as
tested” differs from that “predicted”;
• higher absorbed power / lower overall
efficiency;
• start-up issues;
• poor stability in keeping the load due to the
activation of alarms and blocks by the control
system, generally due to some incorrect
calibration / set-points;
• sealing system issues;
• vibrations out of range due to poor alignment
of the shaftline, due to a not correct alignment
of the rotating elements on the skid.
3.1 Vibrations are out of range
One of the most frequent problems is vibrations out
of range. Most likely the vibrations occur when the
train shaftline is not correctly aligned. This problem
can occur independently from the balancing of the
individual components (compressor bodies, gears,
couplings) that have already been balanced at
factory.
In order to correctly identify the situation, you have
to consider that the entire shaftline is composed
by different rotating shafts, connected together
longitudinally by means of mechanical joints and