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Fig. 1 – Load diagram of the
Mechanical Running Test
• gearbox mechanical run; 20% of the vibration value, the Client and
• seal system test; the Manufacturer shall meet and agree a way
• auxialiaires functionality tests (lube oil etc.). forward for the test completion;
• the measurement of synchronous vibration
The final tests are: amplitude shall be done before and after the
• Mechanical Running Test; test. These measurements shall consider the
• Performance Tests (single compressors); vibration both filtered (one every revolution)
• Complete unit test, with performance curves and non-filtered. The velocity range shall cover
in full load (Type 1) or similarity (Type 2); from zero to trip value of the gas turbine;
• turbine heat rate; • mechanical test shall verify the lateral critical
• emissions (NOx and CO with methane speed.
combustion).
The tests are performed in accordance with the Usually the mechanical run test is
following standards: performed at maximum continuous speed:
• Performance Test: ASME PTC 10, 1, 2 100% for electric driven trains, 115% for
gas turbine driven trains. In accordance
(compressors), 22 (gas turbines); with API 617, the test duration shall be at
• measurement ISO 5167;
• Mechanical Running Test API 617 least four hours.
(compressors), 616 (gas turbines).
1.1 Mechanical Running Test After the Mechanical Running Test is finished, a
visual inspection of the bearings is performed,
This type of test is done only at the Manufacturer’s to ascertain their integrity and the lack of surface
factory. The single compressors are placed on the defects. The test is deemed not acceptable if
test bench and driven by a launch motor with speed replacement or repair of the bearings and seals
increase from zero to 100% maximum continuous or other components is required. Therefore, it is
speed. A certain time is allowed to get the shaft a no-load running test: the purpose of this test is
bearings stabilized, the lube oil temperature and to demonstrate the mechanical functionality of the
the shaft vibration level (figure 1). rotating parts (shaft, bearings, and measurement of
Usually the mechanical run test is performed at the vibration levels).
maximum continuous speed: 100% for electric
driven trains, 115% for gas turbine driven trains. In 1.2 Performance Test
accordance with API 617, the test duration shall be
at least four hours. The single compressors are placed on the test bed
During the test, the vibrations of the compressor and driven by a launch motor. Test gas is used for
bearings are measured and recorded at different the compressor feed; it is a mixture prepared for
speeds. the purpose. At least 4 operating points shall be
Also the overspeed test is carried out with the recorded, such as:
purpose to check the behaviour of the compressor • close to surge;
in off-design condition. During the Mechanical • compressor overload (105% overspeed);
Running Test the following requirements shall be • guarantee point (design point);
met: • max flow.
• with the equipment at full speed the amplitude
The compressor characteristic curve is acquired
and frequencies of the vibrations are monitored and plotted during the test.
with steps from 0.25 to 8 times the maximum
continuous speed within the limit of 90.000
cycles per minute (1500 Hz); if the amplitude
of each non-synchronous vibration exceed
40 Impiantistica Italiana - Luglio-Agosto 2015
