API 613:2003 pdf download

API 613:2003 pdf download.Special Purpose Gear Units for Petroleum, Chemical and Gas Industry Services.
2.6.3.1.5 The corresponding indicated vibration data taken in accordance with 2.6.3.11 shall be vectorially subtracted from the results ol this test.
Note: It is practical to store the residual unbalance vibration nwasuremerns recorded in the step at 2.6.3.l.I and by use of computer csxle pethwm the vectorial subtraction called for in this paragraph at each appropriate speed. This makes the comparison of the test results with the computer analysis of 2.6.2.8 quite practical. It i.s necessary for probe orientation be the same fur the analysis and the machine for the vectorial subtraction to be valid.
2.6.3.1.6 The results of the mechanical run, including the unbalance response verification test, shall be compared with those from the analytical model specified at 2.6.2.8.
2.6.3.2 The vendor shall correct the model if it fails to meet either of the following criteria:
a. The actual critical speeds determined on test (within the range of Lest speeds shall not deviate from the corresponding critical speeds predicted by analysis by more than 5%. Where the analysis predicts more than one critical speed in a particular mode (e.g., as a result of the bearing characteristics being significantly different horizontally and vertically or between the two ends of the machine), the test value shall not be lower than 5% below the lowest predicted value nor higher than 5% above the highest predicted value.
Note: It is possible that the vertical and horizontal stiffness are rignihcanily different and the analysis will piedict two differing critical speeds. Should the operating speed fall between thesc critical specd. these two critical speeds should he treuted separately. as if they resulted from separate modes.
h. The actual major axis amplitude of peak responses from test, including those critically damped. shall not esceed the predicted values. The predicted peak response amplitude range shall be determined from the computer model based on the four radial probe locations.
26.33 If the support stiffness is less than 2 times the bearing oil film stiffness, the absolute vibration of the bearing housing shall be measured and vectorially added to the relative shaft vibration, in both the balanced (see 2.6.3.1.1) and in the unbalanced (see 2.6.3.1.4) condition before proceeding with the step specified in 2.6.3.1.5. In such a case, the measured response shall be compared with the predicted absolute shaft movement.
2.6.3.4 Unless o(herwise specified. the verification test of the rotor unbalance shall be performed only on the first gear set tested, if multiple identical gear sets are purchased.
2.6.3.5 The vibration amplitudes and phase from each pair of x-v vibration probes shall be vectorially summed at each vibration response peak after correcting the model. if required. to determine the maximum amplitude of vibration.
Note: When the anaiysis or test data does not meet the requirements of the standard. additional more stringern testing is required. The purpose of this additional testing is so determine on the tcst stand that the machine will operate successfully.
a. Any critical rcsponsc will fail to meet the separation margin requirements (sec 2.6.2.4.1 and 2.6.2.4.2) or will fall within the operating speed range.
b. The clearance requirements of 2.6.2.10 have not been met.
2.6A.2 Unbalance weights shall be placed as described in
2.6.2.6; this may require disassembly of [he machine. Unbalance magnitudes shall be achieved by adjusting the indicated unbalance that exists in the rotor from the initial run to raise the displacement of the rotor at the probe locations to the vibration limit defined by Equation 8 (see 2.6.2.9) at the maximum continuous speed: however, the unbalance used shall be no less than twice or greater than 8 times the unbalance limit speeified in 2.6.2.6 Equation 6. The measurements from this lest, taken in acconiance with 2.6.3.1.1 and 2.6.3.1.2. shall mcci the following criteria:
a. At no speed outside the operating speed range. including the separation margins, shall the shalt ddlcctions exceed 90% of the minimum design running clearances.