Best Practice SABP-G-002 General Purpose Purp ose Steam Turbines Turbines Dynamic Analysis Factory Acceptance Test Document Responsibility: Consulting Services Dept.
31 October, 2004
Saudi Aramco Desk Top Standards Table of Contents
1 2 3 4 5 6 7 8
Introduction.......... Introduction......................... ............................. .......................... .............. 2 References............. References........................... ............................ ......................... ........... 2 General.................. General................................ ............................ .......................... ............ 3 Definitions........... Definitions........................... ............................. .......................... ............... 3 Vibration Detectors................. Detectors...... .................... ..................... .............. .. 4 Shop Verification of Unbalanced Response Analysis.……………….. Analysis.………………..…… …… 4 Tests Procedure.................. Procedure....... ..................... ..................... ................ ..... 5 FAT Acceptance Criteria............... Criteria..... ...................... ................ .... 6
Previous Issue: New Next Planned Update: 1 November, 2009 Revised paragraphs are indicated in the right margin Primary contact: Khaleel M. Al-Hussain on 873-0311
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Document Responsibility: Responsibility: Consulting Services Dept. Issue Date: 31 October, 2004 Next Planned Update: Update: 1 November, November, 2009
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SABP-G-002 General Purpose Steam Turbines Dynamic Analysis Analysis Factory Acceptance Test
Introduction 1.1
Purpose
The purpose of this Practice is to establish guidelines in reviewing the dynamic analysis of general purpose steam turbines during Factory Acceptance Test (FAT). 1.2
Scope
This Best Practice gives general guidelines for reviewing vibration instrumentation requirements, test procedure and acceptance limits during the Factory Acceptance Test and does not include performance test criteria. 1.3
Disclaimer
This Best Practice is being provided for the general guidance and benefit of Saudi Aramco engineers attending general purpose steam turbines Factory Acceptance Test (FAT). The use of this this Best Practice Practice during factory acceptance test, however, does not relieve the manufacturer from his responsibility or duty to confirm or to verify the accuracy of any information presented or from his contractual liability to perform an accurate FAT that conforms to Mandatory Saudi Aramco Engineering Requirements. Requirements. The use of the information or material contained herein will not guarantee tha t the resulting product satisfies the applicable requirements of Saudi Aramco Standards. Saudi Aramco assumes no responsibility or liability whatsoever for any reliance on the information presented herein or for FAT performed by manufacturer in accordance with this Best Practice document. Moreover, this Best practice is intended only to provide guidelines for Saudi Aramco engineers attending the Factory Acceptance Test and shall not be considered as a replacement for the Mandatory Saudi Aramco Engineering Requirements. Saudi Aramco® is a registered trademark of the the Saudi Arabian Oil Company. Copyright, Saudi Aramco, 2004. 1.4
Conflicts with Mandatory Standards
In the event of a conflict between this Best Practice and other Mandatory Saudi Aramco Engineering Requirement, the Mandatory Saudi Aramco Engineering Requirement shall govern.
2
References This Best Practice is based on the below referenced standard: 2.1
Saudi Aramco References
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Document Responsibility: Responsibility: Consulting Services Dept. Issue Date: 31 October, 2004 Next Planned Update: Update: 1 November, November, 2009
SABP-G-002 General Purpose Steam Turbines Dynamic Analysis Analysis Factory Acceptance Test
Saudi Aramco Engineering Standard SAES-K-501
Steam Turbines (30 September, 2003)
Saudi Aramco Materials System Specifications
2.2
32-SAMSS-009
General Purpose Steam Turbines (29 October, 2003)
34-SAMSS-625
Machinery Protection Systems (30 June, 2002)
Industry Codes and Standards
American Petroleum Institute (API)
3
General Purpose Steam Turbines for Petroleum, th Chemical and Gas Industry Services, 4 Edition
API STD 670
Machinery Protection Systems, 4 Edition
th
General
4
API STD 611
This best practice gives general guidelines for the vibration instrumentation requirements, test procedure and acceptable limits during general purpose steam turbines factory acceptance test. The attendee should review the rotordynamic analysis prior the test. The vendor shall notify the purchaser not less than five working days before the date the equipment will be ready for testing. This requires written written notification of a successful preliminary test. If the testing is rescheduled, the vendor shall notify the purchaser not less than five working days before the new test date. (API STD 611/ P 6.3.1.2)
Definitions Acceptance Level: This is the vibration level (displacement, velocity, or acceleration) at which a machine can run indefinitely without inducing vibration related maintenance. Factory Acceptance Test (FAT): is a test conducted at a factory to ensure that the turbine meets its required performance and mechanical integrity. General purpose steam turbines: are those turbines used to drive equipment that are spared or not critical to plant operation. General purpose steam turbines shall shall not be used for applications requiring a rated power exceeding 2,250 kW (3,000 HP), a maximum continuous speed exceeding 5,000 RPM or for steam conditions exceeding a pressure of 4,800 kPa Gauge (700 psig) and a temperature exceeding 400°C (750°F). (32-SAMSS-009 / P 1.1.1.1). Page 3 of 7
Document Responsibility: Responsibility: Consulting Services Dept. Issue Date: 31 October, 2004 Next Planned Update: Update: 1 November, November, 2009
SABP-G-002 General Purpose Steam Turbines Dynamic Analysis Analysis Factory Acceptance Test
Hydrodynamic bearings: Bearings that use the principles of hydrodynamic lubrication. Their surfaces are oriented so so that relative motion forms forms an oil wedge to support the load without journal-to-bearing journal-to-bearing contact. (API STD 611 / P 3.5). Maximum continuous speed (revolutions per minute): The speed at least equal to 105% of the highest speed required by any of the specified operating conditions. (API STD 611 / P 3.10). Minimum allowable speed (in revolutions per minute): The lowest speed at which the manufacturer’s design will permit continuous operation. (API STD 611 / P 3.14). Trip speed (in revolutions per minute): The speed at which the independent emergency over-speed device operates to shutdown the turbine. The trip speed setting will vary with the class of governor. (API STD 611 / P 3.28).
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Vibration Detectors Vibration detection equipment shall be provided as per the below Table-1. (For more detail see 32-SAMSS-009 Paragraph 4.9.32): Table-1: Required Vibration Instrumentation for General Purpose Steam Turbine HP Rating
Applicable Standard
Relative Measurement Radial
Thrust
Key Φ
> 300 HP with Anti-friction Brg. & 32-SAMSS-009 with no relative relative displace. displace. probes (Sec. 4.9.32)
Seismic Measurement Reading at the monitor Velocity (RMS)
Acceleration
One/Brg.
300 -1000 HP (Hydrodynamic Radial + AntiFriction Thrust Brg.)
(Sec. 4.9.32)
Provisions
300 -1000 HP Hydrodynamic Thrust Brg.
(Sec (Sec.. 4.9. 4.9.32 32))
Prov Provis isio ions ns
Dual Dual
Yes Yes
> 1000 HP
(Sec. 4.9.32)
X&Y
Dual
Yes
Provision
Vibration detectors shall be provided, installed and calibrated in accordance with 34-SAMSS-625.
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Shop Verification of Unbalance Response Analysis 6.1
Shop verification of unbalance response analysis shall be performed as part of the mechanical test and the results shall be used to verify the anlytical model. The method to cdonduct the shop verifcation test is described in (API STD 61 1, Appendix B.1 Shop Verification of Unbalanced Response Analysis).
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Document Responsibility: Responsibility: Consulting Services Dept. Issue Date: 31 October, 2004 Next Planned Update: Update: 1 November, November, 2009
6.2
The results of the verification test shall be compared with those from the original analytical model. The vendor shall correct the model if it fails to meet any of the following criteria: (API STD 611/ Appendix B.1.2.2) a)
The actual critical speeds shall not deviate from the predicted speeds by more than ±5%.
b)
The predicted amplification factors shall not deviate from the actual teststand values by more than ±20%.
c)
The actual response peak amplitudes, including those that are critically damped, shall be within ±50% of the predicted amplitudes.
6.3
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SABP-G-002 General Purpose Steam Turbines Dynamic Analysis Analysis Factory Acceptance Test
When the test data does not meat the requirements of API STD 611, Appendix B.1.3, additional more stringent testing is requires as per API STD 611, Appendix B.1.4. The purpose of this additional testing is to determine determine on the test stand that the machine will operate successfully.
Tests Procedure 7.1
The Vendor shall prove compatibility between contract probes and his test stand readout equipment. Contract axial thrust position probes and oscillatordemodulator shall be used during shop test. (32-SAMSS-009 / P 6.3.3.1.6).
7.2
Bearing housing overall velocity should be measured in in/sec (mm/sec) RMS and shaft vibration in mils (µm) pk-pk.
7.3
The combined total electrical and mechanical runout is presented in Table-2 (for more detail refer to API STD 611, paragraph 4.6.2). Table-2: Allowable Total Runout
Probes Location
Radial
Allowable Total Runout (TR)
Applicable Standard
API STD 611 (Sec. 4.6.2. a)
whichever is greater TR ≤ 0.25 x maximum allowed pk-pk p k-pk • vibration amplitude •
API STD 611 Axial
(Sec. 4.6.2. b)
TR ≤ 0.25 mils pk-pk
whichever is greater • TR ≤ 0.25 x maximum allowed pk-pk p k-pk vibration amplitude •
TR ≤ 0.5 mils pk-pk
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Document Responsibility: Responsibility: Consulting Services Dept. Issue Date: 31 October, 2004 Next Planned Update: Update: 1 November, November, 2009 Note:
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SABP-G-002 General Purpose Steam Turbines Dynamic Analysis Analysis Factory Acceptance Test
If the vendor can demonstrate that electrical or mechanical runout is present and the total runout is within within the above acceptable limit, limit, then the runout may be vectorially subtracted from the vibration signal measured during the factory. factory. (API STD 611/ P4.8.4.7).
7.4
When noncontacting probes or provisions for them have been specified, electrical and mechanical runout shall be determined and recorded by rolling the rotor in V-blocks at the journal centerline while measuring runout with a noncontacting vibration probe and a dial indicator at the centerline of the probe location and one probe-tip diameter to to either side. Accurate records of electrical and mechanical runout, for the full 360 degrees at each probe location, shall be included in the mechanical mechanical test report. (API STD 611 / P 4.8.4.6).
7.5
When noncontacting probes are not provided and when vibration cannot be measured on the shaft, radial vibration of the housings shall be recorded using shop instrumentation during the test. The measurements shall be taken on the the top and side of each bearing housing. (API STD 611/ P 6.3.3.1.5).
7.6
Turbines shall be given a 1-hour uninterrupted no-load running test at maximum continuous speed. (API STD 611/ P6.3.3.2).
7.7
The equipment shall be operated at speed increments of approximately 10% from zero to the maximum continuous speed and run at the maximum continuous speed until bearings, lube-oil temperature and shaft vibrations have stabilized. (API STD 611/ P6.3.3.3.2).
7.8
The speed shall be increased to 110% of the maximum continuous speed, and the equipment shall be run for a minimum of 15 minutes at the increased speed. (API STD 611/ P6.3.3.3.3).
FAT Acceptance Criteria Vibration readings shall be taken at maximum continuous speed, just below trip speed, and at minimum operating speed after the stabilization described in step 7.7. Maximum allowable vibration limits are described in the below Ta ble-3 which is a combination of th API STD 611 4 edition and 32-SAMSS-009 32-SAMSS-009 exceptions. Any critical speeds below maximum continuous shall be determined. (API STD 611/ P 6.3.3.3.4).
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Document Responsibility: Responsibility: Consulting Services Dept. Issue Date: 31 October, 2004 Next Planned Update: Update: 1 November, November, 2009
SABP-G-002 General Purpose Steam Turbines Dynamic Analysis Analysis Factory Acceptance Test
Table-3: Vibration Limits for General Purpose Steam Turbines
Location of vibration Measurement
Vibration On Inboard & Outboard Bearing Housing
Item
(i) Maximum continuous speed or at any other speed within the specified operating speed range
Overall Vibration
(ii) Vibration limits at any speed greater than the maximum continuous speed, up to and including the trip speed
V u ≤ 2.5 mm/sec RMS * (0. 10 in./sec RMS)*
Turbine Shaft (adjacent to bearing)
whichever is less 6 0.5 Au ≤ (5.2X10 /N) µm pk-pk • 0.5 ((12000/N) mils pk-pk) •
150 % of the recorded value at maximum continues speed
Au ≤50 µm pk-pk (2.0 mils pk-pk)
150 % of the recorded value at maximum continues speed
Notes: (*) These specifications are from 32-SAMSS-009 – paragraph 4.8.4.8 not API STD 611. Where: V u u = N =
unfiltered velocity.
Au =
unfiltered displacement determined by FFT.
rotational speed (RPM).
31 October, 2004
Revision Summary New Saudi Aramco Best Practice.
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