sabp-g-001

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Previous Issue: 30 June 2004 Next Planned Update: 1 July 2009 Page 1 of 12 Primary contact: Humaid, Abdallah S. on 966 3 873-7031 Copyright©Saudi Aramco 2007. All rights reserved. Best Practice SABP-G-001 28 January 2007 Centrifugal Pumps Dynamic Analysis Factory Acceptance Test Document Responsibility: Pumps, Seals and Mixers Standards Committee Saudi Aramco DeskTop Standards Table of Contents 1 Introduction..................................................... 2 2 References..................................................... 2 3 General........................................................... 3 4 Definitions....................................................... 3 5 Vibration Detectors......................................... 5 6 Tests Procedure............................................. 6 7 Fat Acceptance Criteria.................................. 7 Appendix A – Methods of Calculating Vibration Acceptance Levels at Reduced Speed........ 12

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Page 1: SABP-G-001

Previous Issue: 30 June 2004 Next Planned Update: 1 July 2009 Page 1 of 12 Primary contact: Humaid, Abdallah S. on 966 3 873-7031

Copyright©Saudi Aramco 2007. All rights reserved.

Best Practice

SABP-G-001 28 January 2007 Centrifugal Pumps Dynamic Analysis Factory Acceptance Test Document Responsibility: Pumps, Seals and Mixers Standards Committee

Saudi Aramco DeskTop Standards Table of Contents 1 Introduction..................................................... 2 2 References..................................................... 2 3 General........................................................... 3 4 Definitions....................................................... 3 5 Vibration Detectors......................................... 5 6 Tests Procedure............................................. 6 7 Fat Acceptance Criteria.................................. 7 Appendix A – Methods of Calculating Vibration Acceptance Levels at Reduced Speed........ 12

Page 2: SABP-G-001

Document Responsibility: Pumps, Seals and Mixers SABP-G-001 Issue Date: 28 January 2007 Centrifugal Pumps Dynamic Next Planned Update: 1 July 2009 Analysis Factory Acceptance Test

Page 2 of 12

1 Introduction

1.1 Purpose

The purpose of this Practice is to establish guidelines in reviewing the dynamic analysis of centrifugal pumps complying with 31-SAMSS-004 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 acceptance criteria.

1.3 Disclaimer

This Best Practice is being provided for the general guidance and benefit of Saudi Aramco engineers attending centrifugal pump Factory Acceptance Test (FAT). The use of this Best 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. The use of the information or material contained herein will not guarantee that 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 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 latest edition of the references below, unless otherwise noted.

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Document Responsibility: Pumps, Seals and Mixers SABP-G-001 Issue Date: 28 January 2007 Centrifugal Pumps Dynamic Next Planned Update: 1 July 2009 Analysis Factory Acceptance Test

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2.1 Saudi Aramco References

Saudi Aramco Engineering Standard

SAES-G-005 Centrifugal Pumps

Saudi Aramco Materials System Specifications

31-SAMSS-004 Centrifugal Pumps

34-SAMSS-625 Machinery Protection Systems

2.2 Industry Codes and Standards

American Petroleum Institute (API)

API STD 610 Centrifugal Pumps for Petroleum, Heavy Duty Chemical, and Gas Industry Services, 10th Edition

API STD 670 Machinery Protection Systems, 4th Edition

3 General

• This best practice gives general guidelines for the vibration instrumentation requirements, test procedure and acceptable limits during centrifugal pumps factory acceptance test for pumps complying with 31-SAMSS-004. If rotordynamic analysis is required, according to 31-SAMSS-004/API STD 610, then it should be reviewed by the attendee prior the test.

• If specified, at least 6 weeks before the first scheduled running test, the vendor shall submit to the purchaser, for his review and comment, detailed procedures for all running tests and all specified optional tests, including acceptance criteria for all monitored parameters. (API STD 610/P 7.3.1.2)

• The vendor shall notify the purchaser not less than five working days before the date the equipment will be ready for testing. However, it is suggested that the vendor send notification six weeks prior to any witness test. If the testing is rescheduled, the vendor shall notify the purchaser not less than five working days before the new test date.

4 Definitions

Factory Acceptance Test (FAT): It is a test conducted at a factory to ensure that the pump meets its required performance and mechanical integrity.

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Document Responsibility: Pumps, Seals and Mixers SABP-G-001 Issue Date: 28 January 2007 Centrifugal Pumps Dynamic Next Planned Update: 1 July 2009 Analysis Factory Acceptance Test

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Acceptance Level: This is the vibration level (displacement, velocity, or acceleration) at which a machine can run indefinitely without inducing vibration related maintenance.

Best Efficiency Point (BEP): Flow rate at which a pump achieves its highest efficiency (API STD 610 paragraph 3.4).

Preferred Operating Region: Portion of a pump's hydraulic coverage over which the pump's vibration is within the base limit of API STD 610 (see Figure 26 and API STD 610 paragraph 5.9.3.1).

Allowable Operating Region: The region, over which the pump is allowed to operate, based on vibration within the upper limit of API STD 610 or temperature rise or other

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Document Responsibility: Pumps, Seals and Mixers SABP-G-001 Issue Date: 28 January 2007 Centrifugal Pumps Dynamic Next Planned Update: 1 July 2009 Analysis Factory Acceptance Test

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limitation; specified by the manufacturer (see Figure 26 and API STD 610 paragraph 5.9.3.1).

Maximum Continuous Speed: Highest rotational speed at which the pump, as built, is capable of continuous operation with the specified fluid at any of the specified operating conditions (API STD 610 paragraph 3.19).

Hydrodynamic bearings: Bearings that use the principles of hydrodynamic lubrication. (API STD 610 paragraph 3.15).

5 Vibration Detectors

Vibration detection equipment shall be provided as per the below Table-1 (for more detail see 31-SAMSS-004 – paragraph 6.4.2.2):

Vibration detectors shall be provided, installed and calibrated in accordance with 34-SAMSS-625. Settings for alarm and shut-down shall be recommended by the Vendor.

Table 1 – Required Vibration Instrumentation for Centrifugal Pumps

Relative Measurement Seismic Measurement Reading at the monitor HP Rating Applicable

Standard Radial Thrust KeyΦ Velocity Acceleration

> 300 HP ( Anti-Friction Radial)

31-SAMSS-004 (Sec. 6.4.2.2.1) One/Brg.

300 - 1000 HP (Hydrodynamic Radial + Anti-Friction Thrust)

(Sec. 6.4.2.2.2) One/Brg.

> 1000 HP (Hydrodynamic Radial + Anti-Friction Thrust)

(Sec. 6.4.2.2.3) X & Y Yes Thrust Brg.

(Radial Direction

(Hydrodynamic Radial and Hydrodynamic Thrust)

(Sec. 6.4.2.2.4) X & Y Dual Yes Thrust Brg.

(Radial Direction)

> 300 HP (vertically suspended pump) With thrust bearing in the pump

(Sec. 6.4.2.2.5) Two on Pump Thrust Brg.

> 300 HP (vertically suspended pump) No thrust bearing in the pump

(Sec. 6.4.2.2.5) Two on Driver Thrust Brg

> 300 HP (Open pit vertical suspended pump)

(Sec. 6.4.2.2.6) Two on bottom Brg

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Document Responsibility: Pumps, Seals and Mixers SABP-G-001 Issue Date: 28 January 2007 Centrifugal Pumps Dynamic Next Planned Update: 1 July 2009 Analysis Factory Acceptance Test

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6 Tests Procedure

6.1 During the pump performance test at the factory, the vendor shall take test data including head, capacity, power and vibration at a minimum of five points (31-SAMSS-004, paragraph 7.3.3.3.a):

a. Shutoff (no vibration data is required) b. minimum continuous stable flow c. Normal flow d. Rated flow e. 120% of rated flow (110% for integral gear pumps)

6.2 Unless otherwise agreed, the test speed shall be within 3% of the rated speed shown on the pump data sheet. Test results shall be converted to anticipated results at the rated speed. (API STD 610/P 7.3.3.3.c). For testing at any speed not within 3% of the rated speed refer to paragraph 7.2 of this document.

6.3 During the performance test, overall vibration measurements over a range of 5 Hz to 1 000 Hz and a Fast Fourier Transform (FFT) spectrum shall be made at each test point except shutoff. (API STD 610/P 5.9.3.2)

6.4 The FFT spectra shall include the range of frequencies from 5 Hz to 2Z times running speed (where Z is the number of impeller vanes; in multistage pumps with different impellers, Z is the highest number of impeller vanes in any stage). If specified the plotted spectra shall be included with the pump test results. (API STD 610/P 5.9.3.3)

6.5 Bearing housing overall velocity should be measured in in/sec (mm/sec) RMS and shaft vibration in mils (µm) pk-pk.

6.6 Variable-speed pumps shall operate over their specified speed range without exceeding the vibration limits of this Standard. (API STD 610/P 5.9.3.8)

6.7 For variable speed multistage pumps, coast down vibration test data shall be recorded to verify pump critical speed. (31-SAMSS-004/P 7.3.4.2.5)

6.8 Electrical + mechanical runout for radial position probes shall not exceed 25% of allowed peak to peak amplitude or 0.25 mil (6.4 µm), whichever is greater. This value may be vectorially subtracted from the vibration signal measured during the shop test. (API STD 610/P 5.6.10.e.1)

6.9 After mounting, the axial total indicated runout of either thrust collars face shall not exceed 13 µm (0,0005 in). (API STD 610/P 8.2.5.2.3)

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Document Responsibility: Pumps, Seals and Mixers SABP-G-001 Issue Date: 28 January 2007 Centrifugal Pumps Dynamic Next Planned Update: 1 July 2009 Analysis Factory Acceptance Test

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6.10 When a re-test is required, all data for original parameters including bearing vibration and temperature data shall again be recorded and submitted to the purchaser for review and approval. (31-SAMSS-004/P 7.3.3.5.c)

6.11 Pumps furnished with proximity probes shall meet both bearing housing and shaft vibration limits. (API STD 610/P 5.9.3.6)

7 FAT Acceptance Criteria

7.1 For centrifugal pumps tested at their rated speed the acceptable vibration levels are shown in table 2 and 3. These tables content is a combination of API STD 610 10th edition Table 7 & 8 and 31-SAMSS-004 exceptions. The below steps 1 to 4 specify the FAT vibration values that need to be checked.

1. The overall vibration of all performance test points inside the preferred operation range should be below the overall limit specified in Table 2 and Table 3.

2. The frequency spectrum for all test points inside the preferred operation range should be checked to identify the highest amplitude and ensure that it is below the maximum limit for discrete frequency amplitude specified in Table 2 & Table 3.

3. The vibration of all test points outside the preferred operation range but within the allowable operating region should not exceed 130% of the overall vibration limit specified for the preferred operation range.

4. At any speed greater than the maximum continuous speed, up to and including the trip speed of the driver, the vibration should not exceed 150% of the maximum value recorded at the maximum continuous speed. (API STD 610/ P 5.9.3.7)

7.2 Test speed shall be within 3% of the rated speed. Reduced test speed requires the approval of the Standards Committee Chairman; Pumps, Seals and Mixers. The vibration acceptance criteria contained in this Specification are not applicable to reduced test speed. The vendor shall propose the vibration acceptance levels at the reduced speed for review and approval by the Standards Committee Chairman; Pumps, Seals and Mixers. (31-SAMSS-004/P 7.3.3.3.c).

The proposed vendor vibration acceptance levels at the reduced speed shall be technically justified in writing taking into account speed and dynamic-related effects and/or by comparison with vibration data provided by the vendor for identical pumps in operation. See Appendix A for more details.

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Document Responsibility: Pumps, Seals and Mixers SABP-G-001 Issue Date: 28 January 2007 Centrifugal Pumps Dynamic Next Planned Update: 1 July 2009 Analysis Factory Acceptance Test

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In additioin, the vendor is to provide a written gurantee that the pump will meet its acceptance criteria on site.

Table 2 - Vibration Limits for Overhung and Between Bearings Pumps

Notes: 1- Values calculated from the basic limits shall be rounded off to two (2) significant figures. 2- (**) These specifications are from 31-SAMSS-004 – paragraph 5.9.3.6 not API STD 610.

Where: Vu = unfiltered velocity. Af = filtered displacement determined by FFT. Vf = filtered velocity. N = rotational speed (RPM). f = the frequency. Au = unfiltered displacement determined by FFT.

Location of Vibration Measurement

Item

Bearing Housing (see Figure 27)

For all bearing types

Pump Shaft (adjacent to bearing) For hydrodynamic

journal bearings type

Overall Vu < 4.5 mm/sec RMS ** (0. 18 in./sec RMS)**

whichever is less

• Au < (5.2X106 /N)0.5 µm pk-pk [(8000/N)05 mils pk-pk]

• Au <50 µm pk-pk

(2.0 mils pk-pk)

(i) Vibration limits at any flow within the pump's preferred operating region

Discrete frequencies (other than N) Vf � 0,67 Vu for f � n: Af � 0,33 Au

(ii) Vibration limits at flows beyond the preferred operating region but within the allowable operating region

Increase in allowable by 30% Increase in allowable by 30%

Page 9: SABP-G-001

Document Responsibility: Pumps, Seals and Mixers SABP-G-001 Issue Date: 28 January 2007 Centrifugal Pumps Dynamic Next Planned Update: 1 July 2009 Analysis Factory Acceptance Test

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Document Responsibility: Pumps, Seals and Mixers SABP-G-001 Issue Date: 28 January 2007 Centrifugal Pumps Dynamic Next Planned Update: 1 July 2009 Analysis Factory Acceptance Test

Page 10 of 12

Table 3 - Vibration Limits for Vertically Suspended Pumps

Notes: 1- Values calculated from the basic limits shall be rounded off to two (2) significant figures. 2- Vibration measurements shall also be taken on the driver, adjacent to the upper bearing for pumps with rigid

coupling (31-SAMSS-004 / P 5.9.3.6).

Where: Vu = unfiltered velocity. Af = filtered displacement determined by FFT. Vf = filtered velocity. N = rotational speed (RPM). Au = unfiltered displacement determined by FFT.

Location of vibration Measurement

Item

Adjacent to the upper bearing (see Figure 28)

For all bearing types

Pump Shaft (adjacent to bearing)For hydrodynamic guide bearing adjacent to accessible region of

shaft

Overall Vu < 5.0 mm/sec RMS (0.20 in/sec RMS)

Au < (6,2 �106 /n)0.5 µm peak-to-peak [(10 000/n)0.5 mils peak-to-peak]

Not to exceed: Au < 100 µm peak-to-peak (4,0 mils peak-to-peak)

(i) Vibration limits at any flow within the pump's preferred operating region

Discrete frequencies (other than N)

Vf � 0.67 Vu Af < 0.75 Au

(ii) Vibration limits at flows beyond the preferred operating region but within the allowable operating region

Increase in allowable by 30% Increase in allowable by 30%

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Document Responsibility: Pumps, Seals and Mixers SABP-G-001 Issue Date: 28 January 2007 Centrifugal Pumps Dynamic Next Planned Update: 1 July 2009 Analysis Factory Acceptance Test

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Revision Summary 30 June 2004 New Saudi Aramco Best Practice. 28 January 2007 Minor revisions.

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Document Responsibility: Pumps, Seals and Mixers SABP-G-001 Issue Date: 28 January 2007 Centrifugal Pumps Dynamic Next Planned Update: 1 July 2009 Analysis Factory Acceptance Test

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Appendix A Methods of Calculating Vibration Acceptance Levels at Reduced Speed

The vendor needs to provide his own method. However, as a best practice, the vibration acceptance levels can be taken as the minimum value obtained using one of the following four methods:

1. By extrapolation of the rundown vibration data obtained from the factory test.

2. By factoring the vibration acceptance levels obtained from Section 7.1, to take account of speed and dynamic-related effects as shown below.

])([ 2

r

trt N

NADA ⋅×= (1)

Where,

At Acceptance vibration level at the test speed.

Ar Acceptance vibration level as obtained from Section 7.1

Nt Pump Test Speed, rpm

Nr Pump Rated Speed, rpm

D Dynamic multiplier to take account of resonant amplification effects.

D should be computed from:

2

2

)/(1)/(1

ct

cr

NNNN

D−

−= (2)

Where Nc is the measured pump structural natural frequency to be obtained from impact-testing the pump bearing housing/supports.

3. By utilization of information obtained from the vendor's rotordynamic analysis.

4. By comparison with vibration data provided by the vendor for identical pumps in operation.

In all cases account should be taken of any expected variations in vibration resulting from differing hydraulic behavior at test and rated conditions.