Ags-22 Rev0

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GENERAL SPECIFICATION EQUIPMENT VIBRATION

AGS-22

Rev.0

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Revision 0

Description Issue For Approval

Date July’ 03

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TABLE OF CONTENTS Section

Page

1.

Scope

4

2.

Codes and Standards.

4

3.

Definitions

5

4.

General

8

5.

Types of Equipment

9

6.

Auxiliary Equipment

10

7.

Acceptance Testing

11

8.

Induced Piping Vibrations

12

9.

Procedures Requirements and Instructions

13

10.

Conversion Information

14

11.

Appendix. A Tables

17

12.

Appendix. B Nomograph Comments

25

13.

Appendix. C Guidelines

29

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1. SCOPE 1.1 This specification states, the acceptable levels of vibration for rotating and reciprocating equipment, including a section limiting mechanically induced vibrations in piping connected thereto. This document may be attached to and made a part of individual specifications and drawings or used in conjunction with other equipment standards provided they do not detract from the basic intent contained herein. The responsibility for proper interpretation of this standard shall rest upon appointed representatives of the vendor, fabricator or contractor, hereafter called the Supplier, and the Issuer. It will be the Supplier’s responsibility to obtain clarification or initiate a discussion of exceptions to this standard with the Issuer or his representative. In all cases, agreements reached jointly shall be final and binding. 2. CODES AND STANDARDS SPECIAL REQUIREMENTS All Codes and Standards referenced in this specification shall be the latest edition and shall supercede any editions dated earlier. As used in this specification, the following definitions shall apply: Issuer

PTT Exploration and Production Public Company Limited

Job Specification

Equipment Specification with applicable General Specifications and; referenced Industry Codes or Standards

2.1 All equipment fabricated, tested, and installed under this standard shall also conform as a minimum to the latest edition of the National and international Codes and Standards specifically stated herein as applicable. No omission from this document shall relieve the Supplier of his aforementioned responsibility. The following codes and standards, if required, supplement this document.

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NATIONAL AND INTERNATIONAL CODES AND STANDARDS:

150-2372-1974

Mechanical Vibration of Machines (10-200 Rev/set)

180-2373-1974

Mechanical Vibration Electrical Machinery

NEMA-MGI-20-1976

Motor and Generator Balance Tolerances

I EC-222

Methods of Specifying Auxiliary Equipment for Vibration Measurements

API-RP541-1972

Recommended Practice for Form-Wound Squirrel-Cage Induction Motors. 200 HP and Larger

API-610

Centrifugal Pumps

API-611

General Purpose Steam Turbines

API-613

High Speed, Special Purpose Gear Units

API-616

Combustion Gas Turbines

API-617

Centrifugal Compressors

API-618

Reciprocating Compressors

API-670-1976

Non contacting Vibration and Axial Position Monitoring Systems

of

Certain

Rotating

3. DEFINITIONS 3.1 For the purposes of this standard the following shall apply: a) Parameters of amplitude measurement. For conversion information see section 10.3

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b) Vibration: an oscillating or alternating motion of a mass caused by a force applied at regular or irregular intervals and measured by an amplitude a frequency and a phase angle. c) Amplitude: the magnitude of the oscillating vibratory motion measured either as the displacement, velocity or acceleration of the mass. d) Displacement: the actual movement of a mass from a rest position usually expressed in mils (0.001 inches) or microns (0.001 mm), peak to peak. e) Velocity: the rate of change of displacement with respect to time, the maximum speed of a point or position on a vibrating mass, rotor, element or unit that is normally expressed as peak in/s or mm/s. f) Acceleration: the rate of change of velocity with respect to time usually stated as peak G’s (gravity units). 366 in/s2 or 9600 mm/s2 are gravitational constants used in converting peak acceleration (in/s2.) values to gravity units. From a practical standpoint acceleration is the maximum rate of increase or decrease of the speed of a vibrating mass considering its structure and/or moving components. g) Frequency: the number of cycles of the vibrating mass per unit of time, stated in cycles per minute(c/mm) or cycles per second (c/s). By international agreement Hertz (Hz) is the unit of frequency and equivalent to cycles per second. h) Phase: The position of the vibrating object (such as a rotor. shaft, sheave, gear, etc.) at any given instant with respect to a reference at some fixed point (bearing housing, case, cover, guard, etc.) normally displayed by an oscilloscope, stroboscopic light or a remote phase meter (electromagnetic pickup or photocell).

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i) Critical Speed: the frequency or speed of a rotating mass (pump impellers, couplings, pinion gears, compressors rotors, etc.) that corresponds to a resonant frequency of the system: j) Resonance: marked increase in vibration amplitude that occurs when the frequency of an exciting or forcing oscillation (such as an unbalanced rotor) corresponds to the natural frequency of the unit or system. k) Simple Harmonic Motion: a vibratory movement that is repetitious with respect to time, i.e., normally considered not containing complex signals and usually described as pure sinusoidal. I) RMS Level: a root mean square measure of vibration amplitude that lakes the lime history into account and gives a value that is directly related lo the energy content of the signal, (an indication of possible destructive capabilities). m) Unfiltered (Filter Out): oscillating disturbances or waves in the form of electrical signals received by a device such as a vibration analyzer that allows all energy levels to pass without distinguishing as to their frequency, i.e., the maximum vibration felt at any given pickup location before analysis. n) Filtered (Filter In): oscillating disturbances that have been separated on the basis of their frequencies with a vibration analyzer. Readings taken with the filter in are used for entering tables found in Appendix. A o) Seismic Pickup: a transducer or sensing device consisting of a moving coil in a permanent magnetic field whose voltage output is directly proportional to the pickup case velocity. This system simulates a fixed point in space (for reference) to determine equipment vibration amplitudes. p) Non Contact Pickup: also called a proximity probe 8 device that is capable of measuring distance or a change thereof between any electrical conductive surface and the small coil In the tip of an eddy current probe-part of an electronic measuring system. Used with monitors or readout devices to provide an equipment protective system with continuous surveillance of machinery condition. q) Signature Analysis: the trace of a filtered vibration signal on an amplitude versus frequency plot where spectrum densities can be analyzed, usually in displacement or velocity modes (see example in Appendix. C)

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4. GENERAL 4.1It shall be the Supplier’s responsibility to bring promptly to Issuer’s attention any error or discrepancies which are found to exist in this standard, attached specifications and/or drawings. 4.2 Requests for substitutions and/or exceptions to this standard shall be submitted in writing, complete with all pertinent engineering information required for the Issuer’s evaluation. When time does not permit compliance with this section, workable agreements may be reached orally. Documentation of any such verbal agreements shall be made including the names of personnel involved, their titles and affiliation. 4.3 The Issuer’s duly authorized agents and/or representatives shall be provided with the following privileges: a) Free access to those portions of the Supplier’s facilities utilized in any manner for the construction, fabrication or assembly of the equipment to be tested or inspected under this standard. b) When required, the right to review any data which may be related to one or all of the following: material selection, fabrication, assembly, balancing or testing of the manufactured equipment. If a unit is found unacceptable and remedial work is required information related to machining tolerances and balancing certification limits utilized, or techniques applied may be requested for an on the spot review. c) The right to inspect: test, and/or witness any activities in conjunction with this standard and to reject any work. Material or procedure deemed sub-standard. 4.4 The Supplier shall have the right to request reasonable compensation for Issuer requested inspection(s), testing and/or witnessing of equipment in order to verily compliance with this standard. 4.5 The Supplier shall be responsible for and assure the Issuer that vibration levels do not exceed the limits established by this standard as listed in Appendix .A under the appropriate tables. 4.6 The Supplier shall assume the responsibility for, and the obtaining of, any and all performance warranties on equipment provided to meet this standard.

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5. TYPES OF EQUIPMENT 5.1 See appropriate tables in Appendix. A for acceptable levels of vibration on specific types of equipment is listed below: TABLE

PAGE

a) Drivers Electric Motors...........................................……………..1

17

Gas Turbines Aircraft Derivative.....................................………3 Industrial.............................................…………..4

19 20

Reciprocating Engines....................................…………5 Steam Turbines...........................................……………6 Others...................................................………………...6

21 22 22

b) Pumps Centrifugal...............................................………………2 Rotary....................................................……………… 6

18 22

c) Compressors Centrifugal...............................................……………….6 Reciprocating.............................................……………..5 Rotary...................................................…………………6

22 21 22

d) Interdrives High Speed..............................................……………….6 Low Speed..............................................………………..7 Bevel Gears..............................................………………7 Planetary, Epicyclic.......................................…………...6

22 23 23 22

e) Generators A. C. or D. C..............................................……………..6

22

f) Axial Flow Fans, Blowers High Speed...............................................……………...6 Low Speed...............................................………………8

22 24

SPECIFICATION

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6. AUXILIARY EQUIPMENT 6.1 All other mechanical equipment not specifically covered in Section 5.1 including such items as skids, vessels, coolers, condensers, refrigeration units and the like shall be designed, fabricated and installed with supports hangers. Pulsation dampeners, etc. as required to prevent excessive vibration to the total system or to individual pieces of equipment. 6.2 Vibration limits are specified elsewhere (see Section 8.1) for piping and/or valve installations that are wholly contained on or within the physical confines of the skid or base mounted unit(s). 6.3 The vibration levels of auxiliary equipment, in no instance shall exceed the following: AUXILIARY EQUIPMENT ACCEPTABLE VIBRATION AMPLITUDES Frequency (c/min)

Displacement (mils, pk-pk)

Velocity (in./sec, pk)

10.0

0.30

601 - 1200

5.5

0.33

1201 - 2000

3.5

0.33

2001 - 4000

2.5

0.35

4001 - 7000

1.5

0.35

7001 - 12000

1.0

0.35

12001 - 16000

0.5

0.33

16001 - 24000

0.35

0.33

24001- 30000

0.25

0.30

30000 and above

0.20

0.27

600 and below

Peak velocity readings are preferred for analysis. All data gathered shall be recorded in both the unfiltered and filtered state. Only filtered readings are to be used in entering the table above for acceptance testing. 6.4 Procedures in Section 9.0 and Guidelines from Appendix. C will be helpful in data acquisition for equipment analysis.

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7. ACCEPTANCE TESTING 7.1 The Supplier shall grant the Issuer or his representative permission to enter his facility during final acceptance testing, i.e. performance, mechanical or no load testing for the purpose of vibration analysis on any equipment being purchased. The Issuer retains the option to supply their own portable instruments and personnel lo analyze the equipment being tested. 7.2 A vibration analysis shall be made on all rotating or reciprocating equipment and any related piping. This analysis may be a requirement within the scope of the mechanical acceptance test if mutually agreed upon by the Supplier and the Issuer. The analysis shall be performed on the equipment simulating field operating conditions whenever possible. In any event, the data gathered shall be made available to the Supplier and/or the Issuer (depending on who made the analysis or operated the instruments) and attached to the test records. 7.3 Basic Requirements for Acceptance Testing: a) The Supplier shall notify the Issuer at least five (5) days prior to a scheduled test unless a different lime frame is mutually agreed upon between the Supplier and the Issuer. b) The duration of all tests shall be in accordance with the applicable API code for that specific type of equipment. If no code applies and the Issuer’s job specifications do not call out testing details, the units to be tested shall be operated at rated speed until bearing temperatures and operating conditions are stable. At this time, the vibration analysis shall begin. In no instance shall the minimum time period be less than one half hour for any acceptance test. Note: A thermally stable condition shall be considered achieved when the equipment bearing temperatures show that no change has occurred which is greater than 2.5% of the previous high reading noted or recorded during any five minute interval. c) The Supplier shall state the critical or resonant speeds, all input and output shaft speeds including those for any intermediate shafts in gear trains, the number of teeth on meshing gears in an inter drive system and any other similar information necessary to identify frequencies during the vibration analysis. This data shall be given to the Issuer or his representative prior lo the acceptance test and made a part of the test report.

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d) The Issuer shall have the right to make on-the-spot interpretations and/or decisions to assure satisfactory equipment performance as well as the validity of the test. The test report shall include all raw data and any interpretations or recommendations that were made by either the Supplier or Issuer personnel. Both parties shall sign the test reports for their respective equipment files. 7.4 Additional requirements: a) The Supplier shall utilize the Issuer’s monitors. non-contact probes and/or seismic pickups wherever possible if such instrumentation is being supplied with the equipment under test. b) Final or trim balancing of any rotor, gear shaft or other element requiring a two plane correction shall be governed as follows: Plane A shall be within ten percent of Plane B’s residual unbalance and vice versa. At no time shall the Supplier’s standard limits for balancing be exceeded by applying this requirement. The intent is to provide for a more uniformity balanced rotating element thus minimizing the couple within the unit. 7.5 This vibration standard does not in any way, manner, or form, supplant other routine pre or post inspections such as hydrostatic, welding, fabrication, disassembly after testing, painting, packaging, etc. 8. INDUCED PIPING VIBRATIONS 8.1 Piping vibrations caused mainly by internal flows (pulsations) are not included in the scope of this standard. However, mechanically induced piping vibrations caused by plant equipment such as those types outlined in Section 5.0 are limited as follows: a) All piping attached to or made a part of the equipment package shall not exceed the amplitude allowed for the unit to which it is connected. b) Piping external to the equipment base or skid mounting shall be governed by the vibration limits imposed on the unit to which it is connected for a distance of ten (10) feet or to the first anchored pipe support. c) General piping beyond the first pipe support shall not exceed twice the Maximum Allowable Amplitude (velocity or displacement amplitudes given in Appendix. A tables) for that particular type of equipment to

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Page 13 of 29 which it is connected over the frequency range of 60 to 6000 c/min (1 Hz to 100 Hz). Additional supports may be required to dampen the piping excitation if the limits above are exceeded. d) Allowable Piping Vibration above 6001 c/min shall be determined for displacement readings by the sum of the Maximum Allowable Amplitude and the square root of 12000 divided by the equipment operating speed in revolutions per minute (rev/min). APV = MAA + 12000 rev/min

mils

e) Allowable Piping Vibration above 6001 c/min shall be determined for velocity readings by the sum of the Maximum Allowable Amplitude and the square root of 12000 divided by the equipment operating speed in revolutions per minute (r/min). APV = MAA +

12000 rev/min

in/s

Example: from Appendix A Table 3 for Aircraft Derivative Gas Turbines at 8000 rev/min using velocity readings. APV = 0.52 +

12000 8000

in/s

9. PROCEDURES, REQUIREMENTS AND INSTRUCTION 9.1 The vibration levels shall be recorded from the horizontal, vertical and axial planes for all accessible bearing locations on the equipment and at other positions designated in the specific vibration tables. Do not record data from locations on thin walled casings, covers, housings or similar enclosures. Flange or structurally rigid locations are acceptable for data points. In general, vibration readings are to be taken on bearing housings, gas turbine case flanges or as close to the horizontal and vertical planes of bearings as possible unless staled otherwise in the specific equipment tables.

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Page 14 of 29 9.2 During the analysis, particular attention shall be given to the vibration levels and frequencies at: a) Equipment’s operating range or design speed (S) b) Twice the above speed (2S) c) One-half the operating speed (0.5S) d) Ten percent above design speed or overspeed (1.1S) 9.3 Standard forms used when recording vibration levels, frequencies and operating conditions shall also require a sketch locating the planes of and for the data acquisition. A typical form, Guideline No. 1, can be found in Appendix. C When signature analysis or X-Y plots are utilized, an equipment sketch on the hard copy is required to locate the planes of data acquisition. These copies shall be made a part of the test records. A typical form for this method is found in Appendix. C as Guideline No. 2. 9.4 During the vibration data acquisition, operational information must be recorded just prior to the start of an analysis. When applicable, such items as temperatures, pressures, flow rates, loads, intermediate shaft speeds, type of couplings, etc. are required for each unit analyzed. 9.5 A representative curve can be obtained, eliminating the step function format when using displacement values (mils) for entering the vibration acceptance level table by plotting all of the velocity values (in/s) at their respective maximum frequency range points on a reproduction of the nomograph in Appendix. B 10. CONVERSION INFORMATION 10.1 ISO, British and other European standards have chosen “vibration severity” to classify acceptable or permissive levels of rotating machinery vibration. The parameter chosen to characterize “vibration severity” is the RMS value of velocity in the frequency range from 600 to 6000 c/min (10 to 100 Hz). All references in this standard are to peak velocity only. To convert to RMS (the value representative of the energy content of the signal received) simply multiply the peak velocity reading by 0.707.

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10.2 Other conversion factors for simple harmonic motion that may be required occasionally are given in the following chart: MULTIPLY NUMERICAL

BY

TO OBTAIN

Average

1.111

RMS

Average

1.571

Peak

Average

3.142

Peak-Peak

RMS

0.900

Average

RMS

1.141

Peak

RMS

2.828

Peak-Peak

Peak

0.636

Average

Peak

0.707

RMS

Peak

2.000

Peak-Peak

Peak-Peak

0.318

Average

Peak-Peak

0.354

RMS

Peak-Peak

0.500

Peak

VALUE OF

Acceleration and velocity used in the vibration nomograph (Appendix. B) or throughout this standard are peak values. Displacement values are always considered peak to peak. For conversion to other formats use the table above. Note that these conversions are for sinusoidal wave forms: however, good approximations can be obtained for a representative overview of more complex vibration signals.

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10.3 Conversions Between the English and Metric Systems: MULTIPLY NUMERICAL

BY

TO OBTAIN

mils

25.4

microns

in/s

25.4

mm/s

2

in/s

25.4

mm/s2

mm

1000

microns

microns

0.03937

mils

mm/s

0.03937

in/s

mm/s2

0.03937

in/s2

VALUE OF

Note: DO NOT USE decimal equivalents for mil values in the above table such as 0.010, 0.0176 or 0.025 inches. Use whole numbers 10, 17.6 and 25 when converting to or from either system.

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APPENDIX. A TABLES TABLE 1 ELECTRICAL MOTORS ACCEPTABLE VIBRATION AMPLITUDES NEMA Frame Series

NEMA Approx: Frame Size

HP

180, 200

143T to 184T

0.5-2.0

3600 and below

0.75

0.15

213R to 286T

2.0-30

3600 and below

1.0

0.2

324T to 445T

40-350

3600 and below

1.0

0.2

350-Up

3600 and below

1.0

0.2

Range

Speed, rev/min or Frequency, c/min

Displacement Velocity (mils, pk-pk)

(in/s)

210, 220 250,280 320 360, 400 440,550 Large Motors All data shall be recorded in both the unfiltered and filtered state. Only the filtered readings are used in entering the table above for acceptance levels. On small motors with anti-friction or sleeve type bearings, vibration readings are to be taken on the bearing housing as close to the center line as possible. On large motors with sleeve type bearings, vibration readings are to be taken on the shaft if possible

TABLE 2

SPECIFICATION

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CENTRIFUGAL PUMPS ACCEPTABLE VIBRATION AMPLITUDES

Speed Range, rev/min or Frequency, c/min

Displacement

Velocity

(mils, pk-pk)

(in/s) Bearing Type

Bearing Type 1

A.F.

2

Sleeve

A.F.1

Sleeve2

1800 or below

3.0

----

0.27

----

1801 – 4500

2.0

2.0

0.3

0.3

4501 – 6000

----

1.5

-----

0.33

6001 and above

----

1.0

-----

0.35

API-610. Design-Section 2, 10a-f 1. Anti-friction (A.F.) bearing vibration readings are to be taken on the bearing housing as close to the center line as possible. 2. Sleeve bearing vibration readings are to be taken on the shaft if possible. All data shall be recorded in both the unfiltered and the filtered state. Only the filtered readings are lo be used in entering the table above for acceptance levels.

TABLE 3

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AIRCRAFT DERIVATIVE GAS TURBINES ACCEPTABLE VIBRATION AMPLITUDES

Speed Range, rev/min or Frequency, c/min

Displacement (mils, pk-pk)

Velocity (in/s, pk)

1000 and below 1001-4000 4001-6000 6001 - 8000 8001- 12000 12001 - 18000 18001 – 25000 25000 and above

8.0 4.0 2.0 1.5 1.0 0.75 0.50 0.30

0.45 0.5 0.52 0.52 0.50 0.45 0.40 0.35

Peak velocity readings are preferred for acceptance testing. Displacement values are selected near the mid-frequency range. All data shall be recorded in both the unfiltered and the filtered state. Only the filtered readings are to be used in entering the table above for acceptance levels.

TABLE 4

SPECIFICATION

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INDUSTRIAL GAS TURBINES ACCEPTABLE VIBRATION AMPLITUDES

Speed Range, rev/min

Displacement

Velocity

or

(mils, pk-pk)

(in/s, pk)

1000 and below

5.0

0.27

1001 - 4000

2.5

0.32

4001 - 6000

1.5

0.33

6001 - 8000

1.0

0.34

8001 - 12000

0.7

0.33

12001 - 18000

0.6

0.32

18001 - 25000

0.35

0.30

25000 and above

0.25

0.27

Frequency, c/min

Peak velocity readings are preferred for acceptance testing. Displacement values are selected near the mid-frequency range. All data shall be recorded in both the unfiltered and the filtered state. Only the filtered readings are lo be used in entering the table above for acceptance levels.

TABLE 5

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RECIPROCATING ENGINES AND COMPRESSORS ACCEPTABLE VIBRATION AMPLITUDES

Speed Range, rev/min

Displacement

Velocity

or

(mils, pk-pk)

(in/s, pk)

50 - 500

10.0

0.30

501 - 1000

7.0

0.32

1001 – 1500

5.0

0.33

1501 - 2000

4.0

0.35

2001 and above

3.0

0.35

Frequency, c/min

All data shall be recorded in both the unfiltered and the filtered state. Only the filtered readings are to be used in entering the table above for acceptable levels.

TABLE

6

SPECIFICATION

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STEAM TURBINES, CENTRIFUGAL AND ROTARY COMPRESSORS, GENERATORS, HIGH SPEED AND EPICYCLIC GEARS, ROTARY PUMPS, HIGH SPEED FANS AND BLOWERS ACCEPTABLE VIBRATION AMPLITUDES

Speed Range, rev/min

Displacement

Velocity

or

(mils, pk-pk)

(in/s, pk)

500 and below

7.0

0.25

501 - 1000

5.0

0.27

1001 - 3000

3.0

0.30

3001 - 4500

2.0

0.31

4501 - 6000

1.5

0.32

6001 - 8000

1.0

0.33

8001 - 12000

0.6

0.33

12001 - 18000

0.4

0.32

18001 - 25000

0.3

0.31

25001 and above

0.25

0.30

Frequency, c/min

Peak velocity readings are preferred for acceptance testing. Displacement values are selected near the mid-frequency range. All data shall be recorded in both the unfiltered and the filtered state. Only the filtered readings are to be used in entering the table above for acceptance levels.

TABLE 7

SPECIFICATION

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LOW SPEED INTERDRIVES, BEVEL GEARS

Speed Range, rev/min

Displacement

Velocity

or

(mils, pk-pk)

(in/s, pk)

100 and below

14.0

0.25

101 - 200

12.0

0.26

201 - 300

10.0

0.27

301 - 400

8.0

0.28

401 - 500

7.0

0.29

501 - 600

6.0

0.3

601 - 700

5.0

0.3

Frequency, c/min

Peak velocity readings are preferred for acceptance testing. Displacement values are selected near the mid-frequency range. All data shall be recorded in both the unfiltered and the filtered state. Only the filtered readings are to be used in entering the table above for acceptable levels.

TABLE 8

SPECIFICATION

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AIR COOLED HEAT EXCHANGERS AND COOLING TOWER FANS (Low Speed)

Speed Range, rev/min

Displacement

Velocity

or

(mils, pk-pk)

(in/s, pk)

120 and below

16.0

0.24

121 - 180

14.0

0.25

181 - 240

12.0

0.26

241 - 300

11.0

0.26

301 - 360

10.0

0.27

361 - 420

9.0

0.27

421 - 480

8.0

0.28

481 – 540

7.0

0.29

541 - 600

6.0

0.3

Frequency, c/min

Peak velocity readings are preferred for acceptance testing. Displacement values are selected near the mid-frequency range. All data shall be recorded in both the unfiltered and the filtered state. Only the filtered readings are to be used in entering the table for acceptable levels.

APPENDIX. B

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MONO GRAPH COMMENTS

The nomograph was developed for vibration consisting of simple harmonic motion or that of a pure sinusoidal waveform exhibiting four

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EQUIPMENT VIBRATION

AGS-22 Rev.0

Page 26 of 29 quantities that make up the respective axes, namely: frequency, displacement, velocity and acceleration. Complex equipment or multiple body trains may produce vibration signals that deviate from the basic sinusoidal wave form. This must be considered when using the nomograph. When the nomograph is used as a guide to determine whether a machine is operating satisfactorily or approaching a necessary overhaul, the velocity mode should be chosen, Peak velocity has been stressed during the development of the nomograph for ease in converting to approximate values of displacement or acceleration. Conversion to RMS values can be made by simply multiplying peak velocity by 0.707. In general, velocity should be used for most acceptance testing or basic trouble-shooting jobs. Displacement is recommended for non-contact proximity type equipment protective systems and any necessary analyses for determining machine conditions. (from nomograph) in mils or microns. Acceleration is considered best for frequencies higher than 60,000 c/min or for in-depth analysis work. These three modes are represented on the nomograph with velocity on the horizontal, displacement on the lines sloping upward from left to right and acceleration on the lines sloping down from left to right. Most line values are found on their outer edges or near the perimeter: Frequency logarithmic graduations are 60 up to 600, 600 up to 6,000, 6,000 up to 60,000, etc. Note: Exact values from the nomograph are not required nor is it necessary to have more significant numbers than the graph format utilizes. Using the Nomograph Example - Problem: Determine the machinery condition of a gas turbine driven generator that has just alarmed at 6 g’s. Unit is operating at 17000 r/min. For practice, find the equivalent readings in displacement and velocity modes. Solution: Follow the 6 g acceleration line to a point slightly to the left of the 18000 c/min intersecting frequency line (vertical line to right of 12000 c/min). Machinery condition is very rough. After finding the approximate intersection or location follow an imaginary parallel line to the lower left hand edge for a displacement value- read approximately

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SPECIFICATION EQUIPMENT VIBRATION

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Page 27 of 29 1.3 mils. Next, to find an equivalent velocity value- follow the horizontal lines to the right or left (from the original intersection point) and read 1.2 in/s. Note that all scales are logarithmic but approximations can be readily made such as: 1/3 of the distance between adjacent graduations is 0.2, ½ the distance is about 0.3 and 2/3 of the distance between lines is approximately 0.5. Use these values for easier nomograph data manipulation.

VIBRATION DATA

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SPECIFICATION EQUIPMENT VIBRATION

APPENDIX. C GUIDELINES

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SPECIFICATION EQUIPMENT VIBRATION REFERENCE GUIDELINE# 2

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