Anyone checked out this book on Vibration? 2

[StressGuy]

Saw this article in the July Hydrocarbon Processing, page 57, regarding vibration risk assessment in process piping systems. It's clearly targeted at the owner company considering changes to a process. Still, it seems like there would be applicability for review of a new design.

I checked out the Marine Technology Directorate website to see what this book was all about. Unfortunately, the only hard info, aside from what is in the article, is that the book is 195# (cost, not weight). The full title is "Guidelines for the Avoidance of Vibration Induced Fatigue in Process Pipework"

Has anyone in the group seen this publication and does it look like it would be a useful reference for an engineering company doing design work, or it is more focused on trying to troubleshoot existing installations?

Thanks, Edward L. Klein
Pipe Stress Engineer
Houston, Texas

All opinions expressed here are my own and not my company's.

 

[LSThill]

Dear Edward L. Klein, Pipe Stress Engineer,Houston, Texas

PRG at

http://www.paulin.com/

for Vibration Gas Compressor API 618 APP. M & N, Please see FPSO: API 618reva.doc 5,566K BOS Fluids API 618 Documentation (Draft) (10/15/02);

API 618 the pulsation and vibration control requirements for compressor and connected piping for Reciprocating Compressors for Petroleum Chemical and Gas industry Services are addressed.

• Three design approaches are different in their requirement of mechanical and acoustical simulation effort to be made by the designer.
• The selection of the proper design approaches depends among others on compressor properties and is clearly defined in the API Standard.

In appendix M of this API standard the various steps to be taken during the different design approaches are defined. In all approaches two different aspects are to be distinguished: the acoustical simulation and the mechanical response.
In the acoustical simulation the level of the pressure pulsations in the various components of the compressor package (cylinder passage, bottles, piping) is analyzed and in the design phase measures are taken to limit the level of the pressure pulsations. API Standard 618 specifies limits to the acceptable pulsation levels. For instance equation (8) of paragraph 3.9.2.7 specifies a rule to determine acceptable limits to the pulsation levels in the piping connected to the compressor battery. The allowable pulsation level is depending on the frequency and the pipe diameter and it is also depending on the average line pressure. In fact the allowable pulsation level is inversely proportional to the square root of the applicable pipe ID and the pulsation frequency and directly proportional to the square root of the line pressure.
In order to assess the pressure levels in the compressor piping several analyses are to be done. Since the allowable level is specified on a per pulsation frequency basis each frequency contribution has to be evaluated separately. Since the allowable pulsation level is depending on the average line pressure separate analyses are to be made for all possible suction and discharge pressures. Further since allowable pressure pulsation levels are dependent on pipe diameter the actual values have to be verified on a per pipe section basis.
Moreover also acceptable pressure pulsations generate unbalanced forces in the compressor suction and discharge piping. The effects of the unbalanced forces are addressed in the mechanical response study.

1.1.Acoustical natural frequencies.
Bos-Fluids is to be used in both stages of the various design approaches.
High pressure pulsation levels could be the result of a number of causes. One of the possible causes is the occurrence of acoustical resonance. Acoustical resonance occurs if the compressor excitation frequency or one of its higher harmonics coincides with one of the acoustical natural frequencies of the system.
By means of BF the user is able to determine the acoustical natural frequencies of the piping system and make sure that sufficient separation exists between the acoustical natural frequencies and compressor harmonics. The acoustical natural frequencies are related to reflection of waves in the pipe system. The wave reflection period is proportional to the ratio of pipe section length and wave speed. Therefore the natural frequency values can be shifted by changing the unfavorable pipe section lengths. In case shifting of frequencies is impossible often additional damping (orifice plate) is to be introduced to limit the pulsation amplitude at (near) resonance condition.

1.2 Pulsation study.
The pulsation time history generated by a reciprocating compressor is periodic with a period related to compressor RPM. However the pulsation time-history in general by no means is perfectly harmonic. The periodic pulsation time history also contains components of higher harmonic frequencies than the basic compressor frequency corresponding to its RPM/60. The other contributions in the periodic pulsation are made by the higher harmonics. The higher harmonics are multiples of the basic compressor frequency.
It was indicated above that the allowable pulsation levels as defined in paragraph 3.9.2.7 of API 618 are defined on a per frequency basis. Therefore the assessment has to be performed on a per harmonic frequency basis. For that purpose Bos-Fluids provides the user a module by which he is able to decompose the compressor pulsation time-history signal into the first 10 harmonic components by means of a Fourier series decomposition.
For each of the resulting Fourier components a pulsation analysis is to be made and the pressure pulsation levels are to be compared to the allowable pulsation level on a per pipe section basis.

1.3 Mechanical response analysis.
One of the important results of the pulsation analysis is for each pipe section the determination of the magnitude (amplitude) of the unbalanced forces. These unbalanced force components are to be used in the mechanical response analysis. This mechanical analysis is performed by means of a pipe stress package with dynamic (harmonic) capabilities. The resulting support/nozzle loads and stresses are assessed by comparison to their allowable levels.
For the stresses guidance on the allowable stress levels is given in paragraph 3.9.2.2.1 of API 618.

Leonard

 

[LSThill]

From Code John Breen Said: Hello All,

I came up with a bunch of very good papers that are available at this address:

http://www.engdyn.com/papers.htm

the following subset are papers that are specifically for piping vibration problems:

17. Escape Piping Vibrations While Designing, J. C. Wachel/C. L. Bates, Hydrocarbon Processing, October, 1976, pp. 152-166.

20. Field Investigation of Piping Systems for Vibration-Induced Stress and Failures, J. C. Wachel, Pressure Vessel and Piping Conference, ASME Bound Volume #H00219, June 27-July 2, 1982.

27. Piping Vibration and Stress, J. C. Wachel, Vibration Institute, Machinery Vibration Monitoring and Analysis Seminar, New Orleans, April 1981, pp. 1-20.

29. Pulsations in Centrifugal Pump and Piping Systems, C. R. Sparks and J. C. Wachel, Hydrocarbon Processing, July 1977, pp. 183-189.

37. Techniques for Controlling Piping Vibration and Failures, J. C. Wachel/C. L. Bates, ASME Paper 76-PET-18, 1976.

59. Vibration Troubleshooting of Existing Piping Systems, J. C. Wachel/D. R. Smith, July 1991.

72. Displacement Method for Determining Acceptable Piping Vibration Amplitudes, J. C. Wachel, 1995 ASME/JSME Pressure Vessels & Piping Conference, Honolulu, HI, July 1995.

Best regards, John.

--------------------
John Breen

 

[stanier]

Have a look at

http://www.hcasia.safan.com/mag/oct01/t37.pdf

 

[LSThill]

PRG has posted the following

http://www.paulin.com/

Downloads [bos1c.doc 12,000K BOS Fluids Beta Chapter C] (11/09/02)

 

[Naren]

Gents,

This in reply to Stressguys questions. The contents of the document are given below. It basically identifies your vibration mechanism, then provides some assesment criteria, without detailed analysis (eg stress) to check if you have a problem or not and then gives some guides to correct the problems. The SBC assessment is very useful.

I have also been involved in Refinery piping vibration assessment. My article is currently under publicationin The International journal of pressure Vessel & piping. (Elsevier publishing)

My article have been published/presented at the Internationa Conference on Operating pressure Equipment, Brisbane, Australia, 2001 & at the Sixth International Colloquium on Aging of Materials & Methods for Assessment of Lifetimes of Engineering Plant, South Africa, 2001 (available from EMAS publishing, Editor RK Penny)

1.0 Introduction
2.0 Vibration Mechanisms
2.1 Excitation Mechanisms and Response
2.1.1 Introduction to Vibration
2.1.2 Flow Induced Turbulence
2.1.3 High Frequency Acoustic Excitation
2.1.4 Mechanical Excitation
2.1.5 Pulsation
2.1.5.1 Reciprocating Pumps and Compressors
2.1.5.2 Periodic Flow Induced Excitation
2.1.5.3 Centrifugal Compressors (Rotating Stall)
2.2 Failure Mode
2.3 Determination of Overall Risk
3.0 Assessment Methodology
3.1 Overview 15
3.2 Stage 1 - Identification of Excitation Mechanisms
3.3 Stage 2 - Detailed Screening of Main Pipe
3.4 Stage 3 - Detailed Screening of Small Bore Connections
4.0 Design Solutions
4.1 Overview
4.2 Design Solutions for Main Pipe
4.2.1 Flow Induced Turbulence
4.2.2 Pulsation
4.2.3 High Frequency Acoustic Fatigue
4.2.4 Mechanical Excitation
4.3. Design Solutions for Small Bore Connections
5.0 Survey Methods
5.1 Introduction
5.2 Survey Methods
5.2.1 Vibration Based Survey Techniques
5.2.2 Fatigue Direct Strain Measurement
5.3 Interpretation of Fatigue Measurement

Best Regards
Naren


Naren Sukaih
naren.sukaih@sapref.com

 

[lawrs]

I have just finished referencing this document on a previous question, the document is basically a procedure for evaluating new or modified piping designs for potential vibration. It can also be used to evaluate the risk from fatigue failure on an existing vibrating system.