1、 Guidance Notes on Structural Monitoring Using Acoustic Emissions GUIDANCE NOTES ON STRUCTURAL MONITORING USING ACOUSTIC EMISSIONS OCTOBER 2016 American Bureau of Shipping Incorporated by Act of Legislature of the State of New York 1862 2016 American Bureau of Shipping. All rights reserved. ABS Plaz
2、a 16855 Northchase Drive Houston, TX 77060 USA Foreword Foreword Ship and offshore structures continue to become larger and more complex, requiring operators to have a more in-depth knowledge of structural integrity. There is a need for non-intrusive, real-time monitoring technique for monitoring st
3、ructural health while the vessel is in operation. Acoustic Emission Testing (AET) is a passive nondestructive examination technology that has been successfully applied to the detection and monitoring of crack propagation, corrosion activity, cavitation erosion, and leaking in structures constructed
4、of steel, aluminum, composite and other materials. AET has found increasingly wider applications in many industries as a feasible technique for detection and health monitoring of storage tanks, suspension bridges, nuclear plants, pressure vessels, LNG tanks, mooring chains, airplanes, etc. ABS first
5、 accepted AET in the Guide for Vessels Intended to Carry Compressed Natural Gases in Bulk (2005) as a feasible tool for real-time monitoring of sub-critical structural flaws. The IACS UR Z17 Procedural Requirements for Service Suppliers (2016) accepts AET for leak testing in gas carriers, and requir
6、es documented procedures based upon recognized standards. These Guidance Notes on Structural Monitoring Using Acoustic Emissions provide best practices for planning and conducting AET in the maritime and offshore oil and gas industries. Descriptions are given to the roles of owner, class and AET ser
7、vice provider, and how they shall collaborate. These Guidance Notes focus on steps to be performed rather than on the methodology of conducting AET. It is not possible for the current Guidance Notes to cover every application, because each AET application depends on several factors including vessel
8、type, flaws to be monitored, vessel condition, and hazardous areas. Sections 1 to 7 describe best practices for conducting AET on a ship or other floating structures. Appendices 1 to 6 provide additional background information, including codes and standards, and example applications. These Guidance
9、Notes become effective on the first day of the month of publication. Users are advised to check periodically on the ABS website www.eagle.org to verify that this version of these Guidance Notes is the most current. We welcome your feedback. Comments or suggestions can be sent electronically by email
10、 to rsdeagle.org. Terms of Use The information presented herein is intended solely to assist the reader in the methodologies and/or techniques discussed. These Guidance Notes do not and cannot replace the analysis and/or advice of a qualified professional. It is the responsibility of the reader to p
11、erform their own assessment and obtain professional advice. Information contained herein is considered to be pertinent at the time of publication, but may be invalidated as a result of subsequent legislations, regulations, standards, methods, and/or more updated information and the reader assumes fu
12、ll responsibility for compliance. This publication may not be copied or redistributed in part or in whole without prior written consent from ABS. ii ABSGUIDANCE NOTES ON STRUCTURAL MONITORING USING ACOUSTIC EMISSIONS .2016 Table of Contents GUIDANCE NOTES ON STRUCTURAL MONITORING USING ACOUSTIC EMIS
13、SIONS CONTENTS SECTION 1 Introduction 1 1 General . 1 3 Scope of These Guidance Notes 2 5 Information to be Submitted 2 7 Alternatives . 3 9 Terminology and Abbreviations 3 SECTION 2 Application of Acoustic Emission in the Marine and Offshore Industry . 5 1 General . 5 3 Test Modes and Overall Proce
14、ss 5 5 Equipment and System . 5 7 Roles of Owner/Operator, Acoustic Emission Test Team and Classification Society (CS) 7 9 Qualification of Acoustic Emission Testing Personnel 8 9.1 AET Trainee 8 9.3 AET Level 1 . 8 9.5 AET Level 2 . 8 9.7 AET Level 3 . 9 11 AET Procedures and Techniques . 9 FIGURE
15、1 Periodic Inspection Using AET 6 FIGURE 2 Continuous Monitoring Using AET . 6 FIGURE 3 Acoustic Emission Testing: Lead Responsibilities and Roles . 7 SECTION 3 Planning 10 1 Responsibilities and Task Planning 10 3 Development, Approvals, and Use of the Test Procedure . 10 5 Acceptance Standards of
16、Planning . 10 TABLE 1 Task Planning Table . 11 ABSGUIDANCE NOTES ON STRUCTURAL MONITORING USING ACOUSTIC EMISSIONS .2016 iii SECTION 4 Installation and Checks . 12 1 General . 12 3 Installation of Sensors and Equipment . 12 5 Systems Checks . 12 7 Acceptance Standards of Installation and System Chec
17、ks 13 SECTION 5 Data Acquisition and Analysis 14 1 General . 14 3 Data from Vessel Owner/Operator . 14 5 Data from Sensors 14 7 Hull Structure Stress Analysis. 14 9 Analysis of Acoustic Emission Signals . 15 11 Warning Levels . 15 FIGURE 1 Procedure for Data Analysis . 15 SECTION 6 Reporting Documen
18、tation . 16 1 Acoustic Emission Test Report . 16 3 Acceptance Standards of Report 17 SECTION 7 Follow-up Inspection 18 APPENDIX 1 An Introduction to Acoustic Emission . 19 1 Acoustic Emission Sources . 19 3 Structural Loading and Acoustic Emission Source Activity 21 5 The Signal Formation Chain . 24
19、 FIGURE 1 Schematic of the Acoustic Emission Process . 19 FIGURE 2 Emission Instability 22 FIGURE 3 Emission on Repeated Loading 23 FIGURE 4 Indication of Crack Face Rubbing . 24 FIGURE 5 The Signal Formation Chain . 25 APPENDIX 2 Test Procedure . 26 1 Content and Format 26 3 Monitoring Area . 26 5
20、Loading . 27 7 Equipment Setup 27 7.1 Specification of the Equipment 27 7.3 Layout of Sensors and Location Techniques . 27 7.5 Equipment Settings 28 7.7 System Performance Checks and Maintenance 28 7.9 Recording and Data Storage . 29 9 Noise Countermeasures . 29 iv ABSGUIDANCE NOTES ON STRUCTURAL MO
21、NITORING USING ACOUSTIC EMISSIONS .2016 11 Data Acquisition and Recording . 29 13 Data Interpretation and Evaluation . 30 15 Reporting 30 APPENDIX 3 Data Acquisition and Analysis 31 1 General Requirements for Data Acquisition . 31 1.1 Data from Vessel Owner/Operator 31 1.3 Data from the Sensors. 31
22、1.5 Data Acquisition Graphs 32 1.7 Data Storage and Transfer 32 1.9 Test Log 32 3 Noise . 33 3.1 Noise Sources . 33 3.3 Noise Countermeasures 33 3.5 Excessive Noise 34 5 Data Analysis 35 5.1 Data Quality Correlation between Stress and Acoustic Emission 35 5.3 Data Quality Signature Recognition . 36
23、5.5 Data Filtering During Analysis . 37 5.7 Source Location 37 7 Recent Advances in Data Processing 39 FIGURE 1 Procedure for Data Analysis . 35 FIGURE 2 An Example of the Energy vs. Amplitude Cross Plot 37 FIGURE 3 Source Location Cluster Formed During Ocean Voyage . 38 APPENDIX 4 Acoustic Emission
24、 Testing Systems and Performance Standards 40 1 General Acoustic Emission System Description . 40 3 Performance Standards 41 3.1 Acoustic Emission Sensors . 41 3.3 Couplant 41 3.5 Signal Cable 42 3.7 Preamplifier . 42 3.9 Power-Signal Cable . 42 3.11 Acoustic Emission Processor Power Supply . 42 3.1
25、3 Main Signal Processor. 42 3.15 Number of Acoustic Emission Channels 43 3.17 System Environmental Requirements . 43 5 Calibration and Verification . 43 7 Software 43 9 Need for Current Equipment . 43 FIGURE 1 Acoustic Emission System Block Diagram . 41 ABSGUIDANCE NOTES ON STRUCTURAL MONITORING USI
26、NG ACOUSTIC EMISSIONS .2016 v APPENDIX 5 Codes and Standards . 44 1 Acoustic Emission in ASTM Standards 44 1.1 Standards Specific to Acoustic Emission Testing 44 1.3 Standards Closely Related/Relevant To Acoustic Emission 44 3 Acoustic Emission in ASME Codes 45 5 Regulatory Code Variances and Exempt
27、ions . 45 7 Acoustic Emission Personnel Qualification and Certification . 45 9 Acoustic Emission Codes and Standards Overseas . 46 APPENDIX 6 Example Test Procedure 47 1 Scope and Purpose 48 2 Referenced Documents 48 3 Safety 48 4 Containership Sample and Monitoring Areas to be Examined . 48 5 Locat
28、ions of Discontinuities Known from Previous Inspections 49 6 Loading to be Applied . 49 6.1 General Description . 49 6.2 Concurrent Load Measurements . 49 6.3 Previous Loading History of the Monitoring Areas . 49 7 Equipment to be Used 51 8 Noise . 51 8.1 Potential Sources . 51 8.2 Precautions to be
29、 Taken 51 9 Sensor Mounting Method, Configuration and Source Location Techniques to be Used . 52 10 System Settings 52 10.1 General Settings 52 11 System Performance Checks . 53 12 Acoustic Emission Test Forms 53 12.1 Sensor Performance Check Appendix 6, Table 1 . 53 12.2 System Performance Check Ap
30、pendix 6, Table 2 54 12.3 Acoustic Emission Test Log Appendix 6, Tables 3 and 4 . 54 12.4 Parametric Setup Table Appendix 6, Table 5 . 55 13 Data Acquisition and Recording . 55 13.1 Data Storage . 55 13.2 Setting Changes 55 13.3 Noise Contingencies 55 14 Data Interpretation and Evaluation . 56 14.1
31、Check Data Quality Correlation between Stress and Acoustic Emission 56 14.2 Check Data Quality Signature Recognition . 56 15 Reporting . 59 16 Verification of Acoustic Emission Testing Results during Complementary Inspection . 59 vi ABSGUIDANCE NOTES ON STRUCTURAL MONITORING USING ACOUSTIC EMISSIONS
32、 .2016 TABLE 1 Sensor Performance Check Form 53 TABLE 2 System Performance Check . 54 TABLE 3 Acoustic Emission Test Log General Information 54 TABLE 4 Acoustic Emission Test Log Detail Information . 55 TABLE 5 Parametric Setup Table 55 FIGURE 1 Typical Design Focus Areas for Containerships . 48 FIG
33、URE 2 Selected Areas That May be Prone to Cracking . 49 FIGURE 3 Arrangement of Strain Gauges for Hull Monitoring System 50 FIGURE 4 Sample Recordings of Strain at Port Main Deck (Raw Data) 50 FIGURE 5 Sample Recordings of Strain at Port Main Deck (Extreme Value in 5 Minutes) . 50 FIGURE 6 Layout of
34、 Acoustic Emission Sensors and Computers . 51 FIGURE 7 Correlation between Stress and Acoustic Emission . 56 FIGURE 8 Cross plot: Number of Acoustic Emission Hits versus Amplitude 57 FIGURE 9 Cross Plot: Energy and Amplitude versus Channels 57 FIGURE 10 Cross Plot: Energy and Duration versus Amplitu
35、de 58 FIGURE 11 Clusters in the Zonal Source Location 58 ABSGUIDANCE NOTES ON STRUCTURAL MONITORING USING ACOUSTIC EMISSIONS .2016 vii This Page Intentionally Left Blank Section 1: Introduction SECTION 1 Introduction 1 General Ships and offshore oil and gas platforms continue to become larger, more
36、complex, and optimized, requiring an in-depth knowledge of structural integrity. This knowledge includes technologies for structural health examination and monitoring. For example, the ABS Guide for Vessels Intended to Carry Compressed Natural Gases in Bulk allows for Acoustic Emission (AE) to be us
37、ed to monitor shipboard gas cylinders for potential failure. ABS has published the Guide for Hull Condition Monitoring Systems that covers hull monitoring systems used for motion monitoring, stress monitoring, and voyage data monitoring. Most current hull condition monitoring systems rely on strain
38、gauges, accelerometers, wave radar, etc., which provide information about structural response (strain). However, these systems are generally not suitable for monitoring localized areas of the hull structure. There are circumstances when a system monitors a local area for crack growth. This may inclu
39、de known problem areas which need to be monitored in case a crack reoccurs or a crack continues to grow, perhaps threatening structural integrity. In this regard, acoustic emission technology shows promise as a monitoring method in ship and offshore structures. Acoustic emission techniques have been
40、 applied successfully in other industries (bridge, dam, storage tank, aerospace, nuclear plant, etc.). For the marine/offshore industry, these techniques can also apply the following applications: Machinery Auxiliary equipment Pressure vessel Pipe system Mooring chain (potential application) Subsea
41、structures (potential application) Acoustic emissions are sounds associated with stress waves generated by cracks and flaws in structures. These sounds of stress are in the form of elastic waves generated by the rapid release of energy from sources within a material. These elastic waves are detected
42、 by electronic monitoring devices to reveal the activity of cracks and flaws and to point to their location. Two distinctive features of the method are: i) It is the active growth of the cracks and flaws that produce Acoustic Emissions. ii) An array of Acoustic Emission sensors can monitor a substan
43、tial area and localize flaw sources if the Acoustic Emission data is acquired and analyzed properly. Because of these features, the method is very well suited for structural health monitoring, integrity management, and early warning of failure. ABSGUIDANCE NOTES ON STRUCTURAL MONITORING USING ACOUST
44、IC EMISSIONS .2016 1 Section 1 Introduction Acoustic Emission Technology has the following benefits: It offers real time monitoring of crack propagation, corrosion activities, and cavitation erosion under the applied stress It detects the growth of defects in the material rather than the presence of
45、 a nonconformity It covers a range up to 4.75 m (15 ft) for most marine/offshore applications It can locate defects (acoustic emission source) by the triangulation method It has an accuracy of approximately 0.15 m (0.5 ft), subject to the complexity of the structure It is intrinsically safe and is a
46、ble to monitor critical areas in hazardous zones Watertight Acoustic Emission equipment has been developed to monitor underwater and subsea structures It provides limited or no disturbance to operations Acoustic Emission technology can be used for monitoring during the stages of: Welding process Ini
47、tial proof test Requalification test In-service/monitoring Leak detection 3 Scope of These Guidance Notes The purpose of these Guidance Notes is to make available an ABS document that contains information related to the use of Acoustic Emission technology for monitoring the structural health of the
48、hull or other structures. These Guidance Notes address: Acoustic Emission application in marine environment (Sections 1 through 7) Background of acoustic emission testing (Appendices 1 through 6) Sections 1 through 7 briefly introduce the technology, outline the test process, and identify the roles
49、and responsibilities of the several parties involved in staging an Acoustic Emission project. By outlining the test process, it material for checklists to the AE test team, Owner, and ABS with that he can use to perform his assigned oversight role. Appendices 1 through 6 gives more technical detail about the Acoustic Emission method for those who wish to understand it in greater depth. Through the application of Acoustic Emission as a condition-monitoring technique, owners/managers/operators should be able to expect improved
