Advanced Acoustic Emission for On-stream Inspection of Petroleum Industry Vessels

1. Advanced Acoustic Emissionfor On-stream Inspection of Petroleum Industry Vessels

2. Current Approach - MONPAC PLUS • Evaluation of Pressure Vessels - MonPac Plus • AE Technology Program Developed by MONsanto and Physical Acoustics Corp. • Applications • Structural Integrity Monitoring • Leak Detection • Process Monitoring • Materials Research

3. PERF 95-11: Advanced AE for On-Stream Inspection • Sponsored by ten companies, including seven financially (Exxon/Mobil, Shell, Saudi Aramco, BP, Chevron and Petrobras) and three vendors (PAC, QSL -Plus and Matrix) for equivalent in-kind contributions • Collaborating with NASA LRC • University Support: Dr. R. Weaver - Univ Illinois (UI), Dr. Chon Tsai, Dr. Stan Rokhlin - Ohio State Univ (OSU), Dr. W. Sachse - Cornell, Dr. Mandayam - Rowan

4. Advanced AE for On-stream Inspection The overall objective of this effort is to deliver reliable AE methods for global, on-stream inspection of pressure vessels in lieu of internal inspection incorporating advances in; • Accurate Source Location • Quantitative AE/FFS Relationship • Reliable Source Discrimination • PERF-PAC AE Software & System • Recommended Practice & Guidelines

5. Advanced AE for On-stream Inspection The result of this work is to be a waveform based, procedure driven, Multi-channel AE System and Software for planning and conducting advanced AE vessel testing composed of; • Pre-Test Support (built into the software) for assisting in setting up an AE Examination based on vessel parameters, attenuation analysis, and user desired minimum detectable crack size. • Real Time Acquisition of waveforms with improved event detection, event timing features, accurate source location, source discrimination, crack size quantification, and Fitness for Service Analysis determination without need for follow-up NDT inspections after the test.

6. Pre-Test AnalysisAdvanced Dispersion Curve analysis Main setup menu • Example • Source: surface • Material: 2”-thick carbon steel plate • Fluid Loading: Water on one side (hydrotest) • Source-to-sensor Dist: 0.5m • Sensor: PAC R-15I sensor • Filter: 3 - 300kHz Bandpass, or 100-300 kHz Bandpass

7. Pre-Test Analysis SupportWaveform Prediction from Material Properties and Dispersion Curves Predicted waveform out of sensor Predicted waveform at sensor face

8. Pre-Test Setup & Analysis SupportAttenuation Setup Attenuation Map on Vessel Attenuation Setup Menu

9. Pre-Test Setup & Analysis SupportAttenuation Analysis Triangular Attenuation Map Zonal Attenuation Map w/0dB weld atten. Zonal Attenuation Map w/4dB weld atten.

10. Pre-Test Setup & Analysis SupportMinimum Crack Size Determination .

11. PERF-PAC Acquisition and AnalysisLocation Graphing Location Graph with Amplitude based points • Vessel is shown overlaid on location plot with welds and nozzles showing. • Graphs show a series of pencil lead breaks along the length of the vessel. • Top graph shows the point plots colored based on the received amplitude at the first hit sensor. • Bottom graph shows the Point Plots colored based on the “Source Amplitude” corrected values, using the Attenuation graph setup during pre-test. FFS assessment relies on the Source Amplitude feature. Location Graph with “Source Amplitude” based points

12. PERF-PAC Acquisition and AnalysisDetailed Event Analysis Just move the data cursor over a point, right click and select Hit/Event Linking to show the waveform and event data. Any event can be accessed by Hit/Event Linking to show the waveform composition and the event and hit data which forms the event.

13. PERF-PAC Acquisition and AnalysisDetailed Event Analysis Just move the data cursor over a point, right click and select FAD Analysis to show the FAD Diagram. Any event can be accessed for Fitness for Service Assessment via a FAD Diagram (Failure Assessment Diagram) in acquisition or replay

14. PERF-PAC Acquisition and AnalysisSphere Location and Event Analysis Traditional longitude/latitude lines to help show position or actual weld lines per ASME can easily be setup in spherical location mode. Note sensor #2 is reference 0,0 position. Note also transparency of location dots on reverse side of sphere. Sphere can be rotated freely in acquisition or replay.

15. Continuing PERF 95-11 Efforts • Continuing Experiments to determine AE to Crack Relationship. (Work is currently being conducted at Rowan University on a bi-axial loading machine). • Reliable Source Discrimination work is continuing at Cornell University with assistance from Univ Illinois. • Testing of Pressure Vessels starting in September 2004. • Completion of Recommended Practice & Guidelines(for PERF-PAC testing)

16. Reliable Source Discrimination • Identify source based on signal response • Discrimination methods evaluated • Time-frequency Analysis • Neural Network • Wavelet • Pattern Recognition • Time-Frequency Analysis and Pattern Recognition are being further investigated.

17. Reliable Source DiscriminationStudying the Inverse Problem Processed Spectrogram with actual colored wave modes overlaid. Original Spectrogram of AE waveform By performing “Frequency - Time” Analysis on the received AE waveform, it is possible to extract the original wave modes as material properties are already known. Then with the determination of source distance, one can determine the original moment tensors, leading to a description of the source. Crack sources can then be distinguished from other sources. However, the above example is based on theoretical wideband waveforms.

18. Field Experience • Items Tested – 8 Total Tests • Cooling Tower • Reactor Vessels • Horizontal Pressure Vessel • Piping

19. Observations • Developments have enhanced ability to perform a more effective AE test • Accurate Source Location improved significantly • FFS analysis very conservative