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

Current Approach - MONPAC PLUS l 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

l 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 l Collaborating with NASA LRC l 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 PERF 95-11: Advanced AE for On-Stream Inspection

l Accurate Source Location l Quantitative AE/FFS Relationship l Reliable Source Discrimination l PERF-PAC AE Software & System l Recommended Practice & Guidelines 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;

l 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. l 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. 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 Analysis Advanced Dispersion Curve analysis Main setup menu l Example l Source: surface l Material: 2”-thick carbon steel plate l Fluid Loading: Water on one side (hydrotest) l Source-to-sensor Dist: 0.5m l Sensor: PAC R-15I sensor l Filter: kHz Bandpass, or kHz Bandpass

Pre-Test Analysis Support Waveform Prediction from Material Properties and Dispersion Curves Predicted waveform at sensor face Predicted waveform out of sensor

Pre-Test Setup & Analysis Support Attenuation Setup Attenuation Setup Menu Attenuation Map on Vessel

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

Pre-Test Setup & Analysis Support Minimum Crack Size Determination.

l Vessel is shown overlaid on location plot with welds and nozzles showing. l Graphs show a series of pencil lead breaks along the length of the vessel. l Top graph shows the point plots colored based on the received amplitude at the first hit sensor. l 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. PERF-PAC Acquisition and Analysis Location Graphing Location Graph with Amplitude based points Location Graph with “Source Amplitude” based points

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

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

PERF-PAC Acquisition and Analysis Sphere 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.

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

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

Reliable Source Discrimination Studying the Inverse Problem Original Spectrogram of AE waveform Processed Spectrogram with actual colored wave modes overlaid. 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.

Field Experience l Items Tested – 8 Total Tests  Cooling Tower  Reactor Vessels  Horizontal Pressure Vessel  Piping

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