Engineering Presentation

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Advanced Acoustic Emissionfor On-stream
Inspection of Petroleum Industry Vessels

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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

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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

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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

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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.

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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

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Pre-Test Analysis SupportWaveform Prediction
from Material Properties and Dispersion Curves
Predicted waveform out of sensor
Predicted waveform at sensor face
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Pre-Test Setup Analysis SupportAttenuation
Setup
Attenuation Map on Vessel
Attenuation Setup Menu
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Pre-Test Setup Analysis SupportAttenuation
Analysis
Triangular Attenuation Map
Zonal Attenuation Map w/0dB weld atten.
Zonal Attenuation Map w/4dB weld atten.
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Pre-Test Setup Analysis SupportMinimum Crack
Size Determination
.
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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
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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.
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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
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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.
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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)

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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.

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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.
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Field Experience

• Items Tested 8 Total Tests
• Cooling Tower
• Reactor Vessels
• Horizontal Pressure Vessel
• Piping

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Observations

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