This document discusses advancements in offshore corrosion monitoring and flaw detection. It summarizes Olympus' corrosion software features for ultrasonic inspections, including automatic probe recognition, V-path correction, true do-zero, automatic gain control, and a thickness gage measurement algorithm. These features allow ultrasonic instruments to switch between precision thickness measurements and flaw detection modes for comprehensive corrosion inspections.

1. Olympus America Inc. | Calvin Jory
Waltham, MA, May 2018
Advancements in Offshore Corrosion Monitoring and
Flaw Detection

2. Agenda
¡ Background
¡ Challenges of Offshore Corrosion Inspections
¡ Conventional UT Corrosion Inspection Methods
¡ Corrosion Software Features
− Automatic Probe Recognition
− V-Path Correction
− True Do-Zero
− Automatic Gain Control
− Thickness Gage Measurement Algorithm
− Color-Coded Grid View

3. Background
¡ Offshore oil platform (rig): a large structure that supports well drilling, extraction,
processing, and the storage of oil and/or natural gas
¡ Platform may be fixed to the ocean floor, consist of an artificial island, or float
¡ Often contains facilities to house workers
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4. Key Area of Interest: Marine Risers
¡ Marine risers form the link between the seabed pipeline and topside
processing equipment
¡ Constant wetting and drying in the splash zone combined with defects in
coatings can contribute to corrosion
¡ Corrosion can reduce wall thickness and threaten the structural integrity
of risers
¡ Assessing the remaining service life of aging risers is often dependent on
corrosion monitoring with NDT technologies
¡ Risers vary in structure and material, which can help determine the
appropriate inspection technique
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5. NDT Methods for In-Service Risers
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§ Several NDT methods are used to inspect marine risers for corrosion:
– Conventional and phased array ultrasonics
– Guided wave
– Eddy current
– Magnetic flux leakage
– Radiography
– Infrared thermography
– Magnetic particle inspection
§ Conventional and phased array ultrasonics are often the most convenient and
cost-effective methods

6. Dual Element Transducers for Ultrasonic Corrosion Inspections
¡ Corroded surfaces can scatter sound away from single element transducers
¡ Dual transducer elements are set at an angle
− Creates a V-path and a pseudo-focus at the base of pits
¡ High-temperature capabilities
¡ Separate transmitting and receiving elements
− Enables a higher initial system gain
− Stable readings on rough entry surfaces
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TX RX
Single element, corroded surface Dual element, corroded surface

7. Challenges of Offshore Corrosion Inspections
¡ Equipment used offshore is subject to extreme environments
− Must be drop tested, meet strict ingress protection (IP) and environmental ratings
¡ Potentially corroded areas are often difficult to access
− May require rope access
− Instrument size and weight are major concerns
− Multiuse instruments are preferred
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8. Rope Access on the Rise
¡ In the past, difficult-to-reach areas of offshore platforms were reached
using scaffolding
− Requires significant time and expense to construct
¡ In comparison, rigging for a rope access inspection can be
accomplished in a short period of time
− Greater flexibility
¡ Rope access inspections have an excellent safety record

9. The EPOCH® 6LT Flaw Detector for Offshore Corrosion Inspections
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¡ Engineered to IP65/67, drop tested, MIL-STD-810G
¡ Lightweight—less than 890 g (1.95 lbs)
¡ Rope access kit
¡ Flaw detection and corrosion gaging capabilities

10. Conventional Ultrasonic Testing (UT) Corrosion Inspection Methods
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1. Point measurement method
– UT corrosion gage
– Precision measurements of remaining wall thickness
– Taken in a defined pattern and repeated over time
– Effective for periodic corrosion monitoring, precision measurements
of discrete defects
– Not for identifying corrosion, corrosion-induced cracking, other flaw
mechanisms
2. Corrosion as a flaw mechanism
– UT flaw detector
– Scan for pits and corrosion-induced cracks
– Size and characterize detected defects
– Effective for finding and sizing isolated defects
– Not for high precision thickness measurements, periodic corrosion
monitoring

11. EPOCH 6LT Corrosion Software—Get the Best of a Thickness Gage and
Flaw Detector
¡ Corrosion software enables users to switch between
precision and flaw detection measurement modes
¡ Combines the key functionality of a precision thickness
gage and flaw detector in one instrument
¡ Users can scrub for pitting and size defects in scanning
mode, then switch to precision measurement mode to
make precise measurements of remaining part
thickness
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12. Key Corrosion Module Features
¡ Automatic probe recognition
¡ ‘True’ do-zero
¡ V-path correction
¡ Automatic gain control
¡ Thickness gage measurement algorithm
¡ Color-coded grid view
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13. Automatic Probe Recognition
¡ Uses the same center-pin transducer ID as Olympus thickness gages
¡ Pulser and receiver are automatically configured when the probe is connected
¡ Saves time during the setup process and enables the operator to easily swap transducers
during an inspection
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14. V-Path Correction
¡ V-path correction compensates for the difference in the sound path created by the dual
transducer’s roof angle
¡ Varies per transducer and is affected by the element diameter, frequency, roof angle, etc.
¡ The V-path correction coefficient is stored with the probe ID data and can be instantly recalled
¡ Traditionally limited to corrosion gages, only recently utilized by UT flaw detectors
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True
Thickness
Sample
Angular
Sound Path
TX RX

15. True Do-Zero
¡ Automatic zero offset compensation measures the time of flight through the transducer
and delay line material
¡ Accounts for the internal delay, cable delay, transducer wear, and thermal drift
¡ Uses two pulsing channels to measure the zero offset from each element of the
transducer for improved measurement accuracy
¡ Traditionally limited to corrosion gages, only recently utilized by UT flaw detectors
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Rx Tx

16. Automatic Gain Control
¡ Automatic gain control automatically adjusts the gain for optimal thickness
measurements
¡ Gain is adjusted so that the measured echo maintains a vertical leading
edge for precise thickness measurements
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17. Thickness Gage Measurement Algorithm
¡ Traditional flaw detectors use edge or peak gate detection modes
¡ Edge measurement accuracy can be affected by the echo amplitude and surface conditions,
while peak detection can be insensitive to pits
¡ Zero-cross measurement algorithm
¡ Measures from the zero-crossing point of the first signal that crosses a defined screen height
threshold
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18. Color-Coded Grid View
¡ Users can log thickness measurements into a grid for easy reporting
¡ Color-coded with customizable thresholds for easy data interpretation
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19. Olympus and EPOCH are registered trademarks of Olympus Corporation.