In this presentation, we discuss the features and technical specifications of the EPOCH® 6LT portable flaw detector’s corrosion module software option and discuss the instrument’s benefits for offshore platform corrosion inspections. The EPOCH 6LT flaw detector with the corrosion module combines the most important features of a corrosion gage with the capabilities of a flaw detector in a highly portable and intuitive instrument. The software enables you to easily switch between precision thickness and high-speed scanning measurement modes and offers automatic gain control and automatic probe recognition for all Olympus thickness gage dual transducers for efficient setups. Offshore rope access inspectors can strap the instrument to their leg or harness with the rope access kit for corrosion inspections in difficult-to-reach locations.

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
¡ Software demonstration

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. Corrosion Module Software Demonstration
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20. Olympus and EPOCH are registered trademarks of Olympus Corporation.