As its name implies atmospheric storage tanks contain liquids at atmospheric pressure. The outer edge at the base of this type of tanks is notoriously difficult to shelter from the elements, exposing this critical area to corrosion and, if left unchecked, leaks and unforeseen tank failures. Read more at www.eddyfi.com

1. Inspecting In-Service Storage Tank
Annular Rings for Corrosion
Application Note

2. The Challenge
As the name implies, atmospheric storage tanks contain
liquids at atmospheric pressure.
• Outer edge at base of tanks notoriously difficult to shelter
from elements
• Outer edge exposed to corrosion leading to:
• Leaks
• Unforeseen tank failures
2 © Eddyfi NDT Inc. 2009–2016

3. The Challenge
Considering the numerous codes and health & safety rules,
essential to:
• Find and monitor thinning in floor along edge of tank
(annular ring)
• Avoid leaks and potentially catastrophic tank floor ruptures
3 © Eddyfi NDT Inc. 2009–2016

4. The Challenge
Assessing the integrity of annular rings can be performed:
• From interior of tank
• From exterior of tank.
Internal inspections:
• Tank must be taken out of service (emptied, cleaned)
• Very costly
• Time consuming
4 © Eddyfi NDT Inc. 2009–2016

5. The Challenge
External inspections:
• Require access to the annular ring
Storage tanks can rest on various foundation materials
including:
• Soil
• Asphalt
• Concrete
5 © Eddyfi NDT Inc. 2009–2016

6. The Challenge
Soft base:
• Floor of atmospheric storage tank can sag, if only slightly, unevenly creating
gaps between base and annular ring, exposing edge of the tank floor to
elements.
Hard base:
• Annular ring inspection requires creating access points around tank base
6 © Eddyfi NDT Inc. 2009–2016

7. The Challenge
External annular ring inspection:
• Require thoroughly removing all corrosion products
• Not safely achievable.
• Not possible with ultrasounds (UT)
• Other in-service inspection methods
• E.g., acoustic emission
• Only offer rough wall-loss indications
• Difficult to analyze
7 © Eddyfi NDT Inc. 2009–2016

8. The Solution
8 © Eddyfi NDT Inc. 2009–2016
Pulsed eddy currents (PEC):
• Perfect for this challenge
• Advanced electromagnetic inspection technology used for:
• Ferrous materials
• Defect detection
• Corrosion detection

9. The Solution
9 © Eddyfi NDT Inc. 2009–2016
Lyft™ PEC solution
• Excellent way to inspect for wall loss
• No need to take atmospheric storage tanks offline
• Three-part solution:
• Tank floor probe
• Lyft instrument
• State-of-the-art software

10. The Solution
10 © Eddyfi NDT Inc. 2009–2016
Tank floor probe:
• Specifically designed for this type of inspection
• Super-thin 4.8 mm (0.2 in) titanium blade
• Liftoff tolerance up to 13 mm (0.5 in)
• Probe can slide up to 400 mm (16 in) under a tank floor edge
• Built-in remote controls + status LEDs
• Probe underside magnetically shielded
• Max. sensitivity
• Optimal component analysis
• Protection against signal distortion
• Titanium blade designed to withstand harshest field conditions

11. The Solution
11 © Eddyfi NDT Inc. 2009–2016
Lyft instrument:
• Sealed—water and dust resistant
• Designed for IP65
• Magnesium alloy casing
• Cools without any external air exchange
• Adjustable stand
• Handle
• Corner anchor points

12. The Solution
12 © Eddyfi NDT Inc. 2009–2016
SmartPULSE™ technology
• Automation
• Advanced algorithms
• Removes operator-specific dependence
• Automatically optimizes pulser and receiver
parameters (gain, duration, time gates, filters, etc.)
• Automatically optimizes wall thickness (WT)
measurements

13. The Solution
13 © Eddyfi NDT Inc. 2009–2016
Gradual wall loss under the tank wall:
• 6.5 mm (0.26 in) deep
• 50.8 mm (2 in) wide
• 190.5 mm (7.5 in) long
• 50.8 mm (2 in) from tank
floor edge (left-hand
indication in C-scan)
Additional wall loss:
• 1.9 mm (0.075 in) deep
• 76.2 mm (3 in) in diameter
• 76.2 mm (3 in) from tank floor edge (right-hand indication in C-scan)

14. The Benefits
Solution has following benefits:
• No surface preparation—Unlike other inspection techniques, PEC does
not require any preparation of the surface under test, making it faster and
more cost effective.
• In-service inspection—PEC technology is designed to be used with air,
soil, water, concrete, asphalt, and corrosion product between the sensor
and the surface under test, enabling it to perform inspections in service.
• Intuitive, quantitative data—A-scan and C-scan imaging, as well as other
tools included in the Lyft software enable quantifying wall loss.
• Lesser operator dependence—Lyft automatically optimizes parameters
and measurements, ensuring repeatability and performance.
• Easy deployment—The entire solution is portable, light, compact, and
quick to deploy for improved productivity.
14 © Eddyfi NDT Inc. 2009–2016

15. www.eddyfi.com