Pulsed eddy current (PEC) inspection with the Lyft system can effectively inspect lead-clad pipes for corrosion under insulation without stripping. Lead does not interfere with PEC signals due to its weakly diamagnetic and poorly conductive properties. Testing of a reference pipe with lead cladding showed the PEC C-scan results were essentially identical with and without the lead, demonstrating lead does not decrease the signal quality. PEC inspection of lead-clad pipes provides benefits over other techniques like avoiding stripping, ensuring high-quality data unaffected by lead, reducing operator dependence through automation, and having no health and safety hazards.

1. Inspecting Lead-Clad Pipes with
Pulsed Eddy Current (PEC)
Application Note

2. The Challenge
The most effective way to minimize the risk of unnecessary
shutdowns and accidents caused by corrosion under
insulation (CUI) is to periodically inspect the condition of
insulated equipment and piping.
2 © Eddyfi NDT Inc. 2009–2016

3. The Challenge
Industrial installations:
• Sometimes generate noise loud enough to be considered hazardous for
worker health and safety
• Turbulence caused by fluids and vibrations in pipes are two major sources of
industrial noise
• Where noise control is important, it is not uncommon to find pipes wrapped in
noise-dampening layers between the conventional insulation layer and the
weather jacket.
3 © Eddyfi NDT Inc. 2009–2016

4. The Challenge
Common techniques used to look for CUI:
• E.g., visual inspection, phased-array UT, etc.
• Time-consuming, costly stripping
• Common alternative to avoid stripping:
radiography
• Due to its high density, lead
is particularly effective in
blocking X-rays
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 Solution
6 © Eddyfi NDT Inc. 2009–2016
Lead is:
• Weakly diamagnetic
• Poorly conductive
• Therefore, does not interfere with pulsed eddy currents (PEC)

7. The Solution
7 © Eddyfi NDT Inc. 2009–2016
Lyft™ PEC solution
Excellent option to inspect lead-wrapped pipes for CUI
without stripping the cladding and weather jacket.

8. The Solution
8 © Eddyfi NDT Inc. 2009–2016
Lyft™ is capable of:
• Scanning wall thicknesses up to 64 mm (2.5 in)
• Through insulation up to 203 mm (8 in) thick
• Over aluminum, stainless steel, and galvanized steel
weather jackets
Lyft features:
• Real-time C-scan imaging
• A-scan analysis
• Grid mapping
• Dynamic scanning (unique to Lyft)
• Acquire data at up to 15 readings per second.

9. The Solution
9 © Eddyfi NDT Inc. 2009–2016
Probe shoes
• Enable operation on surfaces as hot as 120 °C (248 °F)
• Attenuate vibrations induced by pulsed eddy currents in galvanized steel
weather jackets

10. The Solution
10 © 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

11. The Solution
11 © Eddyfi NDT Inc. 2009–2016
Impact of lead cladding:
• Assessed on reference pipe featuring
• 2×square defects
• Remaining wall thickness 60 % ±5 %
• 6.5 cm2 (1 in2) and 26 cm2 (4 in2) in area
C-scan shows results from:
• Pipe covered with 51 mm
(2 in) thick insulation
• Aluminum weather jacket

12. The Solution
12 © Eddyfi NDT Inc. 2009–2016
C-scan shows results from:
• Same pipe covered with a 0.8 mm (0.03 in) lead sheet under the aluminum
jacket
The two C-scans are essentially identical. It is safe to assume
the lead sheet does not decrease the measurement’s SNR.

13. The Benefits
Solution has following benefits:
• No stripping—Unlike other inspection techniques, PEC does not require
stripping the insulation, fireproofing, or coatings from the surface under test,
making it faster and more cost effective.
• High-quality data—Despite the presence of lead, where radiography is
ineffective, acquired data shows no significant signs of attenuation or
deterioration compared to data acquired without lead.
• Lesser operator dependence—Lyft automatically optimizes parameters
and measurements, ensuring repeatability and performance.
• No H & S issues—Unlike radiography, PEC does not pose any hazard to
the health of its users or the environment it is used in.
• Easy deployment—The entire solution is portable, light, compact and fast
to deploy for improved productivity.
13 © Eddyfi NDT Inc. 2009–2016

14. www.eddyfi.com