Alternating Current Field Measurement (ACFM)
What Is It
Find the Crack Without Stripping the Coating First
Surface-breaking cracks in welds and structural components can concentrate stress and propagate rapidly under load.
IRC Engineering’s Alternating Current Field Measurement (ACFM) testing detects and accurately sizes surface-breaking cracks - even through paint and coatings, with minimal surface preparation.
ACFM is suited to:
- Welds and structural components
- Painted or coated surfaces
- Critical components requiring crack sizing
- In-service inspection
Why ACFM
Why Choose ACFM?
A faster way to detect and size surface-breaking cracks without extensive coating removal.
Through-Coating Inspection
Inspect painted or coated welds without stripping the coating first.
No Direct Metal Contact
Reduces surface-preparation time significantly.
Quantitative Sizing
Measures crack length and depth, not just crack presence.
Complex Geometries
Well suited to nodes, nozzles, and hard-to-reach weld configurations.
Non-contact, repeatable testing supports consistent monitoring of crack growth over time.
How It Works
How ACFM Works
ACFM uses an alternating current field to identify and size surface-breaking cracks.
Current Field Introduction
An ACFM probe introduces a uniform alternating current field into the component.
Magnetic Field Formation
The current generates a magnetic field just above the component surface.
Crack Disturbance
A crack disrupts the current path and alters the magnetic field.
Signal Measurement
Changes in magnetic-field magnitude and direction are measured.
Crack Sizing
The measurement is used to calculate crack length and depth.
Our Toolkit
Our ACFM Testing Capability
Through-Coating Detection
Inspect coated welds without extensive surface preparation.
Non-Contact Testing
No direct metal-to-metal contact is required.
Crack Length and Depth
Detect and accurately size surface-breaking cracks.
Complex Weld Inspection
Suitable for nodes, nozzles, and difficult weld configurations.
ACFM delivers precision crack detection with minimal disruption.
Where We Apply It
Applications of ACFM Testing
Structural Steel and Offshore Platforms
Weld inspection for structural steel and offshore platforms.
Pressure Equipment
Surface-crack inspection on critical pressure equipment welds.
Ageing Infrastructure
Fatigue-crack detection on bridges and hydropower structures.
In-Service Inspection
Inspection where coating removal is impractical or cost-effective.
Why IRC
Why IRC Engineering Services?
Advanced NDT Capability
ACFM is part of IRC’s Advanced NDT capability.
Certified Rigor
Applied with the same certified rigor as our wider inspection portfolio.
Defensible Results
Provides a defensible answer on weld integrity.
Minimal Disruption
Detect cracks through coatings with reduced preparation.
Faster Decisions
A faster path to understanding crack size and condition.
Size the crack before it sizes up your downtime.
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