What Are the 5 Main NDT Methods?
Non-destructive testing (NDT) allows engineers and divers to inspect materials and structures without causing damage. It’s a crucial part of marine infrastructure safety and asset management. At Harcan Marine, we use NDT across our diving, construction, and salvage projects to monitor integrity and prevent serious failures.
But what are the five most commonly used methods of NDT, and how do they work underwater?
This blog explains how NDT helps protect submerged assets and why Harcan Marine is trusted for precise, professional underwater NDT and underwater dive services across Australia.
How NDT Methods Work Underwater
NDT techniques are used to check for cracks, corrosion, defects, or signs of wear in materials like steel, concrete, and alloys. These methods must be adapted underwater for limited visibility, strong currents, and access challenges. Safety is also a major factor, so testing must be performed without introducing new risks to the diver or the structure.
So, how do NDT methods work in marine environments? It depends on the asset, location, and inspection goal. Our divers are trained in these methods and use industry-grade tools to perform accurate inspections without interfering with the structure’s integrity. The goal is always the same: reliable data that supports safe operations and long-term asset planning.
Let’s break down the five main types of NDT we use at Harcan Marine.
1. Visual Testing (VT)
Visual inspections are the simplest and most direct form of NDT. Divers or ROVs use cameras, high-powered lights, and reference markers to assess surface conditions.
Used to check for:
- Cracks
- Surface corrosion
- Marine growth or debris buildup
2. Ultrasonic Testing (UT)
Used to detect:
- Internal cracks
- Wall thinning from corrosion
- Faults in welds
3. Magnetic Particle Testing (MT)
Used to find:
- Surface fractures
- Weld discontinuities
4. Eddy Current Testing (ECT)
Used for:
- Non-ferrous metals
- Coating inspections
5. Radiographic Testing (RT)
Used for:
- Detecting internal weld flaws
- Complex structural joints
When to Use These 5 NDT Methods
We use these methods during:
- Scheduled maintenance
- Emergency repairs
- Structural certifications
- Pre-salvage assessments
- Post-installation verification
- Marine salvage services and risk assessments
Why Harcan Marine for Underwater NDT?
Our divers are ADAS-certified, and our team has over 30 years of experience. We offer:
- High-accuracy underwater NDT
- Full dive and inspection reports
- Support for asset management and compliance
- Experience across bridges, jetties, pipelines, and moorings
Ready for an Inspection?
Still wondering how different NDT methods work? Do you need help deciding which inspection type fits your structure?
Talk to Harcan Marine. We’ll guide you through the process and recommend the right tools for the job. Our team works across Queensland, NSW, Victoria, and the Pacific Islands.
Contact us today to learn more about underwater NDT and how we support long-term infrastructure performance with non-destructive inspections.
