Field Inspections
Magnetic Particle (MT)

MISTRAS performs Dry Powder and Wet Fluorescent Magnetic Particle testing (MT) inspection services to find surface/near-surface defects in ferromagnetic material.

MISTRAS’ certified technicians apply this quick, cost-effective inspection method in the field and in our labs. In magnetic particle testing, technicians magnetize a ferromagnetic material and apply finely-milled iron particles coated with a dye pigment to it. The particles indicate discontinuities in the material by clustering directly over it, which can be visually detected under proper lighting conditions.

The technique requires a skilled technician to distinguish between relevant and irrelevant indications. MISTRAS experts can perform every step of the process, including pre-cleaning and surface preparation, magnetic field introduction, media application, and interpretation of the resulting indications.

MISTRAS offers dry powder and wet fluorescent MT inspection services, depending on the application.

Magnetic Particle Inspection Benefits

• Can detect both surface and near-surface indications
• Can inspect irregularly-shaped parts
• Pre-cleaning of the asset to be inspected is less essential than in other inspection methods, as existing contaminants should not affect flaw detection
• Quick to be employed and lower cost than other NDT methods
• Real-time results, as indications are visible directly on the material’s surface
• Portable inspection method makes it ideal for field inspection services

Wet Fluorescent Magnetic Particle (MT) Inspection Services

Wet Fluorescent magnetic particle testing is more accurate than dry powder testing for detecting very small discontinuities, because the particles are smaller. MISTRAS uses wet fluorescent magnetic particle inspections to locate surface and slightly subsurface discontinuities.

 An advantage of wet fluorescent MT is its ease and speed of application, given that technicians can quickly spray the chosen magnetic particle fluid over large surface areas. It is extremely sensitive to even extremely small and fine indications, increasing indication detection with consistent and reliable results while minimizing inspection time. This method can be used for in-service inspections, making it possible to detect asset damage without halting production.

Wet Fluorescent MT Inspection Applications

• Fatigue Cracks
• Flakes
• Grinding Cracks
• Inclusions in aerospace blooms, billets, and bars
• Laps
• Quenching Cracks
• Seams
• Shrink Cracks
• Stress Corrosion Cracking
• Tears
• Welding Defects

Dry Powder Magnetic Particle (MT) Inspection Services

Dry particles are dusted onto the surface of the test object as the item is magnetized. The clustering of the magnetic particles is efficient for detecting defects on rough surfaces, including shallow and subsurface cracks, along with root penetration. Dry powder methods are more portable than wet fluorescent MT.

 Particles of a variety of different sizes can be used, with small particles being more sensitive to small discontinuities, while larger particles offer a stronger resistance to contamination from dirt or surface debris. This method is particularly suited for detecting leakage fields from small flaws.

Dry Powder MT Inspection Applications

• Defects in Rough Surfaces
• Lack of Fusion in Welds
• Root Penetration
• Shallow Cracks