
π Magnetic Particle Testing (MT) Levels I, II, and III
Question & Answer Booklet
(For Personnel Qualification & Certification in Nondestructive Testing – NDT)
π Introduction:
Magnetic Particle Testing (MT) is a widely used Nondestructive Testing (NDT) method for detecting surface and near-surface defects in ferromagnetic materials such as iron, steel, and nickel alloys. It is fast, reliable, and cost-effective for finding cracks, seams, and other discontinuities.
This booklet offers essential Q&A for MT Levels I, II, and III based on international standards.
πΉ MT Level I: Basic Questions & Answers
Q1: What is Magnetic Particle Testing (MT)?
A1: MT is an NDT method used to detect surface and near-surface defects in ferromagnetic materials by applying magnetic fields and ferrous particles.
Q2: How does MT work?
A2: A magnetic field is applied to the test object. If there is a flaw, it disturbs the field, causing magnetic flux leakage. Magnetic particles gather at the leakage site, making the defect visible.
Q3: What materials can be tested using MT?
A3: Only ferromagnetic materials like carbon steel, low alloy steel, cast iron, and some stainless steels.
Q4: What types of particles are used in MT?
- Dry magnetic particles (for rough surfaces or field work)
- Wet magnetic particles (suspended in oil or water for smoother surfaces)
Q5: What are the basic magnetization methods?
- Longitudinal magnetization
- Circular magnetization
- Yoke method
- Prod method
πΉ MT Level II: Intermediate Questions & Answers
Q1: What types of defects can MT detect?
- Surface cracks
- Subsurface cracks (shallow)
- Seams
- Laps
- Porosity (if close to surface)
Q2: What is the difference between AC and DC magnetization?
- AC (Alternating Current): Best for surface defects.
- DC (Direct Current or HWDC/HWAC): Can detect subsurface defects.
Q3: What is the purpose of demagnetization?
A3: To remove any residual magnetism from the part after testing, which could affect further processing or service performance.
Q4: What is an indication vs. a discontinuity in MT?
- Indication: Visible accumulation of magnetic particles.
- Discontinuity: The actual physical defect that caused the indication.
Q5: What acceptance standards are used in MT?
A5: Codes such as ASME Section V, ASTM E709, AWS D1.1 provide guidelines on acceptable and rejectable indications.
πΉ MT Level III: Advanced Questions & Answers
Q1: What factors affect the sensitivity of MT?
- Strength of the magnetic field
- Direction of magnetization
- Particle size and type
- Surface cleanliness and roughness
Q2: What is the importance of magnetizing in multiple directions?
To ensure detection of defects in all orientations, as some discontinuities may not produce indications if the magnetic field is parallel to the defect.
Q3: What are some common magnetization techniques?
- Head shot (circular magnetization)
- Coil shot (longitudinal magnetization)
- Yoke method
- Prods
Q4: What are the safety concerns in MT?
- Electrical hazards from equipment
- Exposure to UV light (for fluorescent MT)
- Skin and inhalation exposure to chemicals
Q5: What international standards apply to MT personnel?
A5: ISO 9712, ASNT SNT-TC-1A, ASTM E709, EN 473.
π§ Magnetic Particle Testing of Welds: Presentation Summary
1οΈβ£ Purpose:
To detect surface and near-surface defects in welds, forgings, castings, and machined parts.
2οΈβ£ Equipment Used:
- Yokes (AC or DC)
- Coils or prods
- Magnetic particles (dry or wet)
- UV light (for fluorescent MT)
3οΈβ£ Defects Detected:
- Cracks
- Incomplete fusion
- Lack of penetration (surface-breaking)
- Seams
- Porosity (near surface)
4οΈβ£ Techniques:
- Continuous method (magnetizing during particle application)
- Residual method (magnetizing before applying particles)
5οΈβ£ Advantages of MT:
β
Fast and sensitive to surface cracks
β
Portable and cost-effective
β
Can inspect large areas quickly
6οΈβ£ Limitations:
β Only for ferromagnetic materials
β Cannot detect deep subsurface defects
β Surface preparation is critical
7οΈβ£ Safety Considerations:
- Electrical safety
- Chemical exposure precautions
- Eye protection when using fluorescent particles
β
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The following Series of NDT Question and answers is also available
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- Question and answer For Radiographic Testing Method
- Question and answer For Liquid Penetrant Testing Method
- Question and answer For Magnetic Particle Testing Method
- Nondestructive Testing NDT Handbook