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Standard Guides:WeldingPipingASMEAPIAsset Matrix
Magnetic Particle Testing
🐘 Tusker VaultCoreSurface & Visual • MT

Magnetic Particle Testing (MT)

Method Overview

Surface and near-surface discontinuity detection in ferromagnetic materials using magnetic flux fields and particle indicators.

Core Method Specifications

Technique IDMT
AcronymMT
CategoryCore
ModalitySurface & Visual
Standardized Report TemplateISO 17020 Ready
MT-Standard-TemplateTest in Sandbox

Target Applications & Governing Standards

2 Scopes Configured
Valves & Pressure Control
API 598 ASME Sec V Art 7
Target Assets / Components:
Valve Body ExteriorFlange Bolt HolesActuator Brackets
Detectable Defects & Anomalies:
• Surface Fatigue Cracks• Stress Cracking
Piping & Loops
API 570 ASME B31.3
Target Assets / Components:
Pipe Support WeldsBranch Connection Fillet Welds
Detectable Defects & Anomalies:
• Toe Cracks• Lack of Fusion• Grinding Cracks

Method Limitations & Operational Boundary Conditions

Critical physics limits, thermal envelopes, blind spots, and ASME Sec V / API procedural boundaries for MT.

Level III Procedure Control
Operating Temp Envelope
Standard Envelope-10°C to +55°C (14°F to 131°F)
High-Temp CapabilityUp to 315°C (600°F) using specialized dry magnetic powders; strictly limited below Curie temperature (770°C for carbon steel)

Wet fluorescent suspension vehicles (petroleum distillates) flash off and smoke above 55°C (131°F). AC yoke lifting power drops at elevated temperatures.

Thickness & Dead Zone
Min ThicknessAny structural wall thickness
Max RangeVolumetric depth penetration is limited strictly to surface and near-surface flaws within 1.5 mm to 3.0 mm depth with half-wave rectified DC; purely surface with AC yoke
Near-Surface Dead Zone

Zero dead zone for surface-breaking discontinuities

Surface Condition & Couplant
Roughness & PrepRa ≤ 12.5 µm (500 µin RMS); heavy weld ripples must be dressed to prevent mechanical particle entrapment in grooves
Coating ToleranceNon-magnetic coatings (paint, primer) > 0.05 mm (2 mils) severely degrade magnetic field strength unless calibrated per ASME Sec V Art 7 Appendix I
Couplant / Media

White contrast paint backing (for visible black/red particles) or UV-A illumination (for fluorescent wet bath)

Geometry & Orientation
Orientation Sensitivity

Magnetic flux lines MUST intersect the defect at 45° to 90° angle. Discontinuities parallel to flux lines produce zero magnetic leakage field

Clearance:Requires adequate clearance for 10 lb (4.5 kg) AC yoke leg span (typically 75 mm to 200 mm contact pitch)
Critical Blind Spots
  • •Non-ferromagnetic materials: Austenitic stainless steels (304, 316), aluminum, copper, and titanium alloys cannot be tested with MT
  • •Sub-surface discontinuities deeper than 2.0 mm (0.08 in) produce broad, diffuse, undetectable particle indications under AC fields
  • •Cracks oriented parallel to the magnetic field vector between yoke contact poles
False Indication Trap:

Magnetic writing caused by steel components rubbing together or residual magnetic poles

Recommended Cross-Validation
PTView Method

For non-ferromagnetic alloys (stainless steel, Inconel, aluminum) where MT physics fails

PAUTView Method

Volumetric crack sizing to measure the through-wall depth of surface cracks revealed by MT

Level III Code Compliance Directive:ASME Section V Article 7 mandates AC yoke lifting power verification of at least 10 lb (4.5 kg) and Pie gauge or Castrol strip field direction checks.

Technique-to-OEM Compatibility Matrix

Verified manufacturers, instrument models, and diagnostic portals supporting MT.

5 Verified OEMs
Magnaflux

Magnaflux

Industry benchmark division of ITW for fluorescent liquid penetrant inspection (FPI), magnetic particle inspection (MPI) consumables, UV-A inspection lamps, and wet horizontal test benches.

Modalities:MTPT
OEM Profile Magnaflux Tech Support
OEM Site
Electronic & Engineering Co. (EECI)

Electronic & Engineering Co. (EECI)

Renowned Indian manufacturer of custom ultrasonic probes, phased array wedges, automated ultrasonic inspection systems, and magnetic particle test benches.

Modalities:UTPAUTTOFDMTET
OEM Profile EECI Support Portal
OEM Site

Parker Laboratories

OEM Manufacturer for MT inspection systems.

Verified Partner

Johnson & Allen

OEM Manufacturer for MT inspection systems.

Verified Partner

Baugh & Weedon

OEM Manufacturer for MT inspection systems.

Verified Partner
ASME Sec V & ISO 9712 Qualified
Rent MT Instruments OEM Hardware CatalogPost MT Project Scope