Magnetic Flux Leakage (MFL) – Major Applications Beyond Long-Distance Oil & Gas Pipelines

Note: MFL technology is applicable only to ferromagnetic carbon steel / low-alloy steel. It detects corrosion pits, wall thickness loss, broken wires, near-surface cracks and metal loss. Its key advantages include inspection through coating, high scanning speed, compatibility with automated probe arrays and digital imaging.

• Aboveground Storage Tank (AST) Floors | Petrochemical & Oil Storage Inspection of AST floors in compliance with API 653 standard. Scans hidden corrosion and pitting on the underside of tank bottoms. This is a well-established MFL application using crawler probe arrays to generate corrosion mapping.
• Wire Ropes, Steel Strands & Bridge Stay Cables For crane ropes, elevator cables, mine hoist ropes, ropeways and stay cables of cable-stayed bridges. Detects internal and external broken wires, cross-sectional loss and corrosion. Wire rope testing is a classic strength of MFL, unlike UT which struggles to identify internal wire breaks.
• Rail Transit | Rail Inspection Detects rail head internal transverse cracks, shelling, crushing and fatigue damage. High-speed MFL arrays fitted on rail inspection vehicles perform in-service inline surveys to prevent rail fracture.
• Pressure Vessels, Boilers, Heat Exchanger Tubes & Well Casings Water walls of utility boilers, heat exchanger bundles, oil & gas well casings and high-pressure vessel shells. Identifies wall thinning and pitting for thermal power, coal chemical and nuclear power projects.
• Steel Structures & Lifting Equipment Steel box girders, factory steel members, gantry/crane main beams, lifting hooks and pins. Screens for fatigue cracks and corrosion thinning.
• On-Line Inspection for Steel Plates, Steel Strips & Steel Tubes in Metallurgical Production Lines In-line MFL testing for hot-rolled / cold-rolled steel plates, welded pipes and seamless pipes before delivery. Automated inline inspection for factory quality control of defects such as laminations, voids and cracks.
• Marine & Offshore Industry Inspection of hull plates, ballast tanks and carbon steel components on offshore platforms for seawater-induced corrosion and pitting.
• Quality Control for Automotive Component Manufacturing Crankshafts, half shafts, steering knuckles and carbon steel chassis parts for batch screening of forging / grinding cracks and inclusions. (Less widely adopted here; Magnetic Particle Testing (MT) is commonly used as an alternative.)
• Building & Construction Corrosion inspection of embedded steel rebars in concrete and large-venue steel structures.

• Case 1: 50,000 m³ Crude Oil Atmospheric Storage Tank (Offshore Oil Processing Plant)

  Project: API 653 outage inspection for carbon steel tank floor (8–10 mm). Robotic MFL crawler for full floor scan, manual MFL probes for annular plate and shell-to-floor weld zones, UT verification for suspicious indications. Outcome: Around 450 m² corroded area across over 20 floor plates was identified. The deepest pitting reached 4–5 mm, with one backing plate perforated. Corrosion mapping guided patch repair and plate replacement to prevent crude oil leakage.

  Case 2: 100,000 m³ Floating Roof Crude Oil Tank (Refinery Tank Farm)

  Project: Aging large floating roof tank with hidden soil-side corrosion caused by trapped water under the floor. Solution: Floormap MFL crawler scanning through existing coating, coordinate-based corrosion heatmap. Outcome: Detected subsurface pitting on the soil side which is easily missed by spot UT thickness gauging. Corrosion rate data updated RBI inspection interval and avoided costly full floor replacement.

  Case 3: Refinery Product Tank (Jet A / Gasoline Tank, 500 m³)

  Project: Aviation kerosene tank with failed floor coating and risk of pinhole perforation. Solution: Full MFL scan, manual coverage around support legs and nozzles, UT confirmation for heavy metal loss. Outcome: One perforated plate and multiple plates with wall loss over 40% were found in advance, enabling timely patch repair and preventing product release and soil contamination.

  Case 4: Wastewater Tank at Coastal Power Plant

  Project: Chloride-rich service environment, high corrosion rate, 8 mm carbon steel floor. Solution: Calibrated array MFL scanner with ±5 mm positioning accuracy. Outcome: 45 corrosion indications were captured; 8 locations showed wall thinning above 30% (max 67%), mostly near drain outlets. The inspection supported CP upgrade and localized repair.

  Case 5: Tank Cluster Project in Kazakhstan (27 ASTs, ROSEN TBIT Ultra)

  Project: Batch integrity assessment for aged crude oil tanks with cathodic protection systems. Solution: Combined MFL + ET scan, ROSOFT for Tanks data analysis. Outcome: Over 97,000 anomalies were catalogued. The dataset revealed ineffective CP on several tanks and scheduled maintenance in batches to cut unplanned shutdowns.

  Case 6: AST for LNG Terminal

  Project: LNG terminal storage tank, high pitting risk on the annular ring plate (hard-to-reach area for crawlers). Solution: Robotic MFL for central plates + manual MFL for perimeter ring plate, PAUT verification. Outcome: Clustered pitting on annular plates was detected. The plan eliminated blind zones of crawler equipment and evaluated combined corrosion & fatigue risk at floor-to-shell welds.