Cable Stay Bridge Inspection Service Using Magnetic Flux Leakage

December 17th, 2018 Author: Doug Thaler

Robotic Cable Stay Bridge Inspection To Locate Loss Of Metallic Area Using Magnetic Flux Leakage, MFL.

Infrastructure Preservation Corporation, IPC is an Engineering company that specializes in developing robotic technology for the inspection of transportation infrastructures. IPC developed the first of its kind robotic infrastructure inspection service called CableScan. CableScan consists of two services. The first is to replace the current NBI (National Bridge Inventory) inspection. The second is a newer inspection using MFL (Magnetic Flux Leakage) nondestructive testing technology.

MFL is an advance NDT method that locates broken wires and loss of metallic area (Corrosion) in ferrous materials. A sensor head with rare-earth magnets magnetizes the material and sensors within the test head is used to measure the flux generated by broken wires or loss of metallic area.

The CableScan MFL robot saturates the internal cables with a magnetic field. The custom software interprets the percentage of loss in metallic area.

CableScan MFL robot saturates the internal cables with a magnetic field. The custom software interprets the percentage of loss in metallic area and it is wirelessly beamed back to the base station for back office processing into a report that is provided to the client.

The footprint for both the equipment and the inspection itself is very small. The equipment ships in 3 small boxes.

A truck was parked in the shoulder with the ground control station and 2 inspectors.

The portable base station can be placed on the bridge depending on space.

The real-time results locates where in the stay the fault is located.

As well as the distance traveled along the Stay and the distance along the deck.

According to Federal Highways, FHWA, “The MFL method can be used to detect the location and extent of corrosion in post-tensioned and precast prestressed strands in concrete girders, and breakage of wires and strands in post-tensioning tendons and prestressing strands. MFL is also commonly used to test the cables of suspension or cable stayed bridges. MFL units can be clamped onto a cable as part of a climbing module or rolled across a surface.”

Infrastructure Preservation Corporation has taken this to the next level with their introduction of CableScan MFL. CableScan MFL can inspect the cables of cable stay bridges without lane closures or bucket trucks. The MFL unit is drawn by a robotic casing and its software interpretation provides the department of transportation with quantitative date to determine loss of metallic area in cable stays. IPC has also developed a unit for wire ropes, and to inspect external post tension tendons.