What is eddy current testing of tubes?

Eddy current testing is a non-destructive testing method widely used to examine tubing in heat exchangers, steam generators, condensers, air coolers and feedwater heaters. The technique is applied to detect corrosion, pitting, cracks, erosion and other changes to both the tube’s interior and exterior surfaces.

How does an eddy current tube work?

As the magnet passes through a given portion of the metal tube, this portion of the tube experiences a changing magnetic field, which induces the flow of eddy currents in an electrical conductor, such as the copper or aluminum tubing. The eddy currents create a magnetic field that exerts a force on the falling magnet.

How does eddy current testing work?

Eddy current testing is based on the physics phenomenon of electromagnetic induction. In an eddy current probe, an alternating current flows through a wire coil and generates an oscillating magnetic field. This in turn affects the movement of electrons in the coil by varying the electrical impedance of the coil.

What are eddy currents give an experiment to explain their origin?

: If a light metallic disc D is placed at the top of electromagnet as shown in figure and when a.c. is passed through the coil, the disc is thrown up due to eddy currents.

Where eddy current testing is used?

Applications. The two major applications of eddy current testing are surface inspection and tubing inspections. Surface inspection is used extensively in the aerospace industry, but also in the petrochemical industry. The technique is very sensitive and can detect tight cracks.

What does eddy current measure?

Eddy Current (EC) testing is based on electromagnetic induction. The technology can be used to detect flaws in conducting materials or to measure the distance between a sensor and a conducting material. The measurement does not require the tested object to be in direct contact with the test equipment.

How does eddy current flow?

Eddy currents are currents which circulate in conductors like swirling eddies in a stream. They are induced by changing magnetic fields and flow in closed loops, perpendicular to the plane of the magnetic field. Like any current flowing through a conductor, an eddy current will produce its own magnetic field.

Are eddy currents AC or DC?

Thus eddy currents are a cause of energy loss in alternating current (AC) inductors, transformers, electric motors and generators, and other AC machinery, requiring special construction such as laminated magnetic cores or ferrite cores to minimize them.

What are eddy currents Give two uses?

Eddy currents are current loops formed over conductor surfaces due to changing magnetic flux. They are useful in induction heating, levitating, electromagnetic damping, and electromagnetic braking.

What is eddy current process?

Eddy current (EC) testing is a no contact method for the inspection of metallic parts. Eddy currents are fields of alternating magnetic current that are created when an alternating electric current is passed through one or more coils in a probe assembly.