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About FSM

Non-destructive inspection is a technology that detects damage such as corrosion and cracks of mechanical parts and structures by applying properties such as radiation and ultrasonic waves without destroying the target.


AEPD(Atlas Electrical Potential Drop) is a non-destructive inspection method that detects damage such as corrosion and cracks that occur in metal, and is one of the inspection methods generally known as the potentiometric method. Currently, AEPD is being applied to monitoring and screening inspections for corrosion and wall thinning of pipes in power plants and for in-service tank's bottom plate inspection. Our have record set of satisfying companies including oil refinaries, power plants, petro-chemical companies.

​AEPD basic principle

AEPD applies a constant direct current to a conductive inspection object such as steel to instantly form an electric field, measures the potential difference at a specific location in the electric field, and measures the potential difference.


It is a non-destructive inspection method that identifies the degree of damage from measured values.


When wall thinning or cracks occur at the measurement site, the electrical resistance at that site increases (electricity becomes difficult to flow).


The potential difference to be measured follows Ohm's law.



Potential difference (V) = electrical resistance (R) x current (I)



When a constant direct current (I0) is supplied, the potential difference increases as the electrical resistance increases. Figure 1 schematically shows the change in potential difference when wall thinning or cracks occur in the target area. In FSM, the two terminals attached to both ends of the target part are called sensing pins, and the potential difference between these sensing pins is measured. Assuming that the potential difference in the sound portion is V0, the potential difference V1 in the portion where the wall thinning or crack occurs is larger than V0. By measuring the rate of change of the potential difference, it is possible to detect the thinning or the occurrence / growth of cracks in the inspection object. Not only can damage be detected, but its degree and magnitude can be quantitatively evaluated.

​Figure 1
​Sensing pin
V rises I is constant
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