In the field of materials testing, Potential Drop (PD) techniques have been widely employed for decades in the petrochemical, aerospace, and power generation industries, particularly for monitoring crack growth and wall thickness variations caused by corrosion or erosion in critical structures. Traditionally, both Direct Current (DC) and Alternating Current (AC) PD methods have been applied, each with its own advantages and limitations. This thesis focuses on the Direct Current Potential Drop (DCPD/DCEPD) method as a means of accurately monitoring crack extension and deriving fracture toughness values. The principle of PD measurement is straightforward: a constant current is injected into a specimen, and the voltage drop across two electrodes placed on the ligament is monitored.