where d is the bolt diameter, v_Land v_Sare the longitudinal and shear wave velocities, respectively. However, the presence of all-thread was observed to destroy the mode conversion process.

Recent experiments were conducted on all-thread and it was noticed that good bolts did not exhibit mode conversion. However, as symmetrical corrosion began to form, the mode converted signal began to appear. It was also noted that the time separation between the end of the bolt signal and the first mode converted signal was determined using the equation

where d' is the diameter of the corrosion.
The purpose of this paper is to discuss the experiments conducted on all-thread with simulated corrosion and how the CGWT can be used to detect the corrosion wastage in all-thread bolts.