Hard spots are local regions that have a considerably higher hardness than the bulk hardness of a pipe. These types of flaws typically occur from uneven cooling or quenching during the manufacture of the steel plate which can lead to failure.
Pipeline Operators are allowed to repair certain defects, such as, cracks, gouges, hard spots and stress corrosion cracking by grinding them out of the pipe. The grind defect is assessed the same way one would assess external corrosion, assuming the COMPLETE removal of the altered metallurgical area.
Other Types of Pipe Flaws:
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