Cathodically protected sections of hotrolled 2-inch steel pipe were subjected to low temperature bend tests. The steels tested were API grades A, B and M (N-80). The presence of a reducible Fe O portion of the mill scale delayed hydrogen absorption. Embrittlement of Grades A and B occurred due to notch formation when adherence of Fe O to base metal was destroyed during cathodic protection. Under conditions of low pH with and without sulfide ion, cathodic protection induced hydrogen absorption, and with sulfide ions present embrittlement of steels A and B was severe. Steel M (normalized) was found to be insensitive to embrittlement during cathodic protection. For the M steel cathodic protection for ten months under conditions of high tensile stress and excessive protection gave no indication of static failure or loss of strength and ductility in destructive tests upon removal from cathodic protection.
5.2.1
