Sections on an underground pipe line in a large city were corroded considerably if located near points with heavy traffic. The pipe, although covered with a reinforced asphalt layer, was attacked locally. Portions of the line crossing districts with traffic vibrated, while other sections did not oscillate at all. On concrete foundations located near the pipe line, vibration frequencies between 10-50 cycles/sec could be measured during traffic hours.
According to these observations it can be assumed that the coating was exposed to the influence of a bending vibrational stress.
The question arose whether or not these stresses exerted an unfavorable influence on the durability of a bituminous covering.
An attempt was made to answer this question by studying the process of crack formation in a coating on a vibrating pipe, by measurements of the electric resistance and corrosion observations.
The apparatus shown in Figure 1 was used to generate vibrations...
