In view of the accelerated atmospheric rusting in Shibukawa area, Gunma, presumably due to the presence of HCl released from chemical plants, a series of atmospheric exposure tests has been carried out for one year starting in September. Data were obtained with steel, stainless steel, aluminum alloy and brass plates at polluted Osaki and Nakamura districts. Control specimens were exposed in the less polluted Toriba atmosphere, Maebashi. The changes in appearance and weight, and X-ray diffraction analysis showed that corrosion was most severe at Nakamura while that at Osaki was moderate, being slightly greater than that at Toriba. For example, the corrosion rates of steel were 6.594 (0.084), 4.698 (0.060) and 4.148g/dm² (0.053mm/yr) at Nakamura, Osaki and Toriba, respectively. The value at Nakamura was 1.6 times that at Toriba. The amounts of Cl and S on the brass specimens as determined by fluorescent X-ray were highest at Nakamutra while those at Osaki were not much different from those at Toriba.

View full abstract

Methods of locating coating flaws and measuring insulating resistance of buried pipelines have been compared using a model pipeline which had artificial flaws. The coating systems were polyethylene and reinforced asphalt. The results show that a pin type electrode method is more sensitive than the Pearson type holiday detector in locating coating flaws. Among several procedures used for the resistance measurements, the voltage drop method is most reliable.

View full abstract