The corrosion resistance and the oxide film of stainless steel containing Mo in simulated condensed water of oil and gas environments were investigated by electrochemical tests and X-ray photoelectron spectroscopy. From the results of potentio-dynamic polarization, Mo improved the corrosion resistance of stainless steel in simulated condensed water. From the results of electrochemical impedance spectroscopy, the oxide film of stainless steel containing Mo had fewer defects than that of stainless steel without Mo. The results of X-ray photoelectron spectroscopy showed that the oxide film containing Mo was formed in the outermost layer on Mo containing stainless steels. The thickness of the oxide film formed on stainless steel containing Mo was thinner than that of the oxide film formed on stainless steel without Mo.

This paper presents the effect of adding calcium sulfate on the anticorrosion performance of an epoxy zinc-rich paint （ZRP）. We focused on gordaite （NaZn₄（SO₄）（OH）₆Cl･6H₂O）, a protective corrosion product, and increased its amount by providing sulfate ions.

First, pure zinc plates were corroded in a cyclic corrosion test （CCT） with a calcium sulfate saturated test solution to investigate the effect of sulfate on zinc corrosion behavior. The results showed that the portion of gordaite increased in the zinc corrosion products and the corrosion rate of the zinc plates decreased.

Next, epoxy ZRP containing calcium sulfate was prepared, and the ZRP-coated steel specimens were subjected to a CCT and out-door exposure test on Miyako Island. In both tests, the ZRP with calcium sulfate showed a remarkably high corrosion resistance compared with ZRP without calcium sulfate.

Living hinges of polypropylene aerial cable closures that had been field-aged for eight years were analyzed in detail. Severe degradation including deep cracking was observed in the hinge central section, which had been subjected to UV light in the outdoor environment and repetitive sharp bending cycles during maintenance. On the other hand, the degradation of the other section was limited to within 10μm from the top surface. A repetitive bending cycle test alone did not reproduce the severe degradation. It was concluded that synergistic effects of solar UV irradiation and repetitive bending stress generated the severe degradation at the hinge section. Micro-cracks initially generated on the UV-degraded brittle top surface were the initial points of major cracks leading to breakage. Microscopic observations revealed craze structures around the major cracks. The crazes, caused by repetitive shear stress during the hinge-bending operations, were considered to be major routes for crack propagation. A test combining UV irradiation and repetitive sharp bending cycles on unused hinge specimens supported the crack generation and propagation mechanism.

The effect of phosphorus of copper tubes on the dissolution behavior of the tubes in an ammonia solution was investigated with electrochemical measurements. It was found that the copper starts to dissolve as [Cu（NH₃）₂]^＋ ions first, and that, when the monovalent ion concentration exceeds a certain level, the reaction shifts to a dissolution yielding divalent [Cu（NH₃）₄]^2＋ ions. In the latter reaction, the phosphorus reduces the charge transfer resistance of copper dissolution. Phosphorus is mainly segregated at grain boundaries, from which copper dissolved preferentially. The results suggest that the segregation of phosphorus is a causes of intergranular stress corrosion crack.