A man died soon after entering the void of an idle boiler of the Lancashire type that had been sealed for three years with a small amount of water. This accident occurred in Sapporo in 1963 is considered to be caused by a deficiency of oxygen due to the long-term corrosion inside the boiler. The possibility is demonstrated by inspecting the degree of corrosion and by estimating the amount of decrease of oxygen at the time of the accident.

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The earlier reports by the authors showed that the climatic condition at various locations in Japan had important effect on the rusting rate of painted mild steel panels exposed.
Since 1961, the authors carried out weathering test to investigate the effect of the kind of steel and the effect of surface preparation on the rusting rate of painted steels.
The results of the five-year test showed that no appreciable effect of the kind of steel was found and that the durability of anti-corrosive paint applied to steel surface was dependent on pretreatment and surface preparation prior to painting. The effectiveness of chemical treatment with phosphate was remarkable in coastal districts where paint film was exposed to severe deteriorating environment, but not in such districts as inland.

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The behavior of sulfur dioxide on low-alloy weathering steel and high strength steel (SM 50) has been clarified as to the rate of sulfate formation in the rust and its removal by water treatments. The rate of sulfate formation can be obtained by exposing steels rusted by pre-exposure to an industrial atmosphere for various periods up to two years to a radioactive SO₂ environment for a few days and by determining the radioactivity of the formed sulfate. The rate of dissolution of the radioactive sulfate is determined either by immersion in distilled water or by spraying tap water on the surface.
The results show that the rate of sulfate formation is lower on weathering steels and on steels pre-exposed to the atmosphere for longer periods. The tendency is in parallelism with the variation of the corrosion rates in the atmosphere with respect to steel composition and exposure time. The amount of dissolved sulfate is less for weathering steels but the percentage is almost the same regardless of steel composition.
The fate of sulfur contained in steel has also been studied. In absence of copper, sulfur changes to sulfate and accumulates in rust in the course of atmospheric corrosion, but the presence of copper drastically reduces the sulfate formation.
The material balance of sulfate in rust mins is considered and a mechanism of corrosion resistance of weathering steels in connection with the behavior of sulfate is discussed.

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