The emphasis of this paper is placed on welding fabrication of marine and space structures. My professional work has been performed at Transportation Technical Research Institute in Japan (from 1948−58, and 1962−63), Battelle Memorial Institute in Columbus, Ohio in the United States of America (1958−62, and 1963−68), and the Massachusetts Institute of Technology (1968−present). Although welding is extremely useful in fabricating various structures, it often causes various problems including residual stresses and distortion caused by heating resulting premature failures. Although most of my work has been related to fundamental research performed in research institutions, I have also been involved in consulting work. Some of my consulting works involved various problems facing Japanese companies fabricating various structures exported to foreign companies. Since many welded structures have been exported from Japan to various countries, I believe that an increasing number of these structures will experience various problems. In my opinion, however, there are only a small number of Japanese technical experts who can handle these problems occurring outside Japan.
Though the high temperature corrosion observed at heavy oil fired boilers is known as a typical vanadium attack, the presence of metallic sulfides under the oxide layer and carburization phenomenon are observed by the investigation on the corroded tubes. Those phenomena can not be explained by the laboratory corrosion tests with synthetic oil ashes. Additives, such as MgO or Mg(OH)2 injected with fuel into boilers to inhibit high temperature corrosion. Decrease of tube corrosion rate is improved by the additive-ash reactions which forms a high melting, non corrosive products. However, these additives cause a reduction in thermal absorption efficiency at the combustion furnace tubes due to white color of Mg additives and promoted generation of undesired thermal NOx in combustion gas. This paper highlights the differences of high temperature corrosion phenomena of actual boiler tubes and laboratory corrosion tests, behavior of Mg additives injected with fuel and V2O5 in the boilers, and important role of engineering on the corrosion control techniques applied to boiler plants.
At first history of the picked out condenser tubes test is considered. Then the present states and problems are described. Finally modifications on the picked out copper alloy tube tests and specification on a picked out copper alloy tube test are proposed as follows : 1) Determination of causes on the corrosions. 2) Recommendation of countermeasures. 3) Assessment of fouling resistance. 4) Discussion on compatibility between corrosion control and fouling control. 5) Examination charts of EDIO.
Retirements of baby-boom generation have made technical know-how vacancy. It is a great issue to transfer the know-how to younger engineers. Chemical plants in Mizushima complex in Okayama prefecture have been 40 several years since they have been fabricated, and they have become aged. In aged chemical plants troubles and personal accidents due to corrosion occur frequently. The role of professional consultant in corrosion and corrosion control engineering is to breed young engineers to qualified corrosion engineers in order to keep aged plants safe. In this paper, the author gives several messages for younger corrosion and corrosion control engineers. Finally, the author presents “Pitting in percolation of pool water made of SUS304” as an example of know-how learning among various troubled cases.
The business in corrosion consulting differs from scientific activity. Therefore, the following actions are required. 1) Corrosion engineer can fully play an active part in other fields using our specific technology. 2) In order to consider the cause of damage, it is necessary to refer analysis investigation and statistical characterization for the damaged components. Moreover, prevention should be observe the phenomena peculiar to mass production electronic component. 3) Since consulting business touches various customers, it is necessary to use plain expression, simile and original sense.
There is a risk of AC stray current corrosion on pipelines that are buried in proximity to overhead AC power transmission lines or AC-powered rail transit systems due to electromagnetic induction caused by magnetic fields around the loading currents. Grounding of the line pipes is generally applied for the mitigation of the induced AC. In the present paper, studies were conducted to predict the induced AC level through the measurement of magnetic flux density using magnetic field sensors in order to provide appropriate assessment of AC stray current corrosion risk as well as the optimum design of grounding systems. The relationship between magnetic flux density around power transmission lines and induced AC level on buried steel pipelines was then obtained through theoretical studies. In addition, as a result of field tests conducted on an existing pipeline buried in proximity to power transmission lines, induced AC level could be predicted through the measurement of magnetic flux density using magnetic field sensors, and thus the relationship obtained in the present study was proven to be appropriate. It is then expected that the AC prediction method using magnetic field sensors can be applied on the pipelines buried in proximity to multiple power transmission lines with complicated configuration.
In assessment of the applicability of weathering steel bridge in a building site, precipitation rate of airborne salts is usually compared with reference value of that. To analyze the precipitation rate of airborne salts at building sites, either Doken tank method (Public Works Research Institute method) or dry gauze method are generally employed. This study compared quantities of airborne salts sampled by Doken tank and dry gauze in order to examine the consistency between the methods with Doken tank and dry gauze. While Doken tank has one window to obtain airborne salts, the dry gauze has back and front sides, both of which can obtain airborne salts. Precipitation rate of salts obtained by the dry gauze facing East and West is higher than average of those by two Doken tanks facing East and West, suggesting that the dry gauze effectively catches airborne salt relative to Doken tank. Considering that the reference value was measured by the method with dry gauze, we had better to discuss the applicability of weathering steel bridge on the basis of precipitation rate of airborne salts obtained by dry gauze.