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CORROSION RESEARCH ROUNDUP

CORROSION RESEARCH ROUNDUP FRANCE face tension is revealed by the presence of certain intermediate layers formed Corrosion by heat-transfer fluids during the melting process, due to ion migration. The interdependence of In a discussion of the corrosive temperatures between 200 and 280°C. surface tension and wettability of effect of fluids used for conveying heat no corrosion takes place. metal-ceramic systems has recently to a place of energy transformation, it In the case of polyglycols, corrosion been investigated by M. Humenik was shown that, although water is, of depends on the moisture content of and W. D. Kingery, using the contact course, the most obvious heat-transfer the products, and can be avoided angle as an index for quantitative agent, its use is limited by the com­ completely by means of an inhibitor measurements. To some extent the paratively low maximum temperature consisting of a mixture of 93% tri- results of their work are borne out by (about 180°C.) obtainable even with ethanolamine orthophosphate and 7% subsequent German research, and it saturated steam or overheated water. mercaptobenzothiazole, and added at is, therefore, highly probable that a Corrosion caused by heat-transfer the rate of 2.5 to 3.5% of the poly- means will be found of increasing water and steam is avoided by raising glycol. These polyglycols, which have the corrosion resistance of refractory the pH value through the addition of a very high flashpoint, are particularly materials by influencing the surface some sodium triphosphate and by suitable for heat-transfer purposes. tension in some way.—(Glas-Email- adding cyclohexylamine or methyl- Mineral oils used for heat transfer Keramo-Technik, May 1955.) ethanolamine at the steam generator. do not cause corrosion. Organo- Ammonium sulphite is suitable for silicates, which are now also used for Milk pasteurisation plants this purpose and it has one advantage this purpose and which must be care­ in that there is no loss when it is used Pronounced corrosion phenomena fully protected against moisture, may in a closed circuit. have been consistently observed on cause corrosion on magnesium, zinc or plate heaters used for the heating of aluminium alloys, but not on mild steel, milk in pasteurisation plants. These nickel, copper or bronze. The heat- Among other heat-transfer fluids phenomena are particularly marked at transfer fluid produced in America causing corrosion problems are chlori­ the gaps near the common support under the name Dowtherm, being a nated hydrocarbons, often favoured points of two adjacent plate heaters. mixture of diphenyl and diphenyl for their heat stability and near- Corrosion apparently has two different oxide, is harmless except for a slight incombustibility. In contrast to the causes: the formation of a galvanic and avoidable risk from obstructions pit corrosion caused by water, the element between the non-ventilated caused by deposits of pyro-products. corrosive effect of hydrocarbons is part of the plate at the support and —(R. Bigeon, Corrosion et Anti- uniform over the whole metal surface. the ventilated marginal zone at the Corrosion, May/June 1955.) However, if they are only used at gap leads to pit corrosion; and, secondly, the steel is affected by the chloride content of the water which is U.S.A. GERMANY contained in the acid solution used for Wood-lined steel pipe Corrosion and heat of activation cleaning the plates. Recent research by Wildbrett has shown that this type Wood-stave and especially wood- The rate of corrosion of water and of corrosion is particularly aggressive lined steel pipe is extensively used to steam on iron follows the equation of if two steel plates of the type used for transport corrosive and abrasive sub­ Arrhenius. The heat of activation milk heaters are juxtaposed with a stances at temperatures up to 185°F. depends on the nature of the material, slight gap. It is, therefore, advisable Wood is particularly useful in hand­ the phase of the water and the phase to use, if possible, water with a low ling pulp suspensions, pulp mill of the electrolytes. Similarly, it has chloride content, e.g. condensation wastes, mine wastes, dilute mineral been possible to express the corrosive water, or water treated with an ion acids and dilute caustic soda solutions. action of water and other agents on exchanger or silver nitrate, and to Its acceptable p H range is from 2.5 to aluminium and on steel by an equation. open the plates after cleaning so that 11. It is not recommended for use Deviations from the rule are explained. they are kept dry when not in opera­ with strong oxidising agents, concen­ —(M. Werner, Werkstoffe & Kor- tion. If the plates are out of service trated mineral acids or highly alkaline rosion, 1955, 6 (3), 113-117.) for a lengthy period they should be or caustic solutions, but may be used filled with a solution of a highly successfully to exhaust many kinds of Protection of refractory materials oxidising acid made from chloride- corrosive fumes and vapours. This survey of recent international free water.—(Hoesch Chemical Works, Short-term laboratory and lengthy literature on refractory materials draws Düren, Deutsche Moikerei Zeitung, service experience have shown that attention to the increasing importance 1955, 19.) even under pressures up to 100 to 200 attached to the phenomenon known as p.s.i. liquids seldom penetrate halfway surface tension. All other known through standard thicknesses of staves. properties of the material were found Cathodic protection in the chemical industry This keeps corrosion at the wood-steel to be inadequate for the prediction of interface of wood-lined pipe to a corrosion resistance, and the only test Numerous instances are quoted from minimum. which appears to permit some predic­ an oil refinery, and the applications tion is the permeability test which is Other assets are sustained low- comprise cathodic protection of buried dependent on the structure of the pipelines, sluice pipes, and the pro­ friction- coefficients and a degree of pores, a feature hardly susceptible to tection of coolers, condensers, tanks, insulation from temperature.—(E. H. production control methods. Bronstein, Corrosion, 1955, 2 (5), etc.—(W. Rausch, Werkstoffe &Kor- 205-209.) rosion, 1955, 6 (4), 189-198.) The existence of considerable sur­ 366 CORROSION TECHNOLOGY November 1955 http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Anti-Corrosion Methods and Materials Emerald Publishing

CORROSION RESEARCH ROUNDUP

Anti-Corrosion Methods and Materials , Volume 2 (11): 1 – Nov 1, 1955

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Emerald Publishing
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Copyright © Emerald Group Publishing Limited
ISSN
0003-5599
DOI
10.1108/eb019124
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Abstract

FRANCE face tension is revealed by the presence of certain intermediate layers formed Corrosion by heat-transfer fluids during the melting process, due to ion migration. The interdependence of In a discussion of the corrosive temperatures between 200 and 280°C. surface tension and wettability of effect of fluids used for conveying heat no corrosion takes place. metal-ceramic systems has recently to a place of energy transformation, it In the case of polyglycols, corrosion been investigated by M. Humenik was shown that, although water is, of depends on the moisture content of and W. D. Kingery, using the contact course, the most obvious heat-transfer the products, and can be avoided angle as an index for quantitative agent, its use is limited by the com­ completely by means of an inhibitor measurements. To some extent the paratively low maximum temperature consisting of a mixture of 93% tri- results of their work are borne out by (about 180°C.) obtainable even with ethanolamine orthophosphate and 7% subsequent German research, and it saturated steam or overheated water. mercaptobenzothiazole, and added at is, therefore, highly probable that a Corrosion caused by heat-transfer the rate of 2.5 to 3.5% of the poly- means will be found of increasing water and steam is avoided by raising glycol. These polyglycols, which have the corrosion resistance of refractory the pH value through the addition of a very high flashpoint, are particularly materials by influencing the surface some sodium triphosphate and by suitable for heat-transfer purposes. tension in some way.—(Glas-Email- adding cyclohexylamine or methyl- Mineral oils used for heat transfer Keramo-Technik, May 1955.) ethanolamine at the steam generator. do not cause corrosion. Organo- Ammonium sulphite is suitable for silicates, which are now also used for Milk pasteurisation plants this purpose and it has one advantage this purpose and which must be care­ in that there is no loss when it is used Pronounced corrosion phenomena fully protected against moisture, may in a closed circuit. have been consistently observed on cause corrosion on magnesium, zinc or plate heaters used for the heating of aluminium alloys, but not on mild steel, milk in pasteurisation plants. These nickel, copper or bronze. The heat- Among other heat-transfer fluids phenomena are particularly marked at transfer fluid produced in America causing corrosion problems are chlori­ the gaps near the common support under the name Dowtherm, being a nated hydrocarbons, often favoured points of two adjacent plate heaters. mixture of diphenyl and diphenyl for their heat stability and near- Corrosion apparently has two different oxide, is harmless except for a slight incombustibility. In contrast to the causes: the formation of a galvanic and avoidable risk from obstructions pit corrosion caused by water, the element between the non-ventilated caused by deposits of pyro-products. corrosive effect of hydrocarbons is part of the plate at the support and —(R. Bigeon, Corrosion et Anti- uniform over the whole metal surface. the ventilated marginal zone at the Corrosion, May/June 1955.) However, if they are only used at gap leads to pit corrosion; and, secondly, the steel is affected by the chloride content of the water which is U.S.A. GERMANY contained in the acid solution used for Wood-lined steel pipe Corrosion and heat of activation cleaning the plates. Recent research by Wildbrett has shown that this type Wood-stave and especially wood- The rate of corrosion of water and of corrosion is particularly aggressive lined steel pipe is extensively used to steam on iron follows the equation of if two steel plates of the type used for transport corrosive and abrasive sub­ Arrhenius. The heat of activation milk heaters are juxtaposed with a stances at temperatures up to 185°F. depends on the nature of the material, slight gap. It is, therefore, advisable Wood is particularly useful in hand­ the phase of the water and the phase to use, if possible, water with a low ling pulp suspensions, pulp mill of the electrolytes. Similarly, it has chloride content, e.g. condensation wastes, mine wastes, dilute mineral been possible to express the corrosive water, or water treated with an ion acids and dilute caustic soda solutions. action of water and other agents on exchanger or silver nitrate, and to Its acceptable p H range is from 2.5 to aluminium and on steel by an equation. open the plates after cleaning so that 11. It is not recommended for use Deviations from the rule are explained. they are kept dry when not in opera­ with strong oxidising agents, concen­ —(M. Werner, Werkstoffe & Kor- tion. If the plates are out of service trated mineral acids or highly alkaline rosion, 1955, 6 (3), 113-117.) for a lengthy period they should be or caustic solutions, but may be used filled with a solution of a highly successfully to exhaust many kinds of Protection of refractory materials oxidising acid made from chloride- corrosive fumes and vapours. This survey of recent international free water.—(Hoesch Chemical Works, Short-term laboratory and lengthy literature on refractory materials draws Düren, Deutsche Moikerei Zeitung, service experience have shown that attention to the increasing importance 1955, 19.) even under pressures up to 100 to 200 attached to the phenomenon known as p.s.i. liquids seldom penetrate halfway surface tension. All other known through standard thicknesses of staves. properties of the material were found Cathodic protection in the chemical industry This keeps corrosion at the wood-steel to be inadequate for the prediction of interface of wood-lined pipe to a corrosion resistance, and the only test Numerous instances are quoted from minimum. which appears to permit some predic­ an oil refinery, and the applications tion is the permeability test which is Other assets are sustained low- comprise cathodic protection of buried dependent on the structure of the pipelines, sluice pipes, and the pro­ friction- coefficients and a degree of pores, a feature hardly susceptible to tection of coolers, condensers, tanks, insulation from temperature.—(E. H. production control methods. Bronstein, Corrosion, 1955, 2 (5), etc.—(W. Rausch, Werkstoffe &Kor- 205-209.) rosion, 1955, 6 (4), 189-198.) The existence of considerable sur­ 366 CORROSION TECHNOLOGY November 1955

Journal

Anti-Corrosion Methods and MaterialsEmerald Publishing

Published: Nov 1, 1955

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