Continuity of glass enamels on petroleum steel pipes

• Published in: Glass and ceramics 1990-03, Vol.47 (3), p.98-99
• Main Authors: Loshagin, A. V., Shardakov, N. T., Sosnin, E. P., Buler, P. I.
• Format: Article
• Language: English
• ISSN: 0361-7610; 1573-8515
• DOI: 10.1007/BF01196180

Enamelled steel pipes for the oil industry must possess a high chemical resistance, and control of the continuity of the coating is essential. The high firing temperature of an industrial enamel, S3-1, was reduced by modifying the starting composition though the addition of iron and manganese oxides, as well as by adding either cryolite or sodium sulphate. This reduced the application temperature to 1073 K, but also increased the number of defects, as revealed by the high-voltage test method. In order to identify the causes of the high voltage breakdown, electrolytic and electroconductivity measurements were made. Incorporating sodium sulphate, Fe and Mn oxides, as well as cryolite, did not increase the conductivity. The increase in defects in compositions containing these additives was explained by the presence of broken sections of the coatings which are formed, apparently, as a result of the increased number of gaseous inclusions in the Fe- and Mn-containing enamels. 1 ref.