Chemical apparatus and process disinfecting – deodorizing – preser – Process disinfecting – preserving – deodorizing – or sterilizing – Maintaining environment nondestructive to metal
Patent
1986-06-09
1989-05-09
Castel, Benoit
Chemical apparatus and process disinfecting, deodorizing, preser
Process disinfecting, preserving, deodorizing, or sterilizing
Maintaining environment nondestructive to metal
422 19, 25238923, 106 1412, 148 615R, C23F 11167
Patent
active
048287962
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to the maintenance of trunk and branched networks of pressure and free-flow steel pipelines, and more particularly, to a compound for protecting the internal surface of a pipeline against corrosion, a method of producing same and a method of protecting the internal surface of a pipeline against corrosion using this compound.
PRIOR ART
Today there are known in the art various compounds for protecting the internal surface of pipelines against corrosion, e.g., silicates of alkaline metals creating a coating of iron ferrosilicates on the surface. At the same time, use is made of silicates, namely, sodium, metasilicate, sodium disilicate and sodium trisilicate (cf. A. O. Akolzin "Oxygen Corrosion of Equipment in Chemical Industry", Khimia Publishers, 1985, Moscow, pp. 162-167).
The application of the afore-mentioned compounds for protecting the internal surface of a pipeline against corrosion calls for the use of high concentrations thereof which makes them unsuitable in protecting drinking water supply lines.
Known in the art is a pipeline corrosion-preventive compound based on phosphates, e.g., sodium hexametaphosphate, trisodium phosphate and superphosphate (A. P. Akolzin. "Oxygen Corrosion of Equipment in Chemical Industry", Khimia Publishers, 1985, Moscow, p. 146-149).
The application of the above-mentioned compounds in the concentration below 3.5 mg/l in terms of P.sub.2 O.sub.5 may enhance the corrosion of pipelines, therefore, they are unsuitable for protecting the drinking water supply lines.
Known in the art is a pipeline crorrosion-preventive compound comprising the mixture of polyphosphate and sodium silicate.
The method of producing the afore-mentioned compound consists in dissolving sodium silicate and sodium polyphosphate in parallel, whereupon two solutions are mixed and diluted with water (V. A. Klyachko, I. E. Apeltsin "Cleaning of Natural Waters", Stroiizdat Publishers, 1971, Moscow, pp. 507-512).
A disadvantage of the above method is a complex process of dissolving sodium silicate which is very slowly dissolved in cold water (the dissolution process lasts dozens of days). A sophisticated equipment is required for dissolving sodium silicate (autoclaves with pressurized steam supply).
Besides, the said compound fails to ensure a reliable corrosion-preventive coating of the pipeline internal surface with a long period of aftereffect.
Known in the art is a method of protecting the pipeline internal surface against corrosion using a compound, e.g., sodium polyphosphate.
The method resides in removing deposits from the clean surface of the pipeline and is treated for 6 days with a solution of sodium polyphosphate with the concentration of 75 mg/l in terms of P.sub.2 O.sub.5, whereupon, the protective coating formed is constantly replenished with a diluted solution of sodium polyphosphate (5 mg/l in terms of P.sub.2 O.sub.5) (V. A. Klyachko, I. E. Apeltsin "Cleaning of Natural Waters", Stroiizdat Publishers, Moscow, 1971, pp. 507-512).
This method is characterized by the fact that it is necessary to constantly maintain a definite relation of calcium and sodium polyphosphates in the pipeline, because sodium polyphosphates may give rise to corrosion. A constant replenishment with a diluted solution of sodium polyphosphate of said concentration makes it impossible to use said method for preventing corrosion in drinking water supply pipelines. Besides, this method cannot provide a protective coating with a long period of aftereffect on the pipeline internal surface.
SUMMARY OF THE INVENTION
It is the main object of the present invention to provide a corrosion-preventive compound for the pipeline internal surface, making it possible to develop a protective coating possessing strength and a long period of aftereffect and capable of being used for protecting drinking water supply pipelines against corrosion.
The main object is attained due to the fact that the compound as claimed for protecting the internal surface of the pipeline against corrosi
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patent: 3974047 (1976-08-01), Ramp
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Akolzin et al., Oxygen Corrosion of Chemical Industry Equipment, Khimia, Moscow, 1985, pp. 162-166 (with trans.).
Akolzin et al., Oxygen Corrosion of Industrial Chemical Equipment, Khimia, Moscow, 1985, pp. 146-149 (with trans.).
Kliachko et al., Purification of Natural Wastes, Moscow, 1971; pp. 506-512 (with trans.).
Abramova Ljubov I.
Chernyai Alexandr I.
Kapralova Viktoria I.
Kryazhevskikh Nikolai F.
Lukin Evgeny G.
Alma-atinsky, Institut, Inzhenero, Zheleznodorozhnogo Transporta
Castel Benoit
Institut Khimicheskikh, Nauk, Akademii, Nauk, Kazakhskoi
Inzhenerny, Tsentr, Po, Selskokhozyaistvenno Vodosnabheniju, I,
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