SU1723197A1 - Composition for protection of ferrous metals against corrosion - Google Patents

Abstract

The invention relates to the protection of metal against corrosion and can be used in water supply systems. The purpose of the invention is to increase the efficiency of protection against corrosion. The composition contains, in May.%: Three-substituted ammonium phosphate 3-7; ammonium oxalate 1-3; o-anisidine 0.1-0.5 and water - the rest. An increase in the effectiveness of corrosion protection is achieved due to the additional addition of ammonium oxaloxane and o-anisidine. 2 tab.

Description

This invention relates to a technique for protecting against internal corrosion in a circulating water supply system, as well as heating systems for greenhouses, poultry farms and

AR

A known composition for treating the inner surface of steel pipelines, boilers, etc., which includes sodium phosphate (meta) + sodium chromate (two) + phosphoric acid. This compound is recommended as a corrosion inhibitor for ferrous metals in water and soil. The following treatment method is recommended: the metal surface is pre-cleaned of rust and scale, degreased with carbon tetrachloride, moistened with 5-20% sodium phosphate solution, after drying, treated with a solution containing 0.67% sodium chromate and 0.5% phosphoric acid dried again. When protecting underground steel structures, a combination of inhibitor treatment and cathodic protection is recommended.

The disadvantage of this composition is its high cost, as well as the fact that it requires many operations and time, so it did not find wide distribution.

Also known is the composition for treating steel pipelines, boilers, and, in general, ferrous metals (chosen as the prototype), including sodium zinc phosphate 8Na2 O ZnO PzOs (US patent name Calgon T). This inhibitor of corrosion of ferrous metals in water and aqueous solutions of salts gives the following results: in water at a concentration of 5000 hours per 1 million hours. Z 96.7%; in 90% dissolved 156 ° C, the degree of protection of ferrous metals Z is 98.2%. Additives are also used, such as sodium ethylenediaminetetraacetic acid (Trilon B) and various non-ionic surfactants, for example ammonium gluconate.

A disadvantage of the known composition is that rare and expensive reagents are added; in addition, the treatment is carried out at high temperatures (156 ° C), therefore, it has not found wide distribution.

The purpose of the invention. Increasing the efficiency of protection of ferrous metals from internal M CO

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Corrosion in aggressive water and cheapening of the process is achieved by introducing three-substituted ammonium phosphate, ammonium oxalate and o-anisidine oxalate in the following optimum ratio of components, wt.%: three-substituted ammonium phosphate 3-7 ammonium oxalate 1-3, o-anisidine 0.1-0.5, water the rest. On average: trisubstituted ammonium phosphate 5%, ammonium oxalate 2%, o-anisidine 0.3% and water 92.7%.

Before treatment with a composition to protect ferrous metals from corrosion previously from the inner surface of pipelines, boilers, tanks, etc. rust and scale are removed with the aid of a solution proposed by us scientists consisting of 83.6-96.5 g of oxalic acid and 16.4-3.5 g of ferric chloride or chlorine aluminum per liter of water.

This composition is filled with cleanable pipelines, boilers, tanks, etc., and left for at least 24 hours, then washed with water until neutral.

The disadvantage of this composition is the high cost and the fact that the processing takes a lot of time. Therefore, a composition for removing rust and scale consisting of 3-5% hydrochloric acid, 0.3-0.5% o-anisidine, 0.03-0.05% tri-sodium phosphate, i.e. 30-50 g of hydrochloric acid, 3-5 g of o-anisidine and 0.3-0.5 g of trisodium phosphate per liter of water.

The proposed composition removes rust, scale and scale for not more than 3 hours, after which it is washed with water until neutral.

Treatment with solutions of the proposed composition for corrosion protection of the internal surface of pipelines, tanks, boilers, etc., from ferrous metals is carried out in the following way: previously the internal surface of pipelines, etc. they are cleaned of rust and scale by the proposed solutions and the mentioned method, after which they are filled with the proposed solutions protecting ferrous metals from corrosion, left for 24 hours, emptied and dried.

Example 1. In 984.6 ml of water are dissolved 10 g of trisubstituted ammonium phosphate, 5 g of ammonium oxalate and 0.4 ml of o-anisidine, i.e. the mixture consists of 1% trisubstituted ammonium phosphate, 0.5% ammonium oxalate, 0.04% o-anisidine, and 98.5% water. After processing it

the composition of the pipelines and after the action of aggressive water, the degree of protection is Z 65%, a score of 7 (low-resistant).

Example 2. 959 ml of water is dissolved

30 g of trisubstituted ammonium phosphate, 10 g of ammonium oxalate and 1 ml of o-anisidine, i.e. the mixture consists of 3% trisubstituted ammonium phosphate, 1% ammonium oxalate, 0.1% o-anisidium and 95.9% of water. After treatment with this composition of pipelines and after the action of aggressive water, the degree of protection is Z 85% persistent).

Example 3. Dissolve in 927 ml of water

5 50 g of trisubstituted ammonium phosphate, 20 g of ammonium oxalate and 3 ml of o-anisidine, i.e. the mixture consists of 5% trisubstituted ammonium phosphate, 2% ammonium oxalate, 0.3% o-anisidium and 92.7% water. After treatment with this solution of pipelines and after the action of aggressive water, the degree of protection is Z 90% and above.

PRI me R 4. Dissolve in 895 ml of water

5 70 g of trisubstituted ammonium phosphate, 30 g of ammonium oxalate and 5 ml of o-anisidine, i.e. the mixture consists of 7% trisubstituted ammonium phosphate, 3% ammonium oxalate, 0.5% o-anisidium and 89.5% water. After treatment with this solution of pipelines and after the action of aggressive water, the degree of protection is Z 98% and higher, a score of 4 (resistant).

Example 5. Dissolved in 863 ml of water

5 90 g of trisubstituted ammonium phosphate, 40 g of ammonium oxalate and 7 ml of o-anisidine, i.e. the mixture consists of 9% trisubstituted ammonium phosphate, 4% ammonium oxalate, 0.7% o-anisidium and 86.3% water. After treatment with this composition of pipelines and after the action of aggressive water, the degree of protection is 2–99%, a score of 4 (resistant);

The study was carried out on water of composition: total hardness 16 mg-eq./l, carbonate 3.40 mg-eq./l, SG 591 mg / l, mg / l, 146 mg / l, Ca + 2 255 mg / l Md 38 mg / l, Na + K 270 mg / l, free oxygen 1.5 mg / l.

0 Comparative tests were carried out in the same conditions, according to the same method (proposed), according to the prototype, and with the use of the composition to protect ferrous metals from corrosion.

5 The results of the corrosion tests in the table show that the most stable protective film is formed using the proposed composition that protects pipelines and ferrous metals in general from

corrosion. Re-treatment is recommended after 9 months. In the prototype, a less resistant protective film is formed and re-treatment should be carried out in 6 months.

Thus, a comparative assessment of the proposed composition and the prototype showed that the proposed composition is more effective.

When processing the proposed composition, the corrosion rate over the course of 9 months was 0.01–0.07 mm / year, a score of 4–5 (persistent), whereas in the prototype over 6 months. the corrosion rate ranged from 0.04 to 0.09 mm / year, the ball l 4-5 (stable), the advantage of the proposed composition is clearly seen here. The proposed composition for removing rust and scale more

economical, requires little time, the degree of purification is higher.

Claims (1)

Claim of the invention Composition for protecting ferrous metals from internal corrosion, containing phosphate and water, characterized in that, in order to increase the effectiveness of protection against corrosion, it additionally contains ammonium oxalate and o-anisidine, and as phosphate - trisubstituted ammonium phosphate in the following ratio components, wt.%: Trisubstituted ammonium phosphate 3-7 Oxalate ammonium1-3 o-Anisidin 0.1-0.5 Water the rest.