RU2231574C1 - Formaldehyde corrosion inhibitor for carbon steels - Google Patents

Abstract

FIELD: corrosion protection.

SUBSTANCE: aqueous carbon steel corrosion inhibitor, which may be used in production and transportation of formaldehyde products such as urea-formaldehyde concentrate, is added in amounts from 0.1 to 3% on the weight of urea-formaldehyde concentrate and 10-40% polyamine, 0.01-4% formaldehyde, and 0.01-3.5% ammonia, said polyamine having general formula

wherein n = 0 or 1, m = 0 or 1, and n+m = 0-2.

EFFECT: expanded corrosion protection possibilities.

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Description

The invention relates to the field of protection of metal from formaldehyde corrosion and may find application in the production and transportation of formaldehyde-containing compounds, for example, urea-formaldehyde concentrate (CPK) and formalin.

For the products under consideration, the corrosive substance is formic acid, which is formed during the oxidation of formaldehyde with atmospheric oxygen or as a result of the Cannizzaro-Tischenko reaction in an alkaline medium. For this reason, corrosion of carbon steels in the presence of formalin or a urea-formaldehyde concentrate is predominantly acidic.

Inhibitors of the latter often use organic substances related to aliphatic and aromatic amines or aldehydes.

Known [SU No. 1761818 A1, cl. C 23 F 11/04] a metal acid corrosion inhibitor containing 98.04-99.26 wt.% Azine of furfuridencyclanes and 0.74-1.06 wt.% Of potassium iodide. Significant disadvantages include the high cost of furfuridenene cyclanes obtained from hydrazine hydrate and furfuridendencyclopentanol, and a low protective effect in the absence of potassium iodide.

The closest in technical essence is the solution that describes the corrosion inhibitor of steel, representing the condensation product of benzylamine with formaldehyde and ammonia. Its disadvantages include insufficient protection of steels under conditions of elevated temperatures.

The aim of the invention is an inhibitor of formaldehyde corrosion of carbon steels.

This goal is achieved by the fact that as this inhibitor is taken a composition containing, wt.%:

Polyamine 10-40

formulas

where n = 0; 1, m = 0; 1, n + m = 0-2,

Formaldehyde 0.01-4.0

Ammonia 0.01-3.5

Water Else

introduced into the formaldehyde-containing product in an amount of 0, 01-3 wt.%.

The structure of these compounds contributes to their multicenter adsorption on the metal surface and, therefore, ensures the achievement of a high anticorrosive effect.

The difference between the claimed inhibitor and the known ones is that in order to reduce the corrosion of carbon steels in contact with urea-formaldehyde concentrate, an aqueous solution of a polyamine of the general formula is used as an amine-containing product

the protective effect of which is enhanced by the presence of small amounts of ammonia in the inhibitory composition.

Corrosion activity parameters for carbon steels “3” and “09Г2С” were determined in round-bottom flasks with a volume of 100 cm ³ equipped with a reflux condenser and placed in a water thermostat with a given temperature. The preparation of rectangular samples of steels 3 and 09G2S was carried out according to generally accepted methods. The KFK-80 urea-formaldehyde concentrate used in the corrosion tests met the requirements of TU 2223-009-00206492-98 and had the following quality indicators:

Mass fraction of urea in all forms, wt.% 21.0-24.0

Mass fraction of formaldehyde in all forms, wt.% 54.5-59.0

Water Else

The molar ratio of formaldehyde: urea 4.9-5.2

As a formaldehyde corrosion inhibitor, a product was taken with the following quality indicators:

polyamine content, wt.% 25.0

formaldehyde content, wt.% 1,5

ammonia content, wt.% 2.2

water rest

The results of corrosion studies are shown in the table.

From the description of the invention and the table shows that according to the claimed technical solution, it is possible to achieve high resistance of carbon steels to formaldehyde corrosion.

Claims (1)

An inhibitor of formaldehyde corrosion of carbon steels, including polyamine, formaldehyde, ammonia and water, characterized in that the product of the general formula is taken as a polyamine

where n = 0; 1, m = 0; 1; n + m = 0-2, with the following content of components in the composition, wt.%: Polyamine 10 - 40 Formaldehyde 0.01 - 4 Ammonia 0.01 - 3.5 Water Else introduced in an amount of 0.1-3 wt.% based on 100 wt.% urea-formaldehyde concentrate.