Investigation of the Protective Effectiveness of Nitrogen-Containing Organic Compounds in Protecting Ferrous and Non-Ferrous Metals

A 16 inches (0.4 metres) wet gas line on one of the wellhead platforms of “field A”(1) was modified to install a cooled probe at the 12 o’clock position to evaluate the efficiency of two volatile corrosion inhibitors which have been shown to provide acceptable levels of protection in laboratory testing. A corrosion inhibitor was injected at the Christmas tree level and the corrosion rate was measured, using a cooled probe downstream of the manifold. This particular facility also includes a chemical injection point at the 6 o’clock position under the cooled probe to send the corrosion inhibitor to the probe surface in order to simulate corrosion inhibitor batching by spray pig. This monitoring system was used to evaluate the efficiency of both volatile inhibitor and the bottom line corrosion inhibitor currently used for batch treatment. The paper additionally describes the field testing set-up, summarizes tests results and discusses the acceptability of corrosion controls through the use of batch treatments and volatile corrosion inhibitors. Field test results have shown the possibility of effective Top of the Line Corrosion (TLC) control by volatile inhibitors and confirm appropriate batching period as was determined through laboratory testing results.

The goal of the study was investigation of the inhibition efficiency and quantitative composition volatile components the extract of bunch grapes - industrial waste processing grapes as volatile corrosion inhibitor. It was studied the influence of plant extract on electrochemical and corrosion behavior of steel. It was established that the extract of bunch grapes acts as inhibitor of mixed type inhibiting both anodic and cathodic reactions. A novel volatile corrosion inhibitor, the extract of bunch grapes, was developed for temporary protection of carbon steel with periodic moisture condensation. Gravimetric method research the possibility of protecting the metal from corrosion with an aqueous solution of a volatile inhibitor. Volatile compounds isopropanol extract of bunch grapes was studied by gas chromatography-mass spectrometry. Found that the major components of the extract of bunch grapes are aldehydes: benzaldehyde, syringaldehyde, сinnamaldehyde, Е-сitral, (E)-2-Hexenal; terpene compound: сarvacrol, geraniol, linalool, nerol. Bibl. 9, Fig. 2, Table 2.

V O L A T I L E corrosion inhibitor is the name applied to compounds which have the ability to vaporize and condense on a metal surface making it less susceptible to corrosion. One of the most important properties of these compounds is vapor pressure. Cyclohexylammonium carbonate, for example, has a high vapor pressure of 0.4 mm. of mercury a t 25 C. and is a very effective corrosion inhibitor. The protective time is very short because of rapid depletion of the inhibitor. There are also inhibitors with low vapor pressures on the order of lo-' mm. of mercury. These compounds, however, cannot vaporize quickly enough before corrosion occurs. Therefore, vapor pressure is important, since it determines the usefulness of the compounds. To utilize volatile corrosion inhibitors it is also important to know the rate of vaporization or the vapor pressure change with temperature. A vapor pressure-temperature curve with 1 / T us. the -log P(mm. of Hg) will ,provide information which can later be related to the effectiveness of the various volatile inhibitors. Most of the information on volatile corrosion inhibitors in the literature does not pertain to their physico-chemical properties, and some of the data are conflicting. For example, the value for the vapor pressure of dicyclohexylammonium nitrite a t 21°C. determined by Rozenfeld ( 4 ) and by Wachter (7) is different by a factor of 10. Therefore, it seemed necessary to find a method which would accurately determine the vapor pressures of these compounds and the@ rates of change with temperature.

Metal products are subjected to atmosphere corrosion during transporting and longtime storing. Utilization of packing materials eliminating the access of water vapor and aggressive gases to the metal products surface is an important ways of struggling against the corrosion. Among the methods of metal products protection against the corrosion, application of volatile inhibitors is one of most effective one. As a carrier of the volatile corrosion inhibitors, polyethylene films can be used. Study of strength and barrier properties of polyethylene films with a volatile corrosion inhibitor and without it accomplished. As an object of the study, the films, produced under laboratory conditions by extrusion with blowing of low-density polyethylene and mixture of low-density polyethylene and IFKhAN volatile inhibitor, developed by the Institute of Physical Chemistry (Academy of Sciences of RF). For accelerated corrosion tests, samples of 08пс cold rolled steel used. The prepared samples packed in the studied films, a part of the closed airtight, and another part – not compact. It was traced, that the samples packed in the polyethylene film without the volatile inhibitor, had a point corrosion. The airtight sealed polymer film casings protect the carbon steel much better, comparing with the not compact casings. The surface of samples corrosion worms, which were airtight packed, was 0.15%, not compact ones – 0.33%. When inhibited polymer film was used for not compact packing, the corrosion had a uniform character, no local corrosion worms (pitting) was observed. The corrosion products were spongy, weekly cohered with the basic metal, easily peeling off. During the test period, the samples airtight packed in polyethylene film, containing IFKhAN volatile inhibitors, had no areas of corrosion. It was found, that input of inhibitor into the polyethylene matrix results in decreasing the film strength properties due to formation structure defects at the sub-molecular level during the extrusion, and also as a result of inhibitor desorption.

Carbon dioxide (CO2) Top of Line Corrosion (TLC) poses a significant problem in oil and gas fields, resulting in both economic losses and health and safety issues. The use of conventional corrosion inhibitors does not typically ensure effective protection against this particular type of corrosion, limiting the working lifetime of carbon steel pipelines. The main chemistry of inhibitors used for such application relies on volatile chemicals that can be transported through the vapor phase to reach the top of the pipeline. Studies have shown that alkanethiol compounds may form self-assembled monolayers in acid environments with good efficiency in mitigating steel corrosion. Recently, long chain thiols (> C6) have been investigated as potential volatile corrosion inhibitors (VCIs), demonstrating good efficiency. This work seeks to evaluate the efficiency, mechanism and bulk-vapor partitioning behavior of volatile thiol corrosion inhibitors through the implementation of a biochemical technique which targets sulphydryl groups, coupled with a miniature electrode configuration for real time, in situ electrochemical TLC measurements. The proposed assay results in a rapid, cost effective screening technique that can monitor thiol-based chemistries that are partitioned in the condensate. The implementation of these methods enables the performance and mechanisms of volatile inhibitors to be better characterized and understood, shedding new light on their behavior, whilst also facilitating more effective optimization of their dose rate.

Ethanolamine with boric acid can form various products, but there have not been any comprehensive studies on their properties as volatile corrosion inhibitors. The aim of thisstudy wasto synthesize products of interaction between ethanolamine and boric acid and to analyze anticorrosion properties of the obtained substances on ferrous and non-ferrous metals. To determine the composition and conditionsfor obtaining an inhibitor with high anticorrosion properties, the authors conducted experiments with a variable ratio of reagents and reaction temperature. As a result, they developed methodsfor obtaining volatile corrosion inhibitors. Four products were synthesized: ethanolamine and boric acid adduct, aminoethylborate, di(aminoethyl)borate and tri(aminoethyl) borate. The anticorrosion properties of the inhibitors were checked in accelerated tests. The evaluation of the protective ability was determined by gravimetric method, after which the corrosion rate, corrosion inhibition coefficient and degree of protection were calculated. Anticorrosive effect of volatile corrosion inhibitors wastested on specimen plates made of steel St3, copper M1 and alloys D16, L63. As a result of tests of the obtained inhibitors, di(aminoethyl)borate showed the best protective properties. Its maximum protective effect of 89.9% was observed on steel, the minimum one of 30.3% - on copper. The obtained results willsignificantly increase the degree of protection of ferrous and non-ferrous metal productsfrom corrosion during operation, transportation and storage while reducing the cost of their maintenance.

The mechanism of formation of protective films on the steel surface in the course of its treatment by the extract of rapeseed (Brassicaceae family) cake regarded as a volatile corrosion inhibitor and its compo- nent composition are experimentally determined and theoretically substantiated. The dynamics of changes in the component composition of volatile compounds in the 2-propanol extract of rapeseed cake is studied by the methods of gas chromatography, mass spectrometry, and IR-spectroscopy. The influ- ence of individual components on the corrosion behavior of steel under the conditions of periodic con- densation of atmospheric moisture is investigated. It is shown that the main components of the 2-propanol extract responsible for its anticorrosion efficiency are aldehydes, ketones, and glycosides. A model of the structure of protective films is proposed. In the course of transportation and conservation, metal products are damaged by corrosion, which decreases their user and export values. Hence, it is necessary to guarantee their temporary anticorrosion protection in or- der to preserve their quality and the outward appearance of the surfaces under the atmospheric conditions (1, 2). In this case, the most efficient and (sometimes) the only possible method for the protection of metals is given by the volatile inhibitors. At present, the production of volatile inhibitors of the atmospheric corrosion is absent in the Ukraine and the domestic market is filled with extremely expensive imported products, sometimes of very low quality. Due to the insufficient supply of these inhibitors, the increase in the cost of raw materials used for their pro- duction, and a permanent strengthening of the sanitary-hygienic requirements to the means of corrosion protec- tion, it is necessary to create new inhibiting compositions based on the natural resources. Thus, the organic compounds obtained from ecologically safe and annually renewed vegetable raw materials seem to be quite promising for the development of new volatile inhibitors of the atmospheric corrosion (3-6). In (7, 8), it is shown that the wastes of the production of oil from rape seeds (Brassicaceae family) may serve as a source of natural organic compounds. Moreover, the chemical compositions of the volatile compounds of 2-propanol extract of rapeseed cake and the inhibiting efficiency of this extract were investigated. However, we do not know the compounds appearing in the composition of this extract and responsible for its inhibiting effi- ciency. Therefore, it is necessary to study the specific features of the mechanism of formation of protective films formed from the vapors of the extract of rapeseed cake on the steel surface and to determine the compositions of these components.

Processes that initiate corrosion in systems with faulty sealing are analyzed in terms of a mathematical model developed to describe metal protection with volatile inhibitors in such systems. It was demonstrated that the protection times are often determined by the kinetics of dilution of an inhibitor with water coming from the atmosphere. The ways of enhancing the vapor-phase protection are proposed. It is found that the effectiveness of a VCI in incompletely sealed systems can be estimated in accelerated tests by decreasing its dosage and increasing the mass exchange surface since these factors stimulate corrosion without violating the similarity principle.

Volatile corrosion inhibitors (VCIs) are used to protect metal objects temporarily, such as during storage and transport. Although widely used, in the last two decades traditional synthetic VCIs have been gradually replaced due to their high toxicity. A viable solution is the use of natural inhibitors. The objective of this study was to evaluate the efficiency of limonene-based natural VCI to protect AISI 1020 carbon steel against corrosion. The vaporization capacity of VCI was evaluated by the standardized sublimation test; the ability to form a protective barrier was analyzed by testing kraft paper as anticorrosive packaging; and the inhibition mechanisms against carbon steel corrosion were investigated by electrochemical methods of open circuit potential (OCP) measurement, potentiodynamic polarization (PP) and electrochemical impedance spectroscopy (EIS). According to the sublimation test, limonene-based VCI provided effective protection to the carbon steel at a concentration of 1.5 g/L. The kraft paper test confirmed the efficiency of the temporary use (4 days) of the natural VCI in packaging, without residue deposition. Furthermore, through electrochemical measurements, we found that limonene-based VCI provided an inhibition efficiency of 99% to AISI 1020 carbon steel in a 3.5% NaCl aqueous solution, thus identifying a potential alternative to toxic synthetic VCIs.

The review analyzes the patent literature dealing with metal protection by volatile corrosion inhibitors (VCIs) and materials based thereon. It has been found inhibitors of atmospheric corrosion with vapor pressure above 10 –5 mmHg can be used as VCIs, including nitrogen-containing bases of various nature, salts of nitrogen-containing bases with some inorganic or organic acids, organic nitro compounds, esters of organic and inorganic acids, heterocyclic nitrogen-containing compounds, etc. Vapor-phase metal protection is also performed using non-volatile compounds and formulations that can release compounds of the above types upon hydrolysis. VCIs for temporary protection can be used in the form of active compounds, solutions, packaging materials, porous emitters, inhibited air, or in special forms intended for the protection of specific product types. VCIs can be used for permanent protection of metal articles within polymer coatings (paints) and working liquids (hydraulic, cooling liquids, etc.).

During operation, long-term storage and transportation through various climatic zones, metal products are exposed to the atmospheric corrosion that leads to billions of losses every year. One of the most progressive and effective methods of corrosion protection is the application of the volatile corrosion inhibitors characterized by high vapor pressure, the ability to saturate closed space with their vapors, to be absorbed by a metal surface and to inhibit the corrosion processes. Polyethylene films, crepe papers, and combined materials are the carriers of volatile inhibitors. The aim of the paper is the study of the performance properties of the polypropylene laminated fabrics used for packaging of zinc-coated metal goods. These fabrics have a number of advantages: durability, moisture resistance, they are easy to weld and sew. The authors carried out the comparative studies of various properties of new packaging materials for metal goods and selected the best-performing material. Physical-mechanical and barrier properties of polypropylene laminated fabric with and without volatile corrosion inhibitor are investigated. The study evaluated the protective ability of polypropylene laminated fabrics for the zinc-coated wire. Tests were carried out under the standard techniques; the inhibitor content was determined using the method of simultaneous thermal analysis and the method of “Walki Wisa” company. The comparative study showed that the polypropylene laminated fabric with the CORTEC corrosion inhibitor had the higher strength (when laminating as well) and deformation properties, better protective ability against corrosion. It is characterized by lower values of water absorption and vapor transmission. The authors propose the recommendations for improving the quality of polypropylene laminated fabric for corrosion protection of zinc-coated metal goods.

This paper presents a review of studies on volatile corrosion inhibitors (VCIs) for humid atmospheres. Emphasis is on the mechanisms of interaction of VCIs with the atmosphere and on methods for quantitative estimation of the volatility of organic compounds. The possibility of predicting the volatility of corrosion inhibitors based on their chemical structure and the scale of ξR-constants of substituents is analyzed. Corrosion initiation by mass and heat transfer in systems protected by VCIs is discussed. The importance of chemisorption in the efficiency of metal protection by VCIs and especially in its post-treatment effect is outlined. The energy of adsorption of lower amines by oxidized iron surface and the irreversibility of VCI adsorption are considered.

Volatile corrosion inhibitors (VCIs) can efficiently protect a variety of items from environmental attack. Many VCI compounds and compositions are known. This paper describes some of the VCI applications that the authors have witnessed in the last 20 years as well as recently developed corrosion protection systems which are designed to include a combination of inhibitors, desiccants and gases. These new developments increase the efficiency of protection and service life of the material being protected.

An appropriate corrosion protection is required for transport and storage of high-quality goods and semi-finished parts made from metals. The application of volatile corrosion inhibitors (VCI) as a means of temporary corrosion protection is based on the release of corrosion inhibitors from films, papers, diffusers or oils to the gaseous phase. By adsorption on the metal surface, the inhibitors prevent the degradation of the primary oxide layer and hence impede corrosion. In principle, the anticorrosive effect is independent of the part geometry, because the protected surfaces do not need direct contact with the VCI material. Also, the VCI method does not require costly cleaning of parts prior to further use after transport and storage. The EXCOR jar test is a common method to examine the efficiency of VCI. A metallic sample and a VCI material are exposed in a jar. After conditioning in dry and humid atmosphere, corrosive stress is applied to the sample. To clarify the VCI’s mechanism of action, the test steps, their duration and the type of inhibitors were varied. Thus, the operating principle of VCI during the test was identified. The acquired knowledge enables to understand and tailor the corrosion protection by VCI in service.

Aqualitative and quantitative system of criteria for evaluating the universality of volatile metal corrosion inhibitors (VCIs) applied to agricultural production conditions was developed. The system of qualitative criteria for universalism includes: 1- an assessment of the effectiveness of corrosion inhibition of metals under the conditions of the action of corrosion-specific stimulants present in the vapor- gas phase separately or together; 2 - suppression of various types of local corrosion caused by them in the composition of a corrosive medium; 3 - suppression in specific conditions of general and local corrosion of contacting metallic structural materials of various nature; 4 - observance of acceptable specific characteristics of VCI: ecological, class-related hazards, influence on chemical oxygen consumption (COC) and biochemical oxygen demand for the biodegradation of substances by microorganisms (BOD5). The system of quantitative criteria for universalism of the VCIs includes quantitative parameters for all the proposed qualitative items. A simplified assessment, taking into account only a part of the criteria for characterizing partially universal inhibitors, is proposed to be applied to the conditions of agricultural production. The experimental data for the volatile inhibitor IFKhAN-114 are given as an example of the effectiveness of the proposed criteria. It was shown that IFKhAN-114 is a partially universal inhi-bitor.