Application of resistant nanocomposite coating on gas transmission pipelines in Mazandaran province to prevent corrosion

Thesis

Master's degree

Department: Chemical Engineering

Abstract

Hard polyurethane [1] is always one of the most effective and practical polymers in various industries, especially It is considered coverage. Excellent adhesive property, curing ability at ambient temperature and corrosion resistance of this polymer are some of its remarkable features. This study was conducted in order to improve the properties and fix some of the defects of this polymer in the matter of coating gas transmission pipelines with emphasis on deployment in the humid Caspian regions. In this study, using nano technology, a polymer nanocomposite (polyurethane/hydrophobic modified silica nanoparticles) was produced. The results obtained from the quality tests of this nanocomposite showed the improvement of hydrophobicity indices, resistance to mechanical wear, delay in flammability and reduction in the fall of fire fragments, improvement of water absorption properties and elasticity of the coating in concentrations lower than one percent by weight of silica nanoparticles in the ground phase. The amount of adhesion to the surface and the gelation time of the samples decreased and increased, respectively, with the increase in the concentration of nanoparticles. By examining the results, a concentration of 0.7 percent by weight of nanoparticles and an average thickness of 1400 micrometers is suggested as the optimal coating mode. One of the most accessible and appropriate ways to access this important is the use of fossil fuels, especially natural gas tanks, which is to create a basis for the use and productivity of these valuable resources, whether in the country's domestic use, including industrial, household, combined cycles, heating, etc. And in terms of export and economic benefit, we will need to send natural gas in different ways. Metal gas transmission pipelines are always one of the most effective and efficient methods of sending natural gas to different parts of the country and the world. With a general survey, you can understand the huge volume of these facilities in the country. It is quite clear that these huge metal facilities are always affected by environmental factors and suffer from damage. One of the most obvious problems that imposes huge costs on the country's gas industries every year is the phenomenon of corrosion. According to the transit location, the establishment of gas transmission pipelines can be divided into four general parts. The first part: the passage of atmospheric pipelines, the second part: underground (buried), the third part: submerged and the fourth part: floating. It is quite clear that according to these situations, the factors of the destruction of gas transmission pipelines will be different, as well as the type of method used to prevent and minimize environmental damage and corrosion, for example, choosing the type of pipeline as well as the desired coating in submerged and underground situations is much easier than choosing for the atmospheric situation, because the atmospheric conditions are much more variable than the other two situations, and there you have to consider different factors such as the effects of solar rays, wind, types of acid and normal rains, night temperature difference and day and considered The National Gas Company of Iran has about 16 thousand kilometers of gas transmission pipelines, of which about 5 thousand kilometers are covered with three layers of polyethylene and the rest, which is about 11 thousand kilometers, have other types of coverings (petroleum base bitumen, coal bitumen, tape). In addition to these coatings, the cathodic protection system is considered for the double protection of gas transmission lines [5]. In this series, first, the explanations needed to better understand the importance of the subject have been discussed, then the laboratory practices and results have been described, in order to introduce a new and reliable coating from different aspects. 

1-1-      Corrosion [1]

1-1-1-           Introduction to corrosion

We are living in a century when metal is one of the main materials available to mankind and the use of metals in various industries and devices is increasing day by day. Considering the increasing use of metals, the issue of protecting and increasing the useful life of parts is of particular importance.Metals in nature are in the form of ores and together with other minerals in thermodynamically stable conditions. In order to use it, it must be extracted and by spending the costs of extraction, construction and production, it should be made into a metal with the desired conditions. After the extraction of the metal, it is thermodynamically unstable, and if there are suitable environmental conditions, it turns into its stable state again. This transformation from unstable to stable state is called corrosion. In fact, the occurrence of corrosion causes waste of the desired materials and the cost of their production. This is where the protection of materials and their better productivity gain new dimensions. Therefore, it should be possible to somehow find the causes of metal destruction as well as the conditions to prevent this destruction [59]. If the corrosion is excessive, the devices become unusable. Corrosion is an electrochemical reaction between a metal and its surroundings. This action is accompanied by cathodic reaction (oxygen regeneration or hydrogen gas evolution). Corrosion conditions are always available due to the constant presence of water, air and humidity in the environment, and as a result, corrosion is inevitable. Of course, it should be noted that corrosion is not only limited to metals, but also affects composites and polymers. Meanwhile, the role of corrosion engineering is to choose materials that are resistant to corrosive factors and should also try to reduce the corrosive effects of environmental factors. Corrosion not only destroys many practical capabilities of the device, but also has a negative effect on the production product and return on investment [2]. It can cause significant financial losses to industries every year. Destruction and corruption or change and transformation in the properties and characteristics of materials, generally metals due to their reaction with the surrounding environment, of course, destructions caused by purely physical or mechanical factors are not called corrosion, such as wear, fatigue, scratches, but in some cases, corrosion processes may be accompanied by such destructions, in which case, with titles such as abrasion corrosion, scratch corrosion, stress corrosion, etc. are described [39]. In the past, it was thought that if we can equip the pipe with coatings that cut off its contact with the environment, then corrosion will be prevented. Of course, this is a logical idea, but the problem is that this type of protection will be complete when:

A- During installation, no coating is left in the pipe. The passage of time is resistant and standing.

Abstract

Rigid polyurethane polymer has a functional role in various industries, especially the coating industry is considered. Excellent adhesion properties, corrosion resistance and ability to cure at room temperature, the polymer is its remarkable features. The aim of this study was to apply the use of nanotechnology in order to produce polymer nanocomposites (polyurethane / hydrophobic modified silica nanoparticles). The results of the quality assessment of the nanocomposite test, indicating improved hydrophobicity index, mechanical abrasion resistance, flame delays in productivity and in segment loss by fire, water absorption properties and elastic casing at concentrations lower than one percentage weight of silica nanoparticles within the matrix. adhesion to the surface and gel time of the sample, respectively, decreased and increased with increasing concentration of nanoparticles.