Corrosion and its control in petrochemical industries
Answers
Corrosion in petroleum industry causes a loss of billions of dollars every year. Many cases of extensive corrosion have occurred in production tubing, valves, and in flow lines from the wellhead to the processing equipment. The reason for this is that oil and gas from the well contain varying amounts of water, which can be precipitated as a separate phase in contact with the material surface, and that this water contains gases such as CO2 and possibly H2S, as well as salts. In most cases of severe corrosion, CO2 plays a major role. Uniform corrosion taking place causes 30% failures and other 70% is caused by localized corrosion. Various methods of controlling corrosion are discussed here.
Introduction
EVERY industry, even every plant, has its own distribution of corrosion phenomena that occur with different frequency. About 75% of all corrosion failure takes place because of insufficient information and knowledge, as well as inadequate interaction among different groups responsible for the acceptance and approval of anti-corrosion decisions. The human factor is one of the main reasons of corrosion failures. Corrosion problems occur in petroleum industry in three main areas: (1) production, (2) transportation and storage, and (3) refinery operations. Many refineries contain over fifteen different process units, each having its own combination of numerous corrosive process streams and temperature and pressure conditions. The deterioration normally occurs very slowly, unless incorrect or defective materials were initially installed. Refinery corrosion can be also categorized as: (1) Low-temperature corrosion which occurs at temperatures below 260°C and in the presence of water. (2) High-temperature corrosion: occurs at temperatures above 260°C, with no water present.
Petroleum Industry
The petroleum industry includes the global processes of exploration, extraction, refining, transporting (often by oil tankers and pipelines), and marketing petroleum products. The largest volume products of the industry are fuel oil and gasoline (petrol). Petroleum (oil) is also the raw material for many chemical products, including pharmaceuticals, solvents, fertilizers, pesticides, synthetic fragrances, and plastics. The industry is usually divided into three major components: upstream, midstream and downstream. Midstream operations are usually included in the downstream category.
Petroleum is vital to many industries, and is of importance to the maintenance of industrial civilization in its current configuration, and thus is a critical concern for many nations. Oil accounts for a large percentage of the world's energy consumption, ranging from a low of 32% for Europe and Asia, to a high of 53% for the Middle East, with developed nations being the largest consumers. The production, distribution, refining, and retailing of petroleum taken as a whole, represents the world's largest industry in terms of dollar value.