Corrosion Failures in Petrochemical Refinery

Mechanical integrity of units and facilities in the petroleum refinery industry remains as a heavy concern due to Health, Safety and Environment (HSE) purposes. Failure of machines and units contribute significantly to the major accidents that happen in the industry. According to the European Union, it is identified that our of 137 major petrochemical refinery accidents, approximately 20 percent of the cases are contributed by corrosion failures. Metallic equipment that are installed in a petrochemical refinery contact numerous substances such as crude oil, natural gas, water and atmosphere. Regardless of the refining processes, all of them involve rigorous reactions together with the participation of that take place in various pressures and temperatures ranging from vacuum to 1000 bar and from -196 ˚C to 1400˚C (Groysman, 2017). Hence, it is vital to evaluate the risk of this vulnerable petroleum refining industry which can potentially create hazards to the environment and society.

To understand corrosion failures in petroleum refinery, it is important to know the natures and properties of the fluids we are dealing with in the refinery. Fluids such as crude oil and natural gas are corrosive. For crude oils, they are mixtures of hydrocarbons containing dissolved gases, water, and salts. Unremovable water in the crudes, varying from nearly fresh to saturated salt contribute mainly to crude oil corrosiveness. Impurities such as sulphur and nitrogen as well as microorganisms also can be present in crude oils, which can corrode the equipment and facilities (Groysman, 2017). On the other hand, natural gas, a homogeneous gaseous mixture of mainly hydrocarbons can be corrosive as well. Substances contained in natural gas such as carbon dioxide, hydrogen sulphide and contaminated fresh water can cause corrosion of metals. Gases such as carbon dioxide and hydrogen dissolve well in this pure water which makes the water acidic and corrosive. (Groysman, 2017).

Corrosion failures in equipment such as pipelines and petroleum refining units pose a heavy risk in the industry. Corrosion failures result in severe damage in assets. Taking the event that happened in 1984, in Romeoville, Illinois for instance, an oil refinery exploded and experienced heavy loss in assets. The event is due to corrosion failure that associated with amine absorber pressure vessels. An amine absorber pressure vessel failed and flammable gases and vapor were released into the atmosphere. The unwanted event resulted in 17 deaths, 17 injuries and damage of over 100 million US Dollar. Test results discovered that the subject plate of the amine absorber was susceptible to hydrogen-induced cracking. In addition, repair welds that were done in the field had not undergone stress relief, making them highly vulnerable to amine-induced corrosion and cracking.

The most significant deterring factor in evaluating corrosion failure to refinery equipment and installations are the dominant mechanisms of deterioration and failure related to corrosion damage. In fact, corrosion damage demands an excellent understanding of the role of equipment metallurgy and dominant corrosion mechanisms. Common corrosions that associates with petrochemical refinery include naphthenic acid corrosion, sour water corrosion and amine corrosion. Cracking concerns which include carbonate cracking, hydrogen induced cracking (HIC), stress-oriented hydrogen induced cracking (SOHIC), and sulphide stress cracking (SSC) need to be considered as well (). A corrosion monitoring program can be a good alternative to mitigate corrosion failure events in petrochemical refineries. Such program offers comprehensive and full monitoring on all the important and major components for any signs of corrosion. The program also identifies non-conforming alloy components which are generally sensitive to fastened corrosion and can contribute to relatively frequent cause of failures. Furthermore, corrosion monitoring is very effective when it comes to corrosion failure prevention when it is integrated into preventative maintenance and the processes that are inherent to safety management programs (). The outcome of the Corrosion Monitoring program shows that good decisions can be well made. The decision covers a lot of aspect in which the decision does not only concerns about the remaining lifespan of the corroded unit. It also covers life extension strategies, prospective and appropriate material selection, and cost-effective alternatives for remedial actions resulting from corrosion. Such asset integrity methodology portrays a lifecycle-based method to control corrosion failure.