Corrosion control in the refining industry

For the safe operation of a refinery, all the disciplines need to be together. Whether it is the accounting person or even the pay slip person, we all need to be on the same page or we will have a problem

- Dr Sadegh Parvizi

From the proximity of assets to saltwater to the production and storage of hazardous chemicals, refineries pose unique challenges that require specialized training to combat corrosion. Dr Sadegh Parvizi, Principal Engineer, McDermott International Inc., UK, was in Mumbai as part of the AMPP Educational Team to conduct a program on Corrosion Control in the Refining Industry. In a chat with C&ACER, Dr Parvizi speaks about corrosion and metallurgical problems that occur in refineries.

What are the major issues in refinery corrosion?

As you will know - in oil and gas corrosion is the main issue for integrity and affects the entire plant.

Crude oil contains a number of contaminants. If it was just hydrocarbon, there would not have been a problem. But because of these contaminants, we are getting corrosion even after processing of crude oil. Some contaminants come from natural sources like sulfur, nitrates, and salt, especially magnesium chloride, calcium chloride and sodium chloride, etc.

And, when processed, we create more corrosive agents like hydrogen sulfide, cyanide, HCL, etc. That is why we have to be careful about the pretreatment of crude oil. Crude oil is pretreated and then enters the distillation tower. I always assimilate every unit of the refinery to give them bucks about the outcome.

Take the example of the distillation tower. The CDU or crude distillation unit is like the heart of the refinery. If you are not talking about the CDU, you are not talking about refinery. Even after crude distillation, some fractions of contamination are still out there. It is not eliminated straight away.

Then we go to other units. All units have different types of corrosion. Upstream is different from refinery, because in upstream you are dealing with low temperatures. But in the refinery, we are dealing with high temperatures where the corrosion mechanisms are quite different.