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Why must salt be removed from crude oil before furnace heating?

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Aerial view of an oil refinery complex near New Orleans, Louisiana, with storage tanks, industrial structures, and smoke rising from the facility, surrounded by open land. — petroleum refining Aerial view of an oil refinery near New Orleans.

Salt must be removed from crude oil before it reaches the furnace because, if left in the mixture, the salt would be deposited on the interior of the furnace tubes. This accumulation leads to plugging, which can obstruct the flow of oil and impair the efficiency of the heating process.1

To prevent this, refineries utilize a desalting drum. In this process, a controlled amount of water is added to the crude oil, and the mixture is passed through an electric field to separate the saltwater phase from the oil before it enters the furnace for high-temperature heating.1