Of all process operations in any refinery or petrochemical plant, heating and cooling streams are the most common. In fact, a typical refinery has anywhere from 200 exchangers on the low end to as many as 350 exchangers for a large, complex refinery. Plants in other process industries may not have quite as many exchangers, but the number is still quite significant.
Many of these heat exchangers are in relatively clean services with only a small probability of failure. The balance is used in in “dirtier” services: Process streams where corrosive materials could be present. It is these exchangers that are much more prone to foul, leak or experience corrosion problems. Often, these problems develop slowly, but they also can be sudden.