The tube in tube heat exchanger, often called a double tube heat exchanger is an all welded heat exchanger. The process fluid passes through the inner tube, while the heating or cooling media goes through the outer tube. Because of the large size of the product tube, these heat exchangers have the ability to process very large particulates. They can handle high pulp products, create low product shear, have a low initial cost, can handle high pressure, and can CIP at the same flow rate as the process piping.