API Plan 23 (Cooled Seal Chamber Circuit) | API 682 Piping Plan for Mechanical Seals

Closed-loop cooling circulation: Process fluid circulates from the seal chamber through a pumping ring and cooler. The cooled fluid then returns to the seal chamber.
Stable circulation: A pumping ring or circulation sleeve drives continuous fluid movement. This helps maintain a stable seal chamber temperature.
Reduced heat transfer: A close-clearance throat bushing can isolate cooled seal chamber fluid from hotter pump fluid. This reduces heat transfer and cooler duty.
Flexible cooling options: The system can use water-cooled or air-cooled coolers. Temperature indicators, vents, and drain connections can also be included.
High-temperature service: Plan 23 reduces seal face temperature without increasing seal chamber pressure. It helps minimize flashing, vaporization, and thermal stress.

API Plan 23 (Cooled Seal Chamber Circuit) is a closed-loop flushing and cooling system for mechanical seals. It uses process fluid from the seal chamber for internal recirculation. A pumping ring or circulation sleeve drives the fluid through a cooler. The cooled fluid then returns to the seal chamber.

This circulation reduces and stabilizes the temperature around the seal faces. It helps suppress flashing and vaporization without increasing seal chamber pressure. The arrangement also improves mechanical seal reliability in high-temperature services.

API Plan 23 is widely used in centrifugal pumps and other rotating equipment. Typical applications include hot water, boiler feedwater, hydrocarbons, and chemical fluids.