Under what conditions are the shell and tube sides of an exchanger pressurized simultaneously?

The scenario in which the shell and tube sides of a heat exchanger are pressurized simultaneously is commonly related to performing hydrostatic testing. During a hydro test, both sides of the exchanger are pressurized to check for leaks and to ensure structural integrity. This testing method involves filling the system with a liquid (usually water) and increasing the pressure to a specified level that is higher than the normal operating pressure. This simultaneous pressurization helps in identifying any weaknesses or faults in the exchanger before it is put into service.

The choice of performing a hydro test is critical in the commissioning phase of the system's life cycle, ensuring that all components are intact and can safely handle operational pressures. Other scenarios, such as bleeding a low pressure system or purging a high pressure system, involve different processes that do not require pressurizing both the shell and tube sides at the same time. The key commissioning test also primarily focuses on different operational aspects rather than the simultaneous pressure testing of both sides. This understanding of testing procedures is vital for maintaining safety and integrity in boiler and heat exchanger operations.