When placing a shell-and-tube heat exchanger with a removable tube bundle such as a bayonet-tube heavy fuel oil service heater into service, to prevent water hammer what statement represents the correct operating procedure?

Correct Answer: Option D — Introduce the heavy fuel oil first, then crack open the condensate drains. Gradually introduce the steam, then close the condensate drains when no longer draining condensate and issuing dry steam.

Introducing fuel first ensures the shell is filled, preventing rapid steam condensation and subsequent water hammer. Cracking condensate drains allows for the safe removal of trapped moisture before full steam pressure is applied. This sequence protects the tube bundle from mechanical shock and potential structural failure during startup.