Where is the branch line for the desuperheater leakage test sample cooler attached?

• A. Between the desuperheater inlet and its outlet
• B. Between the outlet of the motor-operated gate valve and the inlet of the manually-operated stop-check valve to the 600 psi steam main
• C. To the feedwater line
• D. To the main condensate return line

Answer: (B)

The branch line should be taken from the desuperheater discharge side, in a section that can be isolated from both the desuperheater and the steam main. Placing it between the outlet of the motor‑operated gate valve and the inlet of the manually operated stop‑check valve to the 600 psi steam main gives you a defined segment that can be shut off with the gate valve for the leakage test, while the stop‑check valve prevents backflow from the steam main into the branch. This location ensures the sample cooler receives a clean test sample from the desuperheater path and that the main steam line cannot backfeed into the test line.

Options that tap into the feedwater line or the main condensate return line wouldn’t sample the desuperheater leakage properly, and putting the branch in other positions wouldn’t allow the necessary isolation and backflow protection during the test.