When a boiler economizer is fitted with a valved bypass, Coast Guard Regulations (46 CFR) require which of the following devices to be installed?

Correct Answer: Option A — A stop check valve is to be located at the economizer outlet.

When an economizer is fitted with a valved bypass, 46 CFR mandates a stop check valve at the economizer outlet to prevent backflow and protect the economizer tubing from thermal shock, pressure surges, or dry-firing conditions during startup and bypass operations.