🔍 Key Concepts

• Function of waste heat boilers in exhaust gas systems • What forms inside gas passages when hot exhaust meets cooler surfaces • Difference between devices that handle liquid removal vs pressure relief

💭 Think About

• Think about what type of fluid is most likely to collect in the gas side of an exhaust gas/waste heat boiler casing during normal operation and cool-down. • Ask yourself: which option describes something that would typically be removed by a drain line rather than by a vent, relief valve, or sampling line? • Consider whether boiler water from tube leaks, high pressure gas, or test samples are normally handled by the same kind of small, low-point fittings that are called drains.

✅ Before You Answer

• Verify what a casing drain is usually connected to (low points where liquids can collect). • Check which choice describes a normal, routine condition rather than an abnormal emergency condition. • Confirm which option best matches the idea of removing liquid accumulation from the gas passage side, not water on the water/steam side of the boiler.