🔍 Key Concepts

• Function of a bypass line around a main valve in a high‑pressure steam system • Effects of thermal shock and rapid pressurization on main steam piping and turbines • Typical procedures for warming up main steam lines and main engines/turbines

💭 Think About

• Ask yourself: When the main steam stop is fully closed, why would engineers want a small, controlled flow of steam around it? • Consider which option describes something that must be done slowly and carefully before opening a large main steam stop valve on a cold line. • Think about which answer choices describe normal operating practice versus special situations like repairs or cross‑connecting boilers.

✅ Before You Answer

• Verify which choice relates directly to controlling the rate of pressure and temperature rise in the main steam line. • Eliminate any option that describes a use that would require a large, continuous flow of steam (a small bypass cannot safely do that). • Check your steam plant knowledge: the bypass valve is usually used before the main stop is fully opened — which option best matches that sequence?