Question 297Steam Plants - Assistant Engineer

The correct answer is A) gradually increase the pressure and temperature of the main steam piping when warming up. The main steam stop bypass valve is used to slowly increase the pressure and temperature of the main steam piping system when bringing the boilers up to operating conditions. This gradual warming helps prevent thermal shock and uneven expansion that could damage the piping. The bypass valve allows steam to flow through the system at a controlled rate until the proper operating pressure and temperature are reached. The other options are incorrect because the main steam stop bypass valve is not used to supply auxiliary steam (B), isolate the main steam stop for repairs (C), or cross-connect boilers (D). Those functions are served by other valves and components in the steam system.