What is the maximum allowable safety valve lifting pressure tolerance on boilers with a steam drum pressure of 325 psi or below?

The correct choice reflects the maximum allowable safety valve lifting pressure tolerance established for boilers operating with a steam drum pressure of 325 psi or below. Specifically, a tolerance of plus or minus 3 psi ensures both safety and compliance with regulatory standards. Safety valves are crucial in preventing overpressure situations by venting steam when the pressure exceeds safe operational limits.

Setting the tolerance to plus or minus 3 psi allows for a reasonable margin of error while ensuring that the safety valve will lift and function correctly within its designated operational pressure. This balance is important because if the valve lifts too early or too late due to excessive tolerances, it could either lead to unnecessary steam loss or a dangerous overpressure condition, respectively.

Understanding this tolerance is vital for maintaining the integrity of the boiler system and ensuring the safety of personnel working with or around the equipment.