The pipe sizes required for the boiler equalizer line are based on what capacity?

The pipe sizes required for the boiler equalizer line are primarily determined by the safety relieving capacity. This is crucial because the equalizer line is designed to ensure that the pressure in the boiler is balanced with the safety relief valve's capacity to discharge steam or water in case of overpressure situations.

When designing and sizing this line, ensuring that it can handle the maximum flow of steam or water that might be released by the safety relief valve is essential for the safe operation of the system. If the equalizer line is too small, it could restrict flow and potentially cause pressure build-up, defeating the purpose of the safety relief mechanisms.

While the other choices, such as heating capacity, maximum pressure, and flow rate, can play roles in other aspects of boiler piping design, the equalizer line is specifically tied to the safety relief valve's output and its ability to prevent hazardous conditions by handling the appropriate discharge capacity. Thus, safety relieving capacity is the critical factor in determining the necessary pipe sizes for an effective and safe equalizer line.