Which flange size will require a larger diameter stud bolt?

The correct choice indicates that a flange rated at 1-1/2" 300 will require a larger diameter stud bolt compared to options with a lower pressure rating or smaller diameter.

Flanges are categorized by their material properties and pressure ratings. A higher pressure class, such as 300, typically signifies that the flange is designed to withstand higher pressure conditions, necessitating a stronger and larger diameter stud bolt to ensure proper sealing and structural integrity under these conditions.

Flanges of the same nominal size but different ratings will have different dimensions and tolerances. In this case, the 1-1/2" 300 flange supports a significant increase in pressure capacity compared to the 1-1/2" 150 flange, requiring a larger diameter bolt to handle the increased load and pressure.

Additionally, as the nominal size increases, as seen in the 2" 150 and 3" 300 options, the corresponding stud bolt sizes may differ based on the pressure ratings and mechanical considerations. However, the specific combination of a higher pressure rating (300) at the same nominal size (1-1/2") directly correlates with requiring a larger diameter stud bolt to safely secure the connection.