Why are boiler manways and handholes typically oval shaped?

The oval shape of boiler manways and handholes is largely due to ease of installation and maintenance. The design allows these components to be pulled through a restricted opening more straightforwardly than round shapes, making them easier to remove from the pressure vessel. The oval configuration provides a larger area in the center while still maintaining the necessary strength around the edges. This practical consideration is important in industrial settings, where maintenance and inspections are critical for safety and efficiency.

Other options, while they may contain elements of truth, do not directly address the primary reasons for the oval design. For instance, while sealing and structural integrity are important design factors in any opening on a pressure vessel, these do not specifically justify the choice of shape in the same direct and practical manner as ease of removal does.