Which structural feature helps maintain the integrity of a sterilization boiler?

The cylindrical shell is a crucial feature in the design of a sterilization boiler because it effectively withstands both internal pressure and external forces. This shape distributes stress evenly across its surface, reducing the likelihood of structural failure that could arise from the high pressures typically involved in sterilization processes. Additionally, cylindrical shells are efficient in terms of material usage while providing maximum strength, which is essential for maintaining safety and integrity during operation. The design minimizes the chance of weak points where potential ruptures or leaks could occur, ensuring the boiler can function reliably under the demanding conditions required for sterilization.

In contrast, options like an open structural framework or perforated upper surfaces do not provide the same level of pressure resistance and overall robustness. A vertical chimney serves different purposes, mainly related to ventilation and exhaust, rather than the structural integrity of the boiler itself.