What does the efficiency of a joint in boiler construction refer to?

The efficiency of a joint in boiler construction specifically refers to how effectively the materials are used in terms of their strength when the joint is subjected to pressure and temperature changes. This concept is quantified as the percentage of the joint's strength relative to the strength of the base material surrounding it. A higher efficiency indicates that the joint can withstand stress better, which is crucial for the safe operation of a boiler. In this context, it is important for ensuring that the overall structure remains durable and reliable under operational conditions.

While factors such as fitting, cost, and installation time are significant in practical scenarios, they do not define the intrinsic efficiency of the joint in terms of its strength and reliability under operational stresses, making the other options less relevant in this case.