What occurs in the boiler due to overheating of tubes or from stresses developed during installation?

The correct response identifies "tube marriages" as the phenomenon that results from the overheating of tubes or stresses from installation. In the context of a boiler, tube marriages refer to the unwanted fusion of boiler tubes caused by excessive heat and stress. This condition can significantly impair the function of a boiler system, leading to operational inefficiencies or potential failure.

When stresses occur during installation, they can alter the physical and structural integrity of the tubes. Overheating can cause thermal expansion beyond acceptable limits, which may lead to sections of tube material fusing together rather than remaining correctly separated to allow for operational movement, thereby creating a maintenance challenge.

Understanding this is crucial, as it highlights the need for proper installation techniques and monitoring of boiler temperature to prevent outages and costly repairs. Other choices likely refer to different conditions that may occur in boilers under stress or overheating but do not cover the specific problem of tube marriages that arise from the outlined conditions.