What is a flexible link seal used for?

A flexible link seal is specifically designed to seal a pipe within a pipe sleeve, which is crucial for ensuring water, gases, or other substances do not leak around the area where the pipe passes through the sleeve. This type of sealing mechanism accommodates the movement and expansion of the pipes that may occur due to thermal changes, vibrations, or other factors. By providing a flexible barrier, the seal maintains the integrity of the system while allowing for necessary movement, thus preventing leaks and ensuring the system's efficiency and safety.

The other options do not accurately describe the function of a flexible link seal. Sealing the end of a pipe or a valve would typically involve different kinds of fittings or seals designed for those specific applications, such as caps or flanges, which do not provide the flexibility required in a dynamic system. Similarly, sealing a drain would involve a different provisioning method to address the specific needs of drainage systems, which is not suitable for flexible link seals.