In which scenario is it acceptable to use a close nipple?

Using a close nipple is appropriate in scenarios where two pipes need to be connected directly without the use of additional fittings. A close nipple is essentially a short piece of pipe that has male threads on both ends, allowing for a tight connection between two female-threaded components. This is particularly useful in situations where there is limited space or where a seamless transition between pipes is required.

For example, if you are installing a fixture that requires a direct link between two supply lines, using a close nipple allows for a streamlined and compact installation. It provides a solution that minimizes the potential for leaks that might occur with multiple fittings and connects components more efficiently.

In contrast, other options involve applications where additional fittings or different arrangements are typically required, making them unsuitable for a close nipple.