What tool joins two pieces of galvanized pipe where neither side can be turned?

The tool designed to join two pieces of galvanized pipe when neither side can be turned is a pipe union. A pipe union is specifically used in situations where it is necessary to join two pipes, allowing for easy disconnection without needing to rotate either pipe. This is particularly useful in locations where access to the pipes is limited, or where turns would compromise the installation.

The design of a pipe union includes three parts: two male or female ends that screw onto the pipes and a central nut that connects the two ends. This allows the pipes to remain stationary while providing a secure connection that can be easily uncoupled when needed.

In contrast, a pipe tee is used to create a branching point in the piping system, and a pipe elbow is designed to change the direction of the pipe. A pipe nipple is a short piece of pipe used to connect two fittings; however, it does not allow for disconnection without turning one or both of the connected pieces. Therefore, a pipe union is the correct answer for creating a reliable connection without the need for accessibility to turn the pipes.