A pipe coupling fitting is a device used to connect two pipes together. It is typically used in plumbing and piping systems to join two pipes of different sizes or materials. The fitting allows for a secure connection while also allowing for flexibility in the piping system  

Half coupling is only threaded or socket weld at one end, and the other end can be welded directly into the operation of the pipe to form a branch connection. It is a joint that helps to extend or terminate a pipe. On the other hand, full coupling have both ends of threaded or socket welded.

a pipe coupling fitting is a device used for connecting two pipes together. It is commonly used in plumbing and piping systems to join pipes of different sizes or materials. The primary purpose of a coupling fitting is to provide a secure connection while also allowing flexibility in the piping system.

There are three main types of pipe coupling fittings:

Full Coupling: A full coupling is a type of coupling that connects two pipes of the same size. It has threads on both ends and provides a complete connection between the pipes, ensuring a secure fit.

Half Coupling: A half coupling is a type of coupling that connects one end of a pipe to a fitting or valve. It is used when only one end of the pipe needs to be connected. The other end of the half coupling is usually left unthreaded and can be welded directly to the pipe or attached using other methods.

Reducer Coupling: A reducer coupling is a type of coupling used to connect two pipes of different sizes. It is designed to join a larger diameter pipe with a smaller diameter pipe, allowing for a smooth transition in the piping system. The reducer coupling typically has one end with larger threads and the other end with smaller threads to accommodate the size difference between the pipes.

Each type of coupling serves a specific purpose in pipe connections, depending on the requirements of the plumbing or piping system.