A weld coupling is a device used to create a threaded port connection on a tank, cylinder, bulkhead, or the end of a piece of pipe. Essentially, it allows you to weld it onto a surface and then use the threaded connection for various purposes, such as attaching hoses, pipes, or other fittings. This enables flexibility in designing and modifying systems, as it provides a secure and reliable point for connecting components without the need for complex welding or machining. Weld couplings are commonly used in industrial settings to enhance the versatility and functionality of equipment and piping systems, ensuring efficient fluid transfer and operation.

Half couplings have a thread on only one side for adding an external connection only. Full couplings have a thread on both sides. They are often used on reservoirs where connections are not only made on the outside of the tank, but also inside where downpipes typically connect.