Unions are types of connection methods used for joining PVC pipes. There are two types of unions: threaded or socket. They are also locally known as a water moor.
Union Thread: This has male or female threads (or both) that allow the fitting to be screwed onto the corresponding threads of a pipe or another fitting. This type of connection is useful for creating a seal that can easily be undone for maintenance or replacement without cutting the pipe. Union threads are especially useful in situations where some degree of disassembly or adjustment might be necessary.
Union Socket: A union socket involves inserting a pipe into the fitting. These are typically secured with solvent glue, creating a permanent and strong bond. Socket fittings are used when a durable, leak-proof connection is required and where disassembly is not anticipated.