A hex nipple thread refers to a type of threaded fitting commonly used in plumbing and piping systems. It is called a "hex nipple" because it has a hexagonal shape in the middle, allowing for easy gripping with a wrench or other tool.
It's worth noting that hex nipple threads are often used in plumbing and piping systems to connect two pipes or fittings of the same size, providing a secure and leak-resistant joint.