Fipt x Fipt unions are used when you have a need to take the pipes apart again. Like couplings they are used to join two pipes together. However, unions have some special properties that allow them to be taken apart for repairs or for mobility. Once the pipes are connected to the two halfs of the union, they screw together (without the need for the pipes to turn) and include a washer to provide a water-tight seal. If both pipes have threads on the end, you will need a FIPT/FIPT union or threaded union. The abbreviations simply stand for female inside pipe thread. A FIPT/FIPT union has female threads on both sides, meaning that your pipe will need to have male threads on both sides. Once the union sections are connected to the pipes, the union is screwed together to form the joint. All of our Schedule 40 fittings are NSF rated 14 and 61, which means they are certified for use with potable (drinking) water. Maximum temperature is 140 degrees F.