Pipe STI (screw thread insert) taps create threads in thread standards and sizes that are used on pipe and pipe fitting because they form a pressure-tight seal. They create internal threads in a hole on pipes and pipe fittings so a helical-coil screw thread insert can be inserted in the hole. The insert distributes the load across the length of the threads and improves the threads' strength when a part with a standard pipe thread size is installed in the hole.