A thread-o-let is a female by weld connection. It is commonly seen on large diameter pipes where a valve or other connection (typically much smaller in diameter) is made.
what is difference between weldo lite and threadolites
A weldolet is a fitting you weld on a (run) pipe, and then butt weld a branch pipe to it. A tredolet is a fitting you weld on a (run) pipe, and then screw a threaded branch pipe to it. Some people call this a threadolet A sockolet is a fitting you weld on a (run) pipe, and then socket weld a branch pipe to it. A nipolet is the same as a weldolet or thredolet but has an elongated branch connection. You have to specify if it's a welded or threaded nipolet.