Coupolet — Branch Outlet with Coupling End
The Coupolet is a forged integrally reinforced branch outlet fitting that combines the contoured base of a Threadolet with a full coupling-length female NPT internal thread bore at the outlet end. Where a Threadolet provides a short female NPT thread at the outlet, the Coupolet provides the full engagement depth of a standard threaded half coupling, giving a longer, more robust female thread engagement for the branch pipe or nipple that connects to the branch outlet.
The base of the Coupolet is forged and machined to the exact outside diameter contour of the specified run pipe, and is fillet-welded to the run pipe at a drilled branch opening in the same manner as a Threadolet or Weldolet. The fitting body provides the full integral reinforcement required at the branch opening without a separate reinforcing pad. The extended coupling-length female NPT thread at the outlet end engages the male NPT thread of the branch pipe, nipple or instrument fitting with significantly greater thread contact than the shorter threaded end of a standard Threadolet.
The longer thread engagement of the Coupolet is preferred where the branch connection is subject to bending loads from instrument weight, valve weight or thermal movement of the branch pipe, as the longer engaged thread distributes bending stress over more thread turns than the shorter Threadolet engagement.