Outlets fittings or Branch Connection Fittings (also known as O'lets) are fittings which provide an outlet from large pipe to a smaller or same size. The main pipe onto which the connection is welded is usually called the RUN or HEADER SIZE. The pipe to which the Connection provides a Channel is usually called the Branch or Outlet Size. Branch connections are ilike SOCKET WELDING, THREADING & BUTTWELDING ENDS. MSS-SP-97 Standard Practice covers essential dimensions, finish, tolerances, testing, marking, material and minimum strength requirements for 90 and 45 degree integrally reinforced forged branch outlets fittings of buttwelding, socket welding and threaded types.