Branch Connection fittings are fittings which provide an outlet from a larger pipe to a smaller one (or one of the same size). The main pipe onto which the branch connection is welded is usually called the Run or Header size. The pipe to which the branch connection provides a channel is usually called the Branch or Outlet size. Branch connections are in all sizes, types, bores, and classes, in a wide range of stainless steel, chrome-moly, and other alloys.