The Collaborative International Dictionary of English v.0.48:

Pipelaying \Pipe"lay`ing\, n., or Pipe laying \Pipe" lay`ing\
   1. The laying of conducting pipes underground, as for water,
      gas, etc.
      [1913 Webster]

   2. (Polit. Cant) The act or method of making combinations for
      personal advantage secretly or slyly; -- in this sense,
      usually written as one word. [U.S.]
      [1913 Webster] pipeline