Sag or Sagging Posted on 21st December 20159th May 2021 by ThePD (The Project Definition) Sag or Sagging is the settling of particles in the annulus of a well, or a non-uniform downward flow of a wet paint film. Click to share on Twitter (Opens in new window)Click to share on Facebook (Opens in new window)Click to share on LinkedIn (Opens in new window) Related Posted in Construction and tagged construction, painting. ThePD (The Project Definition) ThePD has been developing the Preferred Project Definitions based on the actual project execution and operation experiences and knowledge with the Project Language, and sharing with you daily basis.