A barred tee is a tee or any fitting with a branch used in pipelines that is pigged and has a restriction bar welded internally preventing the pig from traveling down a branch connection. The bars are installed so they are flush with the inside diameter of the pipeline to keep the pig from hanging up when it passes through. The bars should be of a similar or identical material as the parent material.
Bars are placed on the internal side of a tee or really any branch connection big enough to sidetrack a pig while traveling down a pipeline. The size of the bars on the tee should be small enough so that they do not restrict the flow from the branch connection. However, they should be large enough to prevent breakage based on the flow rate through the branch connection of the tee.