Abstract: Significant time is wasted in proving the integrity of a weld associated with the welding of a flange onto a pipe. Generally this takes place by bolting the pipe into the circuit and testing the completed circuit. The test plug according to the invention discloses means for placing a seal internal of the pipe and connecting to a flange which has been welded to end of a pipe a flange plate and bolting the flange plate to the flange in the conventional manner. The test plug defines therethrough at least two channels one for conveying into the pipe bounded by the flange plate and the seal a testing media such a fluid or liquid and the other channel for purging the same. The immediate area around the weld can thus be tested for improper welding rather than requiring the total pipe link to be tested in situ.