Abstract: A unit for producing an X-ray beam tangential to a threaded joint is disclosed. The X-beam is received and compared against a master sample. If there are any differences beyond allowable tolerances a failure indication is given. The tests are performed after the joint is made up but before the pipe is placed in the well, limiting remake costs. The X-ray beam is placed tangentially by shifting or rotating the beam as needed or by having a wide beam, so that tangents are obtained at two or more locations on the circumference of the joint. The unit may also compare pipe before making up a joint.