The test piece consists either of a length of tube or a longitudinal or transverse strip cut from the tube and having the full thickness of the wall tube (see figures 12 and 13), or of a test piece of circular cross-section machined from the wall of the tube.
Machined transverse, longitudinal and circular cross-section test pieces are described in annex A for tube of wall thickness less than 3 mm and in annex C for thicknesses equal to or greater than 3 mm. The longitudinal strip is generally used for tubes with a wall thickness of more than 0,5 mm.