4. Inspection procedure-Each single ring or cluster produced as per para. 3 and treatedsimultaneously in the same furnace and taken from the same heat shall bedefined as "lot" (the number of rings per lot to be certified by the supplier)-Test specimens needed to certify metallurgical and mechanical properties ofthe lot' shall be taken either from a single extension of a ring of equalthickness and circumference or from a ring taken from the lot to bedestroyed.