Patent Number: 059463651
Section: claims

1. Process for producing a guide tube for a nuclear reactor fuel assembly, said guide tube having a substantially constant outside diameter and comprising at least one main part having a first wall thickness and, on a fraction of the length of said guide tube, a reinforced part which has a second wall thickness exceeding said first wall thickness, by rolling a tubular blank on a mandrel in a pilgrim rolling mill, said process comprising the steps of:  receiving at the output end of said pilgrim rolling mill a rolled tubular product comprising successive regions having respectively said first wall thickness and said second wall thickness,  cutting said rolled tubular product into sections in given regions thereof for obtaining a plurality of guide tubes each of which comprises a main part having a first wall thickness and a reinforced part having a second wall thickness exceeding said first wall thickness. 2. Process according to claim 1, comprising effecting in succession along the length of the same blank in a repeated manner, said first rolling stage, a first intermediate displacement of said mandrel, said second rolling stage and a second displacement of said mandrel in the opposite direction to said first displacement, said first intermediate displacement of said mandrel being effected in the axial direction between a first position and a second position permitting said reductions in diameter and wall thickness of said blank in the course of said first stage and said second stage respectively, 3. Process according to claim 2, wherein said tube is cut with the use of a flying cutting device. 4. Process according to claim 2, comprising, prior to said cutting of said rolled product, locating on said rolled product the position of one end of transition regions between the parts of said rolled tubular product having said first wall thickness and second wall thickness respectively. 5. Process according to claim 4, comprising locating said end of said transition regions with the use of an air gauge connected by a pipe to a nozzle which is inserted inside said tubular product. 6. Process according to claim 4, comprising locating said position of said end of said transitions of said rolled tubular product with the use of an eddy current sensor formed by a coil surrounding said rolled tubular product.