Valinox

Valinox Nucleaire

Denis Vuillaume

Alain Muggeo

Jean-Louis Buret

The process relates to the aptitude for detectability of defects using eddy-currents on metal tubes cold laminated using a pilger mill and relates more particularly to the possibility of reducing the background noise and increasing the ratio between a standard signal and this background noise. The process consists of carrying out, after reduction in section by at least 30% in a cold pilger mill, a hollow drawing pass with a reduction in the external diameter of approximately 0.1% to 5%. The signal/background noise ratio can in this way be multiplied by a factor of between 2 and 3.7, in the case of a series of tubes made of INCO 690 alloy, as shown in the single figure. The invention also relates to tubes produced using this process. Application in production of steam generating tubes for nuclear power stations.

Process allowing background noise to be reduced during eddy-current

The method according to the invention relates to the production of a bimetallic tube, the cross-section of which comprises an outer annular zone and an inner annular zone, these zones being of different compositions. The method resides in preparing a blank (1) comprising two tubular components (2, 3) housed one inside the other and of different compositions and separated by an annular space (4) which is filled with divided metal. The whole assembly is made rigid by two end pieces (7, 8) and coextrusion is carried out at a suitable temperature to ensure a metallurgical bond between the inner component (2) and the outer component (3). The bimetallic tube obtained is particularly suitable for uses in which one of its two outer or inner walls is exposed to a medium which is more aggressive than the other.

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Montbard, France

Denis Vuillaume