Procedure and device for measuring resistance to hydriding of tubes and tubular claddings

Apparatus arranged to measure the resistance to hydriding of tubes and tubular claddings characterised by:

• a high or ultra-high vacuum equipment, having a chamber, said chamber containing a mass spectrometer and a total pressure gauge, and being provided with electrically insulating seals, which are flexible so as to absorb expansions;
• a gas line arranged to pass hydrogen gas or a gas mixture of hydrogen and inert gas(es) into the interior of the tube, the permeation of hydrogen through the tube wall causing hydriding of the material thereof;
• Joule effect heating means and thermocouples and temperature control means arranged to heat said tube in a controlled manner;
• the apparatus being arranged to detect hydrogen which has permeated through the wall of the tube at the exterior of the tube by means of the mass spectrometer or by measuring the total pressure in the chamber and to determine a permeation time, on the basis of a permeation curve, i.e. a curve of quantity of hydrogen detected by the mass spectrometer against time, or total pressure detected against time, said permeation time being a time obtained from said permeation curve and representing the first appearance of hydrogen exterior of the tube, and;
• to detect a sudden rise in the total pressure, as an indication of the time of appearance of a first microcrack in the tube.