Abstract: The invention is concerned with the production of pieces by powder metallurgy, and, more particularly, the use of powders with spherical particles, such as those obtained by pulverisation, in a gas of a liquid metal or alloy.The metallic powder according to the invention is constituted by granules, each of these comprising an assembly of spherical particles which have been agglomerated by at least 0.5% of gelatin.This powder is prepared by mixing with the spherical particles an aqueous solution of gelatin; a paste is thus obtained which is broken in such a way that granules are obtained by calibration and drying.Application to the production of pieces made of non-oxidising, fire-proof, or other, steels or alloys.

Abstract: A method for the detection and evaluation of faults existing on the walls of metal tubes having internal helical ribs includes for each fault signal received by an ultrasonic emitter-receiver ER, the length of the to-and-fro travel completed by the ultrasonic beam corresponding to the signal is determined and after the amplitude of the signal has been compared with a specific threshold, a correction is applied to one of the terms of the comparison, taking into account the length of travel completed by the signal.