Process for manufacturing a measuring tube of an electromagnetic flow sensor

A process for manufacturing a measuring tube of an electromagnetic flow sensor, said measuring tube comprising an insulation of desired thickness on its inner surface and a metal tube having a respective metal flange at each of its ends, said process comprising the steps of:

• slipping the respective metal flange at each end of the metal tube over the outside of the latter in such a way
• that a front side of the metal flange projects beyond the respective end of the metal tube by an amount at least equal to the thickness of the insulation;
• permanently and tightly joining a rear side of the respective metal flange to the outside of the metal tube;
• prior to slipping the metal flanges over the metal tube, providing each of the metal flanges, from the respective front side, with a flute
• which forms a first annular groove at its inner end;
• introducing into the lumen of the metal tube a mandrel
• whose diameter is determined by the desired thickness of the insulation, and
• which has a filler inlet and two end flanges, one at each end,
• which cover the flutes of the respective flanges at the front side;
• filling in the insulation through the filler inlet in a liquid state, and
• allowing the insulation to solidify and removing the mandrel.