Abstract: A thermocouple assembly for sensing temperatures of molten metals in a metallurgical vessel, such as a tundish used in continuous steel casting, includes a double bore insulator containing the two noble metal alloy lead wires of the thermocouple. Platinum-rhodium alloys are preferred. The weld bead joining the ends of the leads or hot junction of the thermocouple is positioned within one of the bores of the insulator such that a lower purity alloy lead is exposed in the loop. The loop resides in a blind bore formed in the end of the double bore insulator and is enclosed in a containmemt zone by a refractory plug or foil disc closing off the end of the blind bore. The double bore insulator is received in an axial bore of a refractory sheath having a closed end adjacent the loop area of the thermocouple.

Abstract: An all ceramic thermocouple protector tube is provided having a tubular elongate ceramic thermocouple protector closed at one end and open at the other to receive a thermocouple, an adjacent larger diameter cylindrical ceramic housing spaced from said tubular elongate thermocouple protector and connected thereto by a hollow frusto conical ceramic member having a taper in the range 20.degree. to 60.degree. and an annular pocket in the end of said housing remote from the frusto conical portion adapted to receive a cover.