repair tag by Superior Welding, serial # 05-89-2004-01 with welded 2:1 elliptical heads Internal coil, of 321 SS seamless pipe, is 2 & 3/8" diameter x 0.218 wall thickness. It has 13 turns with a 36" mean diameter on a 4" pitch. Mixing is by a 16" diameter radial type impeller rotating at 258 rpm This drive arrangement features Contamination free mixing, and zero atmospheric leakage