Abstract: This invention provides improved apparatus for clamping together a pair of flanges of a processing vessel. The apparatus includes an elongated tubular stem having a handle at one end thereof for applying torque to the stem. Means defining a surface at the other end of the stem for engaging one of the pair of flanges in the clamping position of the apparatus is provided together with means defining screw threads on at least a portion of the interior of the tubular stem. An elongated threaded stud is at least partially received in the threads of the tubular stem. The end of the stud remote from the stem has a pivot axis defining means thereon for pivotally connecting the stud to the other one of the flanges of the processing vessel.