A reciprocating pump includes a housing, a rod, a sleeve, a bellows, and a nut. The housing includes a bellows chamber and a working chamber. The rod extends into the reciprocating pump such that the rod extends through the bellows chamber and partly into the working chamber. The rod includes a shoulder. The sleeve is connected to the rod such that the sleeve surrounds a portion of the rod. The bellows is connected to the sleeve such that the bellows surrounds a portion of the sleeve. The nut is attached to a bottom end of the sleeve such that the nut clamps an end of the bellows to the bottom end of the sleeve.