Closure key apparatus

Claim 1

A shear ring closure for supporting an end wall structure carried internally within an opening provided in the casing of a pressure vessel including a circumferential groove formed about the interior surface of the opening in the casing having a radially extending outer wall in close proximity to the outer end of the casing, a radially extended inner wall and an axially extended bottom surface therebetween, a shear key seated within the groove and extending inwardly in a radial direction whereby a portion of the key extends into the opening within the casing, a recessed shoulder formed in the outer periphery of the end wall having a radially extending back wall positioned between the inner and outer end walls of said groove in the casing with the back wall of the shoulder being in contact with the inner face portion of the shear key extending into the casing opening, and an axially extending wall perpendicular to said back wall that penetrates the outer face of said end closure, a support key seated against the radially and axially extending walls of the recessed shoulder formed in the end wall with the outer surface of the support key being in contact with the bottom surface of the shear key to support the shear key within said groove, and a pair of raised moment control pads mounted upon the shear key, one of said pads being in contact with the bottom surface of said groove in the casing and the other of said pads being in contact with the outer radially extending end wall of the casing, said pads being strategically located in regard to the center of gravity of the shear key to substantially offset the bending moments exerted thereon by the support key and the back wall of the recessed shoulder formed in the end closure.