An assembly comprises a vessel comprising a shell exhibiting at least one opening extending therethrough, a structure covering an internal surface of the shell, and at least one plug device contacting the shell and the structure. The at least one plug device comprises a rigid body comprising a male connection structure longitudinally extending into the least one opening, and a base structure extending outwardly beyond a lateral periphery of the male connection structure and positioned longitudinally between the structure and the shell. A plug device for a milling application, and a method of plugging a component of an assembly are also described.