Exemplary embodiments of the invention relate to a compressive rod assembly for applying force to a refractory vessel positioned within an outer metal casing. The assembly includes a rigid elongated rod having first and second opposed ends, a threaded bolt adjacent to the first opposed end of the elongated rod, and a compressive structure positioned operationally between the elongated rod and the bolt. Compressive force applied by the bolt to the elongated rod passes through the compressive structure which allows limited longitudinal movements of the elongated rod to be accommodated by the compressive structure without requiring corresponding longitudinal movements of the bolt. Exemplary embodiments also relate to rod structure forming a component of the assembly, and to a metal containment structure having a vessel supported and compressed by at least one such assembly.