Thermal expansion compensation support

A method for maintaining in liquid-tight relationship among a plurality of metallic mold elements that undergo different rates of thermal expansion over a temperature range from an ambient, pre-startup temperature to an elevated operating temperature, comprising the steps of:

• positioning a support member between certain mold elements to apply compressive force, the support member including a spring in a housing, the spring acting to separate the mold elements by a defined gap when the mold elements are at the pre-startup temperature;
• applying a first compressive force by means of the spring in the support member, wherein the first compressive force increases as the mold elements expand with increasing temperature for a first portion of the temperature range from the pre-startup temperature to a temperature less than the operating temperature;
• and
• applying a second compressive force for a second portion of the temperature range after thermal expansion of the mold elements has compressed the spring to close the gap, resulting in direct metal-to-metal contact between the mold elements and the support member prior to the mold elements reaching operating temperature, wherein the second compressive force is greater than the first compressive force and is created primarily by continued thermal expansion of the mold elements after metal-to-metal contact is achieved.