Device and method for thermally insulating a structure to prevent thermal shock therein

In a nuclear steam generator nozzle having an inner surface defined by a fluid-transmitting bore formed through the nozzle for transmitting a fluid therethrough, the nozzle having an integrally attached annular lip portion projecting into the bore, the fluid and the nozzle defining a temperature difference therebetween, a device for thermally insulating the nozzle to prevent thermal shock therein, the device comprising:

• (a) a cylindrical sleeve joined to the lip portion to define a joint therebetween for affixing said sleeve to the lip portion, said sleeve extending into the bore, and interposed between the bore and the fluid for thermally insulating the nozzle as the fluid is transmitted through the bore, the joint and the fluid defining a temperature difference therebetween, said sleeve having an inside surface and an annular flange integrally attached to and inwardly projecting from the inside surface;
• and
• (b) a cylindrical liner concentrically disposed in said sleeve and covering the joint for thermally insulating the joint as the fluid is transmitted through the bore, said liner having a first end portion joined to the flange for affixing said liner to the flange and having a second end portion engaging the inner surface of the bore, whereby the temperature difference between the nozzle and the fluid is maintained as the sleeve extends into the bore so that the nozzle is thermally insulated to prevent thermal shock to the nozzle as the fluid is transmitted through the bore and whereby the temperature difference between the joint and the fluid is maintained as said liner covers the joint so that the joint is thermally insulated to prevent thermal shock to the joint as the fluid is transmitted through the bore.

In a nuclear steam generator having a nozzle having an inner surface defined by a fluid-transmitting bore formed in the nozzle for transmitting a fluid therethrough, the nozzle having an integrally attached lip portion projecting into the bore, the fluid and the nozzle defining a temperature difference therebetween, a method of thermally insulating the nozzle to prevent thermal shock therein, the method comprising the steps of:

• (a) thermally insulating the nozzle by extending a cylindrical sleeve into the bore, the sleeve having an inside surface and an annular flange integrally attached to and inwardly projecting from the inside surface;
• (b) affixing the sleeve to the nozzle by joining the sleeve to the lip portion to define a joint therebetween, the joint and the fluid defining a temperature difference therebetween;
• (c) thermally insulating the joint by concentrically disposing a cylindrical liner in the sleeve and by covering the joint with the liner;
• and
• (d) affixing the liner to the sleeve by joining the liner to the flange, whereby the temperature difference between the nozzle and the fluid is maintained as the sleeve extends into the bore, so that the nozzle is thermally insulated to prevent thermal shock to the nozzle as the fluid is transmitted through the bore, and whereby the temperature difference between the joint and the fluid is maintained as the liner covers the joint so that the joint is thermally insulated to prevent thermal shock to the joint as the fluid is transmitted through the bore.