Patent Number: 052746836
Section: description

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT The drawing illustrates a portion of a pressurizer vessel wall 10 having a nozzle bore 12 therethrough. The interior of the pressurizer is provided with a corrosion resistant cladding 14 such as stainless steel. In this drawing, existing nozzle remnant 16 remains in its original installed position at weld 18 approximately at the junction of cladding 14 and the interior of pressure vessel wall 10. The method of the invention is carried out as follows. The original nozzle is cut by any suitable means such as machining approximately at the junction of cladding 14 and the interior of pressure vessel wall 10. The portion of the original nozzle that extends beyond the exterior of pressure vessel wall 10 is removed. A weld pad 22 is deposited on the exterior of pressure vessel wall 10 around nozzle bore 12. The remaining portion of the original nozzle is removed by any suitable means such as machining. The surface of nozzle bore 12 is then prepared to receive a thermal spray coating. Thermal spray coating 20 is then applied to nozzle bore 12. Thermal spray coating 20 is comprised of a material such as stainless steel, nickel-chromium, or monel that is corrosion resistant and acts as a liquid barrier to prevent corrosion of the carbon steel of pressure vessel wall 10. Replacement nozzle 24 is inserted into nozzle bore 12 and welded in position to weld pad 22 using partial penetration weld 26 all the way around replacement nozzle 24 and weld pad 22. Weld 26 provides the necessary seal at the exterior of pressure vessel wall 10. Replacement nozzle 24 is formed from a corrosion resistant material as the original nozzle was. Therefore, no corrosion will occur to pressure vessel wall 10 or replacement nozzle 24 as a result of any liquid seepage between replacement nozzle 24 and thermal spray coating 20. Because many varying and differing embodiments may be made within the scope of the inventive concept herein taught and because many modifications may be made in the embodiment herein detailed in accordance with the descriptive requirement of the law, it is to be understood that the details herein are to be interpreted as illustrative and not in a limiting sense.