Performance of wear-resistant iron base hardfacing alloys in valves operating under prototypical pressurized water reactor conditions

Abstract

Stroke cycling tests are being conducted on gate valves with iron base hardfacing materials under simulated pressurized water reactor (PWR) conditions to find an alternative to the cobalt-based Stellites. The first phase of the program under PWR conditions where the valves were opened and closed 2000 times over a period of about 1 year has recently been completed. The candidate alloys were EB 5183, EVERIT 50, NOREM 01 and NOREM 04. One valve with Stellite 6 trim served as a standard. Prior to testing, a base-line inaugural inspection was performed. At approximately 3 month intervals and 500 stroke cycles the performance of the alloys was monitored by non-destructive examination, profilometry and leak testing. Also, corrosion coupons were used to monitor metal loss from corrosion alone. The test results show all the candidate alloys performed better than Stellite 6. One valve with EB 5183 and a valve with NOREM 04 did not show any hot leakage as a result of stroke cycling.