NDTsi 2001 Session: Major Component Inspection I-IV
Ultrasonic Testing of Small Bore Piping Socket Welds
R. Linden, B. Swoyer, PPL Susquehanna LLC, USA
ABSTRACT
Vibrational fatigue that have caused fatigue failures in small bore piping socket welds continue to occur frequently in nuclear power plants. Such failures have a high cost impact on the industry. Early detection and replacement of these welds using the present techniques not only avoids the high cost of forced shutdowns due to these fatigue failures, but also increases their life. An ultrasonic technique has been developed that is qualified to identify cracks in these small-bore socket welds. This paper presents this UT technique and the metallurgical evidence that verifies its accuracy. An in-depth presentation of the ultrasonic procedure using 60° shear waves on contoured shoes will be discussed. Flawed specimens were manufactured containing cracks and lack of fusion for the purpose of a performance demonstration on 3/4", 1" and 2" pipe socket welds. There are four plants in the United States that have utilized this procedure. Socket welds that contained cracks identified by this UT technique were analyzed for size and extent of the cracking. This destructive evaluation validated the capability of this UT technique. Although there is always the possibility that the fatigue cracking on standard size fillet welds can initiate and propagate during a two year operating cycle, utilizing this technique greatly reduces the possibility of a through wall failure occurring and forcing a mid-cycle shutdown.
Publication Source: 3nd International Conference on NDE in Relation to Structural Integrity for Nuclear and Pressurized Components, November 14-16, 2001, Seville Spain. Publisher: Tecnatom s.a. - [Homepage]
