F- Chen et aL/ Engineering Failure Analysis 37(2014)42-52 Fig. 1. Bypass pipes. which were designed for shock mitigation of high re steam during start and stop(Fig. 1). As illustrated by the tube rrangement diagram shown in Fig. 2, within t like structure of 9922 heat transfer titanium tubes in each con- denser, samples in Part II are located at the tower under the bypass pipes while the samples we analyzed in Part I 1 were all in the lower part of the tower. So we decided that these special tubes must tell another failure story, which discussed in the current Part ll of the failure analysis. After detailed characterization and analysis, the root cause of the failure was found to be erosion, cavitation corrosion and the synergetic effect of them. Previous work in our lab on the finite element modeling of erosion 5, 6 has been reported but in the current failure case, we are more concerned about the erosion mechanism in real engineering application. actually, avitation corrosion of pure titanium and titanium alloys in electrolyte solutions has been reported 2,3. And cavitation phe- nomenon of commercially pure titanium has been studied in the lab[4. But cavitation corrosion of pure titanium tubes industrially utilized has been rarely touched upon. what's more, erosion and cavitation corrosion interacted and aggravated the wall thinning of titanium tube in our case, which is a relatively novel discovery look fron the outlet: count fron left to right ow number number of tubes in a row failure tubes in PartⅡ 2s is found in 20 Fig. 2. Schematic illustration of the location of failure tubes in Part II in the condenser.which were designed for shock mitigation of high pressure steam during start and stop (Fig. 1). As illustrated by the tube arrangement diagram shown in Fig. 2, within the tower-like structure of 9922 heat transfer titanium tubes in each con￾denser, samples in Part II are located at the tower shoulder under the bypass pipes while the samples we analyzed in Part I [1] were all in the lower part of the tower. So we decided that these special tubes must tell another failure story, which was discussed in the current Part II of the failure analysis. After detailed characterization and analysis, the root cause of the failure was found to be erosion, cavitation corrosion and the synergetic effect of them. Previous work in our lab on the finite element modeling of erosion [5,6] has been reported but in the current failure case, we are more concerned about the erosion mechanism in real engineering application. Actually, cavitation corrosion of pure titanium and titanium alloys in electrolyte solutions has been reported [2,3]. And cavitation phe￾nomenon of commercially pure titanium has been studied in the lab [4]. But cavitation corrosion of pure titanium tubes industrially utilized has been rarely touched upon. What’s more, erosion and cavitation corrosion interacted and aggravated the wall thinning of titanium tube in our case, which is a relatively novel discovery. Fig. 1. Bypass pipes. Fig. 2. Schematic illustration of the location of failure tubes in Part II in the condenser. F.-J. Chen et al. / Engineering Failure Analysis 37 (2014) 42–52 43