16 " A case history of titanium hydriding in a sodium hypochlorite generator system", R. Barráez Derid, A.I. (Sandy) Williamson, NACE Northern Area Eastern Conference, October 2009, Halifax, Nova Scotia. Abstract
ABSTRACT
This paper explains the corrosion mechanisms of crevice/under deposit corrosion and subsequent hydriding attack on titanium alpha alloy at ambient temperature in a sea water system. A case history of a titanium tube failure from a sodium hypochlorite generator system has been used to illustrate these mechanisms. The tests carried out for analysis were visual examination, material analysis (X-Ray fluorescence), microhardness testing, microstructural analysis, water analysis and scale prediction modeling. Microstructural and microhardness analyses confirmed the presence of hydriding and high hardness values. The prediction modeling of scale susceptibility based on water chemistry confirmed a potential possibility to form iron hydroxide, zinc hydroxide and calcite deposits. In conclusion, the titanium tube failed due to the formation of a deposit which led to crevice corrosion/under deposit corrosion and subsequent hydrogen embrittlement. Recommendations to avert this type of attack have been given.