2014 12 Hoewing SMT Sandvik SAF2507 Over 20 years of heat exchanger service
Sandvik SAF 2507® was developed and introduced to the market by Sandvik more than 20 years ago. Sandvik SAF 2507® is a super duplex stainless steel meaning that it has a Pitting Resistance Equivalent (PRE) above 40, giving it the very good resistance toward chloride induced localized corrosion such as pitting and crevice corrosion. During the last two decades the experience with Sandvik SAF 2507® and its potentials has grown enormously. Its excellent corrosion resistance and its mechanical strength have made it a commonly used material in sub sea applications, e.g. umbilical. It has also found extensive use in heat exchanger applications, especially when seawater has been used as cooling media, but also in difficult environments with condensing gases forming, e.g. HCl. This paper will cover some of the experiences gained with Sandvik SAF 2507® in heat exchanger applications, discussing for example the importance of choosing the correct tube sheet and gasket and the effect of crevices and deposits. The properties of seawater and how this will affect the performance of seawatercooled heat exchangers will also be discussed. A further topic will be some experienced material failures and how these problems can be resolved.