A Study of Corrosion of Steel Tubes in Flowing Seawater under Heat-transfer Condition

Abstract

An experimentaL investigation on corrosion of steeL tubes in flowing naturaL seawater under heat-transfer conditioll in the 1l0nboiLing !'al/ge has been carried out using a unique Loop tyjJe test apparatus. The results obtained are summarized as foLLows : (I) Corrosion rate increases rapidly for carbon steels and decreases for stainless steels because of passivity with increase of flow rate of seawater. Two typicaL trends of diffusion controLLed corrosion under aqueous flow were confirmed under heat-transfer condition as weLL. (2) H eat-transfer has an effeet on corrosion rate of aLL of the materiaLs investigated except SUS316 and 329J , stainLess steeLs, though the relationship is not Linear. (3) As for SUS316 and 329J , stainless steels, heat-transfer e./Ject on corrosion rate is almost negLigible unde!' exposure to air. Under oxygen saturated and deaerated cOllditions, however, those steeLs show about the same trends as other materiaLs investigated. (4) P itting corrosion of a /JeCuLiar type occurs on the SUS 329J , two-/Jizased stainLess steeL. (5) The test method using the unique test apparatus has jnoved avaiLabLe .