Search

Free water that wets steel pipes accelerates corrosion via a number of different mechanisms. We report a novel sensor based on ac impedance that has successfully detected free water under laboratory and flow loop conditions with minimal effects from oil fouling. The sensor has also successfully differentiated between free water and water emulsified in oil. This free water sensor is one means for the earlier detection of pipeline corrosion. Smart-pig inspections are expensive and require a significant slowdown in production. The free water sensor is designed to be small and flow with the fluid current. Since the sensor is significantly smaller than the internal diameter of the pipelines, the fluid flow would be minimally impacted. It is also designed to be used more frequently than smart-pig inspection. The sensor is capable of detecting water despite fouled electrodes, determining the difference between free and emulsified water (emulsified water does not, generally, cause a corrosion issue), can potentially be used to determine the amount of free water, and has been demonstrated to work in a system with multi-phase fluid flow. [ABSTRACT FROM AUTHOR]

We have explored the contact conditions under which zinc dialkyl dithiophosphate (ZDDP) is corrosive and, in the presence of carbon black, increases wear. It was found that the corrosivity of ZDDP to steel is due to a load dependent mechanochemical reaction and leads to the antagonism between ZDDP and carbon black which is also likely to be load dependent. Depth-profiled Auger spectroscopic analysis of wear scars produced with ZDDP shows that the iron sulfide layer thickness depends on contact load during the wear process. Higher loading produces a thicker iron sulfide layer but, surprisingly, the thickness is relatively insensitive to time. Indenter nanoscratching measurements demonstrate that the highly corroded surface is less scratch resistant than lightly corroded surfaces made under lower load (or of the native steel), explaining increased wear by abrasion of carbon particles ( e.g. carbon black or soot) under highly loaded conditions. [ABSTRACT FROM AUTHOR]