11330 Water/Hydrocarbon Co-Condensation and the Influence on Top-Of-The-Line Corrosion

Available for download

Product Number: 51300-11330-SG

ISBN: 2011 11330 CP

Author: Thunyaluk Pojtanabuntoeng, Marc Singer, Srdjan Nesic

Publication Date: 2011

Member Price: $0.00

Non Member Price: $20.00

Price: $20.00

Qty:

Top of the line corrosion (TLC) is a great concern in wet gas transportation where temperature gradient between the internals of the pipeline and the outside environment leads to the condensation of water vapor and a lighter fraction of hydrocarbons. Liquid water from the condensation is greatly corrosive as it is saturated with the acid gases; e.g. CO2, H2S, HAc, etc. Extensive work has been previously focused primarily on the hydrocarbon-free systems. In reality, the presence of condensable hydrocarbons affects the overall condensation process as two immiscible liquids with different wettability will form on the steel surface. As a result, less corrosion would be expected if hydrocarbons condense on the steel surface together with water. This work investigates the influence of hydrocarbon co-condensation (n-heptane) on top of the line corrosion. The wettability of water and n-heptane on carbon steel (X65) was determined and corrosion tests under co-condensation were conducted. The results show that following condensation water has higher affinity towards carbon steel than n-heptane in all cases. In a hydrocarbon-free system, corrosion rate increased with the water condensation rate whereas the presence of n-heptane provides some degree of protection in the co-condensation scenario. Under the condition tested where the steel temperature was relatively low (less than 30°C), iron carbonate scale was detected in a co-condensation system but not in a pure water system, suggesting different chemistry in the water condensate phase.

KEY WORDS: Top of the line corrosion, Co-condensation, CO2 corrosion