In wet gas lines, top of line corrosion (TLC) can be controlled by either continuous injection of a neutraliser to decrease the impact of organic acids or batch treatment. In some cases the combination of these two techniques would be necessary. Batch treatment is generally done by placing an inhibitor slug between two pigs. This operation requires generally shut down of the production during preparation/launching of the batch. It is then envisaged to use the inhibited liquid at the bottom of the line to film the top of line surface. In fact TLC takes place in lines with stratified flow regime and the liquid at the bottom of the line is inhibited by continuous injection of a corrosion inhibitor. Several types of pigs designed for this purpose have been tested. Finally, a pig which uses the gas behind the pig to spray the bottom liquid by venturi effect has been designed and successfully tested in a 12" two phase loop. This paper describes the characteristics of the pig, called TLCC-PIG, and test results.
Keywords : top of line corrosion, batch treatment, organic acid corrosion, neutralising, pig.