Pipeline corrosion issue in amine solution regeneration

Things have changed; as the load on the equipment has increased, after more than three years of operation under high loads, corrosion in the shell side of the amine liquid heat exchangers (where the lean liquid flows through the shell side) as well as in the pipes carrying lean amine liquid has become more severe. In 2006, the shell side of the heat exchangers was replaced with stainless steel, and during the major maintenance in 2013, the pipes carrying lean amine liquid at temperatures above 70 degrees Celsius were also replaced with stainless steel. The pipes carrying rich amine liquid still consist of carbon steel (with welds that undergo heat treatment). Previously, the welds of the remaining carbon steel pipes carrying lean amine liquid were not treated with heat, but now they are also treated in this way. It was said at the time that it was due to the low pH value of the lean amine solution; I haven’t figured that out yet, and there’s also the issue of corrosion caused by thermally stable salts.

Temperature is one of the main factors affecting corrosion. It might be a temperature issue. I don’t know exactly where the corrosion is located

The corrosion occurs mostly above the vapor return line of the bottom reboiler

We replaced it with stainless steel around 1996, and the results were very good. The area that is corroded is at the back of the elbow; it has been thinned due to erosion, forming a uniform slanted area of reduced thickness – it’s very obvious.

It is closely related to temperature; another factor is the pipeline flow rate, which you need to calculate

Erosive thinning is the issue of thermally stable salts in the lean solution, which needs to be filtered out