The maintenance team at a sugar mill in Indonesia were fighting a losing battle against corrosion on the welding joints of their CO₂ pipeline. The purpose of the CO₂ gas at the sugar mill was for carbonation, ultimately improving the quality of the sugar.
In the carbonatation process, the melt is spiked with lime [Ca(OH)2] then CO₂ gas is flowed in the carbonatation vessel, a precipitate of calcium carbonate (CaCO3) is formed which absorbs/binds impurities, including reducing dyes so that the acidic pH dissolves again. The source of CO₂ gas comes from boiler gas which has been purified through a scrubber. The carbonation process is carried out in two stages: 1. Add lime as much as 0.5% brix together with flowing CO₂ equivalent to the amount of lime added 2. At the end of the carbonator completes the reaction with CO₂ flow until the pH drops to around 8.3, then the liquor is filtered in a pressure filter (leaf filter) to produce filter liquor and mud.
At that time, the plant was using SS304 & SS316L stainless material for their pipework. But, after just six months in service, the pipework was suffering leaks on the welding joints areas.
Over 220m of pipework was transported to the Corrocoat workshop (in Indonesia), where the team were tasked with providing a long-term solution. Polyglass was the recommended coating system.
So impressed with the result and performance of the Polyglass VE system, once the pipework was put back in to service, the client chose to downgrade their pipework material to carbon steel, and award Corrocoat Indonesia with additional contracts for their expansion and preventive maintenance programs, for further CO₂ piping systems, over the next three years.
