The technology group Wartsila and Danish ship operator A.P. Moller - Maersk have provided a means for preventing corrosion in scrubber discharge pipes. The permanent in-pipe solution is designed to solve corrosion problems associated with open-loop scrubber washwater discharge, according to the company's release.
The majority of the estimated 5,000 scrubber systems installed across the global fleet are of open-loop configuration. With this system, seawater is used to scrub SOx from the exhaust gas, with the used water then being discharged back to the sea after cleaning.
Under IMO Guidelines, the washwater from exhaust gas cleaning systems, commonly referred to as scrubbers, should have a pH of no less than 6.5. However, in reality the pH of scrubber washwater is typically acidic, prior to being diluted by seawater. This creates the risk of structural corrosion to the discharge pipes.
The risk is particularly high for pipes made of mild steel. In some cases, if the discharge pipes are inadequately protected, severe corrosion can damage the surrounding mild steel hull plates, resulting in water ingress.
The new ‘pipe-in-pipe’ solution allows for the original overboard pipe to remain in situ while a new glass reinforced epoxy (GRE) pipe is inserted into it. No metal cutting or welding is necessary. A SMO steel sleeve is inserted between the new GRE pipe and the existing steel pipe. An adhesive permanently secures the GRE pipe in place. Since this ‘pipe-in-pipe’ solution has a small impact on the internal diameter of the pipe, it is best suited for overboard pipes with a diameter greater than 300 mm.
Installations of this unique, patented solution and licensed know-how will be carried out by Wärtsilä Underwater Services. In most cases, the repair will be completed in less than two days, which can avoid the ship having to go ‘off hire’. Considerable time and cost savings compared to alternative repair solutions have already been demonstrated.
The Wartsila/Maersk solution is intended for long-term protection. It reduces complications associated with welding work required on pipes and sometimes hull plates, particularly in underwater repair situations.
Wartsila Marine Systems supports customers with high quality products and lifecycle services related to the gas value chain, exhaust treatment, shaft line, underwater repair and electrical integrations.
Wartsila is a global leader in innovative technologies and lifecycle solutions for the marine and energy markets. In 2021, Wärtsilä’s net sales totalled EUR 4.8 billion. Wärtsilä is listed on Nasdaq Helsinki.