Nowadays, strict limits are imposed in the atmosphere on sulphur emissions from ships by international regulations under the Marpol Treaty. Until January 2020 maximum sulphur content allowed in marine fuels was 3.5% m/m. To meet the new regulations, ship operators have been asked to switch to higher cost low-sulphur fuels or install Exhaust Gas Cleaning Systems (EGCS), otherwise known as “scrubbers.”
Ship Owners have the flexibility in deciding on the options to comply with the IMO Sulphur Cap requirements – using compliant low sulphur fuels or scrubber systems. Scrubbers are generally considered a cost-effective solution, and some studies have been carried out that estimate payback periods less than 18 months in most instances, compared to the continuous expense of cleaner fuels.
Therefore thousands of ships around the world are already using scrubber systems to comply with international environmental standards in a more economical manner.
With the increased use of scrubber technology in the marine industry, corrosion has become one of the main challenges in operational Exhaust Gas Cleaning Systems.
Like most new technologies, ongoing maintenance and operation of scrubber systems have been a learning curve for vessel owners and operators in order to ensure equipment doesn't fail and downtime is minimised. The wash water from scrubbers contains the pollutants which are separated out in the exhaust gases and is very acidic in nature and therefore very corrosive. Furthermore the high temperatures of the exhaust gases actually exacerbate the corrosive effects on the scrubber system and pipework. Therefore, the state of the scrubbers and the associated pipework needs to be checked periodically for corrosion or leaks. Specific areas which need attention are the overboard pipework and “stub piece” inside the engine room.
The renowned ship repair and maintenance company of mainland Europe says that scrubber corrosion has “definitely become an area of concern for us, and we still find scrubbers that have been installed in the last six months that show signs of corrosion – in some cases only 6 months after installation.” The company, which specializes primarily in preventative ship maintenance, advises regular checks to be made for wall thickness reduction caused by corrosion, as early detection makes repair and rectification much easier.
Ultrasonic thickness gauging is one of the easiest, most reliable and low-cost ways to implement these inspections. Cygnus Instruments (www.cygnus-instruments.com) has dedicated more than four decades to producing high accuracy, robust and easy to use ultrasonic thickness gauges. Unlike other ranges, the Cygnus MK5 range can provide readings through coatings up to 20mm thick, without the need for the protective coatings to be removed, or removing and replacing costly epoxy layers. Cygnus gauges are specially designed to meet the challenges of harsh operating conditions, first developed for hull inspection applications. The instruments have passed waterproofing to IP67 standard, shock resistance and drop test to US MIL STD 810G standard.
The gauges also enable readings to be taken and uploaded into software for long term analysis. This allows an operator to track corrosion and wall thinning over time, and make sure that any problems are caught early on before major failure.
All Cygnus gauges come with a 3 year warranty.
Tel: +44 (0) 1305 265533
E-mail: sales@cygnus-instruments.com
Source: https://www.dockyard-mag.com/single-post/marine-scrubbers
