CTI-Maritec identifies cashew-nut shell liquid as source of ship problems in Singapore, Rotterdam

In the past few months, several ships in the Singapore and Rotterdam area reported operational problems including fuel sludging, injector failure, filter clogging, system deposits and corrosion of turbocharger nozzle rings.

In light of the reported problems, CTI-Maritec said Nov. 21 it swiftly carried out extended gas chromatography mass spectrometry (GC-MS) testing for very-low sulfur fuel oil (VLSFO) samples from these vessels.

GC-MS testing by the solid-phase extraction (SPE) method showed the presence of high concentrations (greater than 10,000 parts per million) of cardol, cardanol, anacardic acid and other alkyl resorcinols.

All mentioned compounds, which are substituted long-chain phenols, indicated the fuel was blended with cashew-nut shell liquid (CNSL) from undeclared source materials or production processes.

CNSL is a non-FAME biofuel, which is a naturally occurring byproduct of the cashew nut industry and acts as a low-cost alternative renewable fuel, according to CTI-Maritec.

It’s a substituted phenol, which is highly reactive and less stable owing to its high iodine value.

The application of CNSL is known in the production of plastic, resin, adhesives, laminates and surface coatings.

CNSL has high acid values and is therefore highly corrosive as well.

High potassium found in CNSL blend fuels cause serious post-combustion deposits and corrosion of turbocharger nozzle rings, according to CTI-Maritec.

The latest version of ISO:8217 specifies the accepted biofuels such as FAME-based biofuels and hydrotreated vegetable oil (HVO), defined by the specifications of EN 14214, ASTM D6751 and EN 15940, respectively.

These fuels are now established and acknowledged by original equipment manufacturers (OEMs), classification societies and flag administrations as drop-in fuels.

There is no specification available for CNSL from any authorized body like above.

CTI-Maritec recommendations

CTI-Maritec recommends that shipowners should not use 100 percent CNSL as a marine fuel or use CNSL as a blending component in marine fuel, which is contrary to the guidance by IMO on best practices for suppliers on the quality of fuel oil delivered to ships.

Furthermore, CTI-Maritec recommends not using unestablished bioproducts in marine diesel engines.

Blending these substances in a marine fuel might meet specifications as per ISO:8217 tables 1 and 2 parameter limits but may not fulfill general requirements of compliance, according to CTI-Maritec.