Houston bunker fuel contamination hits more ships

One result of bunker fuel contamination: a seized fuel pump plunger. [Photo: VPS]

Leading fuel testing services provider VPS reports that the bunker fuel contamination issue in Houston that it identified in July has spread. At that time, VPS informed its customers and the wider market, of the presence of Dicyclopentadiene (DCPD) isomers at significantly high levels within VLSFO bunker fuel deliveries in Houston.

Four weeks later, says VPS, it can provide a further update on the spread of this fuel contamination issue: Fourteen vessels in total, have now received this contaminated fuel and suffered some form of damage to their auxiliary engines and fuel delivery systems. Twelve of the vessels received their fuel in Houston, while a further two vessels received their fuel in Singapore, with the fuel being delivered by four suppliers.

This is not the first time that bunker fuel contamination first discovered in Houston has later been found in fuel bunkered elsewhere.

VPS detected the bunker fuel contaminants using its in-house GC-MS (gas chromatography – mass spectrometer) analytical methodologies,n preference to the ASTM D7845, Standard Test Method for Determination of Chemical Species in Marine Fuel Oil by GCMS. The VPS methodology is capable of detecting and measuring the DCPD and its isomers, whereas the ASTM D7845 methodology is limited to detecting only 29 chemical contaminants, which do not include DCPD species.

Initially, VPS reported that eleven vessels had suffered operational issues, such as loss of power and propulsion while at sea. These effects resulted from fuel leakage in the ICU (injection control unit) units and fuel pumps not being able to develop the required fuel pressure, affecting only the auxilary engines and not main engines. The contaminated VLSFO had been delivered in Houston, by one single fuel supplier.

The specific contaminants are: Di-hydro dicyclopentadiene Chemical CAS Number: 448-57-7 Tetra-hydro dicyclopentadiene Chemical CAS Number: 6004-38-2

DCPDs are unsaturated chemical compounds that can polymerize and oxidize under certain conditions. However, the rate of this polymerization process can be reduced by the presence of inhibitors that are typically found within fuel oil.

Should these compounds start polymerizing, the fuel begins to exhibit a level of stickiness and become more viscous, making it difficult for moving components, such as fuel pump plungers and the fuel injector spindles to move freely. These effects cause damage to the fuel injection system. Over a period of time excessive sludge formation is likely to be experienced.

The DCPD compounds that were detected in this fuel ranged from 3,000 to 7,000 ppm (0.3-0.7%) per delivery.

In total, the volume of contaminated fuel delivered to the 32 vessels, was 61,494 metric tonnes.

Three vessels de-bunkered the contaminated fuel prior to burning, following a “Caution” result from the VPS Chemical Screening service, highlighting the value of this pre-burn service.

A further three vessels de-bunkered the fuel after suffering initial engine damage from burning the fuel. Another two vessels burned the fuel in their main engines without issue after switching it from their auxiliary engines, where it had caused operational damage.