As a global clean-fuel mandate takes effect Jan. 1, testing companies examining newer, low-sulfur marine blends acquired in Antwerp, Belgium; Houston and Singapore have found sediment at levels that could damage the engines of ocean-going vessels. Routine tests by AmSpec Services and a unit of Lloyd’s Register have raised alarms about safety and compliance just ahead of the new International Maritime Organization (IMO) 2020 standard. Such tests, paid for by suppliers of bunker fuel, have been conducted more frequently this year due to the shift. The standard prompted an industry wide shift to cleaner burning marine fuel in an effort to reduce coastal air pollution. It requires fuel with less than 0.5% sulfur in ocean-going ships not equipped with emission scrubbers. The potential hazards were demonstrated in 2018 when some ship operators were forced to pay for costly repairs after buying bunker fuel contaminated by a chemical used in epoxy. That incident affected about 200 vessels, according to an attorney for one operator. Some 60% of the recipes for making low-sulfur fuel proposed by bunker suppliers near the top U.S. oil port of Houston failed to meet sediment specifications when tested by AmSpec, said Shannon Boudreaux, a fuel blending specialist at AmSpec, in an interview on Tuesday.