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Analysis: Specification body ISO sets out 0.5% sulfur bunker fuel challenge

Geneva-based specification NGO the International Organization for Standardization has issued its verdict on the new 0.5% sulfur blends that most shipowners will be using next year, confirming how complex bunker procurement is set to become in the era of cleaner fuels.

The organization last issued a full set of its ISO 8217 bunker specifications in 2017, and is unlikely to do so again for another two years at least, but has produced what it terms a publicly available specification (PAS) in the meantime to set out how 0.5% sulfur fuels can fit into its current standards.

The majority of the shipping industry is currently shifting into using new fuel blends ahead of the International Maritime Organization’s global sulfur limit dropping to 0.5% at the start of next year, from 3.5%.

The PAS “defines general requirements that apply to all 0.50 mass % sulfur fuels and confirms the applicability of ISO 8217 for those fuels”, the ISO said in its report.

The document outlines what will be a sharp increase in the difficulty of buying bunker fuels.

“Historically, fuels within the same grade were very similar in kinematic viscosity and typically close to the maximum limit of the ordered grade,” the ISO said.

At present, buying 380 CST high sulfur fuel oil, a bunker buyer will mostly just need to consider the price and whether the supplier can generally be trusted to deliver a quality product in the correct amount. But refiners and suppliers are blending a wide range of new bunker fuel products that meet the IMO’s 0.5% sulfur limit while differing in several other properties.

“The kinematic viscosity is expected to vary widely for 0.50 mass % sulfur fuels, even within the same grade, and is no longer the controlling characteristic that it once was,” the ISO said. “For example, some lower-viscosity fuels may have other characteristics such as density, carbon residue and catalyst fines typical of higher-viscosity grades.”

Earlier this year, bunker market participants reported seeing 0.5% sulfur blend samples with viscosity ranging from 25-300 CST.

As “different-viscosity fuels should be adjusted to the correct temperature to comply with the machinery requirements”, ship operators are advised to find out the kinematic viscosity of the fuel before they buy it, the ISO said.

The organization also recommends knowing the pour point and any storage requirements of the fuel in advance.

One of the main problems likely to occur with the new fuels is incompatibility — the risk that two different blends brought into contact with one another could lose stability as a result, forming sludge that can block engine filters.

Because of that, the ISO recommends that different blends are not brought into contact with each other where possible. But it says this “might not be possible to avoid, for example when switching between fuels”, and that testing for compatibility between fuels may be necessary.

The organization also raised concerns that standard stability and compatibility tests may not be adequate. In particular, it recommends a potential total sediment test using the referee method, and the ISO 10307-2 total sediment aged test.

All of that adds up to a much more complicated world for those involved in bunker procurement, particularly for those desks dealing with large, varied fleets with differing trade routes, tank configurations and fuel heating systems.

A buyer this year will largely need to focus on buying the right quantity of fuel oil at the right port at an advantageous price.

From next year, as well as meeting those requirements, the same buyer will need to consider the particular tank configuration and heating systems of each vessel he or she is buying for, several different properties for the type of 0.5% sulfur fuel it already has on board, the same information about the types that might be available at its next port of call and whether any of those fuels are compatible with each other.

The largest, richest shipping companies will be able to develop more sophisticated procurement strategies to cope with those problems, but the rest of the market may struggle to avoid, at the very least, some initial mistakes.

Expect maritime lawyers, fuel testing companies and engine repair specialists to have a good year.
Source: Platts

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