IMO2020 – Is it all Plain Sailing?

22 May 2020

Relevance of ISO 8217 following IMO 2020

The 1st January 2020 marked a significant day in the world of shipping when legislative reform saw the global sulphur cap for marine fuels reduced from 3.50 % to 0.50%. This monumental change is now generally referred to as IMO 2020.

Over a very short period of time, the industry moved away from using the familiar High Sulphur Fuel Oils (HSFO) and replaced them, in the main, with Very Low Sulphur Fuel Oils (VLSFO) with HSFO being used, and permitted, only on vessels fitted with abatement technology (scrubbers).

The industry standard that applies to bunker fuel, is ISO 8217. This is a commercial standard covering both residual fuel and distillate fuel.

An assessment has been completed on the test data from VLSFOs purchased during Q1 2020, and it shows that the properties of VLSFOs range from that of a typical distillate fuel to that of a typical residual fuel. As a result, the question has been asked on numerous occasions whether the current ISO 8217 specification is still suitable for today's fuels.

In the lead up to IMO 2020, the International Organisation for Standardisation (ISO) produced the Publicly Available Specification - ISO PAS 23263.

This document highlighted that specific consideration should be given to Kinematic Viscosity, Cold Flow Properties, Stability, Ignition Characteristics and Catalyst Fines. It did not include additional specifications for 0.50% mass fuels, but it did recommend that VLSFOs need to meet the ISO 8217:2017 specification.

So why is the relevance of ISO 8217 being questioned?

Firstly, we need to look at how marine fuel is ordered. Historically, procurement departments of shipping companies ordered HSFO against a viscosity specification, e.g. RMG 380, where 380 denotes the maximum allowed viscosity of the fuel (mm2/s). All other parameter specifications within ISO 8217 additionally have to be met for an RMG 380 fuel.

 

Table 1.0

Parameter	Unit	Limit	RMA	RMB	RMD	RME	RMG				RMK
Kinematic viscosity @50°C	mm2/s	max.	10	30	80	180	180	380	500	700	380	500	700

 

Since the introduction of VLSFOs, the shipping community has continued to order fuel against the residual fuel viscosity specifications. However, in the majority of cases, the viscosity of the fuel bunkered is considerably lower than the viscosity of the fuel grade ordered.

Why is this?

In order to accommodate the maximum sulphur limit of 0.50 % mass, in many instances, HSFOs are blended with low sulphur components to reduce the overall sulphur level to 0.50% or below. This has the effect of massively reducing the viscosity of the product and, as ISO 8217 does not state minimum values for many parameters, VLSFOs with viscosities as low as 3 mm2/s have been seen in the market. This results in the vessel having to modify its fuel handling to reflect the characteristics of the fuel. There are several ISO 8217 parameters which have been affected positively by this change: reduced levels of carbon residue, reduced ash content and lower levels of catalytic fines. However, conversely, higher pour points have been observed.

Table 2.0 provides a comparison between HSFO tested in Intertek Lintec laboratories during the first three months of 2019 compared to VLSFO tested in the same laboratories during the first three months of 2020.

 

Table 2.0

Parameter	Unit	Q1 19 HSFO Average	Q1 20 VLSFO Average
Kinematic viscosity @50°C	mm2/s	338	117
Density	kg/m³	982	936
Acid number	mg KOH/g	0.4	0.7
Carbon residue	mass %	13	5.6
Pour point	°C	-4	10
Ash content	mass %	0.04	0.02
Al & Si	mg/kg	28	21

 

To understand the variability experienced with VLSFOs, we need to not only consider the average results but, also examine the variation in results as provided in Table 3.0. This data set considers fuel ordered against all viscosity grades stated in ISO 8217.

 

Table 3.0

Parameter	Unit	Q1 20 VLSFO Minimum (All 0.50% residual grades)	Q1 20 VLSFO Maximum (All 0.50% residual grades)
Kinematic viscosity @50°C	mm2/s	2.75	736.9
Density	kg/m³	833.3	1025.9
Acid number	mg KOH/g	<0.20	3.33
Carbon residue	mass %	<0.01	16.19
Pour point	°C	<-12	42
Ash content	mass %	< 0.001	0.136
Al & Si	mg/kg	2	156

 

If we concentrate solely on fuel ordered against the RMG380 specification, it can be noted that the only difference observed is an overall reduction in viscosity from 736.9 mm2/s to 395.4 mm2/s.

 

Table 4.0

Parameter	Unit	Q1 20 VLSFO Minimum (RMG 380)	Q1 20 VLSFO Maximum (RMG 380)
Kinematic viscosity @50°C	mm2/s	2.75	395.4
Density	kg/m³	833.3	1025.9
Acid number	mg KOH/g	<0.20	3.33
Carbon residue	mass %	<0.01	16.19
Pour point	°C	<-12	42
Ash content	mass %	<0.001	0.136
Al & Si	mg/kg	2	156

 

So, to answer the question……

We might find the next revision of ISO 8217 introduces new fuel grades and additional tests. However, in the meantime, given the variability of marine fuels in the current market, it is essential that fuels continue to be tested against the latest version of ISO 8217 in order to ensure environmental compliance, the safety of the crew and the safe operation of the vessel.