Industry Insight: VPS Discusses Fuel Grades and ISO 8217

by Bill Stamatopoulos, Group Commercial Director, Veritas Petroleum Services
Wednesday October 29, 2014

Despite an initial slow adoption rate, mainly due to long-term charter contracts using the 2005 parameters, non-availability in some ports or the additional price tag imposed on fuel price, Veritas Petroleum Services (VPS) has noticed that since early 2014, the shipping industry has seen a growing understanding of the advantages of the latest edition of ISO 8217.

At almost 10 years old, the 2005 specification does not adequately cover today's requirements of fuels supplied on a world-wide basis in relation to ships' machinery and environmental legislation. Crude oil supplies, refining methods, ships' machinery, environmental legislation and local conditions vary considerably and are constantly developing.

The selection of the most suitable fuel should be based on the latest ISO 8217 edition for the main and auxiliary engines, and on the engine manufacturer's recommendation and fuel treatment plant. A ship operator or owner should always remember that ISO 8217 is a live document to reflect today's reality and he should therefore take note of the finer differences.

For example, ISO 8217:2012 includes distillate grade (DMZ) being identical to the DMA grade except that the minimum viscosity is 3 cSt at 40°C.

This is the result of a major engine designer's recommendation that the fuel viscosity does not drop below 2 cSt at 40C at engine inlet in order for the engine fuel pumps to work properly. Otherwise, there may be difficulty in starting or operating low load as the fuel pumps may fail to build up sufficient pressure for proper injection to take place. 

Note that although the bunkered distillate fuel may be on‐spec, the strong temperature dependency may result in the viscosity falling below the min 2 cSt limit due to the heat generated in the fuel system onboard. 3 cSt at 40°C should hold sufficient safety margin to prevent operational difficulties.

Below is a table indicating calculated viscosities from 40C to 48C:

Viscosity at 40C   Viscosity at 48C
3 cSt                            2.6 cSt
2.5 cSt                         2.2 cSt
2 cSt                            1.8 cSt

The 66 loss of propulsion cases in California recorded by the U.S. Coast Guard (USCG) for the first seven months of 2014, are alarming. Change-over from Heavy Fuel Oil (HFO) to Low Sulphur Marine Gas Oil (LSMGO) is also much more complicated compared to the one from High Sulphur Fuel Oil (HSFO) to Low Sulphur Fuel Oil (LSFO) due to the setup and the complexity of the systems. A lot of information is required for a tailor made study such as fuel system drawings and procedures related to fuel switch equipment/coolers/chillers installed.

As the industry leader, VPS has a pivotal role in ISO, ASTM and CIMAC committees and working groups, to ensure that developments in the bunker industry are of benefit to our customers. Currently, the scope of the next edition of ISO 8217 has been balloted and accepted. The target is to finish by 2016.

What should still be highlighted is that here is no such thing as a perfectly suitable fuel, even if it meets fully every parameter of the ISO 8217 table of specifications. On-spec fuel does not necessarily mean that it is fit for its intended use.

An off-spec or unfit fuel definitely needs the best fuel management partner to provide tailor made advice on fuel handling for optimal performance based on the specific vessel's engines and fuel treatment plan.

From the non-technical perspective, claims support is also a high value service that helps to avoid lengthy and costly processes by settling bunker disputes quickly.