ISO 8217 – Specifications of marine fuels -
ISO 8216-1 – Classification of marine fuels -
The fourth edition of ISO 8217 – Specifications of marine fuels- and ISO 8216-1 – Classification of marine fuels- will be published on the 15th of June 2010 and available on the ISO website www.iso.com.
ISO standards are normally revised every 5 years.
As a result of IMO regulations, there is much increased awareness of safety, health and environmental issues. The experiences gained with operation on low sulphur fuels, air quality, ship safety, engine performance, crew health as well as operational aspects and other changes of the bunker market realities were the main drivers for WG6 work and the agreed changes considered necessary were introduced into the standard.
The ISO 8217 standard specifically refers to petroleum derived products only, however WG6 agreed that Gas to Liquids (GTL) products fall within the scope of the Standard being paraffinic hydrocarbons produced from petroleum natural gas via synthesis gas using gas to liquids technology. Since the GTL products are paraffinic hydrocarbons and they are undistinguishable from the rest of the petroleum based marine fuel, no actual reference needs to be made for GTL synthesized hydrocarbons in the scope of the standard. The GTL products clearly fall within the scope of the standard, unlike bio-derived materials which are specifically excluded.
Changes to both Distillate and Residual Fuels are:
Acid number limits included
Hydrogen sulphide (H2S) limits included
Acid Number – the limits for Distillate fuels were adopted from the accepted industry's guiding limit of 0.5 mg KOH/g. The limits for Residual Fuels are set at max limit of 2.5
Changes for Distillate Fuels only are:
DMA – minimum viscosity was increased to 2 cSt at 40 deg C
DMZ - minimum viscosity was introduced at 3 cSt at 40 deg C
DMB - minimum viscosity was introduced at 2 cSt at 40 deg C4.
OXIDATION STABILITY –
was introduced because the refinery processes used to manufacture distillate fuels can lead to products which may be of limited oxidation stability. In addition, today's non-marine distillate fuels can contain a significant amount of bio-derived components, which might impact on the oxidation stability of the fuel. Also the transportation of pure Distillate Fuels and Distillate Fuels containing bio derived material like FAME, especially through multi product pipeline installations, have shown that some FAME is transferred into the pure Distillate Fuels
A lubricity requirement has been included and is applicable to clear and bright D/Fs with a low sulphur content below 500 mg/kg. The lubricity limit is based on the existing requirements for high speed automotive and heavy duty industrial diesel engines, of 520 wear scar diameter. The 460 wear scar limit was required only for a particular form of passenger car fuel injection equipment and therefore not applicable to marine fuel pumps. Engine manufacturers are in the process of reviewing their limits to this value.
Changes for Residual Fuels only are:
To assess stability Potential Total Sediment (TSP) has been assigned as the reference test method. Accelerated Total Sediment (TSA) has been added as an alternative test method.
due to wide range of various changing limits and requirements both internationally and locally the sulphur limits are not included in Table 2
ASH limits were reduced
for RMA10 – from 0.05 to 0.040 mass%
for RMB30, RMD80 and RME180 – from 0.100 to 0.070 mass%,
for all grades of RMG – from 0.150 to 0.100 mass %
no change for RMK grades – at 0.150 mass%
VANADIUM limits were reduced
for RMA10 – from 100 to 50 mg/kg,
for RMB30 grade – no change at 150 mg/kg
for RMD80 grade – from 350 to 150 mg/kg
for RME180 grade – from 200 to 150 mg/kg
all RMG grades – at 350 mg/kg
for all grades of RMK – from 600 to 450 mg/kg
ALUMINIUM AND SILICON limits were significantly reduced
for RMA10 – same at 25 mg/kg,
for RMB30 and RMD80 – from 80 mg/kg to 40 mg/kg
for RME180 – from 80 to 50 mg/kg
for all grades of RMG and RMK – from 80 to 60 mg/kg
SODIUM CONTENT –
was added to all residual fuel grades at 100 mg/kg with the exception of RMA10 and RME 180 where the limit is set at 50 mg/kg.
From the specification writers point of view it is hard to describe the enormity of the task at hand. The chemistry of residual fuels is probably the most complex of the oil barrel and some of the components of the final blend are rather resultants than controlled fractions. Furthermore, the various specification grades of residual fuels are not blended at the refineries and therefore different cutter stocks of unknown chemistry available to today's supply chain are added. With this in mind, the complexity of the ignition/combustion properties of marine fuels must be fully appreciated and carefully researched. Nonetheless, as an indication of ignition performance, CCAI has been added as in order to avoid fuels with uncharacteristic density-viscosity relationships. For engines and/or applications where ignition quality is known to be particularly critical, Annex F provides a basis for suppliers and purchasers of marine residual fuels to agree on tighter ignition quality characteristics.
The basis for including CCAI was as a substitute for a minimum viscosity limit. The CCAI limit included in the marine fuels standard is there to prevent abnormal or peculiar fuel blends from finding their way into the market. It is recognised that CCAI of 870 is not a guarantee to pose no risk for engines, but neither is a lower value such as 860.
The bulk of bio-derived automotive fuels currently available are the product of a transesterification process which removes the glyceride fraction to produce a Fatty Acid Methyl Ester (FAME) – commonly referred to as bio-diesel. While bio-derived fuels can be produced by other process methods there is no general experience with regard to their application in marine systems and hence this Standard does not address those issues. FAME as defined by EN14214 and ASTM D6751.
In view of this for the purpose of this International Standard it was agreed that:
in the case of distillate fuels (DMX, DMA, DMZ and DMB when clear and bright), it is recommended that “de minimis”be taken as not exceeding approximately 0,1 volume % when determined in accordance with EN 14078.
in the case of DMB when it is not clear and bright and all categories of residual fuels, “de minimis”cannot be expressed in numerical terms since no test method with formal precision statement is currently available. Thus, it should be treated as contamination from the supply chain system.
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