The Rise of LNG “BDN”.



IMO is all set to publish – IGF Code – which expands as “The International Code of Safety for Ships using Gases or other Low-flashpoint Fuels”.

Until this moment, every ship using Heavy fuel oil as fuel has witnessed a conventional BDN (Bunker Delivery Note). New generation ships which are expected to use LNG as fuel is all set to witness LNG BDN. The LNG BDN is set to include detailed information about the properties and composition of LNG. Unlike the conventional fuel oil BDN, sulphur % in LNG is not a major concern. However the 95th session of Maritime Safety Committee (MSC 95) decided to include sulphur % in LNG which is to be reported as percentage of mass over mass. This is in line with how sulphur is expressed on BDNs for regular marine fuels.

LNG as fuel has been driven by the fact that it can help operators meet emission regulations in MARPOL Annex VI, including the strictest limits for sulphur oxides (SOx) and nitrogen oxides (NOx) in emission control areas (ECAs).

It is to be noted that the amount of sulphur in LNG is typically small – which is less than 30 parts per million (ppm), which translates to about 0.004% by mass. Sulphur in LNG is normally not expressed as a percentage of mass over mass (m/m %), but rather as milligrams per cubic metre (mg/Nm3).

Typical LNG specifications for the Japanese market limits

  1. Sulphur – 30 mg/Nm3 maximum,
  2. Hydrogen sulphide (H2S) to 5 mg/Nm3 maximum.

The proposed LNG BDN for the IGF Code has a field listing for:

  1. H2S,
  2. Hydrogen,
  3. Ammonia,
  4. Chlorine,
  5. Fluoride and
  6. Water

as “negligible < 5 ppm”.

Unlike conventional bunker fuels, there is no International Organization for Standardization (ISO) standard for LNG as a marine fuel.

LNG properties to be included are

  1. Methane number,
  2. Calorific value,
  3. Wobbe Indices,
  4. Density,
  5. Pressure and
  6. Temperature.

LNG composition to be included (expressed in m/m%) are

  1. Methane,
  2. Ethane,
  3. Propane,
  4. Isobutane,
  5. N-butane,
  6. Pentane,
  7. Hexane,
  8. Heptane,
  9. Nitrogen and
  10. Sulphur.



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