- LNG cargoes containing heavy hydrocarbons (C6+) are increasingly causing operational delays, equipment failures, and costly disputes for LNG carriers and LNG-fuelled ships.
- Even minute concentrations can freeze at -162°C, clogging pipelines, pumps, and fuel systems, with significant commercial repercussions.
- INTERTANKO’s July 2025 guidance urges early testing, clear contractual safeguards, and defined indemnities to protect owners and operators.
With contributions from Brookes Bell’s maritime risk specialists, recent findings highlight the impact of long-chain hydrocarbons (C6+) in LNG shipments. LNG is predominantly methane but contains other hydrocarbons and nitrogen. Heavy hydrocarbons solidify at cryogenic storage temperatures, potentially blocking pipelines, strainers, and pumps.
Even 0.04 mol%—about 400 ppm—in a 100,000-tonne cargo equates to roughly 40 tonnes of C6+, enough to cause severe operational disruption.
Troubleshooting and Advanced Testing
When facing clogged filters or rising back pressure, operators should inspect equipment for contamination sources such as moisture ingress. If ruled out, cargo and residue samples should undergo GPA 2286 analysis—capable of detecting C6+ concentrations below 0.01 mol%.
This testing method, detailed in Brookes Bell’s technical advice, enables accurate detection of compounds often missed in standard LNG quality reports.
Operational and Commercial Consequences
Heavy hydrocarbon contamination can trigger delays, missed terminal schedules, and disputes between shipowners and charterers. Operational issues may include:
- Failure to meet cooling or pressure requirements.
- Forced switching from gas to oil-based fuels, risking charterparty breaches.
- Off-hire claims and additional port time for equipment repairs.
For LNG-fuelled vessels, clogged fuel systems may require debunkering—a logistically complex and costly process, particularly in ports lacking infrastructure.
INTERTANKO’s Mitigation Strategies
The July 2025 revised guidance calls for proactive steps before cargo loading, particularly at terminals with a history of heavy hydrocarbon presence:
- Engage with charterers early on potential C6+ concerns.
- Request GPA 2286 testing in addition to standard certificates.
- Negotiate explicit composition limits for C6+ in contracts.
Legal Safeguards and Indemnities
Annex 1 of INTERTANKO’s guidance recommends:
- Defining C6+ hydrocarbons as “injurious cargoes” within charterparty terms to ensure indemnity rights.
- Modifying standard clauses (e.g., ShellLNGTime 1 & 2) to include heavy hydrocarbons under harmful cargo definitions.
- Expanding charterer indemnities to cover vessel preparation, voyage disruptions, repair costs, tank cleaning, and unloading expenses.
Given that damage may emerge post-voyage, owners should insist on sampling rights, ideally before or during loading, and test samples using GPA 2286. Documenting results can provide critical evidence in dispute resolution.
Industry Support and Next Steps
The UK Defence Club advises members facing C6+ related disputes to seek early involvement from both P&I and Defence Clubs to manage technical and legal complexities. Prompt action can reduce financial exposure and improve resolution outcomes.
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Source: UK P&I
