Conventional Ocean-Going LNG CarrierQ-FlexEducational data

Q-Flex LNG carrier

Qatari long-haul economics with on-board reliquefaction.

Class overview

Q-Flex vessels were built to move Qatari volumes to Europe and Asia at the lowest possible unit cost. Twin slow-speed diesel engines replaced steam turbines, and on-board reliquefaction returns boil-off gas to the cargo tanks instead of burning it.

Classification

Operational role: Conventional Ocean-Going LNG Carrier
Containment system: GTT Mark III Membrane · GTT NO96 Membrane
Tank geometry: Hull-conforming prismatic membrane tanks
Capacity class: Q-Flex — indicative: approximately 210,000–217,000 m³
Propulsion options: ME-GI · DFDE / TFDE
BOG management: Reliquefaction · BOG as fuel

Key systems

ContainmentFive membrane tanks with reinforced insulation

Boil-offFull reliquefaction plant returning BOG to cargo tanks

PropulsionTwin screws for redundancy on long-haul trades

Operational environment

Long, stable trade lanes between a small number of compatible terminals.

Safety and operational considerations

Vessel dimensions restrict terminal access, so voyage planning starts from berth compatibility.
Twin propulsion arrangements introduce their own machinery redundancy and manoeuvring characteristics.
Cargo retention strategy depends on whether reliquefaction is fitted and in service.

Strengths

Around 50% more cargo per voyage than a conventional carrier
Reliquefaction preserves cargo value on long ballast-free legs
Strong fuel efficiency per tonne-mile

Considerations

Restricted to terminals with sufficient draft and berth length
Reliquefaction plant adds maintenance and power demand

Technical information

Status: Educational overview — editorial review required; Seeded educational summary awaiting editorial and technical review.
Last reviewed: 15 September 2026
Source status: Sources pending editorial review.

Technical parameters are indicative and may vary by vessel design, generation, shipyard, operator and intended service.