OSSA LNG
Carrier library
Conventional Ocean-Going LNG CarrierConventionalEducational data

SPB (self-supporting prismatic) LNG carrier

Prismatic Type B tanks with a flat deck and no sloshing limits.

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Class overview

The IHI Self-supporting Prismatic-shape IMO type B system combines the structural independence of Moss tanks with the space efficiency of a prismatic shape. Internal swash bulkheads suppress sloshing entirely, which makes SPB the reference choice for floating units that operate at any filling level.

Classification

Operational role
Conventional Ocean-Going LNG Carrier
Containment system
SPB / Self-Supporting Prismatic Type B
Tank geometry
Independent prismatic tanks with internal swash bulkheads
Capacity class
Conventional — indicative: approximately 125,000–180,000 m³
Propulsion options
DFDE / TFDE · ME-GI
BOG management
BOG as fuel · Reliquefaction

Key systems

ContainmentAluminium prismatic tanks with internal swash bulkheads and support saddles
InsulationPolyurethane foam panels with a nitrogen-inerted interbarrier space
Cargo handlingIndependent tank monitoring with a partial secondary barrier

Operational environment

Ocean trades in demanding sea states, and hulls where flat deck space supports topsides equipment.

Safety and operational considerations

  • Internal swash bulkheads limit cargo movement, supporting a wide range of filling levels.
  • Independent tanks use a leak-before-failure design philosophy with partial secondary barrier arrangements.
  • Structural inspection plans reflect the more complex prismatic tank fabrication.

Strengths

  • No sloshing restrictions at any filling level
  • Flat weather deck simplifies topside arrangement for floating units
  • Leak-before-failure design with a full secondary drip tray

Considerations

  • Higher steel weight and build cost per cubic metre
  • Small operating fleet, so benchmarking data is limited

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.