GAZTRANSPORT & TECHNIGAZL N G

Mark III membrane system is a cryogenic liner directly supported by the ship’sinner hull. This liner is composed of a primary metallic membrane positionedon top of a prefabricated insulation panel including a complete secondarymembrane:

Primary stainless steel membraneThe primary membrane is made of corrugatedstainless steel 304 L, 1.2 mm thick. It contains

the LNG cargo and is directly supported by and fixedto the insulation system. Standard size of thecorrugated sheets is 3 m x 1m.

Secondary triplex membraneThe secondary membrane is made of acomposite laminated material: a thin sheet of

aluminium between two layers of glass cloth andresin. It is positioned inside the prefabricatedinsulation panels between the two insulation layers.

InsulationThe insulation consists of a load-bearingsystem made of prefabricated panels in

reinforced polyurethane foam including bothprimary and secondary insulation layers and thesecondary membrane.The standard size of thepanels is 3 m x 1 m.The thickness of the insulation isadjustable from 250 mm to 350 mm to fulfill anyB.O.R. requirement.The panels are bonded to theinner hull by means of resin ropes which serve adouble purpose: anchoring the insulation andspreading evenly the loads.

Secondary triplex membrane

Inner hullCorner panel Resin ropes

Primary stainless steel membrane

Top bridge pad

Flexibletriplex joint

ReliabilityThe corrugated membrane technology continuouslyimproved since 1967 is approved by all the major

classification societies. It benefits from more than 30 yearsof experience at sea.

SafetyThe two independent insulation spaces arecontinuously flushed with nitrogen gas.The integrity

of both membranes is permanently monitored by detectionof hydrocarbon in the nitrogen.

Zero stress conceptThe orthogonal corrugation pattern enables themembrane to accommodate any thermal or hull

deflection stresses and to work under the fatigue limit thusproviding outstanding lifetime.

Negligible edge loadsBecause of low stress on the primary membrane,prefabricated foam corner panels can be used to

anchor the membrane to the hull thus minimizing thermalflux.

High resistanceAn insertion of fiberglass in the thick of thepolyurethane foam gives high mechanical properties

to the panels.The high density of the foam and the plywoodcovering both sides of the panels - for an even loaddistribution - allow the insulation to withstand high impactpressures and absorb the energy resulting from liquidmotion.

CompactnessThe low thermal conductivity of the foam and of thecorners results in a thin insulation ; thus maximizing

the cargo capacity for any ship external constraints.

Modular concept This modular system calls for standard prefabricatedcomponents that can accommodate any shape and

capacity of tanks and are designed for mass productiontechniques and easy assembly.

Triplex membrane

Stainless steel membrane

Gaztransport & Technigaz

Aluminium foilAluminium

Glass cloth

Bondingndcompoun

Bonding compound Glass cloth

Flat joint

Plugs

Polyurethane foam panel

GAZTRANSPORT & TECHNIGAZL N G

GAZTRANSPORT & TECHNIGAZ SAsNaval Engineering - Head Office and Technical Departments

46, avenue des Frères Lumière • 78190 Trappes • FranceTel : +33 (0)1 30 16 20 20 • Fax : + 33 (0)1 30 50 90 58 • http : www.gtt.fr • E-mail : gtt@gtt.fr