GTT - Gaztransport & Technigaz)

GTT is a French marine engineering compagny specialised in the design of membrane containment systems for the maritime transportation and storage of LNG (Liquefied Natural Gas).

Leader on the market of Cargo Containment Systems (CGS), GTT provides solutions for all the major steps of the LNG chain: LNG Carriers, Subsea Cryogenic Pipeline, Land Storage.

GAZTRANSPORT & TECHNIGAZ

[NO96 System-MARK III System-CS1 System]

LNG Carrier Containment Systems

NO96 System

NO 96 Membrane System

is a cryogenic liner directly supported by the ship's inner hull.

This liner includes two identical metallic membranes and two independent insulation layers:


Primary & secondary Invar membranes


The primary and secondary membranes are made of Invar, a 36% nickel-steel alloy, 0,7 mm thick. The primary membrane contains the LNG cargo, while the secondary membrane, identical to the primary, ensures a 100 % redundancy in case of leakage. Each of the 500 mm wide invar strakes is continuously spread along the tank walls and is evenly supported by the primary and the secondary insulation layers.

 

Primary & secondary thermal insulation

The primary and secondary insulation layers consist in a load bearing system made of prefabricated plywood boxes filled with expanded perlite. The standard size of the boxes is 1m x 1.2m. The thickness of the primary layer is adjustable from 170mm to 250mm, to fulfill any B.O.R. requirements ; the typical thickness of the secondary layer is 300 mm. The primary layer is secured by means of the primary couplers, themselves fixed to the secondary coupler assembly. The secondary layer is laid and evenly supported by the inner hull through load-bearing resin ropes, and fixed by means of the secondary couplers anchored to the inner hull.

 

 

Reliability

Dual Invar membrane technology continuously improved since 1969 is approved by all the major classification societies. It benefits from more than 40 years of experience at sea.

Safety

The two independent insulation spaces are continuously flushed with nitrogen gas. The integrity of both membranes is permanently monitored by detection of hydrocarbon in the nitrogen.

Minimal thermal stress

The Invar material offers an extremely low thermal contraction coefficient, thus reducing the thermal stresses in the material.


Transversal loads

The membrane strakes are fixed to the boxes by a tongue device enabling the sliding of the membrane on the top of the boxes (no shear stress) and the absorption of the transverse loads through the deflection of the raised edges.

Smooth transfer of longitudinal loads

Along the transverse bulkhead corners, the two membranes are connected to the hull through an Invar tube, so that all the dynamic and thermal loads are directly and uniformly transferred to the steel structure.

High resistance

The boxes are internally strengthened to withstand high impact pressures, and to absorb the energy from liquid motion.

Materials

Plywood and perlite are easily procured, low cost raw materials, available worldwide.


Modular concept

This modular system calls for standard prefabricated components that can accommodate any shape and capacity of tanks. In addition, they are designed for mass production techniques and easy handling.



MARK III System

MARK III Membrane System

is a cryogenic liner directly supported by the ship's inner hull.

This liner is composed of a primary metallic membrane positioned on top of a prefabricated insulation panel including a complete secondary membrane:


Primary stainless steel membrane


The primary membrane is made of corrugated stainless steel 304 L, 1.2 mm thick. It contains the LNG cargo and is directly supported by and fixed to the insulation system. Standard size of the corrugated sheets is 3 m x 1m.

Secondary triplex membrane


The secondary membrane is made of a composite laminated material: a thin sheet of aluminum between two layers of glass cloth and resin. It is positioned inside the prefabricated insulation panels between the two insulation layers.

Insulation


The insulation consists of a load-bearing system made of prefabricated panels in reinforced polyurethane foam including both primary and secondary insulation layers and the secondary membrane. The standard size of the panels is 3 m x 1 m. The thickness of the insulation is adjustable from 250 mm to 350 mm to fulfill any B.O.R. requirement. The panels are bonded to the inner hull by means of resin ropes which serve a double purpose: anchoring the insulation and spreading evenly the loads.

Reliability

The corrugated membrane technology continuously improved since 1967 is approved by all the major classification societies. It benefits from more than 30 years of experience at sea.

Safety

The two independent insulation spaces are continuously flushed with nitrogen gas. The integrity of both membranes is permanently monitored by detection of hydrocarbon in the nitrogen.

Zero stress concept

The orthogonal corrugation pattern enables the membrane to accommodate any thermal or hull deflection stresses and to work under the fatigue limit thus providing outstanding lifetime.

Negligible edge loads

Because of low stress on the primary membrane, prefabricated foam corner panels can be used to anchor the membrane to the hull thus minimizing thermal flux.

High resistance

An insertion of fiberglass in the thick of the polyurethane foam gives high mechanical properties to the panels. The high density of the foam and the plywood covering both sides of the panels - for an even load distribution - allow the insulation to withstand high impact pressures and absorb the energy resulting from liquid motion.

Compactness

The low thermal conductivity of the foam and of the corners results in a thin insulation ; thus maximizing the cargo capacity for any ship external constraints.

Modular concept

This modular system calls for standard prefabricated components that can accommodate any shape and capacity of tanks and are designed for mass production techniques and easy assembly.

CS1 System

CS1 Membrane System for LNG Integrated Tanks

CS1 Membrane system is a cryogenic liner directly supported by the ship's inner hull. This liner is composed of a prefabricated insulation panel including a complete secondary membrane:


Primary invar membrane


The primary membrane is made of Invar, a 36% nickel-steel alloy, 0.7 mm thick. The primary membrane contains the LNG cargo. Each of the 500 mm wide invar stakes is continuously spread along the tank walls and is evenly supported by and fixed to the insulation. Standard size of the corrugated sheets is 3 m x 1m.

 

Secondary triplex membrane


The secondary membrane is made of a composite laminated material: a thin sheet of aluminium between two layers of glass cloth and resin. It is positioned inside the prefabricated insulation panels between the two insulation layers.

Insulation


The insulation consists of a load-bearing system made of prefabricated panels in reinforced polyurethane foam including both primary and secondary insulation layers as well as the secondary membrane. The standard size of the panels is 3 m x 1 m. The thickness of the insulation is adjustable from 250 mm to 350 mm to fulfill any B.O.R. requirement. The panels are bonded to the inner hull by means of resin ropes which serve a double purpose: anchoring the insulation and spreading evenly the loads.

 

 

Reliability

The CS1 membrane technology combines components of NO 96 and Mark III membrane systems and benefits from more than 40 years of experience at sea. It is approved by all of the major classification societies.

Safety

The two independent insulation spaces are continuously flushed with nitrogen gas. The integrity of both membranes is permanently monitored by detection of hydrocarbon in the nitrogen.

Loads

The membrane strakes, made of invar, a material with an extremely low thermal contraction coefficient, are fixed to the panels by a tongue device enabling the sliding of the membrane and the absorption of transversal loads through the deflection of the raised edges. The longitudinal loads are directly and uniformly transferred to the steel structure through an invar tube along the transverse bulkhead corners.

High resistance

An insertion of fiberglass in the thick of the polyurethane foam gives high mechanical properties to the panels. The high density of the foam and the plywood covering both sides of the panels - for an even load distribution - allow the insulation to withstand high impact pressures and absorb the energy resulting from liquid motion.

Compactness

The low thermal conductivity of the foam results in a thin insulation ; thus maximizing the cargo capacity for any ship external constraints.

Modular concept

This modular system calls for standard prefabricated components that can accommodate any shape and capacity of tanks and are designed for mass production techniques and easy assembly.

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