GST®, the membrane Full Integrity System for LNG Land Storage Tanks
The storage of liquefied natural gas makes it possible to ensure an uninterrupted supply and to respond to peaks in energy consumption.
GTT has developed GST® technology, based on Mark III technology, which has proven its reliability and robustness over 60 years of existence. It is a safe and adaptable solution, whatever the tank capacity. It complies fully with international standards and meets the highest safety standards.
Tried and tested for over 50 years for the oldest ones, more than 40 onshore tanks are currently in operation.
Main Characteristics of the Membrane Full Integrity System for LNG Storage Tanks
Separation of the main functions
The GST® concept is based on a clear separation of the 3 main functions required from a land storage tank; tightness, thermal insulation and structural resistance.
- Tightness is provided through the membrane
- Thermal insulation through the insulating panels
- Structural resistance through the concrete or low temperature steel walls (designed for inner and outer loads)
Prefabricated modular elements
The GST® technology consists of a combination of a limited number of modular basic shaped components.
The elements composing the membrane sheet layer as well as the insulating panels (typically 1m x 3m) are prefabricated in qualified supplier’s premises and fitted together on site.
GST® technology
- Primary Barrier
The primary barrier is made of a thin corrugated stainless steel membrane.The double network of corrugations absorbs the thermal contractions resulting from the very low temperature of the LNG and provide the liquid tightness as well as wall & bottom gas tightness
- Insulating panel
The thickness of the panels can be adjusted to provide a large range of boil-off rates according to the operator’s requirements (typically 0.05% per day for LNG).
The outer container provides the structural resistance to internal and external loads. A moisture barrier*, applied on its inner side, prevents moisture from entering the tank.
- Thermal Protection System (TPS)*
On the bottom and up to 5m: a composite laminated material is integrated in the panels.
This consists of a thin sheet of aluminium between two layers of glass cloth and resin. In the event of a failure of the primary membrane, it prevents the build-up of stress concentrations on the concrete corner and ensures the liquid tightness of the concrete wall, as required by standards.
Competitive Advantages
Security
• Comprehensive containment solution
• Proven experience
• Certification from major inspection companies
• Insulation space under inert gas and permanently monitored
• Thermal protection of the bottom/wall junction for a high level of security*
Capacity
• No capacity limitation
• Much more net volume for a given dimension
• Possibility to integrate a sump in order to reduce the impumpables
Ease of supply
• Limited weight of stainless steel
• Economies of scale : same supply chain as the LNG tanker industry with membrane tanks
• Fast production of prefabricated elements
Ease of design
• 95% of elements are standard
• Well-suited for highly seismic areas
• Boil-off rate tailored to customer specifications
• Same design model, regardless of capacity
Ease of construction
• High percentage of prefabricated elements
• 85% of welds performed automatically (TIG procedure without filler metal, only one welding pass)
• Reduced construction schedule
Ease of Operation and Maintenance
• Almost no restrictions on the rate of cooldown
• Quick Shutdown if necessary
• No maintenance required
Competitiveness
• Standard, non exclusive license agreement with EPC, allowing for free competition
Carbon Footprint
• Reduced carbon footprint by up to 16%
• Supports the use of local labor
* Only in case of concrete outer tank
Modular GST® membrane LNG storage tank is for fast track and scalable solutions for onshore LNG terminals in remote or high labour cost areas
This concept involves prefabricating an onshore tank using GTT’s GST® membrane technology, delivering it to the end user’s site on a semi-submersible vessel, and finally completing the installation and commissioning the tank.
The modular GST® membrane technology is an adaptation of GST® technology, modified with the use of a cylindrical, low temperature steel outer tank, along with the use of a movable, patented composite steel/perlite concrete baseplate designed to make the tank light-weight (under 3,500 metric tons for a 45,000m3 tank), and transportable over remote-controlled Self-Propelled Modular Transporters (SPMT).
Main Characteristics
- Low Temperature steel outer tank – SS304L or 9%Ni to act as a secondary barrier.
- Design adapted for transportation – Studies were carried out to validate the containment system with the base plate design.
- Capacity from 10,000 to 45,000 m3 – Up to three 45,000 m3 tanks per ship.
- Schedule – 17 to 20 months for the delivery of 1 tank; 24 to 27 months for 6 tanks.
- Boil-Off Rate (BOR) – 0,066%/day for a 45,000m3 with 400 mm insulation thickness considering an external T° of 19,4°C.
Scalable and cost-effective LNG tank
A pre-fabricated solution in a controlled environment with high productivity
- Mature industrial scheme – Existing network of EPC licensees for membrane installation ready for prefabrication in China
- Well-equipped fabrication shops/yards for efficient fabrication phase.
- Better safety conditions on the prefabrication construction site.
- Optimised planning by parallelizing tank erection and site preparation.
- Adapted for harsh meteorological or political condition on the end site location
Enable significant schedule & cost savings
Comparing one conventional stick built 9%Ni Tank vs several smaller GST® Modular Tanks:
- Expected planning optimization: up to 8 months saving compared to stick built for the same overall net capacity.
- Expected cost saving: up to 40% for remote or with high labour cost areas.
Fully comply with international codes and regulations
- Design in accordance with API 620/625 and revision to come of the EN 14620.
- Full Containment Equivalent.
Benefits from all the advantages of the membrane design
- Bigger storage capacity: +10% to +25% net LNG capacity for the same footprint, compared to a 9% Ni Full Containment system.
- Lower environmental footprint: Eco-friendly solution with -23% impact on the global environment, in comparison with 220,000 m3 standard GST tank built in China (estimation).
In a context where gas resources are localized far from consumers, in remote areas, developing a broad range of solutions adapted to various operational and environmental conditions is necessary. The GBS concept equipped with GTT technologies is one of these solutions.
A Concept suitable for a large range of Applications
A Gravity-Based Structure (GBS) consists in a concrete or steel caisson, laying on the sea floor. Equipped with a membrane containment system designed by GTT, the GBS can be installed in harbors or isolated zones with minimal infrastructure requirements.
The caisson acts as a quay. Completed with an adapted equipment, it allows the mooring of all types of ships, such as bunker vessels (small and mid-scale LNG carriers) and commercial vessels running on LNG (container ships, ferries, etc.), and can be connected directly to the gas distribution network.
GBS can contribute to the LNG supply chain as liquefaction or regasification plants, peak shaving storage, satellite station and for inland distribution. It can also be used for power generation (industry companies, captive power…) and bunkering (LNG as fuel).
A Modular Concept
GBS is a modular concept and can be adapted to projects in several phases. Storage capacity can be gradually increased by adding caissons.
The caisson implantation can adapt to many coast profiles, at quay or nearshore. It can also be equipped with bunkering facilities, equipment for electricity production, liquefaction or regasification.
The Benefits of GTT’s Technologies
GTT’s Membrane containment systems are suitable for different liquid gas applications (LNG, LPG, ethane, ethylene…). Mark III or GST® are suitable and can be used in GBS project.
GTT membrane benefits from being a light system that optimizes the weight and provides schedule management flexibility during construction, allowing a reduction in the critical path compared to a self-supporting tank solution.
GBS equipped with GTT tanks can offer a broad range of storage capacities ranging between 5,000 and 200,000 m3 or more.
Attractiveness of the Solution
For small-scale projects in countries that are looking for solutions that can be quickly deployed to develop LNG as a fuel or switch to gas, GBS can offer a quick delivery time.
GBS can provide the access to energy to countries & island, which are not connected to the grid and which have limited land availability.
The GST® Full Integrity Membrane film
