Design and manufacture of site built, vertical, cylindrical, flat-bottomed steel tanks for the storage of liquefied natural gases—Part 1: General
1 Scope
This part is a technical specification for design and manufacture of site built, vertical, cylindrical, flat-bottomed steel containers for the storage tanks of liquefied natural gases. The secondary container, if applicable, may be of steel or of concrete or a combination of both. An inner tank made only of pre-stressed concrete is excluded from the scope of this part.
This part specifies principles and application rules for the structural design of the “containment” during construction, testing, commissioning, operation (accidental included), and decommissioning. It does not address the requirements for ancillary equipment such as pumps, pumpwells, valves, piping, instrumentation, staircases etc. unless they can affect the structural design of the tank.
This part applies to storage tanks designed to store products, having an atmospheric boiling point below ambient temperature, in a dual phase, i.e., liquid and vapor. The equilibrium between liquid and vapor phases being maintained by cooling down the product to a temperature equal to, or just below, its atmospheric boiling point in combination with a slight overpressure in the storage tank.
The maximum design pressure of the tanks covered by this part is limited to 50kPa (500mbar). For higher pressures, reference may be made to EN 13445, Parts 1 to 5 (References [3], [4], [5], [6], [7]).
The operating range of the gasses to be stored is between 0°C and –165°C.
The tanks are used to store large volumes of liquefied natural gas (LNG) with low temperature boiling point.
Note: general properties of the liquefied natural gas are given in GB/T 19204-2003, main physical properties of the pure gas in liquefied natural gas are given in Annex A.
The requirements of this part cannot cover all details of design and construction because of the variety of sizes and configurations that may be employed. Where complete requirements for a specific design are not provided, the intention is for the designer, subject to approval of the purchaser's authorized representative, to provide design and details that are as safe as those laid out in this part.
This part specifies general requirements for the tank concept, selection and general design considerations.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
GB/T 19204-2003 General characteristics of liquefied natural gas (EN 1160: 1997, IDT)
GB/T 26978.2-2011 Design and manufacture of site built, vertical, cylindrical, flat-bottomed steel tanks for the storage of liquefied natural gases—Part 2: Metal components
GB/T 26978.3-2011 Design and manufacture of site built, vertical, cylindrical, flat-bottomed steel tanks for the storage of liquefied natural gases—Part 3: Concrete components
GB/T 26978.4-2011 Design and manufacture of site built, vertical, cylindrical, flat-bottomed steel tanks for the storage of liquefied natural gases—Part 4: Insulation components
GB/T 26978.5-2011 Design and manufacture of site built, vertical, cylindrical, flat-bottomed steel tanks for the storage of liquefied natural gases—Part 5: Testing, drying, purging and cool-down
EN 1991-1-4 Eurocode 1: Actions on structures — Part 1-4: Wind actions
EN 1991-1-6 Eurocode 1: Actions on structures — Part 1-6: General actions — Actions during execution
EN 1992-1-1:2004 Eurocode 2: Design of concrete structures — Part 1-1: General rules and rules for buildings
EN 1997-1:2004 Eurocode 7: Geotechnical design — Part 1: General rules
EN 1998-1:2004 Eurocode 8: Design of structures for earthquake resistance —Part 1: General rules, seismic actions and rules for buildings
ENV 1998-4:1998 Eurocode 8: Design provisions for earthquake resistance of structures — Part 4: Silos, tanks and pipelines
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
action
a) set of forces (loads) applied to the structure (direct action)
b) set of imposed deformation or accelerations caused for example, by temperature changes, moisture variation, uneven settlement or earthquakes (indirect action)
3.2
annular space
space between the inner shell and outer shell or wall of self-supporting tanks
3.3
base slab
continuous concrete base supporting the tank (either on the ground or elevated)
Foreword i
1 Scope
2 Normative references
3 Terms and definitions
4 Concept selection
4.1 Types of tank
4.1.1 Single containment tank
4.1.2 Double containment tank
4.1.3 Full containment tank
4.1.4 Membrane tank
4.2 Risk assessment
4.2.1 General
4.2.2 Site selection
4.2.3 Pre-selection of storage type
4.2.4 Hazard identification
4.2.5 Methods
4.2.6 Changes
4.2.7 Determination of actions
4.2.8 Risk profiles
5 Quality assurance and quality control
6 Health, safety and environment plan
7 General design considerations
7.1 General
7.1.1 Responsibilities
7.1.2 Performance criteria
7.1.3 Limit state and allowable stress theory
7.1.4 Earthquake design
7.1.5 Tightness
7.1.6 Connections to primary and secondary containers
7.1.7 Maximum design liquid level
7.1.8 Cool down
7.1.9 Foundation
7.1.10 Foundation heating system
7.1.11 Thermal Protection System (TPS) of concrete tank
7.1.12 Bund wall
7.1.13 Lightning
7.2 Protection systems
7.2.1 Instrumentation
7.2.2 Pressure and vacuum protection
7.2.3 Fire protection
7.3 Actions (loadings)
7.3.1 General
7.3.2 Normal actions
7.3.3 Accidental actions
7.3.4 Action combinations
8 Inspection and maintenance
Annex A (Informative) Main physical constants of common pure hydrocarbon gases
Annex B (Normative) Design information
Annex C (Normative) Seismic analysis
Annex D (Informative) Tank heating system
Annex NA (Informative) Technical differences and reasons between this part and EN 14620-1: 2006
Bibliography
