Detail of GB/T 26978-2021

Introduction of GB/T 26978-2021

Codeofchina.com is in charge of this English translation. In case of any doubt about the English translation, the Chinese original shall be considered authoritative. This document is developed in accordance with the rules given in GB/T 1.1-2020 Directives for standardization—Part 1: Rules for the structure and drafting of standardizing documents. This document replaces GB/T 26978.1-2011 Design and manufacture of site built, vertical, cylindrical, flat-bottomed steel tanks for the storage of liquefied natural gases—Part 1: General, 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: Metallic 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 and 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. This document consolidates GB/T 26978-2011 (all parts) into one document. The following main technical changes have been made in addition to structural adjustment and editorial changes: a) The tank type is redefined (see 4.1 hereof; Clause 4 of Part 1 of Edition 2011); b) The clause “tank risk assessment” is deleted (see Clause 4 of Part 1 of Edition 2011); c) The responsibility requirements for the development organization or the buyer are deleted (see Clause 7 of Part 1 of Edition 2011); d) The provisions of limit state and permissible stress theory are modified, and the definition description of two states in limit state theory is modified (see 4.2.3 hereof; Clause 7 of Part 1 of Edition 2011); e) The requirement that “seismic safety assessment report, site ground motion parameters and characteristic parameters of seismic influence coefficient shall be provided for seismic design” is added, and the requirement that “the coordinate value of vertical component response spectrum shall not be less than 65% of the coordinate value of corresponding horizontal component response spectrum” is modified (see 4.2.4 hereof; Clause 7 of Part 1 of Edition 2011); f) The requirement for tightness is modified (see 4.2.5 hereof; Clause 7 of Part 1 of Edition 2011); g) Regulations and technical requirements for foundation and isolation system are added (see 4.2.9 hereof); h) Height requirements for thermal protection system of concrete tank are modified (see 4.2.11 hereof; Clause 7 of Part 1 of Edition 2011); i) Other requirements for membrane tank are added (see 4.2.13 hereof); j) Reference specifications and requirements for permanent action and variable action are modified (see 4.4.2 and 4.4.3 hereof; Clause 7 of Part 1 of Edition 2011); k) The requirement for accidental action is modified (see 4.4.4 hereof; Clause 7 of Part 1 of Edition 2011); l) The requirement that "according to ENV 1998-4: 1998, the inelastic characteristic coefficient q shall not be greater than 1, unless it is reasonable to adjust according to EN 1998-1: 2004 and DD ENV 1998-4: 1998.” is deleted (see Clause 7 of Part 1 of Edition 2011); m) The clause “quality assurance and quality control” is deleted (see Clause 5 of Part 1 of Edition 2011); n) The subclause “health, safety and environmental plan” is modified (see 4.6 hereof; Clause 6 of Part 1 of Edition 2011); o) The requirements for Charpy V-notch impact and maximum permissible design stress of steel classification and new steel classification are modified (see 5.2 hereof; Clause 4 of Part 2 of Edition 2011); p) The requirements for material selection of bolts and pipe components are modified, and some China standards are cited. (see 5.2 hereof; Clause 4 of Part 2 of Edition 2011); q) The minimum width requirement of the bottom edge plate is modified; the minimum straight edge length requirement of the bottom center plate is modified; the requirements for design load of suspended deck is added; allowable pressure difference on both sides of suspended deck is added; the design requirements of nozzle are modified; the surface corrosion allowance requirements of tank anchor system are modified; and the assembly deviation and prefabrication requirements of bent roof, suspended deck, liner, thermal angle protection, inner tank bottom plate, inner tank shell plate and accessories are added (see 5.3 hereof; Clauses 5 and 6 of Part 2 of Edition 2011): r) The reference standards for qualification certification, welding procedure qualification and nondestructive testing of welders, welding operators and flaw inspectors are modified, and the RT testing ratio of girth welded joints of tank shell plate is modified (see 5.5 hereof; Clause 7 of Part 2 of Edition 2011); s) The requirements for pneumatic jacking are added (see 5.8 hereof); t) The curve used to determine the load and fatigue on the membrane in Annex B is deleted (see Annex B of Part 2 of Edition 2011); u) The design, construction and acceptance standards of concrete materials are modified (see 6.1.1 hereof; 6.2 of Part 3 of Edition 2011); v) The reference specifications for prestressing system and low temperature reinforcement are modified (see 6.1.2 hereof; 6.3 of Part 3 of Edition 2011); w) The reference specifications for load design value, load effect and geometric parameters are modified (see 6.2 hereof; 7.2 of Part 3 of Edition 2011); x) The “liquid tightness” section is deleted (see 7.3 of Part 3 of Edition 2011); y) Annex A “Materials” and Annex B “Prestressed concrete tank” are deleted (see Annexes A and B of Part 3 of Edition 2011); z) The design requirements for prestressed system are added (see 6.3.1 hereof); aa) The seismic fortification classification of prestressed concrete outer tank, the design requirements of shells and the minimum requirements for the height of the minimum compression area of shell are added (see 6.3.2 hereof); bb) The requirements that “crack width of pile and pile cap shall be checked under the serviceability limit state, and the crack width shall be controlled” are added (see 6.3.3 hereof); cc) The reference specifications of concrete cover thickness are modified (see 6.3.6 hereof; 8.7 of Part 3 of Edition 2011); dd) The minimum reinforcement area requirements are modified (see 6.3.7 hereof; 8.8 of Part 3 of Edition 2011); ee) The structural strength design requirements of the tank shell are added (see 6.5.2 hereof); ff) The “construction joints” section is deleted (see 8.5 of Part 3 of Edition 2011); gg) The “reinforced concrete cofferdam” section is deleted (see 8.9 of Part 3 of Edition 2011); hh) The “formwork and tie rods” section is deleted (see 9.3 of Part 3 of Edition 2011); ii) The requirements for concrete positioning cushions are deleted (see 9.4 of Part 3 of Edition 2011); jj) The requirements for concrete curing are deleted (see 9.5 of Part 3 of Edition 2011); kk) The “error” section is deleted (see 9.6 of Part 3 of Edition 2011); ll) The coating related contents are deleted (see Clause 10 of Part 3 of Edition 2011); mm) The acceptance requirements for main insulation materials are added (see 7.2.5 and Annex E hereof); nn) The reference to Clause 9 of GB/T 26978.3-2011 on the protective structure formed by the outer tank of the vapour barrier is deleted (see Clause 5 of Part 4 of Edition 2011); oo) The essentials for the design of each component of the full containment tank insulation system are added (see 7.4 hereof); pp) The general requirements for insulation system installation, tank bottom insulation installation requirements, annulus space insulation installation requirements, suspended deck insulation installation requirements and tank roof space cryogenic pipeline insulation installation requirements are added (see 7.5 and Annex G hereof); qq) The testing method of insulation materials is modified and China standards are adopted (see Annex D hereof; Annex B of Part 4 of Edition 2011); rr) The hydrostatic test requirements for cryogenic liquid hydrocarbon tanks such as butane, ethylene and ethane are added (see 8.1.1.2 hereof; 4.1.2 of Part 5 of Edition 2011); ss) The requirements of water quality for tank test are modified (see 8.1.1.4 hereof; 4.1.4 of Part 5 of Edition 2011); tt) The inspection of piping and inner tank support prior to hydrostatic test is added (see 8.1.1.5 hereof); uu) The requirements for settlement observation points in circumferential inspection are modified, and the settlement observation at 1/4 test liquid level height is supplemented (see 8.1.1.6.1 hereof; 4.1.6.1 of Part 5 of Edition 2011); vv) The requirements for water filling time are modified (see 8.1.1.7 hereof; 4.1.7 of Part 5 of Edition 2011); ww) The requirements of opening the intake valve after passing the negative pressure test are added (see 8.1.1.2 hereof); xx) The requirement that “the drying scheme shall meet the requirements of SY/T 4114” is added (see 8.2.2 hereof); yy) The requirements for oxygen concentration during purging are modified (see 8.2.3 hereof; 5.3 of Part 5 of Edition 2011); zz) The requirements for cool-down are modified (see 8.2.4 hereof; 5.4 of Part 5 of Edition 2011); Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. The issuing body of this document shall not be held responsible for identifying any or all such patent rights. This standard was proposed by and is under the jurisdiction of National Technical Committee on Petroleum and Natural Gas of Standardization Administration of China (SAT/TC 355). This document was firstly issued in 2011 as GB/T 26978.1-2011, GB/T 26978.2-2011, GB/T 26978.3-2011, GB/T 26978.4-2011 and GB/T 26978.5-2011. This is the first revision.   Introduction The preparation of a basic national standard is necessarily required in order to standardize the design and manufacture of cryogenic liquefied gas storage tanks and promote the development and standardization of cryogenic liquefied gas storage tank industry in China. Cryogenic liquefaction tanks are used to store products with standard boiling points below ambient temperature in two-phase state (i.e. liquid and boil-off gas). Balance between the liquid and gas phases is maintained by cooling the product to a temperature equal to or slightly below the standard boiling point and by placing the tank at a slightly positive pressure. The manufacture process of cryogenic liquefied gas storage tank includes design, construction, test, trial operation, operation (including failure) and cessation of use. Based on the above conditions, this document specifies the design and manufacture principles of cryogenic liquefied gas storage tanks. The cryogenic liquefied gas storage tank comprises a main structure and auxiliary facilities. Auxiliary facilities will not affect the overall structural design of the storage tank, therefore this document only specifies the design of the main structure of the storage tank. At present, the materials used in cryogenic liquefied gas storage tanks have been basically localized, therefore the materials involved in this document are all GB and ISO designations. If other foreign standards are referred to in the design of storage tank materials, the designations quoted in relevant standards may be used to replace the GB designations. Design and manufacture of site built, vertical, cylindrical, flat-bottomed steel tanks for the storage of cryogenic liquefied gas 1 Scope This document specifies the general requirements for the design, manufacture and installation of site built, vertical, cylindrical, flat-bottomed steel main container storage tanks (including metallic components, concrete components, insulation components, etc.), and describes the procedures and methods for testing, drying, purging and cool-down of storage tanks. This document is applicable to cryogenic liquefied gases with storage temperature ranging from -165°C to 0°C, including cryogenic frozen hydrocarbons such as liquefied natural gas (LNG) and cryogenic liquefied petroleum gas (LPG), and its components are mainly methane, ethane, propane, butane, ethylene, propylene, etc. This document is applicable to tanks with maximum design pressure not greater than 50kPa. This document is not applicable to tanks whose main container is made of concrete. 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 150.2-2011 Pressure vessels—Part 2: Materials GB/T 150.3 Pressure vessels—Part 3: Design GB/T 193 General purpose metric screw threads—General plan GB/T 229 Metallic materials—Charpy pendulum impact test method GB/T 709-2019 Dimension, shape, weight and tolerances for hot-rolled steel strip, plate and sheet GB/T 985.1 Recommended joint preparation for gas welding, manual metal arc welding, gas-shield arc welding and beam welding GB/T 1220 Stainless steel bars GB/T 2518 Continuously hot-dip zinc and zinc alloy coated steel sheet and strip GB 3097 Marine water quality standard GB/T 3531 Steel plates for low temperature pressure vessels GB/T 5224 Steel strand for prestressed concrete GB/T 6478 Steels for cold heading and cold extruding GB/T 9145-2003 General purpose metric screw threads—Limits of sizes for the screw threads of medium quality and preferable plan GB/T 12459 Steel buttwelding pipe fittings—Types and parameter GB/T 13401 Steel buttwelding pipe fittings—Technical specification GB/T 13480 Thermal insulating products for building applications—Determination of compression behaviour GB/T 14370 Anchorage, grip and coupler for prestressing tendons GB/T 19001 Quality Management Systems—Requirements GB/T 23248 Code for design of seawater treatment for recirculating cooling seawater system GB/T 24001 Environmental management systems—Requirements with guidance for use GB/T 24510 Nickel alloy steel plates for low temperature pressure vessels GB/T 24511 Stainless steel and heat resisting steel plates, sheets and strips for pressure equipment GB/T 32983 Thermal insulating products for building applications—Determination of compressive creep GB/T 45001 Occupational health and safety management systems—Requirements with guidance for use GB 50009 Load code for the design of building structures GB 50010 Code for design of concrete structures GB 50011 Code for seismic design of buildings GB 50017 Standard for design of steel structures GB 50021 Code for investigation of geotechnical engineering GB/T 50046 Standard for anticorrosion design of industrial constructions GB 50057 Code for design protection of structures against lightning GB 50204 Code for acceptance of constructional quality of concrete structures GB/T 50448 Code for application technique of cementitious grout GB 51006 Load code for design of buildings and special structures in petrochemical industry GB 51081 Technical code for application of concrete under cryogenic circumstance GB 51156-2015 Code for design of liquefied natural gas receiving terminal GB/T 51408 Standard for seismic isolation design of building HG/T 20592 Steel pipe flanges (PN designated) HG/T 20606 Non-metallic flat gaskets for use with steel pipe flanges (PN designated) HG/T 20607 PTFE envelope gaskets for use with steel pipe flanges (PN designated) HG/T 20609 Metal jacketed gaskets for use with steel pipe flanges (PN designated) HG/T 20610 Spiral wound gaskets for use with steel pipe flanges (PN designated) HG/T 20611 Covered serrated metal gaskets for use with steel pipe flanges (PN designated) HG/T 20612 Metallic ring joint gaskets for use with steel pipe flanges (PN designated) HG/T 20613 Bolting for use with steel pipe flanges (PN designated) HG/T 20614 Specification for selection of steel pipe flanges, gaskets and bolting (PN designated) HG/T 20615 Steel pipe flanges (Class designated) HG/T 20623 Large diameter steel pipe flanges (Class designated) HG/T 20627 Non-metallic flat gaskets for use with steel pipe flanges (Class designated) HG/T 20628 PTFE envelope gaskets for use with steel pipe flanges (Class designated) HG/T 20630 Metal jacketed gaskets for use with steel pipe flanges (Class designated) HG/T 20631 Spiral wound gaskets for use with steel pipe flanges (Class designated) HG/T 20632 Covered serrated metal gaskets for use with steel pipe flanges (Class designated) HG/T 20633 Metallic ring joint gaskets for use with steel pipe flanges (Class designated) HG/T 20634 Bolting for use with steel pipe flanges (Class designated) HG/T 20635 Specification for selection of steel pipe flanges, gaskets and bolting (Class designated) JGJ/T 225 Technical specification for large-diameter belled cast-in-place pile foundation JGJ 369 Code for design of prestressed concrete structures NB/T 47013.2 Nondestructive testing of pressure equipments—Part 2: Radiographic testing NB/T 47013.3 Nondestructive testing of pressure equipments—Part 3: Ultrasonic testing NB/T 47013.4 Nondestructive testing of pressure equipment—Part 4: Magnetic particle testing NB/T 47013.5 Nondestructive testing of pressure equipment—Part 5: Penetrant testing NB/T 47013.7 Nondestructive testing of pressure equipments—Part 7: Visual examination NB/T 47013.8 Nondestructive testing of pressure equipments—Part 8: Leakage testing NB/T 47014 Welding procedure qualification for pressure equipment NB/T 47015 Welding specification for pressure vessels SY/T 4114 Technical code for drying construction of gas pipeline, liquefied gas station (plant) YB/T 4641 Cryogenic ribbed bars for the reinforced concrete tanks of LNG CECS 226 Technical specification for welding of stud TSG Z6002 Examination rules for welding operators of special equipment TSG Z8001 Examination rules for non-destructive testing inspectors of special equipment 3 Terms, definitions, symbols and abbreviations 3.1 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.1.1 boil-off gas; BOG gas produced by the gasification of cryogenic liquefied gas due to the introduction of external heat and the flashing when the pressure changes during the feeding and discharging of the container [Source: GB/T 8423.3-2018, 5.2.4, modified] 3.1.2 daily boil-off rate percentage of daily boil-off of a tank due to heat leakage to the tank gross capacity [Source: GB 51156-2015, 2.0.11, modified] 3.1.3 tank gross capacity maximum permissible storage capacity of the tank under normal operating conditions Note: The capacity is calculated according to the design liquid level of the inner tank. 3.1.4 tank net capacity effective working capacity capacity between the maximum operating level and the minimum operating level allowed under normal operating conditions of the tank 3.1.5 impounding area area delineated on site with protective embankment or using topographic conditions to prevent accidental overflow of cryogenic liquefied gas or flammable refrigerant [Source: GB/T 8423.3-2018, 5.2.22, modified] 3.1.6 foundations structural units used to support the tank and its internal storage Note: It consists of base slab, ring wall or pile. 3.1.7 base slab continuous concrete base for supporting tanks Note: It includes ground type or overhead type. 3.1.8 primary container container used for holding cryogenic liquids and in direct contact with cryogenic liquids [Source: GB/T 8423.3-2018, 5.2.24] 3.1.9 secondary container container that is generally located outside the primary container, contains cryogenic liquid when leaking, and does not contact with cryogenic liquid under normal operating conditions [Source: GB/T 8423.3-2018, 5.2.25] 3.1.10 inner tank metallic self supporting cylindrical primary container 3.1.11 outer tank self supporting cylindrical secondary container made of steel or concrete 3.1.12 annular space space between the inner shell and outer shell or wall of self supporting tanks 3.1.13 insulation space space containing insulation material in the tank annular space, and between the tank bottoms or roofs   3.1.14 vapour barrier barrier to prevent entry of water vapour and other atmospheric gases into the insulation or into the outer tank [Source: GB/T 8423.3-2018, 5.2.33] 3.1.15 liner metallic plate installed against the inside of the concrete outer tank, impervious to product vapour and water vapour 3.1.16 ring beam annular support placed under the inner tank shell plate when the tank is in a low temperature environment during operation 3.1.17 roof structure on top of a shell or wall containing the vapour pressure and sealing off the contents from the atmosphere 3.1.18 shell metallic vertical cylinder 3.1.19 wall concrete vertical cylinder 3.1.20 suspended deck structure used to bear the insulation layer on the roof of tank, prevent perlite from falling into the inner tank, and connect with the steel dome through a suspender 3.1.21 thermal corner protection; TCP structure composed of secondary base, shell and thermal insulation materials arranged between the inner and outer tanks in order to protect the tank bottom and the outer wall of the concrete bottom layer in case of a small amount of leakage of the inner tank and to prevent the tank from failure   3.1.22 self supporting container designed to carry the hydrostatic forces of the stored liquid and the vapour pressure loads, if applicable 3.1.23 vapour container part of a single, double, full containment or membrane tank that contains the boil-off gas during normal operation 3.1.24 design pressure maximum permissible pressure [Source: GB/T 150.1-2011, 3.1.3, modified] 3.1.25 operating pressure maximum possible pressure of the container under normal working condition 3.1.26 test pressure pressure of the container during pressure test or leakage test [Source: GB/T 150.1-2011, 3.1.5, modified] 3.1.27 maximum design liquid level maximum liquid level that will be maintained during operation of the tank used for the static shell thickness determination 3.1.28 maximum normal operating level maximum liquid level that will be maintained during normal operation of the tank. Normally the level at which the first high level alarm is set 3.1.29 design temperature set temperature of element, i.e. the average temperature along the element cross section, under normal operating conditions of tank [Source: GB/T 150.1-2011, 3.1.7, modified]   3.1.30 operating base earthquake; OBE maximum earthquake event for which no damage is sustained and restart and safe operation can continue Note: This event would result in no loss to the operational integrity and public safety is assured. 3.1.31 safe shutdown earthquake; SSE maximum earthquake event for which the essential fail-safe functions and mechanisms are designed to be preserved Note: Permanent damage can be accepted, but without the loss of overall integrity and containment. 3.1.32 roll-over refrigerated liquefied gas at different depths in a container (generally a storage tank) generates heat and mass transfer due to the difference in temperature and / or density, resulting in the rapid mixing of layered liquids and the rapid release of a large amount of evaporated gas from the refrigerated liquefied gas container. [Source: GB/T 8423.3-2018, 5.2.7, modified] 3.1.33 action concentrated or distributed forces exerted on a structure and the causes of external or constrained deformation of the structure. The former is direct action, also known as load; the latter is indirect [Source: GB 50068-2018, 2.1.36] 3.1.34 progressive deformation phenomenon in which the deformations in each part of the membrane increase progressively under the cyclic loads 3.2 Symbols For the purposes of this document, the following symbols apply. A: compression area required, mm2; a: welding shrinkage of each longitudinal welded joint, mm; C: equivalent radiation variation coefficient; c: corrosion allowance, mm; Di: diameter of inner tank, m; Do: diameter of outer tank, m; Dp: design point; E: modulus of elasticity; e: plate thickness, mm; ea: thickness of the annular plate, mm; ea, min: minimum thickness of annular plates (excluding corrosion allowance), mm; ear: thickness of top corner ring, mm; eb: thickness of center plate, mm; ec: calculated plate thickness, mm; eg: thickness of the horizontal girder, mm; eo: shell thickness (excluding corrosion allowance), mm; eos: calculated thickness of shell plate under internal pressure condition, mm; ep: thickness of roof plate at compression ring (excluding corrosion allowance), mm; er: roof plate thickness (excluding corrosion allowance), mm; es: thickness of inner tank shell plate, mm; es, c: calculated thickness of shell plate under operating condition, mm; esi: as ordered thickness of each course in turn, mm; est: as ordered thickness of the top course, mm; es, t: calculated thickness of shell plate under hydrostatic test condition, mm; es, l: thickness of the bottom shell course, mm; F: force, N; fPLDF: permissible load coefficient of thermal insulation creep-prone materials; H: maximum design liquid height, m. He: equivalent stable height of each course at est, m; Hh: calculated height between the bottom of the shell plate and the maximum design liquid level, m; Hp: maximum allowable spacing of reinforced support on the shell with minimum thickness, m; Ht: calculated height between the bottom of the shell plate and the test liquid level, m; hs: height of each course in turn, m; K: calculated stiffening ring coefficient; k: S-N curve coefficient; L: single allowable minimum value of compressive strength; Lr: effective roof length, mm; Ls: effective shell length, mm; la: minimum width between the edge of the irregular plate of the outer ring of the tank bottom and the inner side of the shell plate, mm; m: mean of all test data from fatigue test; nj: number of longitudinal welded joints of the first course; ns: sample quantity of sampling batch; P: design pressure (for open top inner tank, design pressure is 0), kPa; Pe: external loading, kPa; Pi: internal pressure, as a combination of internal gas pressure and insulation pressure, kPa; PLD: permissible load of thermal insulation creep-prone materials, MPa; Pr: internal pressure minus roof plate weight, kPa; Pt: hydrostatic test pressure (for open top inner tank, design pressure is 0), kPa; Q: quality statistics of acceptance sampling inspection; Qe: quality statistics of compressive strength of sampling batches; Qt: quality statistics of conductivity factor of sampling batches; R: characteristic strength value of insulation material, MPa; Rb: radius of assembly circle in the first course, mm; Rel: yield strength of the steel or weld material, whichever is the lesser, MPa; Rf: final radius of 9% nickel steel plate, mm; Ri: radius of inner tank, mm; Rl: radius of outer tank, m; Rm: lower limit of standard tensile strength of steel or weld metal, MPa; Rr: radius of curvature of roof (Rr=R/sinθ for conical roof), m; Ro: initial radius of 9% nickel steel plate (infinity for plate), mm; S: standard deviation; SF: safety factor; s: standard deviation of sampling batch; U: maximum single allowable conductivity factor; Va: design internal negative pressure, kPa; Vw: design wind speed, m/s; : average; : average compressive strength of sampling batch; : average conductivity factor of sampling batch; α: tensile to yield strength ratio Rm/Rel; αn: horizontal seismic influence coefficient of component n before isolation, which is calculated by the mode decomposition response spectrum method according to the seismic influence coefficient curve of the site; αn1: horizontal seismic influence coefficient of component n after isolation; βn: horizontal damping coefficient of the component n, which is the ratio of the maximum acceleration of the component n after isolation to the maximum acceleration of the component n before isolation. The acceleration of the component before and after isolation shall be calculated by using the time-history analysis method according to the OBE seismic acceleration input. The parameters of the isolation support shall be based on the hysteresis curve obtained from the test; γc: safety factor of cylinder effect; γF: material partial coefficient; γi: safety factor of installation; γL: safety factor applied to load; γM: factor for material strength; γm: safety factor of insulation materials; γt: coefficients of possible differences between the reference method for testing insulating products and their installation methods; ε: strain; εef: extreme fiber strain, %; ε1: first principal strain; ε2: second principal strain; ε3: third principal strain; η: welded joint efficiency factor; θ: slope of the roof meridian at roof-shell connection, °; ρ——maximum density of storage medium under operating conditions, kg/m3; ρt: maximum density of test medium under hydrostatic test condition, kg/m3; σ: permissible stress, MPa; σ1: first principal stress, MPa; σ2: second principal stress, MPa; σ3: third principal stress, MPa; σc: permissible compressive stress, MPa; σi: compressive stress applied in the test of load-bearing insulation creep-prone materials, MPa; σm: maximum compressive strength of load-bearing insulation material when yield or failure occurs when deformation is less than 10%, MPa; σn: nominal compressive strength of load-bearing insulation material, MPa; σs: permissible tensile stress, MPa; σst: design permissible tensile stress under hydrostatic test condition, MPa; σ10: compressive stress of load-bearing insulation creep-prone material without yielding or failure at 10% deformation, MPa; φ: foundation slope angle, °; ψ: adjustment coefficient of isolation bearing, which is taken as 0.80 for general rubber bearing; and 0.85 in case of Category S-A bearing shear performance deviation; Δε: equivalent strain radiation; ∑x: sum of compressive strength or conductivity factor of all samples in the sampling batch; ∑x2: sum of squares of compressive strength or conductivity factor of all samples in the sampling batch. 3.3 Abbreviations For the purposes of this document, the following abbreviations apply. ALE——Aftershock Level Earthquake AQL——Acceptance Quality Limit BL——Block Type BOG——Boil-off Gas FIP——Foamed in Place GR——Glass Fibre Reinforced HAZ——Heat Affected Zone HD——High Density LNG——Liquefied Natural Gas LPG——Liquefied Petroleum Gas LQ——Limiting Quality MD——Medium Density ND——Normal Density NDE——Non-destructive Examination OBE——Operating Base Earthquake PIR——Poly Isocyanurate Foam PQR——Procedure Qualification Records PUF——Polyurethane Foam PVC——Polyvinyl Chloride Foam RLG——Refrigerated Liquefied Gas SLS——Serviceability Limit States SPR——Spray Type SSE——Safe Shutdown Earthquake TCP——Thermal Corner Protection ULS——Ultimate Limit States WPS——Welding Procedure Specification 4 Basic requirements and general provisions 4.1 Tank type 4.1.1 Single containment tank It is a tank that has only one self supporting steel storage tank for cryogenic liquids, which can be composed of single-wall or double-wall structures with insulation, and has liquid tightness and air tightness. Product boil-off gas shall be stored: a) in the steel dome of the container; b) in an airtight metal outer tank surrounding the main container when the primary container is shaped in an open cup, which is only designed to store product boil-off gas and support and protect the thermal insulation. Cofferdams shall be built around each single containment tank to accommodate products that may leak.

Contents of GB/T 26978-2021

Foreword i Introduction vi 1 Scope 2 Normative references 3 Terms, definitions, symbols and abbreviations 3.1 Terms and definitions 3.2 Symbols 3.3 Abbreviations 4 Basic requirements and general provisions 4.1 Tank type 4.2 Overall design basis 4.3 Protection system 4.4 Action 4.5 Inspection and maintenance 4.6 Quality management, environmental management, and occupational health and safety management 5 Metal components 5.1 General requirements 5.2 Material 5.3 Design 5.4 Manufacture 5.5 Welding procedures 5.6 Welding 5.7 Inspection 5.8 Pneumatic jacking 6 Concrete component 6.1 Material 6.2 Combination of loads 6.3 Design requirements 6.4 Construction requirements 6.5 Liner 7 Insulation components 7.1 General 7.2 Design, property, testing and selection of insulation materials 7.3 Insulation protection—vapour barrier 7.4 Design of insulation system 7.5 Installation of insulation system 8 Testing, drying, purging and cool-down 8.1 Hydrostatic test and pneumatic test 8.2 Drying, purging and cool-down 8.3 Shutdown Annex A (Informative) Design example of intermediate ring stiffener Annex B (Informative) Loads on membrane Annex C (Informative) Insulation material Annex D (Informative) Testing method for insulation materials Annex E (Informative) Acceptance of main insulation materials E.1 Pressure-bearing foam glass brick at tank bottom E.2 Expanded perlite E.3 Glass wool E.4 Elastic felt E.5 Asphalt felt Annex F (Informative) Thermal insulation at the bottom of main tank — limit state theory Annex G (Informative) Construction and installation of tank insulation system G.1 Tank bottom insulation installation G.2 Annular space insulation installation G.3 Installation of suspended deck insulation G.4 Insulation installation of cryogenic pipeline in roof space Bibliography Figure 1 Single containment tank Figure 2 Double containment tank Figure 3 Full containment tank Figure 4 Membrane tank Figure 5 Typical bottom layout Figure 6 Design flowchart for membranes Figure 7 Typical shell-roof compression areas Figure 8 Typical roof nozzle with insulation component Figure 9 Measuring parts of geometric dimension of dome sheet Figure 10 Measuring parts of geometric dimension of bottom edge plate Figure 11 Measuring parts of geometric dimension of shell Figure 12 Outward and inward peaking Figure 13 Gauge for measuring peaking Figure 14 Schematic diagram of suspended deck Figure 15 Schematic diagram of three layer plate lapping Table 1 Steel types of tank at product storage temperature Table 2 Steel grades and lower limit of storage temperature Table 3 Minimum Charpy V-notch impact test energy Table 4 Steel used for boil-off gas container Table 5 Design permissible tensile stress Table 6 Partial load and material coefficient of low alloy steel plate for low temperature service, low nickel steel and 9% nickel steel Table 7 Minimum shell thickness Table 8 Coefficient k of S-N curve (assumed under normal distribution) Table 9 Minimum dimension of top corner ring Table 10 Mechanical properties of welding stud Table 11 Allowable deviation of geometric dimension of dome sheet Table 12 Allowable deviation of geometric dimension of bottom edge plate Table 13 Allowable deviation of geometric dimension of shell plate Table 14 Radius tolerances Table 15 Maximum deviation between the design and the as built profile Table 16 Tolerance limits on local deformation at welded joints Table 17 Maximum misalignment at vertical joint Table 18 Misalignment of shell plate assembly Table 19 Allowable deviation of radius of any point on the inner surface of bottom ring shell plate Table 20 Angular deformation of welded joint of shell plate Table 21 Concave-convex deformation of shell plate Table 22 Holding time at lower temperatures Table 23 Inspection of welded joints of primary and secondary containers Table 24 Radiographic/ultrasonic testing for shell welded joints Table 25 Inspection of boil-off gas barrier/liner Table 26 Extent of radiographic/ultrasonic testing of shell plate welded joint of vapour containers Table 27 Partial load factor under accidental action Table 28 Requirements for cracks Table 29 Hydraulic test requirement Table A.1 Shell plate dimensions Table B.1 Static load Table B.2 Cyclic load Table B.3 Accidental load Table C.1 Single and double containment tank Table C.2 Full containment tank Table C.3 Membrane tank Table D.1 Thermal resistance property testing Table D.2 Mechanical property testing Table D.3 Temperature resistance testing Table D.4 Permeability testing and influence testing of water and water vapour Table D.5 Testing of material properties immersed in refrigerated liquefied gas environment Table D.6 Chemical characteristic testing Table D.7 Flame retardance/reaction to fire testing Table E.1 Main property requirements of foam glass brick Table E.2 Property requirements of conductivity factor of foam glass brick with temperature change Table E.3 Foam glass brick size, appearance inspection sample size and qualification judgment Table E.4 Sample size and qualification judgment requirements for compressive strength and conductivity factor of foam glass brick in end-of-manufacturing inspection Table E.5 Property inspection of perlite ore Table E.6 Grain size sieving of perlite ore Table E.7 Property inspection of expanded perlite powder Table E.8 Grain size sieving of expanded perlite powder