NB/T 47057-2017Tank containers for liquefied gases (English PDF)

Foreword

This document was issued on 28 March 2017 by the National Energy Administration of the PRC and takes effect on 1 August 2017.

It is a NB/T standard: recommended rather than compulsory, but it is the text a Chinese reviewer applies when assessing a submission.

It is classified under ICS 23.020.01, Chinese classification J74.

It replaces JB/T 4781-2005, which is superseded.

This standard was drafted in accordance with the rules given in GB/T 1.1-2009 Directives for standardization—Part 1: Structure and drafting of standards.

This standard supersedes JB/T 4781-2005 Tank containers for liquefied gases. Compared with JB/T 4781-2005, the main technical changes are as follows.

a) Scope: the requirement on design temperature was deleted, and the delimitation of tanks with a tank volume of not less than 1 cubic metre was added.

b) Terms and definitions: 7 terms such as working pressure and design pressure were deleted, and 4 terms such as liquefied gas were added.

c) Qualification and responsibilities: the former clause 'General' was renamed 'Qualification and responsibilities'; the responsibilities of the user or design client were added, and the requirements on the qualification and responsibilities of the design unit and the manufacturing unit were modified.

d) Materials: the requirements for steel plates, steel forgings, steel pipes and fittings, bulk insulating materials and welding materials for the tank were modified, and a low-temperature impact requirement at minus 20 degrees C for frame materials was added.

e) Design: the requirements on maximum permissible filling mass and minimum design metal temperature were modified; the design-by-analysis method, four media such as dimethyl ether, and leak test requirements were added.

f) Safety accessories, instruments and loading/unloading accessories: the requirements for safety accessories, instruments and loading/unloading accessories were modified.

g) Manufacture: the requirements on welded joints, material re-inspection, cold and hot forming, assembly, welding, non-destructive testing and heat treatment were modified, and Category E welded joints were added.

h) Test methods: ammonia leak detection, halogen leak detection and helium leak detection test methods were added.

i) Inspection rules: the requirement for batch inspection was deleted, and the conditions for exemption from the type test were added.

j) Annexes: two annexes, 'Declaration of conformity to the standard and revisions' and 'Risk assessment report', were added; the two former annexes 'Format and content of the product quality certificate' and 'Format of the test report' were deleted; the former annex 'Design calculation of pressure relief devices' was changed to 'Calculation of the tank safety relief capacity and the discharge capacity of pressure relief devices', and the requirements on the tank safety relief capacity and the discharge capacity of pressure relief devices were modified.

This standard was proposed by and is under the jurisdiction of the National Technical Committee on Boilers and Pressure Vessels of Standardization Administration of China (SAC/TC 262).

The drafting of this standard was organized by the Subcommittee on Transportable Pressure Vessels of the National Technical Committee on Boilers and Pressure Vessels of Standardization Administration of China (SAC/TC 262/SC4).

Drafting organizations of this standard: Jiangxi Zhiyangji Co., Ltd.; Shanghai Qiti Gongye Xiehui; China Special Equipment Inspection and Research Institute; Harbin Jiancheng Jixie Shebei Co., Ltd.; Nantong Zhongji Guanshi Chuyun Shebei Zhizao Co., Ltd.; Shanghai Huayi Jituan Zhuangbei Gongcheng Co., Ltd.; Shanghai Huali Anquan Zhuangbei Co., Ltd.; Shijiazhuang Anruike Qiti Jixie Co., Ltd.; Shanghai Tezhong Shebei Jiandu Jianyan Yanjiuyuan; Zhongguo Chuanjishe Zhiliang Renzheng Gongsi; Changzhou Lanyi Feiji Zhizao Zhuangbei Co., Ltd.

Chief drafters of this standard: Chen Yanshan, Zhou Weiming, Zhang Qijin, Wei Yongbiao, Zhang Jie, Chen Chaohui, Shou Binan, Xie Tiejun, Luo Yongxin, Wu Quanlong, Tang Xiaoying, Chen Xiaohu, Zhai Lanhui, Zhang Jianti.

The previous edition of the standard superseded by this standard is JB/T 4781-2005.

This standard was approved and issued by the National Energy Administration by Announcement No. 6 of 2017, dated 28 March 2017, together with 158 other industry standards (34 NB energy standards, 39 DL electric power standards and 86 SY petroleum standards); boiler and pressure vessel standards are published and distributed by Xinhua Publishing House.

1 Scope

NB/T 47057-2017 governs steel tank containers for liquefied gases, replacing JB/T 4781-2005. These are the ISO-framed pressure tanks that carry propane, butane, ammonia, chlorine, LPG mixtures and similar gases liquefied under pressure at ambient temperature, moved by road, rail and sea. The standard applies to tanks with a design pressure of at least 0.1 MPa and a volume of at least one cubic metre; it excludes tanks in non-ferrous or non-metallic materials, vacuum-insulated tanks, and military use. It sets the scope, some fifty-seven normative references and the defined terms, then the qualification and responsibilities of the designer, the manufacturer and the inspection body. Materials are specified for the shell, heads, frame and fittings - carbon, low-temperature and austenitic stainless plates by grade - with the impact energy required at the design temperature. Design covers the shell under internal pressure and under the dynamic load cases of intermodal transport, the heads, openings and reinforcement, the frame and its connection to the tank, the filling ratio for each gas, and the sizing of the service equipment: valves, emergency shut-off, pressure relief devices, level and pressure gauges. Fabrication, welding and heat treatment, non-destructive examination, the hydraulic and leak tests, the frame tests for lifting, stacking and impact, marking, delivery documentation and storage complete the standard. It applies to tank containers built in China.

1.1 This standard specifies the requirements for the materials, design, manufacture, test methods, inspection rules, marking, delivery documents, and storage and transportation of tank containers for liquefied gases (hereinafter referred to as tank containers).

1.2 This standard is applicable to steel tank containers with a design pressure of not less than 0.1 MPa and a tank volume of not less than 1 cubic metre.

1.3 This standard is not applicable to the following tank containers: those whose tank material is a non-ferrous metal or a non-metal; those whose tank is of vacuum-insulated construction; and those with special requirements, such as national defence and military equipment.

1.4.1 The tank container covered by this standard includes the tank, piping, safety accessories, instruments, loading and unloading accessories, as well as the frame, supports and the like.

1.4.2 The boundaries of the tank are as follows: a) the groove face of the first circumferential joint where the tank is connected to piping by welding; b) the end face of the first threaded joint where the tank is connected to piping or safety accessories by threads, or the first flange sealing face where connected by flanges; c) the end caps, plugs and their fasteners of openings in the tank; d) the welds connecting the tank to non-pressure parts.

1.4.3 The main pressure parts include the shell, the heads, and pressure-bearing nozzles with a nominal diameter of not less than 50 mm, bosses, flanges, flange covers and the like.

1.4.4 The piping includes all pipes and fittings connected to the tank.

2 Normative references

The following documents are indispensable for the application of this document. For dated references, only the edition cited applies to this document. For undated references, the latest edition (including all amendments) applies to this document.

GB/T 150.1 Pressure vessels—Part 1: General requirements

GB/T 150.2 Pressure vessels—Part 2: Materials

GB/T 150.3 Pressure vessels—Part 3: Design

GB/T 150.4-2011 Pressure vessels—Part 4: Fabrication, inspection and testing, and acceptance

GB/T 196 General purpose metric screw threads—Basic dimensions

GB/T 197 General purpose metric screw threads—Tolerances

GB/T 567.1 Bursting disc safety devices—Part 1: Basic requirements

GB/T 567.2 Bursting disc safety devices—Part 2: Application, selection and installation

GB/T 567.3 Bursting disc safety devices—Part 3: Classification and installation dimensions

GB/T 713 Steel plates for boilers and pressure vessels

GB/T 1413 Series 1 freight containers—Classification, dimensions and ratings

GB/T 1804-2000 General tolerances—Tolerances for linear and angular dimensions without individual tolerance indications

GB/T 1835 Series 1 freight containers—Corner fittings

GB/T 1836 Freight containers—Coding, identification and marking

GB/T 3531 Low alloy steel plates for low temperature pressure vessels

GB/T 6479-2000 Seamless steel tubes for high-pressure chemical fertilizer equipment

GB 6944 Classification and code of dangerous goods

GB/T 8163 Seamless steel tubes for liquid service

GB/T 9948 Seamless steel tubes for petroleum cracking

GB/T 12241 Safety valves—General requirements

GB/T 12243 Spring loaded safety valves

GB 12268 List of dangerous goods

GB/T 14976 Seamless stainless steel pipes for fluid transport

GB/T 16563 Series 1 tank containers for liquids, gases and pressurized dry bulk—Technical requirements and testing

GB/T 17393 Specification for thermal insulating materials used in covering austenitic stainless steel

GB/T 17600 (all parts) Steel—Conversion of elongation values

GB/T 22653 Emergency shut-off valves for liquefied gas equipment

GB/T 24511 Stainless steel plate, sheet and strip for pressure equipment

GB/T 25198 Heads for pressure vessels

GB/T 26929 Terminology of pressure vessels

GB 50126 Code for construction of industrial equipment and pipeline insulation engineering

GBZ 230 Classification of occupational hazards from exposure to toxic substances

NB/T 47008 Carbon and alloy steel forgings for pressure equipment

NB/T 47009 Low alloy steel forgings for low temperature pressure equipment

NB/T 47010 Stainless and heat-resisting steel forgings for pressure equipment

NB/T 47013.1 Nondestructive testing of pressure equipment—Part 1: General requirements

NB/T 47013.2 Nondestructive testing of pressure equipment—Part 2: Radiographic testing

NB/T 47013.3 Nondestructive testing of pressure equipment—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 47013.10 Nondestructive testing of pressure equipment—Part 10: Ultrasonic time of flight diffraction technique

NB/T 47013.11 Nondestructive testing of pressure equipment—Part 11: Digital radiography with X-rays

NB/T 47013.14 Nondestructive testing of pressure equipment—Part 14: X-ray computed radiography

NB/T 47014 Welding procedure qualification for pressure equipment

NB/T 47016 Mechanical property tests of product welded test coupons for pressure equipment

NB/T 47018 (all parts) Technical conditions for procurement of welding materials for pressure equipment

JB/T 4711 Coating and packing for transport of pressure vessels

JB 4732-1995 Steel pressure vessels—Design by analysis (confirmed in 2005)

HG/T 20592 Steel pipe flanges (PN designated)

HG/T 20610 Spiral wound gaskets for steel pipe flanges (PN designated)

HG/T 20614 Selection of steel pipe flanges, gaskets and bolting (PN designated)

HG/T 20615 Steel pipe flanges (Class designated)

HG/T 20631 Spiral wound gaskets for steel pipe flanges (Class designated)

HG/T 20635 Selection of steel pipe flanges, gaskets and bolting (Class designated)

HG 20660 Classification of toxicity hazard and explosion risk of chemical media in pressure vessels

TSG R0005 Supervision regulation on safety technology for transportable pressure vessels

TSG Z6002 Rules for the examination of welding operators of special equipment

3 Terms and definitions

For the purposes of this document, the terms and definitions given in GB/T 150.1, GB/T 150.4, GB/T 16563 and GB/T 26929 and the following apply.

3.1 liquefied gas: a gas which is partially liquid when pressurized at a temperature above minus 50 degrees C, including high-pressure liquefied gases with a critical temperature between minus 50 degrees C and 65 degrees C and low-pressure liquefied gases with a critical temperature above 65 degrees C.

3.2 tank containers for liquefied gases: a transportable pressure vessel for filling with liquefied gases, consisting of two basic parts, namely the tank and the frame.

3.3 rating: the gross mass of the tank container, being the maximum value in operation and the minimum value in testing, usually denoted by the letter R.

3.4 geometric volume: the internal volume of the tank determined from the design geometric dimensions, without considering manufacturing tolerances but deducting the volume occupied by internals.

3.5 equivalent pressure: the pressure borne by the tank caused by the inertial loads of the medium under normal transport conditions.

3.6 reference steel: a reference material with a specified lower limit of standard tensile strength (Rm) of 370 MPa and an elongation after fracture (A) of 27%.

4 Qualification and responsibilities

4.1.1 In addition to complying with this standard, the design, manufacture, inspection and acceptance of tank containers shall comply with the relevant laws, regulations and safety technical specifications promulgated by the State.

4.1.2 The qualification of the design and manufacturing units of tank containers shall comply with the relevant provisions of TSG R0005, and they shall hold the corresponding special equipment design and manufacturing licences.

4.2.1 User or design client: the user or design client shall submit the design conditions of the tank container to the design unit in formal written form. The design conditions shall include at least: a) the main standards and safety technical specifications to be followed in design and manufacture; b) the mode of transport, including rail, road, waterway or intermodal transport combining these modes; c) the working conditions, including ambient temperature, working temperature range, working pressure range, loading and unloading conditions and methods, loading and unloading pressure, additional loads and the like; d) the filling medium, including the number, name, class, physical and chemical properties, content of harmful impurities of the medium and the corrosion rate of the medium on the tank material; e) the tank volume; f) the container dimensions; g) the expected service life; h) the number of pressure cycles corresponding to fluctuating pressure; i) dimensional requirements and nozzle orientation; j) other conditions necessary for design (such as tank material selection, corrosion protection, surface treatment and special tests).

4.2.2.1 The design unit shall complete the overall design of the tank container on the basis of the content of the risk assessment report, and shall be responsible for the correctness and completeness of the design documents.

4.2.2.2 The management and use of the design licence seal shall meet the requirements of TSG R0005.

4.2.2.3 The design unit shall retain all design documents throughout the design service life of the tank container.

4.2.3.1 The tank container shall be manufactured as a whole, and the manufacturing unit shall be responsible for the manufacturing quality of the tank container.

4.2.3.2 The manufacturing unit shall carry out manufacture in accordance with the requirements of the design documents. When the original design is modified, written evidence of the consent of the original design unit to the modification shall be obtained, and detailed records of the modified parts shall be kept.

4.2.3.3 Before manufacture, the manufacturing unit shall draw up a quality plan, which shall include at least the manufacturing process control points, inspection items and acceptance requirements of the tank container.

4.2.3.4 During and after manufacture, the inspection department of the manufacturing unit shall carry out the various inspections and tests specified in this standard, the design drawings and technical documents and the quality plan, issue the corresponding reports, and be responsible for the correctness and completeness of the reports.

4.2.3.5 After each tank container has passed inspection, the manufacturing unit shall issue a product certificate of conformity.

4.2.3.6 The manufacturing unit shall accept supervisory inspection of its manufacturing process by a special equipment inspection and testing institution, and obtain the Special Equipment Manufacturing Supervision and Inspection Certificate issued by the supervisory inspection unit.

4.2.3.7 The manufacturer of tank containers shall carry out a prototype type test for each model and obtain a certificate of conformity recognized by the competent authority.

4.2.3.8 For each tank container it manufactures, the manufacturing unit shall retain at least the following technical documents for reference throughout its design service life: a) manufacturing process drawings or process cards; b) welding procedure and heat treatment procedure documents of the tank; c) records of the inspection and test items specified in the standard; d) records of examinations, inspections and tests during and after manufacture; e) delivery documents (complying with Clause 12); f) the original design drawings.

5 Materials

5.1.1 Materials in contact with the filling medium shall be compatible with the medium.

5.1.2 Materials of non-pressure parts welded to pressure parts shall have good weldability.

5.1.3 The material manufacturer shall apply clear and durable steel stamp markings, or other traceable markings, at a conspicuous position on the material.

5.1.4 The material manufacturer shall provide a material quality certificate to the tank container manufacturer. The content of the material quality certificate shall be complete and clear, and it shall bear traceable information markings and the quality inspection stamp.

5.1.5 When the tank container manufacturer obtains tank materials from a unit other than the material manufacturer, it shall obtain the original of the material quality certificate provided by the material manufacturer, or a copy bearing the official seal of the material distributor and the seal of the responsible person.

5.1.6 The tank container manufacturer shall be responsible for the authenticity and consistency of the quality certificates of the materials and purchased parts obtained.

5.2.1 Materials selected for the tank shall comply with the relevant national or industry standards. When selecting materials for pressure parts of the tank, consideration shall be given to the service conditions of the tank (such as design temperature, design pressure, medium characteristics and operating characteristics), the properties of the material (mechanical, processing, chemical and physical properties), the manufacturing process of the tank and economic rationality.

5.2.2 The use of materials of foreign grades or new materials shall comply with the relevant provisions of TSG R0005.

5.2.3.1 Steel for pressure parts of the tank shall be killed steel.

5.2.3.2 Low alloy steel plates with a lower limit of standard tensile strength of not less than 540 MPa, and low-temperature steel plates and low-temperature steel forgings used at design temperatures below minus 20 degrees C, shall additionally be produced with out-of-furnace (secondary) refining.

5.2.4.1 For carbon steels and low alloy steels used for welding, the carbon content shall not exceed 0.250%, the phosphorus content shall not exceed 0.035% and the sulphur content shall not exceed 0.035% (heat analysis).

5.2.4.2 The phosphorus and sulphur contents of carbon steel and low alloy steel products dedicated to pressure vessels (steel plates, steel pipes and steel forgings) shall comply with the following: a) for steels with a lower limit of standard tensile strength not exceeding 540 MPa, phosphorus not more than 0.030% and sulphur not more than 0.020%; b) for steels with a lower limit of standard tensile strength above 540 MPa, phosphorus not more than 0.025% and sulphur not more than 0.015%; c) for steels used at design temperatures below minus 20 degrees C with a lower limit of standard tensile strength not exceeding 540 MPa, phosphorus not more than 0.025% and sulphur not more than 0.012%; d) for steels used at design temperatures below minus 20 degrees C with a lower limit of standard tensile strength above 540 MPa, phosphorus not more than 0.020% and sulphur not more than 0.010%.

5.2.5.1 For carbon steel or low alloy steel products for the tank, the standard value of yield strength at room temperature shall not exceed 460 MPa and the standard value of the upper limit of tensile strength shall not exceed 725 MPa; the material shall be suitable for the environmental conditions encountered by the tank container in transport and use, and shall comply with the design drawings.

5.2.5.2 For carbon steel or low alloy steel products for the tank, the ratio of yield strength to tensile strength at room temperature given in the material quality certificate shall not exceed 0.85.

5.2.5.3 Impact absorbed energy tests of carbon steel or low alloy steel (steel plates, steel pipes and steel forgings) for the tank shall comply with the following: a) the impact test temperature shall be as required by the design documents; b) the Charpy impact absorbed energy (KV2) shall comply with Table 1; c) where the Charpy impact absorbed energy specified in the steel product standard is higher than that in Table 1, the steel product standard shall also be complied with; d) steel plates less than 6 mm thick may be exempted from the Charpy impact absorbed energy test.

5.2.5.4 The sampling location and specimen orientation of Charpy impact specimens shall comply with the relevant steel product standard. Each set of impact tests shall consist of 3 standard specimens (10 mm wide); the impact absorbed energy of one specimen is permitted to be lower than the value specified in Table 1, but not lower than 70% of that value. When standard specimens cannot be prepared from the steel product, subsize impact specimens 7.5 mm or 5 mm wide shall be prepared in that order, for which the impact absorbed energy requirement is 75% or 50% respectively of the requirement for standard specimens.

Table 1 — Charpy impact absorbed energy of carbon steel or low alloy steel plates, steel pipes and steel forgings: lower limit of standard tensile strength of the steel Rm (MPa) against the average Charpy impact absorbed energy of 3 standard specimens KV2 (J).

Table 1, row 1: Rm not more than 510 MPa — KV2 not less than 27 J.

Table 1, row 2: Rm above 510 MPa up to 570 MPa — KV2 not less than 34 J.

Table 1, row 3: Rm above 570 MPa up to 630 MPa — KV2 not less than 38 J, with lateral expansion LE not less than 0.53 mm.

Table 1, note: for steels whose Rm decreases with increasing thickness, the Charpy impact absorbed energy requirement is determined from the Rm of the minimum thickness range of the steel.

5.2.5.5 Requirements for elongation after fracture (A): a) the elongation after fracture of steel plates for the tank shall be not less than 10 000/Rm (%), and shall also meet the following: when the lower limit of standard tensile strength (Rm) is not less than 540 MPa, A shall be not less than 17%; when the lower limit of standard tensile strength (Rm) is less than 540 MPa, A shall be not less than 20%; b) where the elongation after fracture specified in the relevant steel plate standard is higher than in a), that standard shall also be complied with; c) the elongation after fracture of steel plates, steel pipes and steel forgings for other pressure parts shall comply with the relevant steel product standards; d) when specimens of different dimensions are used, the elongation after fracture shall be converted in accordance with GB/T 17600 (all parts), and the converted value shall comply with a) or b) and c).

5.2.6 Ultrasonic testing of steel plates: carbon steel and low alloy steel plates for the tank shall be ultrasonically tested plate by plate in accordance with NB/T 47013.3, and the acceptance level shall be not lower than Level II.

5.2.7.1 The properties of steel plates commonly used for the tank shall comply with Table 2.

5.2.7.2 When steel plates other than those in Table 2 are used, they shall comply with the relevant material standards in addition to the requirements of this standard.

Table 2 — Properties of steel plates commonly used for the tank: steel grade, steel plate standard, delivery condition, thickness (mm), room-temperature tensile strength Rm and yield strength ReL (Rp0.2) (MPa), and elongation after fracture A (%).

Table 2, Q245R (GB/T 713, hot rolled, controlled rolled or normalized): thickness 5 mm to 16 mm, Rm 400 MPa to 520 MPa, ReL not less than 245 MPa; thickness above 16 mm up to 36 mm, Rm 400 MPa to 520 MPa, ReL not less than 235 MPa; A not less than 25%.

Table 2, Q345R (GB/T 713, hot rolled, controlled rolled or normalized): thickness 5 mm to 16 mm, Rm 510 MPa to 640 MPa, ReL not less than 345 MPa; thickness above 16 mm up to 36 mm, Rm 500 MPa to 630 MPa, ReL not less than 325 MPa; A not less than 21%.

Table 2, Q370R (GB/T 713, normalized): thickness 10 mm to 16 mm, Rm 530 MPa to 630 MPa, ReL not less than 370 MPa; thickness above 16 mm up to 36 mm, Rm 530 MPa to 630 MPa, ReL not less than 360 MPa; A not less than 20%.

Table 2, 16MnDR (GB/T 3531, normalized, or normalized and tempered): thickness 6 mm to 16 mm, Rm 490 MPa to 620 MPa, ReL not less than 315 MPa; thickness above 16 mm up to 36 mm, Rm 470 MPa to 600 MPa, ReL not less than 295 MPa; A not less than 21%.

Table 2, S30408 (GB/T 24511, solution treated): thickness 4 mm to 30 mm, Rm not less than 520 MPa, Rp0.2 not less than 220 MPa, A not less than 40%.

Table 2, S30403 (GB/T 24511, solution treated): thickness 4 mm to 30 mm, Rm not less than 490 MPa, Rp0.2 not less than 210 MPa, A not less than 40%.

Table 2, S31608 (GB/T 24511, solution treated): thickness 4 mm to 30 mm, Rm not less than 520 MPa, Rp0.2 not less than 220 MPa, A not less than 40%.

Table 2, S31603 (GB/T 24511, solution treated): thickness 4 mm to 30 mm, Rm not less than 490 MPa, Rp0.2 not less than 210 MPa, A not less than 40%.

5.2.8.1 Carbon steel and alloy steel forgings for the tank shall comply with NB/T 47008; low alloy steel forgings for low-temperature tanks shall comply with NB/T 47009.

5.2.8.2 Stainless steel forgings for the tank shall comply with NB/T 47010.

5.2.8.3 Steel forgings in contact with the medium in the tank and with a nominal diameter of not less than 50 mm shall be of a grade not lower than Grade III; other steel forgings shall be of a grade not lower than Grade II.

5.2.9.1 Steel pipes shall comply with GB/T 150.2 and the design drawings, and shall meet the following requirements: a) carbon steel and low alloy steel pipes shall comply with GB/T 6479-2000, GB/T 9948 or GB/T 8163; steel pipes in contact with media of extreme or high toxicity hazard shall comply with GB/T 6479-2000 or GB/T 9948 and shall be pressure tested pipe by pipe in accordance with the relevant standards, with a test pressure of not less than 1.6 MPa or as specified in the design drawings; b) stainless steel pipes shall comply with GB/T 14976.

5.2.9.2 Pipe fittings shall comply with the relevant standards; when pipe fittings are made from steel forgings, their requirements shall comply with 5.2.8.

5.2.10.1 Welding materials for pressure parts of the tank shall comply with NB/T 47018 (all parts) and shall bear clear and durable markings.

5.2.10.2 The selection of welding materials shall take into account the matching of the mechanical properties of the welded joint with the tank base metal; the tensile strength of the weld metal shall not be lower than the lower limit specified in the base metal standard, the impact absorbed energy shall comply with Table 1, and, when necessary, other properties shall also not be lower than the corresponding requirements for the base metal.

5.2.10.3 Welding materials shall be subjected to welding procedure qualification in accordance with NB/T 47014 and may be used only after passing the qualification.

5.2.10.4 The manufacturing unit shall establish and strictly implement a system for the acceptance, re-inspection, storage, drying, issue and return of welding materials.

5.3 Bulk insulating materials shall comply with the following: a) they shall have good chemical stability, shall not corrode equipment and piping, and shall not release large quantities of toxic gases in a fire; b) they shall have good thermal insulation and flame-retardant properties; c) where in contact with austenitic stainless steel surfaces, their chloride ion content shall comply with GB/T 17393.

5.4.1 Sunshield materials shall have good chemical stability and shall not produce large quantities of toxic gases in a fire.

5.4.2 Sunshield materials shall be inorganic, non-flammable materials.

5.5.1 Steel plates, sections and the like used for corner posts, end beams, side beams and supports shall have good weldability and sufficient strength and toughness, and shall comply with the relevant steel product standards.

5.5.2 The main load-bearing members of the frame, such as corner posts, end beams and side beams, shall have sufficient impact toughness at minus 20 degrees C; when the Charpy impact absorbed energy test is carried out at a test temperature of minus 20 degrees C, the average impact absorbed energy (KV2) of 3 standard specimens shall be not less than 27 J.

5.5.3 Materials for the frame, supports and the like shall take into account the corrosive effect of the external environment and the influence of ambient temperature.

5.6.1 Purchased parts shall comply with the relevant national or industry standards and shall be accompanied by quality certificates or product certificates of conformity.

5.6.2 Corner fittings shall comply with GB/T 1835.

5.6.3 Fasteners shall comply with the relevant national or industry standards.

5.6.4 Sealing gaskets shall comply with the relevant standards and shall not contain asbestos.

6 Design

6.1.1 In addition to the requirements of this standard, the design of tank containers shall comply with the relevant laws, regulations and safety technical specifications; the arrangement of the tank, piping, safety accessories, instruments and loading/unloading accessories shall meet the requirements of use and safety.

6.1.2 The design loads borne by the tank container shall be determined by calculation or testing.

6.1.3 Tank containers for international intermodal transport shall comply with the requirements of the relevant international conventions.

6.1.4 In the design of tank containers, appropriate protective measures shall be considered to prevent damage or leakage of the filling medium caused by longitudinal or transverse impact or by overturning.

6.1.5 For tank containers used in rail transport, the structural strength and rigidity of the prototype shall withstand, when fully loaded, an impact force of not less than 4 times the rating multiplied by the acceleration due to gravity, arising from the typical mechanical vibrations experienced in rail transport.

6.1.6 The design of tanks with bulk insulation construction shall meet the provisions of the design documents.

6.1.7 For tank containers loaded and unloaded from the top, the necessary safety protection devices shall be provided on the top of the tank container when loading and unloading is carried out on non-dedicated platforms.

6.1.8 The design service life of tank containers shall be not less than 15 years.

6.2.1 The design documents of a tank container shall include at least the following: a) the risk assessment report, including the main failure modes and risk control in the design, manufacture and use stages, the basic content of which shall comply with Annex B; b) the design specification, describing the main physical and chemical properties of the filling medium (number, name, class, and saturated vapour pressure and density corresponding to the working temperature), its hazardous characteristics, the limiting components of mixed media, the limiting content of harmful impurities and compatibility with the tank material, and also the selection of design codes and standards, the principles for determining the main design structure and main design parameters, the selection of tank and frame materials, and the selection of safety accessories, instruments and loading/unloading accessories; c) the design calculations, including calculation of the strength, rigidity, external pressure stability and volume of the tank, the safety relief capacity and the discharge capacity of pressure relief devices, structural strength analysis and, when necessary, heat transfer calculation; d) the design drawings, including the general assembly drawing, the tank drawing, and the piping system and flow diagram; e) the manufacturing technical conditions, including the main manufacturing process requirements and inspection and test methods; f) the instructions for use, including the main technical performance parameters, applicable media, specifications and connection methods of safety accessories, instruments and loading/unloading accessories, operating instructions, precautions for use, necessary safety warnings and emergency measures; g) the test programme, including the main test methods and acceptance requirements.

6.2.2 The general assembly drawing, the tank drawing, the risk assessment report and the design calculations shall bear the three-level signatures of design, checking and review, and shall be approved by the technical director of the design unit or his authorized person.

6.2.3 The general assembly drawing shall indicate at least: a) the product name, model, and the main safety technical specifications and standards on which design and manufacture are based; b) the applicable rail, road or waterway mode of transport, or intermodal transport combining these modes; c) the working conditions, including ambient temperature, working temperature, working pressure and medium characteristics (toxicity and explosion hazard); d) the design parameters, including design temperature, minimum design metal temperature, design loads (including pressure loads and other necessary loads), medium (composition) and corrosion allowance, and, for media with a tendency to stress corrosion, the limiting content of the medium; e) the main characteristic parameters, including the rating, tare mass, geometric volume of the tank, filling ratio per unit volume and maximum permissible filling mass; f) the design service life; g) insulation measures for tanks requiring insulation; h) special manufacturing requirements, such as nitrogen or inert gas purging.

6.2.3 (continued) The general assembly drawing shall also indicate: i) leak test requirements; j) special corrosion resistance requirements (when necessary); k) the specifications, performance parameters and connection methods of safety accessories, instruments and loading/unloading accessories; l) the orientation and specifications of loading and unloading nozzles and the connecting flange standards; m) gas protection requirements during transport, such as the limit on the sealing pressure of nitrogen or other insoluble gases; n) other relevant requirements specified by the rail, road or waterway transport authorities; o) the permissible stacking mass; p) the position of the nameplate.

6.2.4 The tank design drawing shall indicate at least: a) the grades and standards of the materials of the main pressure parts; b) the main design parameters, including design temperature, design pressure, minimum design metal temperature, corrosion allowance, filling ratio per unit volume, maximum permissible filling mass, the filling medium and its hazards, geometric volume and weld joint coefficient, and, for media with a tendency to stress corrosion, the limiting content of the medium; c) the design thickness and minimum formed thickness of the shell and heads; d) non-destructive testing requirements; e) heat treatment requirements (when necessary); f) pressure test requirements; g) the design service life (for tanks subject to fatigue, the number of cycles shall be indicated).

6.3.1 The external dimensions and tolerances of tank containers shall comply with GB/T 1413; tank containers of types 1AX, 1BX, 1CX and 1DX may have a reduced height. Tank containers whose external dimensions exceed those specified in GB/T 1413 (such as over-length or over-width) shall be designed, manufactured, inspected and accepted in accordance with standards recognized by the competent authority, and shall be marked accordingly.

6.3.2 No part or accessory of the tank container shall project beyond the specified external dimensions.

6.3.3 The rating of tank containers shall comply with GB/T 1413. When tank containers of types 1EEE, 1EE, 1AAA, 1AA, 1A, 1BBB, 1BB, 1B, 1CC and 1C are designed and tested to a rating, the rating is permitted to exceed the value specified in GB/T 1413. When the rating exceeds the value specified in GB/T 1413, in addition to design, inspection, testing and marking to that rating, an overweight marking shall also be applied.

6.4.1.1 For strength calculation and external pressure stability checks, design by rule shall comply with GB/T 150.3 and design by analysis shall comply with JB 4732.

6.4.1.2 When the strength of the tank is calculated in accordance with GB/T 150.3, local stress analysis may be carried out in accordance with JB 4732, and the allowable stresses of the materials shall be taken from GB/T 150.2.

6.4.1.3 The tank shall be designed on the basis of the failure modes that may occur.

6.4.2.1 The tank shall be designed to withstand the static loads, such as internal pressure, external pressure and internal/external pressure difference, as well as the dynamic loads and thermal stress loads that may occur under the various conditions of normal loading, unloading, transport and use, together with combinations of these loads. Fatigue failure caused by the repeated application of these loads within the design service life shall also be considered.

6.4.2.2 The following loads and their most unfavourable possible combinations shall be considered in the design of the tank: a) internal pressure, external pressure or maximum pressure difference; b) the hydrostatic pressure of the liquid column when the load reaches the rating; c) inertial forces during transport or lifting; d) forces at the connections or bearing points of supports, frames and other supporting members with the tank; e) forces from connecting pipes and other components; f) gravity loads of the tank under its own weight and under normal working or test conditions; g) gravity loads of auxiliary equipment, piping, ladders, platforms and the like; h) forces caused by temperature gradients or differential thermal expansion; i) impact loads caused by rapid pressure fluctuations; j) impact forces, such as those caused by liquid surge; k) cyclic dynamic loads caused by pressure or temperature changes, by equipment and frames connected to the tank, or by mechanical loads; l) loads during the type test.

6.4.2.3 The inertial loads borne by the tank container and its fastenings under transport conditions shall be considered as follows: a) in the direction of travel, 2 times the maximum mass multiplied by the acceleration due to gravity; b) horizontally perpendicular to the direction of travel, the maximum mass multiplied by the acceleration due to gravity (where the direction of travel is not clearly determined, 2 times the maximum mass multiplied by the acceleration due to gravity); c) vertically upwards, the maximum mass multiplied by the acceleration due to gravity; d) vertically downwards, 2 times the maximum mass multiplied by the acceleration due to gravity.

6.4.2.3 Note 1: when calculating the inertial loads borne by the tank under transport conditions, the maximum mass is the maximum permissible filling mass of the medium; when calculating the inertial loads borne by the connections between the tank and the frame under transport conditions, the maximum mass is the sum of the maximum permissible filling mass of the medium and the mass of the tank and its accessories.

6.4.2.3 Note 2: the above loads are applied at the centroid of the tank and do not cause the vapour space inside the tank to rise.

6.4.2.4 The external pressure load on the tank shall be determined as follows: a) generally not less than 0.04 MPa external pressure; b) where the tank may be subjected to an external pressure greater than 0.04 MPa during manufacture, transport, loading and unloading, inspection and testing, use or other conditions, the maximum possible actual external pressure shall be taken; where this cannot be determined, an external pressure of 0.1 MPa shall be taken.

6.4.2.5 a) A tank meeting either of the following conditions may be exempted from fatigue analysis. The designed tank has a shape and load conditions comparable with those of a tank with successful service experience, and it can be demonstrated from that experience that fatigue analysis is not required. Special attention shall however be paid to the adverse effects arising in the following cases: non-integral construction, such as openings reinforced by reinforcing pads or attachments connected by fillet welds; significant changes in thickness between adjacent parts; stress concentrations at the connections of frames, supports and stiffening rings to the tank.

6.4.2.5 b) When steels with a room-temperature tensile strength Rm not exceeding 540 MPa are used, the sum of the following numbers of cycles does not exceed 1 000: the expected (design) number of full-range pressure cycles, including filling and discharge; the expected (design) number of working pressure cycles whose fluctuation range exceeds 20% of the design pressure; the effective number of fluctuations of the metal temperature difference between any two adjacent points, including nozzles.