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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 24159-2009 Welded insulated cylinders. In addition to structural adjustments and editorial changes, the following main technical changes have been made with respect to GB/T 24159-2009:
a) The volume, the range and type of medium of the cylinder have been changed:
The volume has been expanded from 450L to 10000L (see Clause 1 hereof; Clause 1 of Edition 2009);
Liquefied natural gas has been introduced as a medium (see Clause 1);
The horizontal type has been added (see 5.1);
b) The details of welding procedure qualification have been modified [see 8.10.3 hereof; 7.2.1, 7.2.2, 7.2.3, 7.2.4, 7.2.6a), 7.2.6b), 7.2.6c), 7.2.7, 7.14.2, 7.14.3, 8.2.2, 8.2.4.1, 8.2.4.2, 8.2.4.3 and 9.3.3 of Edition 2009 ].
c) The provisions on the maximum allowable filling ratio have been introduced (see Annex A hereof);
d) The provisions on the inlet connector and outlet connector of valves have been introduced (see Annex B hereof);
e) The provisions on the safety relief rate and relieving area have been modified (see Annex C hereof; Annex A of Edition 2009), and the recommended values for thermal conductivity (see C.1 hereof), conversion relationships for flows (see C.2 hereof), formulae for calculating gas compressibility (see C.4 hereof), and methods for calculating gas coefficients at a pressure greater than or equal to the critical pressure (see C.5.2 hereof) have been introduced;
f) The provisions on vibration test have been introduced (see Annex D hereof).
g) The provisions on drop test have been introduced (see Annex E hereof).
h) The provisions on air supply test method have bee removed (see Annex B of Edition 2009).
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 document was proposed by and is under the jurisdiction of the National Technical Committee on Gas Cylinder of Standardization Administration of China (SAC/TC 31).
This document was firstly issued in 2009, and this edition is the first revision.
Welded insulated cylinders
1 Scope
This document specifies symbols, designation, basic parameters, materials, design, manufacturing, test methods, inspection rules, type tests, marking, packaging, transportation, end-of-manufacturing documents and data retention, among others, for welded insulated cylinders (hereinafter referred to as “cylinders”).
This document is applicable to refillable cylinders intended for use at normal ambient temperature (-40 °C to 60 °C), with nominal capacity of 10 L to 1000 L for storing liquid oxygen, liquid nitrogen and liquid argon, nominal capacity of 150 L to 1000 L for liquefied natural gas, design temperature up to -196 °C and nominal working pressure of 0.2 MPa to 3.5 MPa.
For cylinders storing liquid carbon dioxide and liquid nitrous oxide, this standard may apply in terms of manufacture and inspection.
Note: Any pressure not specified in this standard refers to the gauge pressure.
2 Normative references
The following documents contain provisions which, through reference in this text, constitute provisions 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 228.1 Metallic materials—Tensile testing—Part 1: Method of test at room temperature
GB/T 229 Metallic Materials—Charpy Pendulum Impact Test Method
GB/T1804 General tolerances—Tolerances for linear and angular dimensions without individual tolerance indications
GB/T 2653 Bend test methods on welded joints
GB/T 7144 Coloured cylinder mark for gases
GB/T 9251 Methods for hydrostatic test of gas cylinders
GB/T 12137 Methods for leakage test of gas cylinders
GB/T 12241 Safety valves—General requirements
GB/T 12243 Spring loaded safety valves
GB/T 13005 Terminology of gas cylinders
GB/T 15384 Designation for gas cylinders
GB/T 16804 Precautionary labels for gas cylinders
GB/T 16918 Bursting disc safety devices for gas cylinders
GB/T 17925 Standard practice for X-ray digital radioscopic examination of cylinder weld
GB/T 18442.1 Static vacuum insulated cryogenic pressure vessel—Part 1: General requirements
GB/T 18442.3 Static vacuum insulated cryogenic pressure vessel—Part 3: Design
GB/T 18443.2 Testing method of performance for vacuum insulation cryogenic equipment—Part 2: Vacuum degree measurement
GB/T 18443.3 Testing method of performance for vacuum insulation cryogenic equipment—Part 3: Leak rate measurement
GB/T 18443.4 Testing method of performance for vacuum insulation cryogenic equipment—Part 4: Leak-outgassing rate measurement
GB/T 18443.5 Testing method of performance for vacuum insulation cryogenic equipment—Part 5: Static evaporation rate measurement
GB/T 18443.8 Testing method of performance for vacuum insulation cryogenic equipment—Part 8: Volume measurement
GB/T 18517 Terminology of refrigeration
GB/T 24511 Stainless steel and heat resisting steel plate,sheet and strip for pressure equipments
GB/T 25198 Heads for pressure vessels
GB/T 26929 Terminology for pressure vessels
GB/T 31480 Materials for high vacuum multilayer insulation of cryogenic vessel
GB/T 31481 Guidance for gas/materials compatibility of cryogenic vessels
GB/T 33209 Welding procedure qualification for welded gas cylinders
GB/T 33215 Pressure relief devices for gas cylinders
GB/T 34530.1 Valve for cryogenic insulated cylinder—Part 1: Pressure regulating valve
GB/T 34530.2 Valve for cryogenic insulated cylinder—Part 2: Shut-off valve
JB 4732-1995 Steel Pressure Vessels—Design by Analysis
JB/T 6896 Surface cleanliness of air separation plants
NB/T 47013.2 Non-destructive testing of pressure equipments—Part 2: Radiographic testing
NB/T 47013.11 Nondestructive testing of pressure equipments—Part 11: Standard practice for X-ray digital radiography
NB/T 47013.14 Nondestructive testing of pressure equipments—Part 14: X-ray compute radiographic testing
NB/T 47018.1 Technical permission of welding materials for pressure equipment—Section 1: General rule
NB/T 47018.3 Technical permission of welding materials for pressure equipment—Section 3: Steel electrodes and rods for gas shielded arc welding
TSG 23 Regulation on safety technology for gas cylinder
3 Terms and definitions
For the purposes of this document, the terms and definitions given in GB/T 12241, GB/T 13005, GB/T 16918, GB/T 18442.1,GB/T 18442.3,GB/T 18443.2, GB/T 18517, GB/T 26929,GB/T 33209, GB/T 33215 and below apply.
3.1
lot/batch
a certain number of cylinders (or inner vessels) composed under the same criteria
3.1.1
lot/batch of inner vessel
a certain number of cylinder inner vessels continuously produced using the same design, the same grade of material and the same process, mainly in terms of the welding process, non-destructive testing process, pressure test process
3.1.2
lot/batch of cylinder
a certain number of cylinders continuously produced using the same design, the same batch of inner vessels and the same process, mainly in terms of the insulation process and vacuumizing process
3.2
tare of cylinder
mass of the empty cylinder (if horizontal,including the frames or seats) that meet basic functions of filling, storage, transportation, use and safety, etc.
3.3
effective volume
maximum volume of liquid allowed to be filled in the cylinder
3.4
heat transfer coefficient
Heat transfers between fluids at different temperatures per unit area, unit differential temperature and unit time, characterizing the intensity of heat transfer process
[Source: adapted from GB / T 18517-2012, 2.6.2]
3.5
free air
air at absolute pressure of 1.01325×105Pa and temperature of 15.6°C
4 Symbols
For the purposes of this document, the following symbols apply.
Di: inside diameter of head or cylindrical shell, mm.
D0: outside diameter of head or cylindrical shell, mm.
E0: elastic modulus of material, MPa.
g: gravitational acceleration, g=9.81m/s2;
Hi: height inside head, equal to the sum of the depth of curved surface inside the head and the height of the straight portion of head, mm.
hi: depth of curved surface inside the head, mm.
h0: total height of curved surface outside the head, h0=hi+Sn, mm.
k1: coefficient determined by the ratio of major axis to minor axis of an ellipse.
L: sum of the length of cylindrical shell, and the height of straight portion and 1/3 depth of inside curved surface of heads, mm.
P: nominal working pressure, MPa.
Pb: design burst pressure of blasting piece, MPa.
Pcr: critical pressure, MPa.
Pd: design pressure, MPa.
Pf: relieving pressure of safety valve or design burst pressure of blasting piece-based safety device, MPa.
Pt: pressure used for pressure test, MPa.
Pz: set pressure of safety valve, MPa.
P1: external pressure, MPa.
R: outside radius of spherical shell of disc head and equivalent outside radius of spherical shell of ellipsoidal head, mm.
S: design wall thickness, mm.
Sb: measured minimum wall thickness of cylindrical shell, mm.
Se: effective thickness, equal to nominal wall thickness minus corrosion allowance and negative deviation of steel thickness, mm.
Sh: minimum wall thickness with head formed, mm.
Sn: nominal wall thickness, mm.
σ: wall stress, MPa.
ΔHi: inside height tolerance of head, mm.
ΔπDi: tolerance of inside circumference of head, mm.
5 Designation and basic parameters
5.1 Designation
Vertical cylinders are represented by “DPL” while horizontal ones by “DPW”. The others are designed as specified in GB/T 15384. Design changes, if any, may be reflected by Roman numerals, i.e. I, II, III, etc.in sequence, following the model designation.
5.2 Basic parameters
5.2.1 Nominal capacity and inside diameter of inner vessel
The nominal capacity and inside diameter of inner vessel should be selected from Table 1. The nominal capacity should be taken as an integer multiple of 5.
Table 1 Nominal capacity and inside diameter of inner vessel
Nominal capacity/ L 10 – 25 25 – 50 50 – 150 150 – 200 200 – 500 500 – 800 800 – 1000
Inside diameter of inner vessel/mm 200 – 300 250 – 350 300 – 450 400 – 550 450 – 800 600 – 900 750 – 1200
5.2.2 Pressure
5.2.2.1 The design pressure is used as the pressure for calculating the internal pressure of the wall thickness of the cylindrical shell of inner vessel, and is the pressure used in the pressure test of the inner vessel, which shall not be less than 2 times the nominal working pressure (Pd=Pt≥2P).
5.2.2.2 The external pressure applied to the inner vessel and outer vessel of cylinder shall not be less than 0.21MPa.
5.2.3 Effective volume
5.2.3.1 The effective volume of liquid oxygen, liquid nitrogen, liquid argon cylinders shall not be greater than 95% of the nominal capacity.
5.2.3.2 The effective volume of liquefied natural gas cylinders shall not be greater than 90% of the nominal capacity.
6 Materials
6.1 General
6.1.1 The main material for inner vessel (cylindrical shell and head) shall be austenitic stainless steel as specified in GB/T 24511 and the design documents. Any use of materials with foreign designation shall comply with TSG 23. The material quality certificate of the main material for inner vessel shall be as specified in 6.1.4, and the results of re-test shall comply with the requirements given in 6.2, 6.3 and the design documents.
6.1.2 Any elements welded on the inner vessel all be made of austenitic stainless steel as specified in relevant material standards and the design documents. Other materials in direct contact with the storage medium shall be compatible with the medium and meet relevant material standards.
6.1.3 The chemical composition and tensile properties of welding materials and their deposited metals shall conform to the provisions of NB/T 47018.1 and NB/T 47018.3 and the design documents.
6.1.4 Pressure elements and welding materials, if purchased from the material manufacturer, shall be provided with the original material quality certificate by the manufacturer, which bears the quality inspection seal of the manufacturer and a traceable mark (QR code, bar code, etc.) to provided information including the material manufacturer data, material grade, specification, heat lot, delivery status, issue date of the quality certificate, etc. Those otherwise purchased shall be provided with the original or a photocopy of the material quality certificate from the material manufacturer. The photocopy, if it is the case, shall bears the official inspection seal of the material supplier and the transactor's seal.
6.1.5 The outer vessel shall be made of austenitic stainless steel.
6.1.6 When the temperature of the contained medium is lower than -182 °C, insulating materials that do not react dangerously with oxygen or oxygen-enriched atmosphere shall be used. The properties of insulating material shall comply with the provisions of GB/T 31480 and the test provisions of GB/T 31481.
6.1.7 Absorbent materials shall be compatible with the stored medium.
6.2 Chemical composition
The chemical composition of the main material of the inner vessel and tolerances shall comply with the provisions in Table 2.
Table 2 Chemical composition and tolerances
Chemical composition C Mn P S Si Ni Cr
Content (m/m) ≤0.08 ≤2.00 ≤0.035 ≤0.015 ≤0.75 8.00 – 10.50 18.00 – 20.00
Tolerance ±0.01 ±0.04 +0.005 +0.005 ±0.05 ±0.10 ±0.20
6.3 Mechanical properties
The mechanical properties of the main material of inner vessel shall conform to the provisions of Table 3 and the design documents.
Table 3 Mechanical properties
Tensile strength Rm Proof strength of plastic elongation Rp0.2 Elongation at break A
≥520MPa ≥220MPa ≥40%
7 Design
7.1 General
7.1.1 Composition
7.1.1.1 The cylinder is mainly composed of inner vessel, outer vessel, insulation system, connections between inner vessel and outer vessel, valve piping system, protections for valve piping system, foot ring, etc. The valve piping system includes valves, instruments, safety relief devices, pipe fittings, pipes and pipe supports. The protections should be in forms of cover, ring (loop), frame, etc.
7.1.1.2 The main body of the inner vessel shall be composed of three portions at maximum, that is, no more than one longitudinal weld and no more than two circumferential welds.
7.1.2 Connections between the inner vessel and the outer vessel
The stress value of the connection between the inner vessel and the outer vessel shall not be greater than 2/3 of the material yield strength at normal temperature (or the proof strength of plastic elongation) under individual loads as follows:
a) Vertical cylinders shall meet the following requirements:
1) The load perpendicular to the cylinder axis shall not be less than the product of the maximum mass and 2g;
2) The load longitudinally along the cylinder axis shall not be less than the product of the maximum mass and 3g.
b) Horizontal cylinders shall meet the following requirements:
1) The load perpendicular to the cylinder axis and horizontal to the floor shall not be less than the product of the maximum mass and 2g;
2) The load along the cylinder axis shall not be less than the product of the maximum mass and 2g;
3) The longitudinal load perpendicular to the cylinder axis shall not be less than the product of the maximum mass and 3g.
Note: The “maximum mass” refers to the total mass of the medium (i.e., saturated medium at standard atmospheric pressure filled to the effective volume), plus the mass of the metal inner vessel and the mass of the insulation.
7.1.3 Performance indicators
The leak rate of vacuum interlayer, leak and outgassing rate of vacuum interlayer shall be as specified in Table 4. The static evaporation rates with nominal working pressure not greater than 2.4 MPa shall be as specified in Table 4, while those with nominal working pressure greater than 2.4 MPa shall be as specified in the drawings.
Table 4 Static evaporation rate, leak rate of vacuum interlayer, leak and outgassing rate of vacuum interlayer
Nominal capacity/ L 10 50 175 300 500 800 1000
Upper limit of static evaporation rate of liquid nitrogen η/(%/d) 5.45 4.0 2.5 2.2 1.9 1.7 1.5
Leakage rate of vacuum interlayer (20 °C)/(Pa·m3/s) ≤2×10-8 ≤6×10-8
Leak and outgassing rate of vacuum interlayer (20°C)/(Pa·m3/s) ≤2×10-7 ≤6×10-7
Low temperature vacuum degree (absolute interlayer pressure)/Pa ≤2×1O-2
7.1.4 Maximum filling volume and maximum filling mass
7.1.4.1 When the pressure reaches the set pressure of the primary safety relief device, the liquid phase volume of liquid oxygen, liquid nitrogen and liquid argon shall in no case exceed 98% of the nominal capacity, and that of liquefied natural gas shall in no case exceed 95% of the nominal capacity.
7.1.4.2 The maximum filling mass is the mass calculated from the product of the effective volume and the maximum allowable filling ratio specified in Annex A in accordance with the method specified in 9.14.
7.1.5 Design service life
The design service life shall not exceed 20 years, and shall be indicated in the design documents and included in the nameplate.
7.1.6 Accessories
7.1.6.1 The cleanliness of the accessories in contact with oxygen such as valves, pressure gauges, safety relief devices and liquid level meters shall comply with 8.13.2.
7.1.6.2 Pressure regulating valves shall comply with the provisions of GB/T 34530.1. Cut-off valves shall comply with the provisions of GB / T 34530.2. When the valve interface is threaded, for liquefied natural gas, left-hand threading shall be used, while for other media, right-hand threading shall be used.
7.1.6.3 The accuracy of the pressure gauge shall not be lower than Grade 2.5, and the measuring range shall be 1.5 to 3 times the nominal working pressure.
7.1.6.4 For liquefied natural gas cylinders, capacitive level meters, if used, shall meet the explosion-proof requirements.
7.1.6.5 LNG cylinder as a whole shall be designed into an anti-static structure to ensure that the cylinder shell, valves and any parts in contact with LNG have conductive continuity, and the total ground resistance shall not exceed 10 Ω.
7.1.6.6 It is recommended to set up a device that enables direct detection of vacuum in the interlayer space.
7.1.6.7 The valve inlet connector and outlet connector (with one end connected to the valve, and the other connected to the hose, etc.) shall conform to the provisions of Annex B.
7.1.6.8 The valve piping system protections shall be adapted to static and dynamic loads during transportation and loading.
7.1.6.9 The foot ring shall ensure the stability of the cylinder. Cylinders with nominal capacity greater than 500L shall not be equipped with wheels. Wheeled cylinders and wheeled frameworks shall be equipped with brake locking devices.
7.1.6.10 When the total mass with the medium filled exceeds 40kg, lifting attachments shall be set up.
7.1.6.11 Protective covers, protective rings (loops) shall be made of metal materials, and shall be connected to the cylinder by welding.
7.2 Inner vessel
7.2.1 The inner vessel head shall be concaved for pressure bearing into the shape of a hemisphere or a standard ellipse with a major-to-minor axis ratio of 2:1, and the minimum wall thickness shall not be less than 0.9 times the design wall thickness of the cylindrical shell calculated for Formula (1).
7.2.2 The internal pressure design wall thickness of the cylindrical shell of inner vessel shall not be less than the value calculated from Formula (1).
(1)
where the wall stress σ takes the minimum value of the following:
——310 MPa;
——50% of the minimum tensile strength Rm of the main material of the inner vessel determined as specified in 9.1;
——The proof strength of plastic elongation Rp0.2 of the main material of the inner vessel determined as specified in 9.1;
——50% of the minimum tensile strength Rm of the welded joint determined as specified in 8.10.4.3;
——for inner vessels with longitudinal weld, the wall stress shall not exceed 85% of the minimum value among the above.
7.2.3 Openings are allowed in the head only and shall be round and welded with pipe connectors, pipe seats or flanges, etc. The diameter of the opening shall not be larger than 1/3 of the inside diameter of the head and shall not be greater than 76mm. The edge of the opening shall be located within 80% of the inside diameter of the head centered at the center of the head. When the opening diameter or edge of opening exceeds those specified in this standard, strength check shall be carried out as specified in JB 4732-1995.
Foreword i
1 Scope
2 Normative references
3 Terms and definitions
4 Symbols
5 Designation and basic parameters
6 Materials
7 Design
8 Manufacture
9 Inspection method
10 Inspection rules
11 Marking, packaging and transportation
12 Ex-factory data
13 Data preservation
Annex A (Normative) Maximum allowable filling ratio
Annex B (Normative) Inlet connector and outlet connector of valves
Annex C (Normative) Safe relief rate and relieving area
Annex D (Normative) Vibration test
Annex E (Normative) Drop test
Annex F (Informative) Product certificate
Annex G (Informative) Quality certificate for batch inspection
