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GB/T 34510-2017 PDF in English


GB/T 34510-2017 (GB/T34510-2017, GBT 34510-2017, GBT34510-2017)
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GB/T 34510-2017: PDF in English (GBT 34510-2017)

GB/T 34510-2017
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 23.020.30
J 74
Liquefied natural gas cylinders for vehicles
ISSUED ON: OCTOBER 14, 2017
IMPLEMENTED ON: MAY 01, 2018
Issued by: General Administration of Quality Supervision, Inspection and
Quarantine of the People's Republic of China;
Standardization Administration of the People's Republic of China.
Table of Contents
Foreword ... 3 
1 Scope ... 4 
2 Normative references ... 4 
3 Terms and definitions, symbols ... 6 
4 Types and basic parameters ... 10 
5 Materials ... 11 
6 Design ... 13 
7 Manufacturing ... 18 
8 Test methods ... 26 
9 Inspection rules ... 30 
10 Marks, packaging, transportation, storage ... 34 
11 Product certificate, product instruction manual and batch inspection quality
certificate ... 36 
12 Terms of use ... 37 
Annex A (normative) Safety performance test ... 38 
Annex B (normative) Calculation of safe discharge capacity of gas cylinder and
discharge capacity of safety valve ... 44 
Annex C (informative) Design calculation of safe space ... 47 
Annex D (normative) Test method for automatic safe-space insurance function ... 48 
Annex E (informative) Product certification ... 50 
Annex F (informative) Batch inspection quality certificate ... 52 
Bibliography... 54 
Liquefied natural gas cylinders for vehicles
1 Scope
This Standard specifies the terms and definitions, symbols, types, basic parameters,
materials, design, manufacture, test methods, inspection rules, marks, packaging,
transportation, storage, product qualification certificates, product instruction manuals,
batch inspection quality certificates and usage regulations for liquefied natural gas
(LNG) cylinders for vehicles (hereinafter referred to as the cylinders).
This Standard is applicable to the insulated cylinders that are used under normal
ambient temperature (-40℃~60℃), that the storage medium is LNG, the design
temperature is not higher than -196℃, the nominal volume is 150L~500L, and the
nominal working pressure is 0.8MPa~3.5MPa, that are used for refillable welding for
automotive fuel tanks.
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 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/T 1804, 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 13005, Terminology of gas cylinders
GB/T 13550, Molecular sieve 5A and its determination
GB/T 15384, Designation for gas cylinders
device shall not affect the maintenance or replacement of valves, piping and vacuuming
connections.
6.5.4 Liquid-filling pipeline
A dedicated liquid-filling joint shall be provided on the liquid-filling pipeline. The
liquid-filling joint shall have a non-return function for the medium in the gas cylinder
to flow to the outside. It shall have a dust cover. If no special liquid-filling joint is
provided, a stop valve, a threaded plug, or a flange and other sealing structure shall be
provided. Ensure that the medium does not leak after filling and during use.
6.5.5 Liquid outlet pipeline
The liquid outlet pipeline and the joints on the pipeline, the diameter of the valve, the
installation position and the installation method shall be able to meet the requirements
of the discharge capacity.
The liquid outlet pipeline shall be provided with stop valve and excess-flow unit.
The excess-flow unit is installed between the liquid side end of the liquid outlet pipeline
and the front end of the vaporizer. It can automatically cut off the pipeline in the event
of a large amount of leakage, rupture, or rupture of the fuel supply pipeline at the rear.
For structural gas cylinders equipped with an external vaporization supercharger, a
check valve (or check valve) shall be installed at the joint of the gas cylinder return pipe.
Prevent the gas in the cylinder from leaking out.
6.5.6 Pressure relief pipe
The pressure relief pipeline shall be in direct communication with the gas phase space
of the gas cylinder inner containment vessel. The diameter of the pipeline shall meet
the requirements for safe discharge.
The pressure relief pipeline is divided into automatic pressure relief (the safety valve is
opened to release pressure) and manual pressure relief.
When the gas cylinder is installed on the vehicle, the outlet of the pressure relief
pipeline shall be connected to a safe location for discharge. When the vehicle is parked,
the pressure relief pipe shall also meet the requirements of 10.8c).
If it is necessary to release the pressure during filling, it is strictly forbidden to directly
discharge it to the atmosphere. It can be discharged into the LNG storage container of
the filling station.
6.5.7 Safety valve
The inner containment vessel shall be provided with at least two safety valves. The inlet
pipes of the safety valve shall be directly connected to the gas-phase space of the inner
containment vessel. The discharge capacity of each safety valve shall be able to
independently meet the requirements for safe discharge. Safety valve can be installed
in any orientation. However, a stop valve shall not be installed before the safety valve.
The outlet of the main safety valve of the gas cylinder shall meet the requirements of
6.5.5.
The gas cylinders shall not be fitted with bursting discs.
See Annex B for the calculation of the safety relief volume and the discharge capacity
of the safety valve. The opening pressure of the main safety valve is not more than 1.2
times the nominal working pressure. The opening pressure of the auxiliary safety valve
is not more than 1.8 times the nominal working pressure.
6.5.8 Pressure gauge
The pressure gauge range is 1.5 times to 3.0 times the nominal working pressure. The
precision is not less than level 2.5. The inlet pipeline of the pressure gauge shall be
directly connected with the gas phase space of the inner containment vessel.
6.5.9 Level gauge
Each gas cylinder shall be provided with a liquid level gauge capable of transmitting
the liquid level signal to the cab of the vehicle. It has a warning function when the
remaining fuel in the cylinder is 5% of the maximum filling amount.
6.6 Safety space
There shall be enough safety space in the cylinder. When filling LNG with a saturated
vapor pressure of 0.8MPa (gauge pressure, the same below), and the opening pressure
of the safety valve is 1.6MPa, the safety space shall be at least 10% of the total volume
of the inner containment vessel. When the saturated steam is filled with other pressures,
or the safety valve adopts LNG cylinders with other opening pressures, then the volume
of the safety space shall be calculated according to the density difference of LNG under
the filling pressure and the opening pressure of the safety valve. See Annex C for the
calculation method of the safety space. The safety space of the gas cylinder and the
corresponding saturated vapor pressure and opening pressure of the safety valve shall
be indicated in the design drawings and technical documents provided to the user.
6.7 Automatic safe-space insurance function
The gas cylinder shall have the function of automatic charging limit. When refilling
with any residual amount of LNG in the cylinder, ensure that the actual safety space in
the cylinder is consistent with the design value. See Annex D for the test method of the
automatic safe-space insurance function.
6.8 Hold time
The hold time of the cylinder shall not be less than 5 days.
7 Manufacturing
7.1 Batching
Gas cylinders are manufactured in batches of inner containment vessel. That is, a
cylinder product batch generally contains only the inner containment vessels of the
same batch. However, one inner containment vessel batch is allowed to be divided into
several cylinder product batches.
7.2 Welding procedure qualification
7.2.1 Welding procedure qualification shall be carried out separately for longitudinal or
circumferential welded joints. When the wall thickness of the material is less than 6mm,
each wall thickness needs to be evaluated. When the wall thickness is the same, the
evaluation results of small-diameter gas cylinders can be substituted for large-diameter
gas cylinders. When the cylinder manufacturer changes the inner containment vessel
material, welding material, welding process and welding equipment, welding procedure
qualification shall be carried out before production. In addition to the requirements of
this Standard, the welding procedure qualification shall comply with the requirements
of GB/T 33209.
7.2.2 Welding procedure qualification for longitudinal welded joints can be carried out
on welded test panels. The welding procedure qualification of the circumferential
welded joint shall be carried out on the simulated cylindrical test piece, or it can be
carried out directly on the inner containment vessel cylinder body. The welded joints
for procedure qualification shall be able to represent the main welded joints
(longitudinal, annular and corner welded joints) of the inner containment vessel.
7.2.3 The test piece for welding procedure qualification shall be free from defects such
as undercuts, cracks, surface pores, welding slag, pits, welding flashes. The welded
joints of the test plate are tested by 100% radiography. The testing results shall meet the
requirements for level II of NB/T 47013.2.
7.2.4 The number of welded joint specimens for welding procedure qualification is
specified as follows: 2 tensile test specimens, 4 transverse bending specimens (2 pieces
each for face bending and back bending), 6 low temperature impact specimens (3 for
welded joints and 3 for heat affected zones) at the lowest operating temperature of the
inner containment vessel material.
7.2.5 When the measured thickness of the inner containment vessel material for welding
procedure qualification is not enough to prepare a low temperature impact specimen
with a thickness of 2.5mm, specimens with a thickness of 2.5mm shall be prepared from
welded test panels not exceeding 3.2mm in thickness as specified in 5.1, 5.2 and 5.3 of
this Standard. The carbon content of the test plate material shall not be less than 0.05%.
metal.
7.8.3 Welded joints and heat-affected zone surfaces on gas cylinders are not allowed to
have defects such as undercut, incomplete penetration, cracks, pores, depressions and
irregular sudden changes. Spatter on both sides of the welded joint shall be removed.
7.9 Nondestructive testing
7.9.1 After passing the visual inspection, the longitudinal and annular welded joints of
the inner containment vessel shall be subjected to nondestructive testing one by one.
Personnel engaged in nondestructive testing of gas cylinders shall hold a valid
qualification certificate for nondestructive testing of special equipment.
7.9.2 Carry out 100% radiographic testing for the longitudinal and ring welded joints
of inner containment vessel. Welded joint defect level evaluation shall be carried out
according to NB/T 47013.2. The defect level is not lower than level II. The radiographic
inspection technology level is not lower than level AB. For the part that can perform
radiographic testing, ultrasonic testing can be used instead.
7.9.3 Digital imaging method can be used for nondestructive testing. When it is used,
it shall meet the requirements of GB/T 17925.
7.10 Solder joint repair
7.10.1 Weld joint repair shall be carried out according to the repair process. It shall be
performed by a person with the qualifications specified in 7.7.1. The repaired parts shall
be subject to appearance testing and nondestructive testing according to 7.8 and 7.9.
7.10.2 The number of repairs on the same part of the welded joint of inner containment
vessel shall not exceed two times. If it exceeds, it shall be approved by the technical
chief of the manufacturer before repairing.
7.10.3 The number of repairs and the repaired parts shall be recorded in the production
inspection record of the product.
7.11 Surface quality and cleanliness
7.11.1 The inner and outer surfaces of the inner containment vessel and the outer shell
shall be smooth. There shall be no cracks, heavy skin, scratches and other defects,
otherwise it shall be repaired. The grinding shall be smooth and clean. The wall
thickness of the inner containment vessel shall meet the requirements of 6.2. The wall
thickness of the outer shell shall meet the requirements of 6.3.
7.11.2 The inner and outer surfaces of the inner containment vessel and all parts in
contact with the medium shall be degreased, in line with the relevant regulations of
JB/T 6896 and have good protection measures.
7.11.3 All surfaces and parts under vacuum shall be clean and dry. There must be no oil
and dust.
7.12 Volume and weight
7.12.1 The measured water volume of the gas cylinder liner shall not be less than its
nominal volume. The measured volume can be replaced by theoretical calculation, but
there shall be no negative deviation.
7.12.2 After the cylinders are manufactured, the net weight shall be measured one by
one.
7.13 Pressure test
7.13.1 The inner containment vessel of the gas cylinder shall be subjected to a pressure
test one by one after passing the radiographic test. The pressure test uses water pressure
or air pressure test. The test pressure shall be as specified in 4.2.4. The hydrostatic test
medium is clean water. The chloride ion content shall not exceed 25mg/L. The air
pressure test shall use dry oil-free air or nitrogen.
7.13.2 Safety precautions shall be taken in the air pressure test.
7.13.3 The holding pressure shall not be less than 30s under the test pressure. The inner
containment vessel must not have macroscopic deformation, leakage and abnormal
sound. The pressure gauge range is 2.0 to 3.0 times the test pressure. The accuracy is
not less than level 1.6.
7.13.4 After the hydraulic test, the water in the inner containment vessel and the
connecting pipe shall be drained in time. Make them dry.
7.13.5 If a leak is found in the welded joint during the pressure test, it shall be repaired
as specified in 7.10. After the repair is accepted, the pressure test shall be carried out
again as required.
7.14 Mechanical properties test of welded joint of inner containment vessel
7.14.1 Each batch of inner containment vessels shall be tested for mechanical properties
of welded joints. It can take samples from the inner containment vessel or product
welding test plate. When the specimens are taken from the welded test plate, only the
mechanical properties test of the longitudinal welded joint is carried out.
7.14.2 The welding test plate of the product shall be loaded and unloaded on the same
steel plate (or the same batch of steel plates) with the test inner containment vessel. As
an extension of the longitudinal welded joint of the test inner containment vessel, it is
welded together with the longitudinal seam. The test plate shall be marked with the
code of the test inner containment vessel and welder. Welded joints on test plates shall
be subject to external inspection and 100% radiographic inspection, in accordance with
the provisions in 7.8 and 7.9. The size of the welded test plate and the sampling location
of the mechanical property specimen are as shown in Figure 6.
7.15.1 The selection of thermal insulation materials and adsorption materials shall
comply with the provisions of 5.1.7 and drawings.
7.15.2 The insulation layer shall be tightly wrapped. Collapse shall not occur.
7.16 Vacuum leak detection
7.16.1 The cylinders shall be vacuum leak-tested one by one. The leak rate shall meet
the requirements of 4.2.3.
7.16.2 If a leak is found in the welded joint during the vacuum leak test, it may be
repaired in accordance with the provisions of 7.10. After the repair is accepted, carry
out the pressure test again according to the requirements of 7.13. After passing the test,
conduct a vacuum leak test as required.
7.17 Vacuum
After the gas cylinder is filled with liquid nitrogen, the vacuum degree of the interlayer
shall not be lower than 2×10-2Pa.
7.18 Pipeline air tightness test
After the valve and safety accessories of the gas cylinder are assembled, the air tightness
test of the pipeline shall be carried out with dry and oil-free clean air or nitrogen. The
test pressure is the nominal working pressure. The hold time is not less than 1min.
Valves, joints and safety accessories must not leak.
8 Test methods
8.1 Material reinspection
For the reinspection of the chemical composition and mechanical properties of the
stainless-steel material of the gas cylinder, sampling, analysis and testing shall be
carried out according to the method specified in the material standard.
8.2 Mechanical properties test for welding procedure evaluation test plate
8.2.1 According to the requirements of 7.2.2, when cutting the blank from the welding
procedure qualification test plate (refer to Figure 6 for dimensions), the part discarded
from the two ends of the test plate is not less than 50mm. The sample blank is generally
cut by machining method. When thermal cutting is used, the heat affected zone shall be
removed. When cutting the sample blank from the inner containment vessel by thermal
cutting (refer to Figure 7 for the cutting position), no heat-affected zone shall be left on
the specimen.
8.2.2 The number of welded joint specimens for welding procedure qualification shall
be as specified in 7.2.4.
as possible. The low temperature impact test method is carried out according to GB/T
229. The cooling temperature of the specimen is -196℃. The time from the time the
specimen is taken out to the completion of the impact test shall not be greater than
5s.
8.3 Nondestructive testing of welded joints
The radiographic inspection of the longitudinal and annular welded joints of the inner
containment vessel is carried out in accordance with NB/T 47013.2. It may use digital
imaging methods for X-ray inspection. When it is used, it shall meet the requirements
of GB/T 17925. Carry out the ultrasonic testing in accordance with NB/T 47013.3.
8.4 Mechanical properties test of welded joints
8.4.1 Take welded joint specimens from the inner containment vessel: Respectively take
1 tensile force specimen, 1 transverse face bend specimen and 1 back bend specimen,
3 low temperature impact specimens (notch is located in the center of the welded joint)
from longitudinal and circumferential welded joints. The intercepted parts of the test
plate and the sample blank are shown in Figure 7.
8.4.2 Take welded joint specimens from the product welding test plate: 1 tensile test
specimen, 1 transverse face bend specimen and 1 back bend specimen, 3 impact
specimens (the notch is located in the center of the welded joint). The intercepted part
of the sample blank is shown in Figure 6.
8.4.3 The method of cutting the sample blank from the inner containment vessel of the
gas cylinder or the welding test plate of the product shall comply with the provisions of
8.2.1.
8.4.4 The fabrication and testing of tensile, bending and impact test specimens for
welded joints shall be carried out in accordance with the provisions of 8.2.3 and 8.2.4.
8.4.5 When the measured thickness of the inner containment vessel material is less than
2.5mm, the impact test can be exempted.
8.5 Pressure test of inner containment vessel
8.5.1 When the hydraulic test is used, it shall be carried out in accordance with the
provisions of GB/T 9251.
8.5.2 When using the air pressure test, first slowly increase the pressure to 10% of the
specified test pressure. Make enough time to hold pressure. Conduct initial inspection
of all welded joints and connections. If there is no leakage, continue to increase the
pressure to 50% of the specified test pressure. If there is no abnormal phenomenon, the
pressure shall be gradually increased by 10% of the specified test pressure until the test
pressure is reached. Hold the pressure for at least 30s. Then reduce to the nominal
working pressure. Check welded joints for air tightness.
8.6 Air tightness test of pipeline
The air tightness test of the pipeline shall be carried out according to the provisions of
GB/T 12137. The test medium is dry, clean, oil-free air or nitrogen.
8.7 Determination of weight and volume
8.7.1 Use weighing method to determine the net weight of the gas cylinder. The unit of
weight is kilograms (kg).
8.7.2 Weighing shall use a weighing instrument with a maximum weight of 1.5 to 3.0
times the actual weight. Its accuracy shall meet the requirements of minimum weighing
error.
8.7.3 The inner containment vessel shall be volumetrically measured. The
determination method is carried out according to the provisions of GB/T 18443.8. Due
to the structure and other reasons, the volume can be measured and calculated by the
geometric dimension measurement method.
8.7.4 Determination of weight and volume shall retain three significant figures. The rest
of the numbers shall be rounded up by 1 for the weight. The volume shall be rounded
up.
8.8 Determination of wall thickness
Use an ultrasonic thickness gauge to measure the wall thickness.
8.9 Visual inspection
8.9.1 Visually inspect the surface of the inner containment vessel and outer shell,
appearance of welded joints, and safety accessories.
8.9.2 Wipe the degreased surface with a white, clean, dry filter paper. The paper shall
be free of traces of grease and dirt. The surface in contact with the medium shall be
checked according to the requirements of JB/T 6896.
8.10 Vacuum degree test
The test method of vacuum degree shall be carried out according to the provisions of
GB/T 18443.2.
8.11 Vacuum leak test
Vacuum leak detection can be carried out by means of helium mass spectrometry leak
detection.
8.12 Vacuum interspace leak rate test
The test method for vacuum interspace leak rate shall be carried out in accordance with
g) Nominal working pressure, MPa;
h) Hydraulic test pressure, MPa;
i) Filling medium;
j) Maximum filling volume, kg;
k) Net weight of gas cylinder, kg;
l) Inspection mark;
m) Date of manufacture;
n) Safety space, L;
o) Note: The gas phase safety space of this gas cylinder is only suitable for filling
saturated LNG whose vapor pressure is not less than ×.× MPa.
10.2 The gas cylinder shall be firmly set with a warning sign of "Safe use notice" in the
obvious position. The content shall at least include: "Keep away from fire sources,
concentrate discharge".
10.3 The font, font color and color ring of the gas cylinder can be in accordance with
the relevant provisions of GB/T 7144.
10.4 When the gas cylinder leaves the factory, the inner containment vessel shall be
filled with 0.01MPa~0.05MPa dry nitrogen. Close all valves.
10.5 The packaging of gas cylinders shall be in accordance with the drawings or user
requirements.
10.6 During transportation and loading and unloading of gas cylinders, it is necessary
to prevent collision, moisture and damage to accessories.
10.7 The prominently raised LNG medium symbol shall be suppressed at the position
where the front cover of the casing is easy to observe. Its font height shall not be less
than 60mm.
10.8 The storage of gas cylinders shall meet the following requirements:
a) Gas cylinders shall be stored in a cool, dry place.
b) Before the gas cylinder is installed on the vehicle, it is forbidden to store it with
liquid (LNG).
c) For vehicles already installed with gas cylinders, during the storage period, the
exhaust port of the safety relief device with liquid gas cylinders shall be connected
to the pressure relief discharge pipe made according to the regulations. Lead the
......
 
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