GB/T 35544-2017 PDF English
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Fully wrapped carbon fiber reinforced cylinders with an aluminum liner for the on-board storage of compressed hydrogen as a fuel for land vehicles
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GB/T 35544-2017: PDF in English (GBT 35544-2017) GB/T 35544-2017
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 23.020.30
J 74
Fully-wrapped carbon fiber reinforced cylinders with an
aluminum liner for the on-board storage of compressed
hydrogen as a fuel for land vehicles
[Including 2020XG1 No.1 Amendment List]
ISSUED ON: DECEMBER 29, 2017
IMPLEMENTED ON: JULY 01, 2018
Issued by: General Administration of Quality Supervision, Inspection and
Quarantine of PRC;
Standardization Administration of PRC.
Table of Contents
Foreword ... 3
1 Scope ... 4
2 Normative references ... 4
3 Terms, definitions, symbols... 6
4 Types, parameters, classifications, models ... 9
5 Technical requirements ... 10
6 Test methods and qualification indicators ... 16
7 Inspection rules ... 36
8 Marking, packaging, transport, storage ... 40
9 Product certificate and batch inspection quality certificate ... 41
Appendix A (Informative) Determination method of maximum allowable defect size of
aluminum liner ... 44
Appendix B (Normative) Type test method and qualification index of temperature-
driven safety pressure relief device and valve ... 46
References ... 62
No.1 Amendment sheet ... 63
Fully-wrapped carbon fiber reinforced cylinders with an
aluminum liner for the on-board storage of compressed
hydrogen as a fuel for land vehicles
1 Scope
This standard specifies the type and parameters, technical requirements, test methods,
inspection rules, marking, packaging, transportation, storage requirements of fully-
wrapped carbon fiber reinforced cylinders with an aluminum liner for the on-board
storage of compressed hydrogen as a fuel for land vehicles (hereinafter referred to as
gas cylinders).
This standard is applicable to the design and manufacture of refillable gas cylinders,
which have a nominal working pressure not exceeding 70 MPa, a nominal water volume
not exceeding 450 L, storage medium of compressed hydrogen, working temperature
not lower than -40 °C and not higher than 85 °C, fixed on road vehicles as fuel tanks.
Note: Gas cylinders for hydrogen supply, such as hydrogen fuel cell for urban rail transit, can
be manufactured and inspected with reference to this standard.
2 Normative references
The following documents are essential to the application of this document. For the dated
documents, only the versions with the dates indicated are applicable to this document;
for the undated documents, only the latest version (including all the amendments) is
applicable to this standard.
GB/T 192 General purpose metric screw threads - Basic profile
GB/T 196 General purpose metric screw threads - Basic dimensions
GB/T 197 General purpose metric screw threads - Tolerances
GB/T 228.1 Metallic materials - Tensile testing - Part 1: Method of test at room
temperature
GB/T 230.1 Metallic materials - Rockwell hardness test - Part 1: Test method
(scales A, B, C, D, E, F, G, H, K, N, T)
GB/T 231.1 Metallic materials - Brinell hardness test - Part 1: Test method
A gas cylinder, which is fully wound with a carbon fiber reinforced layer, on the
outer surface of the aluminum liner AND cured by heating.
3.1.4
Nominal working pressure
The limited filling pressure of the cylinder, at the reference temperature (15 °C).
3.1.5
Autofrettage
A compression process, through which an internal pressure is applied to the gas
cylinder, to plastically deform the aluminum liner, so that the aluminum liner is
subjected to compressive stress and the carbon fiber is subjected to tensile stress,
under zero pressure.
3.1.6
Autofrettage pressure
The maximum pressure (gauge pressure), which is applied to the cylinder, during
autofrettage.
3.1.7
Batch of cylinder
The limited number of gas cylinders, that use the same design conditions, have the
same structure and size of aluminum liner and composite materials, are wound and
cured by the same process.
3.1.8
Batch of aluminum liner
The limited number of aluminum liner, which adopts the same design conditions,
has the same nominal outer diameter and design wall thickness, is made of the same
furnace material by the same manufacturing process, is continuously heat treated
according to the same heat treatment specification and the same process parameters.
3.1.9
Service life
The number of years for which the gas cylinder is allowed to be used, under the
specified conditions of use.
3.1.10
Fiber stress ratio
The ratio -- of the carbon fiber stress of the cylinder, at the minimum burst pressure,
TO the carbon fiber stress, at the nominal working pressure.
3.1.11
Rejection elastic expansion; REE
The allowable upper limit of the elastic expansion of the gas cylinder, which is
specified by the manufacturer, in the design and finalization stage of each type of
gas cylinder, in the unit of millimeter. This value shall not exceed 1.1 times the
average value of elastic expansion, under the hydraulic test pressure of the same
specification and model of the design batch.
3.2 Symbols
The following symbols apply to this document.
A - The measured value of the elongation at fracture of the aluminum liner material, at
room temperature, %;
αo - The original thickness of the tensile specimen of the aluminum liner material, mm;
bo - The original width of the tensile specimen of the aluminum liner material, mm;
Df - The diameter of bending center, in cold bending test, mm;
Do - The nominal outer diameter of aluminum liner, mm;
H - The distance between the indenters for the flattening test of the aluminum liner
material, mm;
lo - The original gauge length of the tensile specimen of the aluminum liner material,
mm;
Nd - The design number of cycles of cylinders;
p - The nominal working pressure of gas cylinder, MPa;
pbmin - The minimum burst pressure of gas cylinder, MPa;
pb0 - The expected value of cylinder's burst pressure, MPa;
pm - The allowable pressure of gas cylinder, MPa;
ph - The hydrostatic test pressure of cylinder, MPa;
number Nd of the category B gas cylinder is 7500.
5.1.3 Service life
The service life of category A gas cylinders is 15 years; the service life of category B
gas cylinders is 10 years. When the actual service life of the gas cylinder has not reached
the service life, BUT the number of fillings reaches the design cycle number, the gas
cylinder shall be scrapped.
5.1.4 Allowable pressure
During filling and use, the allowable pressure pm of the gas cylinder is 1.25 times the
nominal working pressure p.
5.1.5 Temperature range
During filling and use, the temperature of the gas cylinder shall not be lower than -
40 °C and not higher than 85 °C.
5.1.6 Hydrogen quality
The compressed hydrogen composition of the refillable gas cylinder shall meet the
quality requirements of hydrogen, which is used in fuel cell vehicles.
5.1.7 Working environment
When designing a gas cylinder, it shall consider its ability to continuously withstand
mechanical damage or chemical attack. Its outer surface shall at least be able to adapt
to the following working environments:
a) Intermittent immersion in water, or road splashes;
b) The vehicle is driven near the ocean, OR on roads where the ice is melted with
salt;
c) UV radiation in sunlight;
d) Vehicle vibration and gravel impact;
e) Exposure to acid and alkali solutions, fertilizers;
f) Exposure to automotive fluids, including gasoline, hydraulic oil, battery acid,
glycols, oils;
g) Exposure to exhaust gases.
5.2 Materials
5.2.1 General requirements
5.2.4.1.1 Continuous untwisted carbon fibers shall be used for load-bearing fibers;
mixed fibers are not allowed.
Note: When carbon fiber is used as the load-bearing fiber, AND glass fiber is used as the anti-
galvanic corrosion layer or the outer surface protective layer, it is not considered to be a mixed
fiber.
5.2.4.1.2 The mechanical properties of each batch of carbon fibers shall comply with
the requirements of the gas cylinder design documents.
5.2.4.1.3 The gas cylinder manufacturer shall re-inspect the carbon fiber materials, by
batch. Fiber's linear density (metric number) shall be determined, according to GB/T
3362 or GB/T 30019. The fiber's dipping tensile strength shall be determined, according
to GB/T 3362 or GB/T 26749.
5.2.4.2 Glass fiber
5.2.4.2.1 S-type or E-type glass fiber shall be used. Its mechanical properties shall meet
the requirements of the gas cylinder design documents.
5.2.4.2.2 Glass fiber is only allowed to be used as a protective layer or anti-galvanic
corrosion layer, on the outer surface of gas cylinders.
5.2.4.2.3 Use the method, which is specified in GB/T 7690.3, to re-inspect the
mechanical properties of glass fibers, by batch.
5.3 Design
5.3.1 Aluminum liner
5.3.1.1 The end of the aluminum liner shall adopt a convex structure.
5.3.1.2 The end of the aluminum liner shall be designed with a gradient thickness; the
cylinder body and the end shall have a smooth transition.
5.3.1.3 The minimum design wall thickness of the aluminum liner shall be verified by
stress analysis.
5.3.1.4 The mouth of the gas cylinder shall be opened at the end of the gas cylinder,
which shall be coaxial with the aluminum liner.
5.3.1.5 The outer diameter and thickness of the cylinder mouth shall meet the torque
requirements, when the bottle valve is assembled. If necessary, the cylinder mouth can
adopt a reinforced structure, such as a steel sleeve.
5.3.1.6 The thread of the cylinder mouth shall be straight thread; the thread length shall
be greater than the effective length of the cylinder valve thread, AND shall comply with
the provisions of GB/T 192, GB/T 196, GB/T 197 or GB/T 20668.
5.3.1.7 The shear stress safety factor of the cylinder thread, under the hydraulic test
pressure, shall not be less than 4. When calculating the safety factor of thread shear
stress, the shear strength of aluminum alloy is 0.6 times the guaranteed value of material
tensile strength.
5.3.2 Gas cylinders
5.3.2.1 The hydraulic test pressure of the gas cylinder shall not be lower than 1.5 times
the nominal working pressure.
5.3.2.2 The fiber stress ratio shall not be less than 2.25.
5.3.2.3 The minimum burst pressure of the gas cylinder shall not be lower than 2.25
times the nominal working pressure.
5.3.2.4 Appropriate protective layers may be used, to protect the outer surface of gas
cylinders. If the protective layer is used as part of the design, it shall meet the
requirements specified in 6.2.11.
5.3.2.5 Additional loads, which are caused by external forces, are not included in the
use conditions of gas cylinders.
5.3.3 Stress analysis
The finite element method is used, to establish a suitable gas cylinder analysis model,
to calculate the stress and strain in the aluminum liner and wrapping layer of the gas
cylinder, under the autofrettage pressure, zero pressure after autofrettage, nominal
working pressure, allowable pressure, hydraulic test pressure, minimum burst pressure.
The analytical model shall take into account the material nonlinearity of the aluminum
liner, the anisotropy of the composite material, the geometric nonlinearity of the
structure.
5.3.4 Maximum allowable defect size
Use the normal temperature pressure cycle test method of the cylinder with cracks OR
the engineering evaluation method based on fracture mechanics, to determine the
maximum allowable defect size, during the nondestructive testing of the aluminum liner,
as shown in Appendix A.
5.4 Manufacturing
5.4.1 General requirements
5.4.1.1 The gas cylinder shall comply with the provisions of the product design
drawings and relevant technical documents.
5.4.1.2 The manufacturing shall be managed in batches. For the finished aluminum liner
and finished gas cylinder, a batch shall not be more than 200 pieces plus the number of
pressure relief devices and valves shall meet the requirements of Appendix B.
6 Test methods and qualification indicators
6.1 Aluminum liner
6.1.1 Wall thickness and manufacturing tolerances
6.1.1.1 Test method
The wall thickness shall be measured, by an ultrasonic thickness gauge. The
manufacturing tolerance shall be checked, by standard or special measuring tools and
templates.
6.1.1.2 Qualification indicators
The wall thickness and manufacturing tolerances of the aluminum liner shall meet the
following requirements:
a) The wall thickness shall not be less than the minimum design wall thickness;
b) The deviation -- between the average outer diameter of the cylinder and the
nominal outer diameter -- shall not exceed 1% of the nominal outer diameter;
c) The difference -- between the maximum outer diameter and the minimum outer
diameter, on the same section of the cylinder -- does not exceed 2% of the nominal
outer diameter;
d) The straightness of the cylinder shall not exceed 3‰ of the length of the cylinder.
6.1.2 Internal and external surfaces
6.1.2.1 Test method
Visually inspect the outer surface. Use an endoscope, to inspect the inner surface.
6.1.2.2 Qualification index
The inner and outer surfaces of the aluminum liner shall meet the following
requirements:
a) There are no visible surface indentations, bulges, overlaps, cracks, inclusions on
the inner and outer surfaces; there are no sudden changes or obvious wrinkles in
the transition between the neck and the end;
b) The cylinder body and the end shall have a smooth transition;
c) If machining or mechanical grinding is used to remove surface defects, the defect
inspection.
6.1.5 Hardness test
6.1.5.1 Test method
The test method shall be implemented, in accordance with the provisions of GB/T
17394.1, GB/T 230.1 or GB/T 231.1.
6.1.5.2 Qualification index
The hardness value shall not exceed the range, which is specified by the design and
manufacturing organization.
6.1.6 NDT
6.1.6.1 Test method
Use ultrasonic testing or other suitable testing methods, to carry out non-destructive
testing of aluminum liner.
6.1.6.2 Qualification index
The maximum defect size of the aluminum liner shall be smaller than the maximum
allowable defect size, which is specified in 5.3.4.
6.2 Gas cylinders
6.2.1 Mechanical properties of wrapping layer
6.2.1.1 Interlaminar shear test
6.2.1.1.1 Test method
According to the provisions of GB/T 1458, make representative specimen of wrapping
layer; the number of valid specimens shall not be less than 6. After the specimen is
boiled in boiling water for 24 h, the test shall be carried out, according to the method
specified in GB/T 1458.
6.2.1.1.2 Qualification index
The interlaminar shear strength value of the wrapping layer composite material shall
not be less than 13.8 MPa.
6.2.1.2 Tensile test
6.2.1.2.1 Test method
According to the provisions of GB/T 3362, make representative tensile specimens; the
number of valid specimens shall be not less than 6. Carry out test, according to the test
methods stipulated in GB/T 3362.
6.2.1.2.2 Qualification index
The measured tensile strength shall not be lower than the guaranteed value of the design
and manufacturing organization.
6.2.2 Appearance of the wrapping layer
6.2.2.1 Test method
Visual inspection.
6.2.2.2 Qualification index
There shall be no defects, such as bare fibers, fiber breakage, resin buildup,
delamination, fiber non-saturation.
6.2.3 Hydrostatic test
6.2.3.1 Test method
The water pressure test is carried out, according to the external test method, which is
specified in GB/T 9251; the test pressure ph is 1.5p.
6.2.3.2 Qualification index
Hold the pressure, under the test pressure for at least 30 s, the pressure shall not drop;
the cylinder shall not leak or deform significantly. The elastic expansion of the gas
cylinder shall be less than the limit elastic expansion; the residual deformation rate of
the volume, after pressure relief, is not more than 5%.
6.2.4 Air tightness test
6.2.4.1 Test method
After passing the hydraulic test, carry out the air tightness test with nitrogen, according
to the test method specified in GB/T 12137; the test pressure is p.
6.2.4.2 Qualification index
Keep it under the test pressure for at least 1 min; the cylinder body, the cylinder valve,
the connection between the cylinder body and the cylinder valve shall not leak. For the
leakage caused by assembly, it is allowed to redo the test, after repair.
6.2.5 Hydraulic burst test
6.2.5.1 Test method
6.2.7 Fire test
6.2.7.1 Test method
The gas cylinder and its accessories shall be subjected to the fire test AND meet the
following requirements at the same time:
a) The local fire location shall be the area on the gas cylinder, that is farthest from
the safety pressure relief device. If both ends of the gas cylinder are equipped
with safety pressure relief devices, the fire source shall be located in the center of
the safety pressure relief devices;
b) Before the test, use hydrogen or air to slowly pressurize the cylinder to the
nominal working pressure p;
c) The fire source is a liquefied petroleum gas (LPG), natural gas or kerosene burner;
its width shall be greater than or equal to the diameter of the gas cylinder, so that
it is surrounded with flame, by the lower part and both sides of the gas cylinder.
The length of the fire source, during partial fire, is (250 ± 50) mm; the length of
the fire source, during the overall fire, shall engulf the entire gas cylinder;
d) The gas cylinder shall be placed horizontally; its lower surface shall be about 100
mm away from the fire source. At least 5 thermocouples shall be installed in the
area of the cylinder, not exceeding 1.65 m in the axial direction (at least 2 shall
be installed in the local fire range; at least 3 shall be installed in other areas).
Thermocouples, installed in other areas, shall be arranged at equal intervals; the
spacing shall be less than or equal to 0.5 m. The distance -- between the
thermocouple and the lower surface of the gas cylinder is (25 ± 10) mm. If
necessary, more thermocouples can be installed, in the safety pressure relief
device and other parts of the gas cylinder;
e) During the test, wind shielding measures, such as windshield, shall be adopted, to
make the gas cylinder heated evenly;
f) During the fire test, the temperature indicated by the thermocouple is shown in
Figure 5. In the local fire stage, the temperature indicated by the thermocouple,
on the fire area of the gas cylinder, shall reach at least 300 °C within 1 min after
ignition, at least 600 °C within 3 min; meanwhile, it shall not be lower than 600 °C
within the next 7 min, but shall not be higher than 900 °C. After 10 minutes of
ignition, it enters the overall fire stage. The flame shall quickly fill the entire
length of the gas cylinder; the temperature indicated by the thermocouple shall
reach at least 800 °C, but not higher than 1100 °C. The temperature, which is
indicated by the thermocouple, shall meet the requirements in Table 4.
......
Source: Above contents are excerpted from the PDF -- translated/reviewed by: www.chinesestandard.net / Wayne Zheng et al.
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