QC/T 746-2006: Download Full-PDF & Invoice in 9 seconds. Excerpt from above true-PDF:
QC/T 746-2006
QC
AUTOMOBILE INDUSTRY STANDARD
OF THE PEOPLE’S REPUBLIC OF CHINA
High Pressure Pipelines for
Compressed Natural Gas Vehicles
ISSUED ON. MARCH 7, 2006
IMPLEMENTED ON. AUGUST 1, 2006
Issued by. National Development and Reform Committee
Table of Contents
Foreword ... 3 
1 Scope ... 4 
2 Normative references ... 4 
3 Definitions ... 5 
4 Technical requirements... 6 
5 Test method ... 9 
6 Inspection rules ... 15 
7 Marking, packaging, operation instructions, transport and storage ... 16 
Annex A ... 18 
Foreword
Annex A of this Standard is normative.
This Standard is formulated for the first time.
This Standard was proposed by National Technical Committee for Standardization of
Automobiles.
This Standard shall be under the jurisdiction of National Technical Committee for
Standardization of Automobiles.
Drafting organizations of this Standard. Chongqing Automotive Research Institute,
Chongqing China Natural Gas Vehicles Co., Ltd.
Main drafters of this Standard. Chen Wanying, Zhang Haihui, Wang Kai.
This Standard shall be responsibly interpreted by National Technical Committee for
Standardization of Automobiles.
High Pressure Pipelines for
Compressed Natural Gas Vehicles
1 Scope
This Standard specifies the definitions, technical requirements, test methods, inspection
rules, marking, packaging, transport, and storage of high pressure pipelines for
compressed natural gas vehicles (hereinafter referred to as high pressure pipelines).
This Standard applies to high-pressure pipelines that use compressed natural gas as
vehicle fuel, of which the rated working pressure is 20MPa (all pressure values stated in
this Standard refer to gauge pressure), and the operating environmental temperature is
-40°C ~ 120°C.
2 Normative references
The provisions in following documents become the provisions of this Standard through
reference in this Standard. For dated references, the subsequent amendments (excluding
corrigendum) or revisions do not apply to this Standard, however, parties who reach an
agreement based on this Standard are encouraged to study if the latest versions of these
documents are applicable. For undated references, the latest edition of the referenced
document applies.
GB/T 528 Rubber, Vulcanized or Thermoplastic - Determination of Tensile Stress -
Strain Properties
GB/T3765 Cone Connectors - Specification
GB/T5563 Rubber and Plastics Hoses and Hose Assemblies - Hydrostatic Testing
GB/T 5564 Rubber and Plastics Hoses - Subambient Temperature Flexibility Tests
GB/T9571 Ozone Resistance Test Method of Rubber and Plastic Hoses under Static
Conditions
GB/T9576 Rubber and Plastics Hoses and Hose Assemblies - Guidelines for
Selection, Storage, Use and Maintenance
GB/T 9577 Rubber and Plastics Hoses and Hose Assemblies - Rules for Marking,
Package and Transportation
GB 9969.1 General Principles for Preparation of Instructions for Use of Industrial
Products
GB 18017 Compressed Natural Gas as Vehicle Fuel
GB/T 14976 Seamless Stainless Steel Pipes for Fluid Transport
GB/T 17895 Natural Gas Vehicle and Liquefied Petroleum Gas Vehicle - Vocabulary
QC/T 245 Technical Conditions of Compressed Natural Gas Vehicles - Specific
Devices
3 Definitions
The terms and definitions established in GB/T 17895 and following terms and definitions
apply to this Standard.
3.1
High-pressure pipelines
A generic term of all pipe fittings and joints that are installed to natural gas vehicles and
connect air cylinder with decompression regulator.
3.2
Connectors
Parts in natural gas fuel system that connect devices or pipelines.
3.3
Rigid high-pressure fuel pipes
High-pressure steel pipes that connect parts of natural gas fuel system for circulation of
natural gas.
3.4
High-pressure flexible fuel pipes
Flexible pipes that connect parts of natural gas fuel system for circulation of high-pressure
natural gas.
4.2.1.3 Ultra-torque characteristics
High-pressure pipeline shall be subjected to ultra-torque characteristics test according to
the test prescribed in 5.5; test piece shall be free of thread damage, deformation and
break; air tightness test shall conform to the provisions of 4.2.1.2.
4.2.1.4 Durability
High-pressure pipeline shall be subjected to durability test according to the test method
prescribed in 5.6; air tightness test shall conform to the provisions of 4.2.1.2.
4. 2.1.5 Corrosion resistance
After high-pressure pipeline receives salt spray corrosion test according to the method
prescribed in 5.7, air tight test shall conform to the provisions of 4.2.1.2.
4.2.1.6 Compatibility
After high-pressure pipeline receives compatibility test according to the test method
prescribed in 5.8.1, test piece is inspected by 25-times magnifying glass, and shall be free
of conspicuous fracture traces.
4.2.1.7 Bending resistance
After high-pressure pipeline receives bending test according to the test method prescribed
in 5.9; test piece shall be free of cracks or fracture.
4.2.1.8 Pull strength
High-pressure pipe shall be subjected to pull strength test according to the test method
prescribed in 5.10; if F≥f, then test piece passes the test, .
4.2.1.9 Vibration resistance
After high-pressure pipeline receives vibration test according to the method prescribed in
5.11; air tight test shall conform to the provisions of 4.2.1.2.
4.2.2 High-pressure flexible fuel pipe
4.2.2.1 Hydrostatic pressure strength
a) High-pressure strength shall be subjected to pressure test according to the test
method prescribed in 5.3.2.1; pressure-containing parts of high-pressure pipeline
shall be free of leakage.
b) High-pressure pipeline shall be subjected to bursting pressure test according to the
test method prescribed in 5.3.2.2; pressure-containing parts of high-pressure
pipeline shall be free of fracture.
High-pressure flexible fuel pipe and joint shall be able to pass the test prescribed in
4.2.2.1 a) after receiving impact test for 15, 000 times according to the method prescribed
in 5.17.
5 Test methods
5.1 Test conditions
5.1.1 General provisions
Unless otherwise specified, tests prescribed in this Standard shall be carried out under
following conditions.
a) Test environment temperature is 20°C±5°C;
b) Test medium shall be clean dry air or nitrogen.
5.1.2 Requirements for precision of test instruments
a) Pressure instrument. Accuracy is not lower than grade 2.5; measurement error is
less than ±10% of reading.
b) Flow instrument. Accuracy is not lower than grade 2.5; measurement error is less
than ±10% of reading.
c) Temperature instrument. Accuracy is ±0.5°C; the minimum resolution is not greater
than 2 times the accuracy.
5.2 Visual inspection
Inspect high-pressure pipeline assembly visually; the results shall conform to relevant
provisions in chapter 4.
5.3 Hydrostatic pressure strength test
5.3.1 High-pressure rigid fuel pipe
Securely install test piece to an enclosed special test bench; block off the outlet of test
piece; test hydraulic pressure is slowly added to test piece; pressurizing duration shall not
be less than 3min; make it reach 45Mpa; stabilize the pressure for 3min and release the
pressure.
Samples that have received this test must not be used for other tests.
5.3.2 High-pressure flexible fuel pipe
is necessary to pick out four most severe resonance frequencies from them. During test
period, if resonant frequency changes, change occurring time shall be recorded and
vibration frequency shall be immediately adjusted in order to maintain resonance state of
peak value. Record the final resonance frequency. Test piece shall be subjected to air
tight test after it is completed.
5.12 Tensile strength test of high-pressure flexible fuel pipe follows the provisions GB/T
528.
5.13 Ozone resistance test
Ozone resistance test of high-pressure pipe follows the provisions of GB/T 9571.
5.14 Low-temperature bending test
High-pressure flexible fuel pipe follows the provisions on method B in GB/T 5564; place at
a temperature of -40°C±2°C for 24h; check the surface of test piece with 2-times
magnifying glass.
5.15 Oxygen aging resistance test
Hang the samples vertically in oxygen pressure vessel, in a free state. Samples shall not
be crowded, or contact each other, or touch container wall. Samples with different
formulas may not be tested in the same container. Heat the constant temperature control
system; after the medium is preheated to working temperature, place container with
samples into heading medium; pressurize with pressurized oxygen when test temperature
is constant; calculate aging time when the pressure reaches the predetermined value. It is
required to drop container pressure to normal pressure slowly and evenly, in at least 5min,
after reaching predetermined time and before taking samples out of the container.
5.16 Leakage test
Leakage test of high-pressure flexible fuel pipe follows the provisions in annex A.
5.17 Impact test of high-pressure flexible fuel pipe
This test ...
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