GB/T 9251-2022 English PDF (GBT9251-2022)

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GB/T 9251-2022: Methods for hydrostatic test of gas cylinders
GB/T 9251-2022
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 23.020.30
CCS J 74
Replacing GB/T 9251-2011
Methods for hydrostatic test of gas cylinders
ISSUED ON. MARCH 09, 2022
IMPLEMENTED ON. OCTOBER 01, 2022
Issued by. State Administration for Market Regulation;
Standardization Administration of the People's Republic of China.
Table of Contents
Foreword... 3 
1 Scope... 5 
2 Normative references... 5 
3 Terms and definitions... 5 
4 Principle... 6 
5 Test conditions... 7 
6 Instruments and equipment... 7 
7 Pressure proof test... 10 
8 Water jacket method... 12 
9 Direct expansion method... 16 
10 Rounding rules for calculated values... 20 
11 Precautions in the test... 20 
Annex A (normative) Verification of test devices for water jacket method... 22 
Annex B (informative) Average compression factor of water... 26 
Methods for hydrostatic test of gas cylinders
1 Scope
This document specifies the basic requirements for hydrostatic test methods and devices
of gas cylinders.
This document is applicable to the hydrostatic test of gas cylinders whose nominal
working pressure is not more than 70MPa (gauge pressure, the same below).
This document does not apply to gas cylinders filled with solid fillers.
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 13005, Terminology of gas cylinders
GB/T 35015, Calibration method for calibrated cylinder used in water jacket
hydrostatic test
JJG 539, Digital Indicating Weighing Instruments
JJG 1036, Verification Regulation for Electronic Balance
3 Terms and definitions
For the purposes of this document, the terms and definitions defined in GB/T 13005 as
well as the followings apply.
3.1 testing cylinder
Cylinders to be tested or being tested.
3.2 pressure proof test
A process of testing and verifying the safe bearing capacity of the testing cylinder after
it is pressurized to its hydraulic test pressure and maintained for a specified period of
time.
3.3 water jacket method
A test method that puts the testing cylinder into a special water jacket, pressurizes it to
its hydrostatic test's pressure and holds the pressure for a specified time, to determine
the total volumetric deformation, volumetric elastic deformation and volumetric
residual deformation of the testing cylinder by the amount of water overflowing from
the water jacket and the remaining overflowing volume after pressure relief.
3.4 direct expansion method
A test method that pressurizes the testing cylinder to its hydrostatic test pressure and
holds the pressure for a specified time, to determine the total volumetric deformation,
volumetric elastic deformation and volumetric residual deformation of the testing
cylinder by the pressurized water volume after pressurizing and the indication value of
water volume measuring instrument after pressure relief.
3.5 special water jacket
A special equipment for measuring the volumetric deformation of the testing cylinder
during the hydrostatic test by water jacket method.
3.6 calibrated cylinder
A bottle equipment that if the corresponding relationship between the calibration
pressure and the expansion value has been determined, the expansion value shall have
the characteristics of repeatability and linearity, and there will be no permanent
deformation under the calibration pressure. It is used to verify the accuracy of the
hydrostatic test device of gas cylinders.
3.7 calibrated gauge
A pressure measuring instrument for verifying the pressure value of the test system. Its
accuracy level shall not be less than that of other pressure measuring instruments.
3.8 reference zero point
Zero reading on water volume measuring instrument. The error shall be the larger value
of ±0.1% of the total volumetric deformation value and ±0.1mL.
4 Principle
The hydrostatic test of gas cylinders uses water as the pressurized medium. Gradually
increase the pressure in the testing cylinder to its hydrostatic test pressure according to
the specified pressurization rate. Hold the pressure for a specified time. Use different
test methods to test and verify the safe bearing capacity of the testing cylinder. Measure
the total volumetric deformation, volumetric elastic deformation (if required) and
volumetric residual deformation of the testing cylinder under the hydraulic test pressure.
6.1.5 The dimensions and materials of all associated piping of the hydrostatic test
devices for water jacket method and direct expansion method shall be such that they do
not deform under the weight of water. The size shall be large enough. The installation
shall be able to prevent air accumulation, flow obstruction and external damage. All
associated piping valves shall be properly selected and installed to ensure no leakage.
6.1.6 The calibration of the calibrated cylinder shall comply with the provisions of
GB/T 35015.The calibration data of the calibrated cylinder shall be able to meet the
test requirements of the testing cylinder (at least three pressure levels). A clearly
identifiable calibration certificate and label shall be attached.
6.1.7 The test device shall be able to display, record and save test data including time,
pressure and water volume automatically, accurately and in real time. All original test
records stored in real time shall be immutable.
6.1.8 The test device shall be able to automatically generate and output test records.
The test records shall meet the requirements of 7.4.1, 8.4.1 and 9.4.1 respectively.
6.1.9 The frequency of collecting pressure and water volume data by the test device
shall not be less than 10 times/s.
6.1.10 The test system shall take appropriate safety precautions to ensure the safety of
operators and equipment during the test.
6.2 Measuring instruments
6.2.1 Pressure measuring instrument
6.2.1.1 A pressure gauge and a calibrated gauge for calibration shall be installed on the
pressure proof test device. A pressure gauge, a pressure transmitter (or a digital pressure
gauge that can output pressure signals) and a calibrated gauge for calibration shall be
installed on the test devices for water jacket method and direct expansion method at the
same time. The installation position of pressure gauge, pressure transmitter (or digital
pressure gauge that can output pressure signal) and calibrated gauge shall be able to
display the test pressure correctly.
6.2.1.2 The pressure display value of the pressure measuring instrument shall be
verified via a calibrated gauge before the test. If the pressure display value is abnormal,
it shall be replaced in time. A calibrated gauge may not be used when performing a
hydrostatic test.
6.2.1.3 The range of the pressure measuring instrument shall be 1.5 times to 3 times the
pressure of the hydrostatic test of the testing cylinder. The accuracy level of the pressure
gauge shall not be lower than level 1.0.The accuracy level of the pressure transmitter
(or digital pressure gauge that can output pressure signals) shall not be lower than level
0.5.
6.2.1.4 Pressure measuring instruments shall be regularly verified or calibrated. The
verification or calibration cycle shall be carried out in accordance with relevant
regulations.
6.2.2 Water vo...