Methods for hydrostatic test of gas cylinders English
1 Scope
This document specifies the methods for hydrostatic test of gas cylinders and the basic requirements for test devices.
This document is applicable to the hydrostatic test of gas cylinders with a nominal working pressure not greater than 70MPa (gauge pressure, the same below).
This document is not applicable to gas cylinders already filled with solid packing.
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 Verification regulation of digital indicating weighing instrument
JJG 1036 Verification regulation for electronic balance
3 Terms and definitions
For the purposes of this document, the terms and definitions given in GB/T 13005 and the following apply.
3.1
testing cylinder
gas cylinder to be tested or under test
3.2
pressure proof test
process of testing and verifying the safe bearing capacity of a testing cylinder after it is pressurized to the hydrostatic test pressure and kept with it for a specified period of time
3.3
water jacket method
test method for determining the values of total volumetric expansion, elastic volumetric expansion and permanent volumetric expansion of a testing cylinder by placing the cylinder in a special water jacket to pressurize it to the hydrostatic test pressure and hold for a specified period of time, and then measuring the quantity of water overflowed from the jacket and the quantity of remaining overflow after pressure relief
3.4
direct expansion method
test method for determining the values of total volumetric expansion, elastic volumetric expansion and permanent volumetric expansion of a testing cylinder by placing the cylinder in a special water jacket to pressurize it to the hydrostatic test pressure and hold for a specified period of time, and then reading the indications of the water quantity measuring instrument for the quantity of pressed water after pressure application and that of remaining water after pressure relief
3.5
special water jacket
special device used to determine the volumetric expansion of a testing cylinder generated during the water jacket hydrostatic test
3.6
calibrated cylinder
cylinder-type device which has the corresponding relationship between the calibration pressures and its expansion values (characteristic of repeatability and linearity already determined) and will suffer no permanent deformation any more under calibration pressure, used to calibrate the accuracy of the hydrostatic test devices for gas cylinders
3.7
calibrated gauge
pressure measuring meter, used to calibrate the pressure of the test system, whose accuracy level shall not be less than those of any other pressure measuring instrument
3.8
reference zero point
zero reading on water quantity measuring instrument, with its error to be ±0.1% of the total volumetric expansion or ±0.1mL, whichever is larger
4 Principle
In the hydrostatic test on a gas cylinder, the testing cylinder has its inner pressure gradually increased at the specified pressurization rate to the hydrostatic test pressure and maintained for a specified period of time. By different test methods, test and verify the safe bearing capacity of the testing cylinder, and determine the total volumetric expansion, elastic volumetric expansion under the hydrostatic test pressure (if required) and the permanent volumetric expansion after pressure relief of the testing cylinder.
5 Test conditions
5.1 The test water shall be clean fresh water. If the testing cylinder is made of steel containing chrome alloy, the chloride ion content in the test water shall not be larger than 25mg/L. In the test on a testing cylinder filled with oxygen or other strong oxidizing medium, the test water injected or pressed into cylinder shall not be contaminated by grease.
Foreword II
1 Scope
2 Normative references
3 Terms and definitions
4 Principle
5 Test conditions
6 Equipment and instruments
7 Pressure proof test
8 Water jacket method
9 Direct expansion method
10 Rules for rounding of numerical values
11 Precautions for test
Annex A (Nominative) Calibration of water jacket test devices
Annex B (Informative) Average coefficient of compressibility of water
