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GB/T 18443.2-2010 English PDF (GBT18443.2-2010)

GB/T 18443.2-2010 English PDF (GBT18443.2-2010)

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GB/T 18443.2-2010: Testing method of performance for vacuum insulation cryogenic equipment -- Part 2: Vacuum degree measurement

This Part of GB/T 18443 specifies the test principles and methods, test devices, equipment and instruments, test conditions and preparation, test procedures, data processing, test records and test reports of the vacuum degree measurement of the interspace of vacuum insulated cryogenic equipment. This Part is applicable to the vacuum degree measurement of the interspace of vacuum insulated cryogenic equipment, such as: vacuum insulated cryogenic pressure vessels, vacuum insulated cryogenic welding gas cylinders and vacuum insulated pipes and their pipe fittings, except for liquid hydrogen storage and transportation media. The other equipment may take this as a reference.
GB/T 18443.2-2010
NATIONAL STANDARD OF THE
PEOPLE REPUBLIC OF CHINA
ICS 23.020
J 74
Replacing GB/T 18443.2-2001, GB/T 16876-1997
Testing Method of Performance for Vacuum Insulation
Cryogenic Equipment - Part 2.Vacuum Degree
Measurement
ISSUED ON. SEPTEMBER 26, 2010
IMPLEMENTED ON. FEBRUARY 1, 2011
Issued by. General Administration of Quality Supervision, Inspection and Quarantine of the PEOPLE Republic of China;
Standardization Administration of the PEOPLE Republic of China.
Table of Contents
Foreword... 3
1 Scope... 5
2 Normative References... 5
3 Terms and Definitions... 5
4 Test Principles and Methods... 6
5 Test Devices, Equipment and Instruments... 7
6 Test Conditions and Preparation... 7
7 Test Procedures... 8
8 Data Processing... 9
9 Test Records and Reports... 10
Appendix A (informative) Test Records of Interspace Vacuum Degree of Normal Atmospheric Temperature or Interspace Vacuum Degree after Loaded... 11 Appendix B (informative) Test Reports of Interspace Vacuum Degree of Normal Atmospheric Temperature or Interspace Vacuum Degree after Loaded... 12 Testing Method of Performance for Vacuum Insulation
Cryogenic Equipment - Part 2.Vacuum Degree
Measurement
1 Scope
This Part of GB/T 18443 specifies the test principles and methods, test devices, equipment and instruments, test conditions and preparation, test procedures, data processing, test records and test reports of the vacuum degree measurement of the interspace of vacuum insulated cryogenic equipment.
This Part is applicable to the vacuum degree measurement of the interspace of vacuum insulated cryogenic equipment, such as. vacuum insulated cryogenic pressure vessels, vacuum insulated cryogenic welding gas cylinders and vacuum insulated pipes and their pipe fittings, except for liquid hydrogen storage and transportation media. The other equipment may take this as a reference.
2 Normative References
The clauses of the following documents become clauses of this Part through the reference in this Part of GB/T 18443.In terms of references with a specified date, all subsequent amendments (excluding errata content) or revisions do not apply to this Part. However, the various parties that reach an agreement in accordance with this Part are encouraged to explore whether the latest versions of these documents are applicable. In terms of references without a date, the latest versions apply to this Part.
GB/T 18443.1-2010 Testing Method of Performance for Vacuum Insulation Cryogenic Equipment - Part 1.Basic Requirements
3 Terms and Definitions
What is established in GB/T 18443.1, and the following terms and definitions are applicable to this Part.
3.1 Interspaced Vacuum Degree
Interspaced vacuum degree refers to the absolute pressure (expressed in Pa) of the gas in the interlayer space of the vacuum insulated cryogenic equipment.
3.2 Static Interspace Vacuum Degree
Static interspace vacuum degree refers to the vacuum degree (expressed in Pa) of the interspace of the vacuum insulated cryogenic equipment under the airtight state.
3.3 Dynamic Interspace Vacuum Degree
Dynamic interspace vacuum degree refers to the vacuum degree (expressed in Pa) of the interspace of the vacuum insulated cryogenic equipment under the pumping state of the pumping system.
3.4 Interspace Vacuum Degree of Normal Atmospheric Temperature
Interspace vacuum degree of normal atmospheric temperature refers to the static interspace vacuum degree (expressed in Pa) when no cryogenic liquid is injected into the vacuum insulated cryogenic equipment, and the inner tank and outer shell are both at atmospheric temperature. 3.5 Interspace Vacuum Degree after Loaded
Interspace vacuum degree after loaded refers to the static interspace vacuum degree (expressed in Pa) when the vacuum insulated cryogenic equipment has been injected with cryogenic liquid and is under the thermal equilibrium state.
3.6 Sealing-off Vacuum Degree
Sealing-off vacuum degree refers to the interspace vacuum degree when sealing at room temperature.
4 Test Principles and Methods
4.1 The measurement of the interspace vacuum degree is divided into direct measurement method and indirect measurement method. The schematic diagram of the test device of the direct measurement method is shown in Figure 1; the schematic diagram of the test device of the indirect measurement method is shown in Figure 2.
4.2 The direct measurement method refers to the direct measurement of the vacuum degree of the interspace by using the vacuum gauge installed on the measured piece. 4.3 The indirect measurement method refers to the measurement of the vacuum degree of the interspace after externally connecting the vacuum maintenance system to the measured piece. To pumping system
shall not be ?€?degassed?€? within 15 min before the test.
6.5 When adopting flammable cryogenic liquid as the test medium, safety inspection shall be carried out before filling. During filling, the vacuum degree shall be measured. If the vacuum degree rises, immediately stop filling and drain the liquid, and finally, use nitrogen to replace the flammable medium.
7 Test Procedures
7.1 Direct Measurement Method
7.1.1 For the direct measurement method, connect in accordance with Figure 1. 7.1.2 Adjust the vacuum measuring instrument; determine an appropriate measuring range; turn on the vacuum gauge; from the lower vacuum, predict the vacuum degree of the interspace. 7.1.3 The stable reading of the vacuum gauge is the vacuum degree of the interspace of the measured piece.
7.2 Indirect Measurement Method
7.2.1 Connect the measured piece and the vacuum measurement system in accordance with Figure 2.
7.2.2 When the vacuum valve of the measured piece and the vacuum valve of the pumping system are closed, start the vacuum unit.
7.2.3 Open the vacuum valve of the pumping system. Use the low vacuum pump to pump the pressure of the measurement pipeline to below 3 Pa, then, use the high vacuum pump to pump it. When the measurement pipeline receives air pumping, heating degassing is allowed. 7.2.4 For the measured pieces with different thermal insulation structures and cryogenic media, the vacuum degree of the measurement pipeline shall comply with the requirements of Table 1. 7.2.5 During the measurement of the sealing-off vacuum degree and the interspace vacuum degree after loaded, the leak-outgassing rate of the measurement pipeline shall comply with the requirements of Table 2.
7.2.6 After the leak-outgassing rate of the measurement pipe reaches the requirements, the pumping shall be continued for 10 min, then, record the background vacuum degree P0 of the pipeline; immediately close the vacuum valve of the pumping system, open the vacuum valve of the measured piece and observe the changes of the vacuum degree of the measurement pipeline.
7.2.7 After 2 min of observation, after the pressure between the interlayer space and the measurement pipeline space is balanced, record the vacuum degree P1 of the connected space after it becomes stable.
8.2 During the measurement of interspace vacuum degree after loaded through the indirect measurement method, calculate in accordance with the following formulas. a) When the vacuum degree P1 of the connected space is higher than 1 ??? 10-2 Pa, calculate in accordance with Formula (1).
b) When the vacuum degree P1 of the connected space is lower than 1 ??? 10-2 Pa, calculate in accordance with Formula (2).
Where,
P---the vacuum degree of the interspace of the measured piece, expressed in (Pa); T---(cryogenic liquid temperature + atmospheric temperature) / 2, expressed in (K); T0---atmospheric temperature, expressed in (K);
P1---the vacuum degree of the connected space during the test, expressed in (Pa); P0---the background vacuum degree of the measurement pipeline, expressed in (Pa); V1---the volume of the measurement pipeline (including the vacuum gauge) between the vacuum valve of the measured piece and the vacuum valve of the pumping system, expressed in (m3);
V---the effective volume of the interspace of the measured piece, expressed in (m3). 9 Test Records and Reports
9.1 The format of test records is shown in Appendix A.
9.2 The format of test reports is shown in Appendix B.

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