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GB/T 30824-2014 English PDF (GBT30824-2014)

GB/T 30824-2014 English PDF (GBT30824-2014)

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GB/T 30824-2014: Testing method for temperature uniformity of gas heat treatment furnace
GB/T 30824-2014
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 25.200
J 36
Testing method for temperature uniformity of gas heat
treatment furnace
ISSUED ON: JUNE 24, 2014
IMPLEMENTED ON: DECEMBER 31, 2014
Issued by: General Administration of Quality Supervision, Inspection and
Quarantine;
Standardization Administration of the People’s Republic of China.
Table of Contents
Foreword ... 3
1 Scope ... 4
2 Normative references ... 4
3 Terms and definitions ... 5
4 Classification of gas heat treatment furnaces ... 6
5 Implementation conditions and test cycle ... 6
6 Test device ... 8
7 Test methods ... 11
8 Evaluation of temperature uniformity of the effective heating zone ... 19
9 Test records and test reports ... 20
10 Management ... 20
Appendix A (Informative) Gas heat treatment furnace effective heating zone
temperature uniformity test record form ... 22
Appendix B (Informative) Effective heating zone temperature uniformity test certificate
... 25
Bibliography ... 26
Testing method for temperature uniformity of gas heat
treatment furnace
1 Scope
This Standard specifies the implementation conditions and test cycle, test device, test
methods, and evaluation of temperature uniformity of the effective heating zone of gas
heat treatment furnaces.
This Standard applies to gas heat treatment furnaces heated by direct combustion gas
in the furnace, including cycle (intermittent) and continuous heat treatment furnaces.
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 1598, Platinum-10%Rhodium/Platinum thermocouple wires - Platinum-
13%Rhodium/Platinum thermocouple wires - Platinum-30%Rhodium/Platinem-
6%Rhodium thermocouple wires
GB/T 2614, Nickel-Chromium/Nickel-Silicon thermocouple wires
GB/T 4989, Extension and compensating cables for thermocouples
GB/T 4990, Alloy wires of extension and compensating cables for thermocouples
GB/T 7232, Terminology of metal heat treatment
GB/T 9452, Testing method for working zone of heat treatment furnace
GB/T 13324, Terminology of heat treatment equipment
GB/T 17615, Nickel-Chromium-Silicon/Nickel-Silicon-Magnesium thermocouple
wires
GB/T 18404, Mineral insulated metal-sheathed thermocouple cables and
thermocouples
3 Terms and definitions
Terms and definitions given in GB/T 9452, GB/T 7232 and GB/T13324, as well as the
following, are applicable to this document.
3.1
temperature control system error
An offset to the temperature measurement results produced by the temperature control
system composed of temperature sensors, extension and compensating cables, display
adjustment instruments, etc. Its value is the algebraic sum of the errors of temperature
sensors, extension and compensating cables, display adjustment instruments and other
components.
3.2
maximum permit error
The allowable error limits of measuring instruments and measuring systems specified
in technical specifications and standards.
3.3
correction
The opposite of error. The uncorrected measurement result and the correction are added
algebraically to obtain the true measurement result to compensate for the influence of
system error.
3.4
initial test
The first test of temperature uniformity of the effective heating zone carried out before
the gas heat treatment furnace is put into use.
3.5
cycle test
The test of temperature uniformity of the effective heating zone carried out by the gas
heat treatment furnace in use at certain time intervals.
3.6
simulation load test
The size and shape of the bracket or frame used to fix the thermocouple depends on the
test method. Such materials shall have sufficient strength and shall have no obvious
deformation after testing.
7 Test methods
7.1 Test requirements
7.1.1 The gas heat treatment furnace shall realize automatic temperature control, and
the qualified test status shall be able to be reproduced in the production process.
7.1.2 The ambient temperature of the connection parts of the extension and
compensating cables, transfer switches, and display instruments shall be controlled, and
the temperature change during the test shall not exceed 1 °C.
7.1.3 The initial test shall be carried out with no-load test first, and then the load test
after qualification. During the load test, the loading capacity shall be the rated loading
capacity of the furnace, or at least not less than 70% of the rated loading capacity.
7.1.4 The cycle test can be carried out in either no-load or load test. When the no-load
test fails, the load test can be carried out, and the test result shall be subject to the load
test. During the load test, the loading capacity shall be consistent with that of the actual
production.
7.1.5 During the no-load test, the measuring ends of the test thermocouples distributed
near the burner and flue shall be protected with protective covers. It is also
recommended to add protective covers to the measuring ends of test thermocouples
distributed in other locations to reduce the impact of temperature fluctuations on the
test results. The material of the protective cover shall be compatible with the material
of the heat treatment product, the length shall be about 10 times the aperture, and the
wall thickness shall be no greater than the thickness of the thinnest workpiece. During
the load test, the measuring end of the test thermocouple shall be as close as possible to
the workpiece.
7.1.6 The gas heat treatment furnace shall be heated at the heating rate specified by the
process. The furnace temperature shall not rise above the test temperature and then drop
to the test temperature.
7.1.7 During the test process, all parameters of the furnace shall reflect the normal
production operation process of the equipment.
7.1.8 Thermocouples arranged at the corners and end faces of the effective heating area
are not allowed to fail. Two adjacent thermocouples are not allowed to fail at the same
time. The maximum allowable number of failures for test thermocouples is shown in
Table 5.
A unit volume is the volume of pallets, frames, etc. loaded according to the rated loading
capacity. The number and location of test points of the unit volume method are
determined according to the size of the unit volume, and the distribution of test points
shall be able to reflect the temperature distribution within the unit volume. The
determination method is as follows:
a) When the width of the pallet or material frame is less than 1.5 m and the length is
less than 1.0 m, if the height of the effective heating zone is less than 0.5 m, 3 test
thermocouples shall be arranged. 2 thermocouples shall be arranged diagonally
at the front and rear end surfaces along the feeding direction, and 1 at the
geometric center of the unit volume. If the height of the effective heating zone is
not less than 0.5 m and less than 1.0 m, 5 test thermocouples shall be arranged,
two of which at each corner of the front and rear ends along the feeding direction,
and one at the geometric center of the unit volume. If the height of the effective
heating zone is not less than 1.0 m, 9 test thermocouples shall be arranged. One
shall be arranged at each of the four corners of the fro...
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