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GB/T 9452-2023 (GB/T9452-2023, GBT 9452-2023, GBT9452-2023) & related versions
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GB/T 9452-2023: PDF in English (GBT 9452-2023)
GB/T 9452-2023
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 25.200
CCS J 36
Replacing GB/T 9452-2012
Test method for qualified work zone of heat treatment
furnace
ISSUED ON: MAY 23, 2023
IMPLEMENTED ON: DECEMBER 01, 2023
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 ... 6
4 Classification of heat treatment furnaces according to temperature uniformity ... 7
5 Initial test and periodic test of qualified work zone ... 9
6 Test system ... 11
7 Test methods ... 15
8 Evaluation of qualified work zone test ... 22
9 Records and reports ... 22
10 Management ... 23
Annex A (informative) Test record sheet for qualified work zone ... 25
Annex B (informative) Test certificate of qualified work zone ... 26
Test method for qualified work zone of heat treatment
furnace
1 Scope
This document specifies the requirements for classification of heat treatment furnaces
according to temperature uniformity, initial test and periodic test of qualified work
zones, test systems, test methods, result evaluation, records and reports, and
management.
This document is suitable for determining the qualified work zone of a heat treatment
furnace that meets temperature uniformity requirements within the operating
temperature range. This document does not apply to work zones in continuous heating
furnaces where there is no fixed process-specified heating temperature or where
temperature uniformity is not required. This document can be used as a reference for
other heating equipment.
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 2903, Copper/Copper-Nickel (Constantan) 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 4993, Nickel-Chromium/Copper-Nickel (Constantan) thermocouple wires
GB/T 4994, Iron/Copper-Nickel (Constantan) thermocouple wires
GB/T 5977, Platinum wires for resistance thermometers
GB/T 7232, Metal heat treatment - Terminology
GB/T 13324, Terminology of heat treatment equipment
GB/T 16839.1, Thermocouples -- Part 1: EMF specifications and tolerances
GB/T 17615, Nickel-Chromium-Silicon/Nickel-Silicon-Magnesium thermocouple
wires
GB/T 18404, Mineral insulated metal-sheathed thermocouple cables and
thermocouples
GB/T 30825, Pyrometry for heat treatment
JB/T 8901, Sheathed noble metal thermocouple cables
3 Terms and definitions
For the purposes of this document, the terms and definitions defined in GB/T 7232,
GB/T 13324 and GB/T 30825 as well as the followings apply.
3.1 process temperature
The heating temperature specified by the heat treatment process is based on the purpose
of heat treatment of the workpiece and the type of material.
3.2 temperature uniformity
The degree of temperature uniformity in the qualified work zone of the heat treatment
furnace refers to the maximum deviation of the temperature of each test point in the
qualified work zone relative to the set temperature.
NOTE: Usually it is expressed as "±℃".
3.3 qualified work zone
In the heating furnace, the working space that meets the process temperature and
temperature uniformity specified by the heat treatment is determined through
temperature detection.
3.4 previewed qualified work zone
In order to judge the qualified work zone of the heat treatment furnace, before testing,
it is a pre-assumed temperature measurement space based on the structure, control
method and other conditions of the heat treatment furnace. It is generally a work space
stipulated by the heat treatment furnace manufacturer or relevant standards.
3.5 no load test
A test to determine the qualified work zone without loading workpieces or substitutes
into the heat treatment furnace.
3.6 load test
A test to determine the qualified work zone when the workpiece or substitute is loaded
into the heat treatment furnace.
3.7 initial test
It is a qualified work zone test that is performed to determine the qualified operating
area, operating temperature range and furnace category for heat treatment furnaces that
are newly put into production or have undergone overhaul, technical transformation,
and repairs, changes, and adjustments during use.
3.8 periodic test
A qualified work zone test that is carried out regularly at a certain frequency during the
use of the heat treatment furnace.
3.9 stabilization
All control and recording sensor temperatures are within the allowable uniformity
deviation range, and the temperature control of each zone is maintained at the set
temperature to achieve equipment stability. All qualified work zones determine that the
sensor temperature reaches the required uniformity range. And it can be determined that
the temperature of all sensors does not show a continuous trend of upward or downward
deviation from the set point, and the temperature uniformity measurement is stable.
4 Classification of heat treatment furnaces according to
temperature uniformity
4.1 Heat treatment furnaces are divided into seven categories according to the
temperature uniformity of the qualified work zone. The corresponding temperature
control instrument accuracy level and digital recording instrument accuracy level are
shown in Table 1.
be moved on wheels or other portable means);
b) When the position of the qualified work zone changes or the volume expands;
c) When the operating temperature range is extended;
d) When there are changes in furnace gas flow pattern and speed (such as baffle
position, wind speed, air volume, etc.);
e) When there are changes in type or thickness of refractory materials;
f) When the number, type or location of heating elements is changed;
g) When burner size, number, type or location changes;
h) When the vacuum furnace hot zone design or materials change;
i) When the temperature control sensor changes (such as type, specification,
structure) and location changes;
j) When the combustion pressure setting changes;
k) When the furnace pressure setting changes;
l) When the setting parameters of the control instrument are changed;
m) When the production objects or processes of the heat treatment furnace are
changed, the temperature uniformity of the qualified work zone needs to be
improved;
n) When heat-treated products appear unqualified, it is found to be related to
temperature uniformity;
o) When a heat treatment furnace that exceeds the specified testing period and has
not been used for more than three consecutive months is reactivated.
5.2 Periodic test
5.2.1 During the use of the heat treatment furnace, the qualified work zone shall be
periodically tested. The test period shall comply with the requirements in Table 3.
and the data recorder installed in the heat insulation box into the furnace. The data
recorder will automatically track and record the temperature of each test point.
7 Test methods
7.1 General requirements
7.1.1 Under normal circumstances, no load test or load test can be used during testing.
If it is a no load test, the measuring temperature sensor can be used directly for testing,
or the measuring temperature sensor can be connected or inserted into the test block.
The thickness of the test block shall be less than or equal to the thickness of the thinnest
workpiece in the furnace. The maximum thickness shall not exceed 13 mm. The
material of the test block shall have a room temperature thermal conductivity similar to
that of the main material of the workpiece in the heat treatment furnace. If it is a load
test, the test temperature sensor shall be connected to the dummy or workpiece. The
simulated piece shall represent the thickness of the workpiece processed in the furnace.
7.1.2 The heat treatment furnace is in normal working condition during the test. Warm
up at normal rate. The fan operates normally. The furnace door of the mesh belt furnace
is in a normal opening and closing state.
7.1.3 The atmosphere used in the heat treatment furnace shall be the normal atmosphere
used in production. For temperature sensors that are prone to contamination (for
example, carburizing, nitriding, endothermic and exothermic atmospheres) or process
atmospheres that pose safety risks (for example, atmospheres containing hydrogen or
ammonia), air or an inert atmosphere can be used instead. The vacuum degree of the
vacuum furnace shall be the lowest vacuum degree used in production, but the vacuum
pressure shall not be less than 0.13 Pa.
7.1.4 When the workpiece is hot loaded into the furnace, the temperature at which the
test temperature sensor is placed into the furnace shall not exceed the test temperature.
When the process requires that the workpiece is cold and the furnace heats up, the test
temperature sensor shall also heat up with the furnace.
7.1.5 A heat treatment furnace can have multiple qualified work zones. For multiple
operating temperature ranges with different temperature uniformity requirements, or
multiple qualified work zones with different temperature uniformity requirements,
temperature uniformity measurements shall be performed separately.
7.2 Test temperatures
7.2.1 Initial test
The test temperatures for the initial test of the qualified work zone shall be the highest
and lowest temperatures of each operating temperature range. When the operating
temperature range is greater than 335°C, the test temperature point shall be added
7 Test steps
7.4.1 Test preparation
The measuring instruments and test sensors used for qualified work zone testing shall
comply with the provisions of this document, be qualified in verification or calibration,
and be within the effective period of use. The verification or calibration certificate of
measuring instruments and test sensors shall indicate the correction value or error value
at each verification or calibration temperature.
7.4.2 Sensor installation
7.4.2.1 According to the test temperature, select appropriate metal wire or other
materials to fix the measurement sensor. If galvanized iron wire is used to fix the
measuring sensor, the galvanized layer shall be removed in advance. When testing a
vacuum furnace, stainless steel wire or nickel-based alloy wire shall be used to fix the
measuring sensor.
7.4.2.2 When using a temperature measuring stand, each measuring sensor shall be
fixed on the temperature measuring stand in a suitable manner to ensure that the
measuring end of the sensor is at the specified position and the position does not change
during the test.
7.4.2.3 When the measuring sensor or material rack with a temperature measuring
frame is fixed, it can be placed in the furnace under cold furnace conditions according
to process requirements. It can also be placed in the furnace at any temperature within
the lower limit of the allowable temperature deviation from the lowest test temperature
point.
7.4.2.4 Lead the reference end of the measuring sensor from the special temperature
measuring hole of the heat treatment furnace. When leading out the reference end,
prevent damage to the sealing and heat preservation properties of the heat treatment
furnace. At the same time, the measuring sensor shall be prevented from being damaged
by extrusion.
7.4.3 Sensor and instrument connection
7.4.3.1 Sensors and instruments are generally connected in the following three ways:
a) The sensor reference terminal is directly connected to the input terminal of the
instrument or data acquisition processor;
b) The sensor reference terminal is connected to one end of the compensation wire.
The other end of the compensation wire is connected to the input terminal of the
measuring instrument or data acquisition processor;
c) The sensor reference terminal is connected to the multi-channel automatic
(scanning) switch input terminal of the measuring system device directly or
through a compensation wire.
7.4.3.2 When the sensor is connected to the instrument, it shall be ensured that each
terminal does not generate additional thermal electromotive force or resistance (the
additional thermal electromotive force or resistance is small enough) to ensure the
accuracy and reliability of the measurement results.
7.4.3.3 When connecting components such as connectors, plugs and sockets (including
pins), terminal blocks or wiring boards are used for connection, it shall be ensured that
the thermoelectric characteristics of these components are the same as or compatible
with the measuring sensor.
7.4.4 Data collection and processing
7.4.4.1 When testing temperature uniformity, data collection and recording shall start
before the temperature of the first test sensor reaches the lower limit of the allowed
deviation of the required temperature uniformity.
7.4.4.2 After the heat treatment furnace reaches a steady state, the collected data can be
recorded in Table A.1 of Annex A. The collection time or frequency shall comply with
the requirements in Table 10.
7.4.4.3 The effective data of the measuring sensor is corrected according to the
correction value (or error value) of the corresponding temperature point of each
measuring sensor, compensation wire and measuring instrument. Obtain the actual
temperature value of each measurement position at each test temperature point.
7.4.4.4 For each test temperature point, use the difference between the actual
temperature value of each measurement position and the test temperature set value as
the temperature deviation value of the test position. Determine the maximum and
minimum temperature deviation values for each test temperature.
7.4.4.5 When performing error correction, if the verification or calibration temperature
point of the measuring sensor or measuring instrument does not correspond to the
specified qualified work zone test temperature point, the error value of the verification
sensor.
8 Evaluation of qualified work zone test
8.1 Through testing, it is assumed that when the actual temperatures of each test point
in the qualified work zone are within the temperature uniformity range specified by the
process, that is, the temperature uniformity is qualified, then this space is the qualified
work zone of the process.
8.2 Based on the temperature uniformity test results, refer to Table 1 to determine the
type of heat treatment furnace.
8.3 For the data measured according to the method specified in this document, if the
temperature uniformity of one test point cannot meet the requirements, the
measurement of the qualified work zone will fail. The assumed qualified work zone
shall be changed or the heat treatment furnace shall be adjusted and retested. For
example, when using a heat treatment furnace that lowers the furnace temperature
uniformity requirements, repeated testing is not required as long as the new temperature
uniformity conditions are met.
9 Records and reports
9.1 All original records during the testing process shall be retained (see Table A.1). The
original record shall contain the following content:
a) The name, model, equipment number, and category of the heat treatment furnace;
b) The no load or load condition of the equipment under test and the loading amount
of the loading test;
c) The type of atmosphere or salt bath used by the device under test;
d) Operating temperature range, test temperature and temperature uniformity
requirements of the equipment under test;
e) Configuration type of process instrumentation of the equipment under test;
f) The name, model, accuracy level, error value and validity period of the measuring
instrument;
g) Correction values for all measuring sensors;
h) A schematic diagram (three-dimensional view or plan view) of the pre-specified
or determined qualified work zone shape, size and sensor arrangement location;
i) Whether all measuring sensors use temperature test blocks and the shape and
specifications of the test blocks;
j) Time, temperature data or/and temperature curves recorded by all test area
measurement sensors and process sensors (excluding alarm sensors);
k) The time when each test temperature point starts and ends the temperature
measurement, the temperature display value and the actual temperature value
after data processing;
l) The temperature deviation values of all measuring sensors after data processing at
each test temperature point;
m) Qualified work zone test and evaluation conclusion;
n) Test start and end date and time, validity period and next due date of test;
o) Signature of the responsible person (tester, reviewer).
9.2 Based on the original records, a test report for qualified work zone is formed,
including:
a) Name, number, category, manufacturer, and model of the heat treatment furnace;
b) No load or load conditions and loading amounts for loading tests;
c) Operating temperature, test temperature and temperature uniformity;
d) Name and accuracy of the temperature measuring instrument;
e) Type of atmosphere or salt bath used (composition, characteristics);
f) Loading capacity, furnace loading type, material transport speed, workpiece
characteristics (material, shape, size and weight, etc.) of the loading test;
g) Maximum temperature deviation value of each test point;
h) Evaluation results of qualified work zone;
i) Test date and next test date;
j) Name and signature of the responsible person (tester, reviewer, approver), testing
agency and seal;
k) Test certificate of qualified work zone (see Table B.1 in Annex B).
10 Management
10.1 All original records and documentation of the qualified work zone testing process
......

BASIC DATA
Standard ID GB/T 9452-2023 (GB/T9452-2023)
Description (Translated English) Test method for qualified work zone of heat treatment furnace
Sector / Industry National Standard (Recommended)
Classification of Chinese Standard J36
Classification of International Standard 25.200
Word Count Estimation 20,277
Date of Issue 2023-05-23
Date of Implementation 2023-12-01
Older Standard (superseded by this standard) GB/T 9452-2012
Drafting Organization Guangdong Shichuang Metal Technology Co., Ltd., Beijing Electromechanical Research Institute Co., Ltd., Jiangsu Fengdong Thermal Technology Co., Ltd., AVIC Great Wall Metrology and Testing (Tianjin) Co., Ltd., Tianjin Heat Treatment Research Institute Co., Ltd., Erzhong (Deyang) Heavy Equipment Co., Ltd. Company, Zhuzhou CRRC Tianli Forging Co., Ltd., Changzhou New District Hehai Heat Treatment Engineering Co., Ltd., Jiangsu Fengdong Heat Treatment and Surface Modification Engineering Technology Research Co., Ltd., Xi'an Hantang Analysis and Testing Co., Ltd., Xi'an Flat Heat Treatment Co., Ltd.
Administrative Organization National Heat Treatment Standardization Technical Committee (SAC/TC 75)
Proposing organization National Heat Treatment Standardization Technical Committee (SAC/TC 75)
Issuing agency(ies) State Administration for Market Regulation, National Standardization Management Committee