GB/T 38804-2020 English PDF (GB/T38804-2020)

GB/T 38804-2020: Test method for oxidation of metallic materials exposed in high-temperature steam
Delivery: 9 seconds. Download (& Email) true-PDF + Invoice.
Get Quotation: Click GB/T 38804-2020 (Self-service in 1-minute)
Historical versions (Master-website): GB/T 38804-2020
Preview True-PDF (Reload/Scroll-down if blank)

GB/T 38804-2020
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 77.040.99
H 21
Test method for oxidation of metallic
materials exposed in high-temperature steam
ISSUED ON: JUNE 02, 2020
IMPLEMENTED ON: DECEMBER 01, 2020
Issued by: State Administration for Market Regulation;
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 Test principle ... 6
5 Test apparatus and conditions ... 6
6 Specimen ... 7
7 Test procedure ... 9
8 Result analysis ... 10
9 Test report ... 12
Annex A (informative) Typical surface and cross-sectional morphology of oxide
scale ... 14
Bibliography ... 15
Test method for oxidation of metallic
materials exposed in high-temperature steam
1 Scope
This Standard specifies the terms and definitions, test principle, test apparatus
and conditions, specimen, test procedures, result analysis and test report of
test method for oxidation of metallic materials exposed in high-temperature
steam.
This Standard applies to the oxidation test of metallic materials exposed in high-
temperature steam.
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 1216 External micrometer
GB/T 1227 Accurate pressure gauge
GB/T 11446.1-2013 Electronic grade water
GB/T 21389 Vernier, dial and digital display calipers
GB/T 26497 Electronic balance
JJF 1637 Calibration specification for base metal thermocouples
JJG 141 Verification regulation of working noble metal thermocouples
JJG 368 Verification Regulation of Working Copper/Copper. Nickel
Thermocouple
JJG 2063 Verification scheme of measuring instruments for liquid flow
7 - Protective gas;
8 - Steam;
9 - Specimen;
10 - Test water.
Figure 1 -- Schematic diagram of test apparatus
5.2 Test section’s temperature
The temperature of the test section reflects both the temperature of the steam
and the specimen. The temperature of the test section is controlled by a
temperature control device, and thermocouples are used for real-time
temperature monitoring. The selection and use of thermocouples shall comply
with the provisions of JJG 141, JJF 1637 or JJG 368. The temperature deviation
of the test section shall comply with the following provisions:
a) it shall be less than ±3 °C when below 650 °C;
b) it shall be less than ±4 °C when at 650 °C ~ 800 °C;
c) it shall be less than ±5 °C when above 800 °C.
5.3 Reaction chamber’s pressure
During the test, a pressure gauge or pressure sensor is used to monitor the
pressure of the reaction chamber. The selection and use of pressure gauges
and pressure sensors shall comply with the provisions of GB/T 1227. The
pressure deviation of the reaction chamber shall be minimized. When the test
pressure value is greater than 10 MPa, the pressure deviation of the reaction
chamber shall be less than ±2 %.
5.4 Test steam
The test steam is prepared from deionized water or distilled water, and the test
water shall comply with the provisions of Class III electronic water in GB/T
11446.1-2013. The test water shall be deoxygenated before the steam is
produced, and the oxygen content in the steam or test water shall be indicated
in the test report. If other gases are added to the steam, the final gas content
ratio of the steam shall be indicated in the test report.
5.5 Flowmeter
During the test, the steam flow rate or water flow rate shall be monitored. The
selection and use of flowmeters shall comply with the provisions of JJG 2063.
6 Specimen
6.1 Shape and size
The storage environment of specimens shall be kept dry.
7 Test procedure
7.1 Preparing the specimen
After machining, the specimen is subjected to surface treatment according to
6.3. Measure size and mass and record the initial value. Avoid touching the
specimen directly with your hands during measurement.
7.2 Placing the specimen
7.2.1 When placing the specimen, it should be suspended so that the surface
of the largest area of the specimen is parallel to the direction of steam flow. The
diameter of the specimen hanging hole shall be 1 mm, and if it is larger than 1
mm, it shall be indicated in the report. There shall be enough space between
the suspended specimens to prevent the specimens from touching each other.
When hanging the specimen, the contact between the hanging wire and the
specimen shall be reduced, and nickel-chromium alloy is recommended as the
hanging wire.
7.2.2 When hanging specimens cannot be used due to equipment layout and
other problems, the specimen can be placed flat in the tubular specimen holder.
When laying the specimen flat, the contact area between the specimen and the
specimen holder shall be minimized. Each specimen shall be placed separately
and shall not be in contact with each other. The surface of the largest area of
the specimen shall be parallel to the direction of steam flow. The material of the
specimen holder should be corundum.
7.3 Deoxygenating the reaction chamber
After the specimen is placed in the reaction chamber, close the reaction
chamber to ensure that air cannot enter the reaction chamber, and use inert
gas argon or nitrogen to purge the reaction chamber so that the oxygen content
(volume fraction) in the reaction chamber is less than 0.0003 %.
7.4 Heating up the reaction chamber
The reaction chamber begins to heat up after deoxygenation, and the
temperature rise rate shall not be too fast to cause the oxide scale to exfoliate.
The recommended temperature rise rate is 55 °C/h ~ 220 °C/h. When the
difference between the temperature of the test section and the preset test
temperature is less than 50 °C, steam is filled. When the temperature of the
test section reaches the preset temperature and stabilizes, it is regarded as the
starting time of the test timing. If the test needs to be carried out under high
in square centimeters (cm2);
a1 - the average mass gain per unit area of the reference specimen, in
milligrams per square centimeter (mg/cm2);
B - the total area of the non-machined surface of the specimen before the
test, in square centimeters (cm2).
8.3 Oxide scale thickness
The measurement of oxide scale thickness requires cross-sectional
observation of the specimen. The oxide scale shall be protected by
electroplating, inlay, etc. before preparation of the cross-section specimen. The
cross-section of the oxide scale is prepared by wire cutting or sanding, and the
cross-section shall be perpendicular to the surface of the specimen. When
measuring the thickness, the cross-sectional characteristics of the oxide scale
shall be considered, and the oxide scale thickness at the edge position or
exfoliating position shall not be recorded as the general thickness. During
recording, it shall observe a cross-section with a length of at least 10 mm, and
record including but not limited to the maximum thickness, minimum thickness,
and average thickness above 5 data points. If there is delamination in the
specimen, the inner layer, outer layer, internal oxidation zone and total
thickness of the oxide scale (inner oxide scale + outer oxide scale + internal
oxidation zone) shall be recorded separately.
8.4 Observation of oxide scale morphology
8.4.1 The surface morphology of oxide scale should be observed and recorded
using a scanning electron microscope. See Figure A.1 for the surface
morphology of typical oxide scale.
8.4.2 The cross-sectional morphology of oxide scale should be observed and
recorded using an optical metallographic microscope or a scanning electron
microscope with backscatter mode. See Figure A.2 for the cross-sectional
morphology of typical oxide scale.
9 Test report
The test report shall include but not limited to the following:
a) serial number of this Standard;
b) material name, designation, specification, batch number and other
relevant information;
c) specimen size and surface treatment method;
GB/T 38804-2020
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 77.040.99
H 21
Test method for oxidation of metallic
materials exposed in high-temperature steam
ISSUED ON: JUNE 02, 2020
IMPLEMENTED ON: DECEMBER 01, 2020
Issued by: State Administration for Market Regulation;
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 Test principle ... 6
5 Test apparatus and conditions ... 6
6 Specimen ... 7
7 Test procedure ... 9
8 Result analysis ... 10
9 Test report ... 12
Annex A (informative) Typical surface and cross-sectional morphology of oxide
scale ... 14
Bibliography ... 15
Test method for oxidation of metallic
materials exposed in high-temperature steam
1 Scope
This Standard specifies the terms and definitions, test principle, test apparatus
and conditions, specimen, test procedures, result analysis and test report of
test method for oxidation of metallic materials exposed in high-temperature
steam.
This Standard applies to the oxidation test of metallic materials exposed in high-
temperature steam.
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 1216 External micrometer
GB/T 1227 Accurate pressure gauge
GB/T 11446.1-2013 Electronic grade water
GB/T 21389 Vernier, dial and digital display calipers
GB/T 26497 Electronic balance
JJF 1637 Calibration specification for base metal thermocouples
JJG 141 Verification regulation of working noble metal thermocouples
JJG 368 Verification Regulation of Working Copper/Copper. Nickel
Thermocouple
JJG 2063 Verification scheme of measuring instruments for liquid flow
7 - Protective gas;
8 - Steam;
9 - Specimen;
10 - Test water.
Figure 1 -- Schematic diagram of test apparatus
5.2 Test section’s temperature
The temperature of the test section reflects both the temperature of the steam
and the specimen. The temperature of the test section is controlled by a
temperature control device, and thermocouples are used for real-time
temperature monitoring. The selection and use of thermocouples shall comply
with the provisions of JJG 141, JJF 1637 or JJG 368. The temperature deviation
of the test section shall comply with the following provisions:
a) it shall be less than ±3 °C when below 650 °C;
b) it shall be less than ±4 °C when at 650 °C ~ 800 °C;
c) it shall be less than ±5 °C when above 800 °C.
5.3 Reaction chamber’s pressure
During the test, a pressure gauge or pressure sensor is used to monitor the
pressure of the reaction chamber. The selection and use of pressure gauges
and pressure sensors shall comply with the provisions of GB/T 1227. The
pressure deviation of the reaction chamber shall be minimized. When the test
pressure value is greater than 10 MPa, the pressure deviation of the reaction
chamber shall be less than ±2 %.
5.4 Test steam
The test steam is prepared from deionized water or distilled water, and the test
water shall comply with the provisions of Class III electronic water in GB/T
11446.1-2013. The test water shall be deoxygenated before the steam is
produced, and the oxygen content in the steam or test water shall be indicated
in the test report. If other gases are added to the steam, the final gas content
ratio of the steam shall be indicated in the test report.
5.5 Flowmeter
During the test, the steam flow rate or water flow rate shall be monitored. The
selection and use of flowmeters shall comply with the provisions of JJG 2063.
6 Specimen
6.1 Shape and size
The storage environment of specimens shall be kept dry.
7 Test procedure
7.1 Preparing the specimen
After machining, the specimen is subjected to surface treatment according to
6.3. Measure size and mass and record the initial value. Avoid touching the
specimen directly with your hands during measurement.
7.2 Placing the specimen
7.2.1 When placing the specimen, it should be suspended so that the surface
of the largest area of the specimen is parallel to the direction of steam flow. The
diameter of the specimen hanging hole shall be 1 mm, and if it is larger than 1
mm, it shall be indicated in the report. There shall be enough space between
the suspended specimens to prevent the specimens from touching each other.
When hanging the specimen, the contact between the hanging wire and the
specimen shall be reduced, and nickel-chromium alloy is recommended as the
hanging wire.
7.2.2 When hanging specimens cannot be used due to equipment layout and
other problems, the specimen can be placed flat in the tubular specimen holder.
When laying the specimen flat, the contact area between the specimen and the
specimen holder shall be minimized. Each specimen shall be placed separately
and shall not be in contact with each other. The surface of the largest area of
the specimen shall be parallel to the direction of steam flow. The material of the
specimen holder should be corundum.
7.3 Deoxygenating the reaction chamber
After the specimen is placed in the reaction chamber, close the reaction
chamber to ensure that air cannot enter the reaction chamber, and use inert
gas argon or nitrogen to purge the reaction chamber so that the oxygen content
(volume fraction) in the reaction chamber is less than 0.0003 %.
7.4 Heating up the reaction chamber
The reaction chamber begins to heat up after deoxygenation, and the
temperature rise ra...