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GB/T 1531-2020 PDF in English


GB/T 1531-2020 (GB/T1531-2020, GBT 1531-2020, GBT1531-2020)
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GB/T 1531-2020: PDF in English (GBT 1531-2020)

GB/T 1531-2020
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 77.150.30
H 62
Replacing GB/T 1531-2009
Copper and Copper Alloy Capillary Tube
ISSUED ON: SEPTEMBER 29, 2020
IMPLEMENTED ON: AUGUST 1, 2021
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 and Marking ... 7 
5 Technical Requirements ... 9 
6 Test Methods ... 17 
7 Inspection Rules ... 18 
8 Signs, Packaging, Transportation, Storage and Quality Certificate ... 22 
9 Order Sheet (or contract) Content ... 23 
Appendix A (informative) Pressure Difference Determination Method of Tubes
... 25 
Appendix B (informative) Flow Determination Method of Tubes ... 27 
Appendix C (informative) Internal Surface Residue Determination Method of
Tubes ... 29 
Appendix D (informative) Internal Surface Oil Content Determination Method of
Tubes ... 31 
Appendix E (informative) Internal Surface Water Content Determination Method
of Tubes ... 33 
Copper and Copper Alloy Capillary Tube
1 Scope
This Standard specifies the technical requirements, test methods, inspection rules,
signs, packaging, transportation, storage, quality certificate and order sheet (or
contract) content of copper and copper alloy capillary tubes.
This Standard is applicable to copper and copper alloy capillary tubes used for air
conditioners, refrigeration equipment, instruments, and apparatuses (hereinafter
referred to as tubes).
2 Normative References
The following documents are indispensable to the application of this document. In
terms of references with a specified date, only versions with a specified date are
applicable to this document. In terms of references without a specified date, the latest
version (including all the modifications) is applicable to this document.
GB/T 242 Method for Flaring Test on Tubes of Metals
GB/T 245 Metallic Materials - Tube - Flanging Test
GB/T 2828.1 Sampling Procedures for Inspection by Attribute - Part 1: Sampling
Schemes Indexed by Acceptance Quality Limit (AQL) for Lot-by-lot Inspection
GB/T 4340.1 Metallic Materials - Vickers Hardness Test - Part 1: Test Method
GB/T 5121 (all parts) Methods for Chemical Analysis of Copper and Copper Alloys
GB/T 5231 Designation and Chemical Composition of Wrought Copper and Copper
Alloys
GB/T 8170 Rules of Rounding off for Numerical Values & Expression and Judgement
of Limiting Values
GB/T 8888 Wrought Heavy Non-ferrous Metal Products - Packing, Marking,
Transportation, Storing and Certificate of Quality
GB/T 10567.2 Wrought Copper and Copper Alloys - Detection of Residual Stress -
Ammonia Test
GB/T 26303.1 Measuring Method for Dimensions and Shapes of Wrought Copper and
Copper Alloy - Part 1: Tube
GB/T 34505 Copper and Copper Alloy Materials - Tensile Testing at Room
Temperature
YS/T 347 Copper and Copper Alloys - Estimation of Average Grain Size
YS/T 482 Methods for Analysis of Copper and Copper Alloys - The Atomic Emission
Spectrometry
YS/T 483 Methods for Analysis of Copper and Copper Alloys - X-ray Fluorescence
Spectrometric (wavelength dispersive)
YS/T 668 Sampling Method of Physical and Chemical Testing for Copper and Copper
Alloys
YS/T 815 Preparation Method of Test Pieces for Mechanical and Technological
Properties of Copper and Copper Alloys
YS/T 999 Capillary Tube of Copper and Copper Alloy-eddy Current Testing Method
3 Terms and Definitions
The following terms and definitions are applicable to this document.
3.1 Capillary
Capillary refers to a copper tube for current limiting, and with an outer diameter of not
greater than 6.1 mm and an inner diameter of not greater than 4.45 mm.
3.2 Pressure Difference
Pressure difference refers to the resistance drop of the inner hole of tubes of a certain
length.
3.3 Flow
Flow refers to the volume of air flow passing through a tube per unit time at a certain
temperature, a certain atmospheric pressure and a certain inlet pressure.
3.4 Residue
Residue refers to solid impurities remaining on the inner surface of a tube unit.
3.5 Oil Content
Oil content refers to processing oil remaining on the inner surface of a tube unit.
3.6 Bulge Circle (limit)
6 Test Methods
6.1 Chemical Composition
The analysis method for the chemical composition of the tubes shall comply with the
stipulations of GB/T 5121 (all parts) or YS/T 482 and YS/T 483. The arbitration shall
comply with the stipulations of GB/T 5121 (all parts).
6.2 Overall Dimensions and Allowable Deviations
The measurement method for the overall dimensions and allowable deviations of the
tubes shall comply with the stipulations of GB/T 26303.1.
6.3 Mechanical Properties
The tensile test of the tubes shall be conducted in accordance with the stipulations of
GB/T 34505; the tensile test specimens shall comply with the stipulations of full-section
test specimens in GB/T 34505.
The Vickers hardness test of the tubes shall be conducted in accordance with the
stipulations of GB/T 4340.1.
6.4 Process Properties
6.4.1 Air permeability
The air permeability test of the tubes shall be conducted under the air pressure of not
greater than 7.8 MPa; continuously pressurize it, and when there is relatively violent
bubble-turning phenomenon at one end of the tube placed in the water, it proves that
the tube is unblocked.
6.4.2 Air tightness
For the air tightness test of the tubes, seal one end of the tube; immerse it in the water;
ventilate at the other end, so that it complies with the test requirements of Table 8.
6.4.3 Pressure difference
The test method for the pressure difference of the tubes shall take Appendix A as a
reference. When there are special requirements, the test method shall be determined
by the demand-side and the supply-side through negotiation.
6.4.4 Flow rate test
The test method for the flow rate of the tubes shall take Appendix B as a reference.
When there are special requirements, the test method shall be determined by the
demand-side and the supply-side through negotiation.
supply-side in the written form, and the supply-side and the demand-side shall solve
this through negotiation. Objections related to surface quality and overall dimensions
shall be proposed within 1 month from the date of receipt of the products; objections
related to other properties shall be proposed within 3 months from the date of receipt
of the products. If arbitration is required, it may be entrusted to an organization
acknowledged by the demand-side and the supply-side, and samples shall be jointly
taken at the demand-side’s place.
7.2 Batch
The products shall be submitted for acceptance inspection in batches. Each batch shall
be composed of products of the same designation, the same state and the same
specification. The weight of each batch shall not exceed 500 kg.
7.3 Inspection Items
The inspection items of the tubes shall comply with the stipulations of Table 11.
Under any of the following circumstances, type inspection shall be carried out in
accordance with the stipulations of this Standard:
a) During trial production and appraisal of new products;
b) After formal production, if there are relatively significant changes in structures,
materials and processes that might affect product performance;
c) When type inspection has not been carried out for two consecutive years;
d) When requested by the demand-side;
e) When a national quality supervisory institution requests for type inspection.
c) Specification;
d) Batch No.;
e) Net weight or quantity;
f) Production date;
g) Inspection seal of the supply-side’s technical supervision department;
h) Implemented standard;
i) Others.
8.1.2 Packaging signs
The signs of the packaging box of the tubes shall comply with the stipulations of GB/T
8888.
8.2 Packaging, Transportation, Storage and Quality Certificate
8.2.1 The requirements for the packaging, transportation, storage and quality
certificate of the tubes shall comply with the stipulations of GB/T 8888.
8.2.2 When there are special requirements for the packaging mode, they shall be
determined by the demand-side and the supply-side through negotiation.
9 Order Sheet (or contract) Content
The order sheet (or contract) ordering the materials listed in this Standard shall include
the following content:
a) Product name;
b) Alloy designation;
c) State;
d) Specification;
e) Dimensions and accuracy grade (the outer diameter, inner diameter or other
dimensional requirements of the tubes; the accuracy grade must be indicated
in the contract, otherwise, choose the ordinary grade by default);
f) Shape of delivery;
g) Weight or quantity;
A.3.5 The gas temperature shall maintain relatively constant, and generally 20 °C ±
5 °C.
A.3.6 The inner hole of the tested tube shall be clean, and free of oil stains, oxides and
other impurities. The tube mouth of the tested tube shall be rounded off, and without
bending or breakage phenomenon.
A.4 Test Procedures
A.4.1 Accurately measure the inner diameter and length of the tube.
A.4.2 On the test device, close the shut-off valve; open the gas source switch. Adjust
the pressure regulator, so that the pointer of the inlet pressure gauge reaches the
pressure required by the process.
A.4.3 Insert the tested tube into the test hole.
A.4.4 Open the shut-off valve; observe changes of the pointer of the outlet pressure
gauge, and whether the value of the outlet pressure gauge of the tube complies with
the specified requirements.
A.4.5 Close the shut-off valve; remove the tested tube.
A.4.6 For continuous determination, the second tube may be inserted into the test hole.
A.5 Measurement Accuracy
The measurement accuracy is ± 0.01 MPa.
Appendix C
(informative)
Internal Surface Residue Determination Method of Tubes
C.1 Method Summary
Use an extractant to clean the internal surface of the tube; use a microporous
membrane to filter the extractant. After drying, through weighing, calculate the solid
impurity content on the internal surface of the tube. In accordance with the area of the
internal surface, calculate the amount of residual solid impurities per unit surface area.
C.2 Instruments, Equipment and Reagents
C.2.1 Vacuum filter.
C.2.2 Microporous membrane.
C.2.3 Glass dish.
C.2.4 Crucible clamp.
C.2.5 Analytical balance (division value: 0.1 mg).
C.2.6 Constant-temperature drying oven.
C.2.7 Beaker (50 mL).
C.2.8 Syringe (20 mL).
C.2.9 Blocking cap.
C.2.10 Carbon tetrachloride, tetrachloroethylene, a mixture of methanol and acetone,
or other extractants.
C.3 Test Procedures
C.3.1 Place the microporous membrane in a glass dish; place it in a constant-
temperature drying oven at 110 °C to dry for 20 min; weigh it and record it as G0.
C.3.2 Accurately measure-take 1 m ~ 2 m length of the test specimen.
C.3.3 Use a cotton ball dipped in the reagent to wipe off the oil stains on the external
surface of the both ends of the test specimen.
C.3.4 Add blocking caps on both ends of the test specimen. Use a syringe to inject the
reagent into the specimen with the blocking cap at one end; fill it up.
Appendix D
(informative)
Internal Surface Oil Content Determination Method of Tubes
D.1 Method Summary
Use a special solvent to dissolve the remaining oil on the internal surface of the tube.
At the wavelength of 3.4 μm ~ 3.5 μm in the infrared region, there is a characteristic
absorption spectral line of C-H bond. Through quantitative analysis of the intensity of
the spectral line, the oil content can be obtained.
D.2 Instruments, Equipment and Reagents
D.2.1 OCMA-305 oil content analyzer.
D.2.2 H-997 extractant.
D.2.3 The domestic infrared spectrophotometer and corresponding reagents (carbon
tetrachloride, tetrachloroethylene, etc.) may also be selected.
D.3 Test Procedures
D.3.1 Sample preparation
Take a tube of 1 m length; place it at an angle of about 70°. Use a syringe to draw 20
mL of reagent; inject it from the upper end of the tube; place a clean beaker on the
lower end for reception. Each time, rotate the sample by about 90° and rinse it for 4
times; the received volume is about 80 mL.
D.3.2 Instrument preheating
Turn on the instrument; preheat it for 20 min. At the solvent discharge port, place a 200
mL beaker to receive the discharged solvent.
D.3.3 Blank measurement
D.3.3.1 Set the extraction time to 40 s; close the inlet valve and discharge valve.
D.3.3.2 Use a syringe to take 20 mL of the reagent in the same bottle used to rinse the
sample; inject it from the small hole above the extraction pool.
D.3.3.3 Press the extraction button to perform extraction. After extraction, press the
measurement button, until the solvent is completely discharged.
D.3.3.4 Repeat for 3 times. Record the instrument display as M0, then, return to the
initial state. Among them, the first 2 times are used for system cleaning.
Appendix E
(informative)
Internal Surface Water Content Determination Method of Tubes
E.1 Method Summary
Use dry nitrogen to bring the water content in the tube into the detector. The water
content is absorbed by P2O5 in the detector and electrolyzed into hydrogen and oxygen
to be discharged. The power consumption is integrated and converted into water
content.
E.2 Instruments and Equipment
Type USI-3 refrigerator system water content tester.
E.3 Test Procedures
E.3.1 Sample preparation: from a finished tube with both ends being sealed, take a 1
m ~ 2 m long sample; seal both ends of the sample.
E.3.2 Connect the gas source. Firstly, open the main valve of the nitrogen cylinder,
then, slowly open the pressure reducing valve to maintain at the flow rate of 70 mL/min
± 20 mL/min.
E.3.3 Turn on the power (turn the power switch on), meanwhile, pressure the “Zero
Adjustment” key. At this moment, the instrument value is relatively high, and as the air
flow system gradually dries, the displayed value gradually decreases, until it drops to
below 0.050 mg and is basically stable.
E.3.4 Zero adjustment: after pressing the “Zero Adjustment” key, firstly, turn the “Zero
Adjustment” knob to the left end. After the displayed value is less than 0.050 mg, turn
the “Zero Adjustment” knob to the right (clockwise) to reduce the displayed value, until
the displayed value is 0.001 mg ~ 0.005 mg (cannot be adjusted to display 0.000 mg).
After zero adjustment is completed, in the following continuous determination process,
the position of this knob maintains stationary.
E.3.5 Press the bypass gear for 20 min.
E.3.6 Press the “Measurement” gear. Use a cutter to cut one end of the sample, then,
quickly connect it to the A end of the instrument; connect the other end to the B end of
the instrument (A end before B end is merely allowed). Then, immediately press the
“Reset” switch; the instrument starts to display the cumulative water content (the
shorter the above operation time, the more reliable the displayed value).
E.3.7 When the solenoid valve stops switching, the accumulative speed gradually
......
 
Source: Above contents are excerpted from the PDF -- translated/reviewed by: www.chinesestandard.net / Wayne Zheng et al.