GB/T 20928-2020 English PDF (GBT20928-2020)

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GB/T 20928-2020: Seamless inner grooved copper tube
GB/T 20928-2020
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 77.150.30
H 62
Replacing GB/T 20928-2007
Seamless inner grooved copper tube
无缝内螺纹铜管
ISSUED ON: SEPTEMBER 29, 2020
IMPLEMENTED ON: AUGUST 01, 2021
Issued by: State Administration for Market Regulation;
Standardization Administration of the PRC.
Table of Contents
Foreword ... 3 
1 Scope ... 5 
2 Normative references ... 5 
3 Terms and definitions ... 6 
4 Classification and labeling ... 6 
5 Technical requirements ... 8 
6 Test methods ... 11 
7 Inspection rules ... 12 
8 Marking, packing, transporting, storing and quality certificate ... 15 
9 Order form (or contract) content ... 16 
Appendix A (Informative) Recommended specifications of inner grooved copper
tube ... 17 
Appendix B (Normative) Determination method for internal surface residues of
inner grooved copper tube ... 19 
Appendix C (Informative) Method for determining heat transfer coefficient and
fluid resistance characteristics of seamless inner grooved copper tube ... 22 
Bibliography ... 27 
Foreword
This Standard is drafted in accordance with the rules given in GB/T 1.1-2009.
This Standard replaces GB/T 20928-2007 "Seamless inner grooved copper
tube". Compared with GB/T 20928-2007, the main technical changes are as
follows:
- Modify the representation method of designation and state (see Table 1;
Table 1 of the 2007 edition);
- ADD two designations: TU1 and TU2; specify their mechanical properties
and grain size requirements (see Table 1, Table 8, Table 9);
- Modify the cut slope index of straight tube, from "not greater than 2 mm" to
"not greater than 0.40 mm" (see 5.2.3; 4.3.3 of the 2007 edition);
- Modify the previous "specified non-proportional elongation strength RP0.2"
in the mechanical properties to "specified plastic elongation strength RP0.2"
(see Table 8; Table 6 of the 2007 edition);
- Delete Table 7 and Table 8 of the previous standard. Modify to "The artificial
defects of the standard sample tube shall meet the requirements of GB/T
5248" (see 5.6; 4.6 of the 2007 edition);
- Modify the test method of mechanical properties from "in accordance with
the provisions of GB/T 228" to "in accordance with the provisions of GB/T
34505" (see 6.3; 5.2 of the 2007 edition);
- Modify the grain size. The grain size of the softening annealing (O60) state
is changed from "0.020 mm~0.060 mm" to "0.015 mm~0.060 mm". The
grain size of the light annealing (O50) state is changed from "0.015
mm~0.035 mm" to "0.010 mm~0.035 mm" (see Table 9; Table 6 of the 2007
edition);
- ADD "The sampling method shall be carried out in accordance with YS/T
668. The preparation of drift-expending test pieces shall be carried out in
accordance with YS/T 815." (see 7.4);
- Delete the normative appendix "Measurement method of tooth profile
parameters of seamless inner grooved copper tube" (see Appendix A of the
2007 edition).
This Standard was proposed by China Nonferrous Metals Industry Association.
This Standard shall be under the jurisdiction of National Technical Committee
Seamless inner grooved copper tube
1 Scope
This Standard specifies the classification and labeling, technical requirements,
test methods, inspection rules, marking, packing, transporting, storing and
quality certificate, and order form (or contract) content of seamless inner
grooved copper tube.
This Standard applies to seamless inner grooved copper tube for air
conditioning and refrigeration equipment (hereinafter referred to as "tube").
2 Normative references
The following documents are indispensable for the application of this document.
For the dated references, only the editions with the dates indicated are
applicable to this document. For the undated references, the latest edition
(including all the amendments) are applicable to this document.
GB/T 242 Metal materials - Tube - Drift-expending test
GB/T 2828.1 Sampling procedures for inspection by attributes - Part 1:
Sampling schemes indexed by acceptance quality limit (AQL) for lot-by-lot
inspection
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 5248 Electromagnetic (eddy-current) examination of copper and
copper alloy seamless tube
GB/T 8170 Rules of rounding off for numerical values and expression and
judgement of limiting values
GB/T 8888 Wrought heavy non-ferrous metal products - Packing, marking,
transporting, storing and quality certificate
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 The 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
3 Terms and definitions
The following terms and definitions apply to this document.
3.1
Seamless inner grooved copper tube
The copper tube with a smooth outer surface, a certain number of regular
grooves on the inner surface, and a continuous section circumference.
3.2
Weight per metre
The mass of the inner grooved copper tube per 1 m length, in grams per metre
(g/m).
4 Classification and labeling
4.1 Product classification
The designation, code, state and supply shape of the tube shall meet the
requirements of Table 1. The tooth profile of the tube is shown in Figure 1. The
specification and dimension range shall meet the requirements of Table 2. The
inner and outer diameter and height (width) dimensions of the layer wound coil
shall meet the requirements of Table 3. Refer to Appendix A for the
recommended specifications of this Standard.
TW - Bottom wall thickness;
Hf - Tooth height;
TWT - Total wall thickness;
W - Groove bottom width;
n - Number of grooves;
α - Addendum angle;
β - Helix angle.
Figure 1 -- Schematic diagram of tooth profile
4.2 Product labeling
The labeling of the tube is indicated in the order of product name, standard
number, designation, state, outer diameter, bottom wall thickness, tooth height,
addendum angle, helix angle and number of grooves.
Example 1: For right-handed inner grooved coil tube with a designation of TP2 (C12200),
state of light annealing (O50), outer diameter of 9.52 mm, bottom wall thickness of 0.30
mm, tooth height of 0.20 mm, addendum angle of 53°, helix angle of 18, and 60 grooves,
it is labeled as:
Inner grooved coil tube GB/T 20928-TP2O50-9.52×0.30+0.20-53/18-60
Or Inner grooved coil tube GB/T 20928-C12200O50-9.52×0.30+0.20-53/18-60
Example 2: For left-handed inner grooved straight tube with a designation of TU2 (T10180),
state of softening annealing (O60), outer diameter of 7.00 mm, bottom wall thickness of
0.27 mm, tooth height of 0.20 mm, addendum angle of 53°, helix angle of 18, 60 grooves,
and length of 3000 mm, it is labeled as:
Inner grooved straight tube GB/T 20928-TU2O60-7.00×0.27+0.20-53/L18-60×3000
Or Inner grooved straig...