GB/T 34020.2-2017 in English

《GB/T 34020.2-2017双层卷焊钢管 第2部分：汽车管路系统用管》由TC183（全国钢标准化技术委员会）归口，TC183SC1（全国钢标准化技术委员会钢管分会）执行，主管部门为中国钢铁工业协会。

ChinaStandards.net is in charge of this English translation. In case of any doubt about the English translation, the Chinese original shall be considered authoritative.

GB/T 34020 consists of the following three parts under the general title Double wall copper-brazed steel tubes:

——Part 1: Tubing system for refrigerator;

——Part 2: Tubing system for automobiles;

——Part 3: Tubing system for air conditioner and refrigeration.

This part is Part 2 of GB/T 34020.

This part is developed in accordance with the rules given in GB/T 1.1-2009.

Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. The issuing body of this document shall not be held responsible for identifying any or all such patent rights.

This part was proposed by China Iron and Steel Industry Association.

This standard is under the jurisdiction of the SAC/TC 183 National Technical Committee on Iron and Steel of Standardization Administration of China.


Double wall copper-brazed steel tubes - Part 2: Tubing system for automobiles

1 Scope

This part of GB/T 34020 specifies the classification and designation, dimensions, shape, weight and tolerances, technical requirements, test methods, inspection rules, packaging, marking and quality certificate of double wall copper-brazed steel tubes used in tubing system for automobiles.

This part is applicable to double wall copper-brazed steel tubes used in the brake, clutch, power steering, fuel supply/return, engine, ventilation and cooling tubing systems of automobiles as well as double wall copper-brazed steel tubes (hereinafter referred to as "double wall tubes") used in mechanical and hydraulic tubing systems and general engineering 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 222 Permissible tolerances for chemical composition of steel products
GB/T 228.1-2010 Metallic materials - Tensile testing - Part 1: Method of test at room temperature
GB/T 241 Metal materials - Tube - Hydrostatic pressure test
GB/T 242 Metallic materials - Tube - Drift expanding test
GB/T 244 Metallic materials - Tube - Bend test
GB/T 246 Metallic materials - Tube - Flattening test
GB/T 682 Chemical reagent - Trichloromethane
GB/T 686 Chemical reagent - Acetone
GB/T 688 Chemical reagent - Carbon tetrachloride
GB/T 2102 Acceptance, packing, marking and quality certification of steel pipe
GB/T 2975 Steel and steel products - Location and preparation of samples and test pieces for mechanical testing
GB/T 7735-2016 Automated eddy current testing of seamless and welded (except submerged arc-welded) steel tubes for detection of imperfections
GB/T 34020.1 Double wall copper-brazed steel tubes - Part 1: Tubing system for refrigerator
YB/T 069 Copper-coated steel strips for welded pipe

3 Terms and definitions

For the purposes of this document, the terms and definitions given in GB/T 34020.1 apply.

4 Classification and designation

4.1 See Table 1 for the states and codes of the outer surface of double wall tubes.

Table 1 States and codes of the outer surface of double wall tubes
Surface state Code Surface state Code Surface state Code
Copper layer in original state Cu Hot dip galvanized coating + fluororesin Z/F Zinc electroplated coating + nylon Zn/P
Hot dip galvanized coating Z Zinc electroplated coating + fluororesin Zn/F Hot dip galvanized aluminum alloy + aluminum-rich resin ZA/E
Zinc electroplated coating Zn Hot dip galvanized aluminum alloy + fluororesin ZA/F — —
Hot dip galvanized aluminum alloy ZA Hot dip galvanized aluminum alloy + nylon ZA/P — —
When it is necessary to specify the thickness of the coating, the thickness (unit: μm) shall be marked immediately after the corresponding coating mark. When it is necessary to specify the corrosion resistance time by salt spray test, the corrosion resistance time (unit: h) shall be marked by a hyphen "—" after the corresponding coating mark.

4.2 According to the dimensional precision, double wall tubes are divided into:

a) Common precision, with a code of PA;

b) Advanced precision, with a code of PC.

4.3 For double wall tubes with galvanized coating on the outer surface, the passivated conversion film is divided into:

a) Bright, with a code of A;

b) White, with a code of B;

c) Rainbow, with a code of C;

d) Dark, with a code of D;

e) Black, with a code of F.

4.4 Designation example:

For a strip-shaped fixed-length double wall tube of common precision with an outer diameter of 8.00mm, a wall thickness of 0.70mm and a length of 6,000mm, which is provided with a 5μm-thick hot dip galvanized coating and then a 15μm-thick fluororesin coating on the outer surface, the designation is: PA 8.00×0.70×6,000 Z5/F15—GB/T 34020.2-2017

For a coil-shaped double wall tube of advanced precision with an outer diameter of 6.00mm, a wall thickness of 0.70mm, which is provided with a layer of hot dip galvanized aluminum alloy and then coated with nylon on the outer surface, and also has a corrosion resistance time by salt spray test for 1,000h, the designation is: PC 6.00×0.70 ZA/P-1,000—GB/T 34020.2-2017

5 Order contents

Contracts or orders made based on this part shall cover the following items:

a) No. of this part;

b) Product name;

c) Specifications and dimensions (outer diameter, wall thickness and length of double wall tube, expressed in millimeters);

d) Dimensional precision;

e) Coating/plating(s) on the outer surface;

f) Quantity ordered (total weight or total length);

g) Special requirements.

6 Dimensions, shape, weight and tolerances

6.1 Dimensions

6.1.1 The outer diameter (D), wall thickness (S) and theoretical weight of double wall tubes shall meet the requirements of Table 2. As required by the purchaser, double wall tubes with specifications other than those given in Table 2 may be supplied upon agreement between the supplier and the demander.

Foreword I
1 Scope
2 Normative references
3 Terms and definitions
4 Classification and designation
5 Order contents
6 Dimensions, shape, weight and tolerances
7 Technical requirements
8 Test methods
9 Inspection rules
10 Packaging, marking and quality certificate
Annex A (Informative) Burst pressure of double wall tubes
Annex B (Normative) Double wall drift expanding test
Annex C (Normative) Test methods for residues for cleanliness of inner surfaces
Annex D (Informative) Coating/plating(s) on double wall tubes
Bibliography