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GB/T 3639-2021 (GB/T3639-2021)

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GB/T 3639-2021English245 Add to Cart 0-9 seconds. Auto-delivery. Seamless cold-drawn or cold-rolled steel tubes for precision applications Valid


GB/T 3639-2021: PDF in English (GBT 3639-2021)

GB/T 3639-2021
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 77.140.75
CCS H 48
Replacing GB/T 3639-2009
Seamless cold-drawn or cold-rolled steel tubes for
precision applications
ISSUED ON: AUGUST 20, 2021
IMPLEMENTED ON: MARCH 01, 2022
Issued by: State Administration for Market Regulation;
Standardization Administration of PRC.
Table of Contents
Foreword ... 3 
1 Scope ... 5 
2 Normative references ... 5 
3 Terms and definitions ... 7 
4 Classification and code ... 7 
5 Order content ... 8 
6 Dimension, shape, weight, allowable deviation ... 8 
7 Technical requirements ... 12 
8 Inspection and test methods ... 16 
9 Inspection rules ... 17 
10 Packaging, marking, quality certificate ... 18 
Seamless cold-drawn or cold-rolled steel tubes for
precision applications
1 Scope
This document specifies the classification, code, order content, size, shape,
weight, tolerance, technical requirements, test methods, inspection rules,
packaging, markings, quality certificates of seamless cold-drawn or cold-rolled
steel tubes for precision applications.
This document is applicable to seamless cold-drawn or cold-rolled steel tubes
for precision applications (hereinafter referred to as steel tubes), which have
special dimensional accuracy and high surface quality requirements, for the
manufacture of mechanical structures, hydraulic equipment, automobile parts.
2 Normative references
The contents of the following documents constitute the indispensable clauses
of this document through normative references in the text. Among them, for
dated reference documents, only the version corresponding to that date is
applicable to this document; for undated reference documents, the latest
version (including all amendments) is applicable to this document.
GB/T 222 Permissible tolerances for chemical composition of steel products
GB/T 223.5 Steel and iron - Determination of acid-soluble silicon and total
silicon content - Reduced molybdosilicate spectrophotometric method
GB/T 223.9 Iron steel and alloy - Determination of aluminium content -
Chrome azurol S photometric method
GB/T 223.12 Methods for chemical analysis of iron, steel and alloy - The
sodium carbonate separation-diphenyl carbazide photometric method for the
determination of chromium content
GB/T 223.23 Iron, steel and alloy - Determination of nickel content - The
dimethylglyoxime spectrophotometric method
GB/T 223.26 Iron, steel and alloy - Determination of molybdenum content -
The thiocyanate spectrophotometric method
longitudinal and/or transverse imperfections
GB/T 7735-2016 Automated eddy current testing of seamless and welded
(except submerged arc-welded) steel tubes for detection of imperfections
GB/T 12606-2016 Automated full peripheral flux leakage testing of seamless
and welded (except submerged arc-welded) ferromagnetic steel tubes for
the detection of longitudinal and/or transverse imperfections
GB/T 17395 Dimensions, shapes, masses and tolerances of seamless steel
tubes
GB/T 20066 Steel and iron - Sampling and preparation of samples for the
determination of chemical composition
GB/T 20123 Steel and iron - Determination of total carbon and sulfur content
Infrared absorption method after combustion in an induction furnace (routine
method)
GB/T 20124 Steel and iron - Determination of nitrogen content - Thermal
conductimetric method after fusion in a current of inert gas
GB/T 20125 Low-alloy steel - Determination of multi-element contents -
Inductively coupled plasma atomic emission spectrometric method
GB/T 30062 Terminology of steel tubes and tubes
GB/T 40080 Nondestructive testing of steel tubes - Automated
electromagnetic testing of seamless and welded (except submerged arc-
welded) steel tubes for the verification of hydraulic leak tightness
3 Terms and definitions
The terms and definitions, which are defined in GB/T 30062, apply to this
document.
4 Classification and code
The steel tubes are classified and coded, according to their delivery state, as
follows:
a) Cold working/hard state: +C;
b) Cold working/soft state: +LC;
c) Stress relief annealing state: +SR;
d) Annealing state: +A;
e) Normalizing state: +N.
5 Order content
The contract or order, for ordering steel tubes, according to this document, shall
include the following:
a) Number of this document;
b) Product name;
c) Steel designation;
d) Size specifications;
e) The quantity ordered (total weight or total length);
f) Delivery state;
g) Special requirements.
6 Dimension, shape, weight, allowable deviation
6.1 Dimensions
6.1.1 Steel tubes are usually delivered, based on nominal outer diameter (D)
and nominal wall thickness (S). According to the requirements of the buyer AND
after negotiation between the supplier and the buyer, the steel tube can also be
delivered, based on the nominal outer diameter and the nominal inner diameter
(d) OR the nominal inner diameter and the nominal wall thickness.
6.1.2 The dimensions of the steel tube shall meet the requirements of Table 1.
6.1.3 For steel tubes, which are delivered in cold working (+C, +LC) state, the
allowable deviation of the nominal outer diameter and the nominal inner
diameter shall meet the requirements of Table 1. For steel tubes, which are
delivered in the heat treatment (+SR, +A, +N) state, the allowable deviation of
the nominal outer diameter and the nominal inner diameter shall meet the
requirements of Table 2.
6.3.1 The curvature per meter of the steel tube shall not be greater than 1.5
mm/m.
6.3.2 For steel tubes, which have an outer diameter greater than 16 mm, the
curvature along the total length (L) shall meet the following requirements:
a) When the minimum upper yield strength ReH ≤ 500 MPa is specified (or
calculated, applicable to delivery in +C, +LC, +A states): It is not more than
0.15%L;
b) When the minimum upper yield strength ReH > 500 MPa is specified (or
calculated, applicable to delivery in +C, +LC, and +A states): It is not more
than 0.2%L.
6.3.3 According to the requirements of the buyer, after negotiation between the
supplier and the buyer, as indicated in the contract, other requirements may be
adopted, for the curvature per meter and full length of the steel tube.
6.4 End shape
The end faces of both ends of the steel tube shall be perpendicular to the axis
of the steel tube. The cut burrs shall be removed.
6.5 Out-of-roundness and uneven wall thickness
The out-of-roundness and uneven wall thickness of the steel tube shall not
exceed 80% of the outer diameter tolerance AND wall thickness tolerance,
respectively.
6.6 Weight
Steel tubes are delivered, according to actual weight or theoretical weight. The
theoretical weight per meter of steel tube is calculated according to GB/T 17395
(the density of steel is 7.85 kg/dm3).
7 Technical requirements
7.1 Steel designation and chemical composition
7.1.1 The designation and chemical composition (melting analysis) of the steel
shall meet the requirements of 10, 20, 35, 45, 25Mn in GB/T 699; the Q355B,
Q420B in GB/T 1591; the 25CrMo and 42CrMo in GB/T 3077, where P, S
content shall not be greater than 0.025%.
7.1.2 When the purchaser requires a finished product analysis, it shall be
specified in the contract. The allowable deviation of the chemical composition
of the finished steel tube shall meet the requirements of GB/T 222.
D - The nominal outer diameter of the steel tube, in millimeters (mm).
7.5.2 Flaring
According to the requirements of the buyer, after negotiation between the
supplier and the buyer, as indicated in the contract, the steel tubes, which have
an outer diameter of not more than 150 mm AND a wall thickness of not more
than 10 mm, in the designations 10, 20, Q355B, in the state of +A and +N, can
be subject to flaring test. The top core taper of the flaring test is 60°. The flaring
rate of the outer diameter of the specimen shall meet the requirements of Table
5. After the test, the specimen shall not show cracks.
Table 5 -- Outer diameter flaring rate of steel tube's flaring test
7.6 Compactness
According to the requirements of the buyer, after negotiation between the
supplier and the buyer, as indicated in the contract, the steel tube can be subject
to the compactness test, in accordance with the provisions of GB/T 40080.
7.7 Surface roughness
7.7.1 For steel tubes, which have an outer diameter not greater than 260 mm,
the inner and outer surface roughness Rα shall meet the following requirements:
a) When delivered in +SR, +A, +N states, the outer surface is not more than
4 μm;
b) When delivered in +C and +LC states, the inner and outer surfaces of the
steel tube are not greater than 4 μm; wherein the requirements for the
inner surface are applicable to steel tubes, which have a nominal inner
diameter or a calculated inner diameter of not less than 15 mm.
7.7.2 For steel tubes, which have an outer diameter greater than 260 mm, the
inner and outer surface roughness Rα shall not be greater than 6 μm.
7.7.3 The surface roughness is measured, in the axial direction of the steel tube,
according to the arithmetic mean deviation Rα of the profile, which is specified
in GB/T 1031, AND the recommended sampling length.
7.7.4 According to the requirements of the buyer, after negotiation between the
supplier and the buyer, as indicated in the contract, it may specify other surface
roughness requirements.
7.8 Surface quality
7.8.1 The inner and outer surfaces of steel tubes shall be smooth. The depth of
local pits, scratches, small scratches shall not exceed 0.08 mm. The actual wall
thickness of the steel tube, at these defects, shall not be less than the minimum
allowable wall thickness deviation.
7.8.2 Defects on the inner and outer surfaces of the steel tube can be removed,
by appropriate methods. The actual wall thickness, at the removal location, shall
not be less than the minimum allowable wall thickness deviation.
7.8.3 The inner and outer surfaces of cold-worked steel tubes may have
phosphate and lubricant adhesion layers, which are formed in the
manufacturing process. The inner and outer surfaces of the delivered steel tube,
in the heat-treated condition, may have an oxide film layer, that does not affect
the surface inspection; however, there shall be no loose oxide scale.
7.9 Non-destructive testing
According to the requirements of the buyer, after negotiation between the
supplier and the buyer, as indicated in the contract, the steel tube can be
subjected to eddy current, magnetic flux leakage or ultrasonic testing. During
eddy current testing, the acceptance level shall meet the requirements of E4H
or E4 in GB/T 7735-2016. During magnetic flux leakage testing, the acceptance
level shall meet the requirements of F4 in GB/T 12606-2016. During ultrasonic
testing, the acceptance level shall meet the requirements of U4 in GB/T 5777-
2019.
8 Inspection and test methods
8.1 Sampling of steel tubes for chemical composition analysis shall comply with
the rules of GB/T 20066. The chemical composition analysis usually complies
with the provisions of GB/T 4336, GB/T 20123, GB/T 20124, GB/T 20125 or
other general methods. The arbitration shall comply with the requirements of
GB/T 223.5, GB/T 223.9, GB/T 223.12, GB/T 223.23, GB/T 223.26, GB/T
223.37, GB/T 223.53, GB/T 223.59, GB/T 223.63, GB/T 223.85, GB/T 223.86,
GB/T 20125.
8.2 The size and shape of steel tubes shall be measured one by one, by the
measuring tools, that meet the accuracy requirements.
8.3 The inner and outer surfaces of steel tubes shall be visually inspected one
......
 
(Above excerpt was released on 2021-11-05, modified on 2021-11-05, translated/reviewed by: Wayne Zheng et al.)
Source: https://www.chinesestandard.net/PDF.aspx/GBT3639-2021