GB/T 3639-2021 English PDF (GBT3639-2021)

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GB/T 3639-2021: Seamless cold-drawn or cold-rolled steel tubes for precision applications
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 ...