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GB/T 38681-2020: Seamless corrosion resistant alloy pipes and tubes for industrial furnace
GB/T 38681-2020
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 77.140.75
H 59
Seamless corrosion resistant alloy pipes and tubes
for industrial furnace
ISSUED ON: MARCH 31, 2020
IMPLEMENTED ON: OCTOBER 01, 2020
Issued by: State Administration for Market Regulation;
Standardization Administration of the People's Republic of
China.
Table of Contents
Foreword ... 3 
1 Scope ... 4 
2 Normative references ... 4 
3 Classification and codes ... 6 
4 Ordering contents ... 6 
5 Dimensions, shapes ... 7 
6 Technical requirements ... 9 
7 Test methods ... 15 
8 Inspection rules ... 17 
9 Packaging, marks and quality certificate ... 18 
Seamless corrosion resistant alloy pipes and tubes
for industrial furnace
1 Scope
This Standard specifies the classification and codes, ordering contents,
dimensions, shapes, technical requirements, test methods, inspection rules,
packaging, marks and quality certificates of seamless corrosion resistant alloy
pipes and tubes for industrial furnace.
This Standard is applicable to iron nickel base, nickel base corrosion resistant
alloy seamless tubes for industrial furnaces in petroleum refining, chemical
industry, polysilicon of which the nominal outer diameter is not greater than
406mm and the nominal wall thickness is not greater than 60mm (hereinafter
referred to as alloy pipes and tubes).
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 223.5, Steel and iron - Determination of acid-soluble silicon and total
silicon content - Reduced molybdosilicate spectrophotometric method
GB/T 223.8, Methods for chemical analysis of iron, steel and alloy - The
sodium fluoride separation - EDTA titration method for the determination of
aluminium content
GB/T 223.9, Iron steel and alloy - Determination of aluminium content –
Chrome azurol S photometric method
GB/T 223.11, Iron, Steel and Alloy - Determination of Chromium Content -
Visual Titration or Potentiometric Titration Method
GB/T 223.17, Methods for chemical analysis of iron, steel and alloy - The
diantipyryl methane photometric method for the determination of titanium
content
GB/T 223.18, Methods for Chemical Analysis of Iron, Steel and Alloy - The
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 5777-2019, Automated full peripheral ultrasonic testing of seamless
and welded (except submerged arc-welded) steel tubes for the detection of
longitudinal and/or transverse imperfections
GB/T 6394, Metal - Methods for estimating the average grain size
GB/T 7735-2016, Automated eddy current testing of seamless and welded
(except submerged arc-welded) steel tubes for detection of imperfections
3 Classification and codes
3.1 Alloy pipes and tubes are divided into two categories according to the
method of product manufacturing. The category and code are:
a) Hot extruded alloy pipes and tubes, W-H;
b) Cold rolled (drawn) alloy pipes and tubes, W-C.
3.2 Alloy pipes and tubes are divided according to the dimensional accuracy,
as well as the codes, as follows:
a) Ordinary level, PA;
b) High level, PC.
4 Ordering contents
The contract or order ordered according to this Standard shall include at least
the following information:
a) Reference to this Standard;
b) Product name;
c) Alloy designation;
d) Dimensions (outer diameter × wall thickness, in millimeters);
e) Delivery quantity (total weight, total length or count);
f) Manufacturing method;
6.2.1 Smelting method
The alloy shall be smelted by electric arc furnace plus external refining (or
electroslag remelting). After agreed by the supplier and purchaser and indicated
in the contract, other smelting methods that meet the requirements of this
Standard may also be used.
6.2.2 Pipes and tubes making method
6.2.2.1 Hot rolled or hot forged round bars shall be used for alloy ingots used
for pipes and tubes making. The parts of the round bar material equivalent to
the alloy ingot head and tail shall be fully removed.
6.2.2.2 Alloy pipes and tubes shall be manufactured by hot extrusion or cold
rolling (drawing).
6.3 Delivery status
6.3.1 Alloy pipes and tubes shall be heat treated and pickled for delivery. See
Table 4 for recommended heat treatment system. All alloy pipes and tubes that
have undergone integral grinding, boring or heat treatment in a protective
atmosphere may not be pickled.
6.3.2 As required by the purchaser, after agreed by the supplier and purchaser
and indicated in the contract, NS3306 alloy pipes and tubes can be stabilized
after solution treatment. The stabilization treatment system is determined by the
supplier and the purchaser through consultation.
6.4 Mechanical properties
6.4.1 The room temperature longitudinal tensile properties of the alloy pipes
and tubes in the delivery state shall meet the requirements of Table 4.
6.4.2 As required by the purchaser, after agreed by the supplier and purchaser
and indicated in the contract, alloy pipes and tubes with wall thickness not less
than 2.5mm can be tested for Rockwell hardness or Brinell hardness. The
hardness value is determined by the supplier and the purchaser through
consultation.
6.4.3 As required by the purchaser, after agreed by the supplier and purchaser
and indicated in the contract, alloy pipes and tubes can be subjected to high
temperature tensile test. The specific test temperature and mechanical
properties are determined by the supplier and the purchaser through
consultation.
Where,
H - Distance between two parallel pressing plates after flattening, in millimeters
(mm);
α - Deformation coefficient per unit length, taking 0.09;
S - Nominal wall thickness of the alloy pipes and tubes (calculated according to
the minimum wall thickness when ordering according to the minimum wall
thickness), in millimeters (mm);
D - Nominal outer diameter of alloy pipes and tubes, in millimeters (mm).
6.5.1.2 The following conditions shall not be used as the basis for judging
whether the flattening test is qualified or not:
a) Cracks or gaps caused by surface defects in the sample;
b) When S/D> 0.1, the cracks and gaps on the inner surface of the sample
at 6 o'clock (bottom) and 12 o'clock (top).
6.5.2 Flaring
The alloy pipes and tubes with a nominal outer diameter not greater than
150mm and a wall thickness not greater than 10mm shall be subjected to flaring
test. The taper of the top core of the flaring test is 60°. The outer diameter flaring
rate of the sample shall be 22%. There shall be no cracks or gaps in the sample
after flaring.
6.5.3 Bending
Alloy pipes and tubes with a nominal outer diameter greater than 168.3mm shall
be subjected to bending test. There shall be no cracks or gaps in the sample
after bending.
6.6 Grain size
The average grain size of NS1102 and NS1104 alloy pipes and tubes shall be
level 5 or coarser. As required by the purchaser, after agreed by the supplier
and purchaser and indicated in the contract, other designations of alloy pipes
and tubes can be tested for average grain size and the qualified level is
determined by the supplier and the purchaser through consultation.
6.7 Non-metallic inclusions
use other levels for acceptance.
6.10 Ultrasonic testing
6.10.1 The alloy pipes and tubes shall be subjected to ultrasonic testing, and
its acceptance level shall meet the requirements of U2 level in GB/T 5777-2019.
6.10.2 As required by the purchaser, after agreed by the supplier and purchaser
and indicated in the contract, ultrasonic testing can use other acceptance levels.
6.11 Penetration testing
6.11.1 Penetrant testing shall be carried out on the repaired surface defects of
alloy pipes and tubes.
6.11.2 As required by the purchaser, after agreed by the supplier and purchaser
and indicated in the contract, penetrant testing can be performed on the outer
surface, end and reachable inner surface of the alloy pipes and tubes.
6.11.3 Penetration testing shall meet the quality level I requirements of other
components in NB/T 47013.5-2015.
6.12 Surface quality
6.12.1 There shall be no cracks, folds, chaps, delamination and scars on the
inner and outer surfaces of the alloy pipes and tubes. These defects shall be
completely removed. The actual wall thickness at the removal site shall not be
less than the minimum value allowed by the wall thickness.
6.12.2 The allowable depth of the straight line on the inner and outer surfaces
of the alloy pipes and tubes shall meet the following requirements:
a) Cold rolled (drawn) alloy pipes and tubes: not more than 4% of the wall
thickness, and not more than 0.3mm;
b) Hot extruded alloy pipes and tubes: not more than 5% of the wall thickness,
and not more than 0.4mm.
6.12.3 Allow other defects that do not exceed the deviation under the wall
thickness.
7 Test methods
7.1 The inspection items and test methods of alloy pipes and tubes shall comply
with the requirements in Table 6.
7.2 The chemical composition analysis of alloy pipes and tubes is carried out
GB/T 38681-2020
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 77.140.75
H 59
Seamless corrosion resistant alloy pipes and tubes
for industrial furnace
ISSUED ON: MARCH 31, 2020
IMPLEMENTED ON: OCTOBER 01, 2020
Issued by: State Administration for Market Regulation;
Standardization Administration of the People's Republic of
China.
Table of Contents
Foreword ... 3 
1 Scope ... 4 
2 Normative references ... 4 
3 Classification and codes ... 6 
4 Ordering contents ... 6 
5 Dimensions, shapes ... 7 
6 Technical requirements ... 9 
7 Test methods ... 15 
8 Inspection rules ... 17 
9 Packaging, marks and quality certificate ... 18 
Seamless corrosion resistant alloy pipes and tubes
for industrial furnace
1 Scope
This Standard specifies the classification and codes, ordering contents,
dimensions, shapes, technical requirements, test methods, inspection rules,
packaging, marks and quality certificates of seamless corrosion resistant alloy
pipes and tubes for industrial furnace.
This Standard is applicable to iron nickel base, nickel base corrosion resistant
alloy seamless tubes for industrial furnaces in petroleum refining, chemical
industry, polysilicon of which the nominal outer diameter is not greater than
406mm and the nominal wall thickness is not greater than 60mm (hereinafter
referred to as alloy pipes and tubes).
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 223.5, Steel and iron - Determination of acid-soluble silicon and total
silicon content - Reduced molybdosilicate spectrophotometric method
GB/T 223.8, Methods for chemical analysis of iron, steel and alloy - The
sodium fluoride separation - EDTA titration method for the determination of
aluminium content
GB/T 223.9, Iron steel and alloy - Determination of aluminium content –
Chrome azurol S photometric method
GB/T 223.11, Iron, Steel and Alloy - Determination of Chromium Content -
Visual Titration or Potentiometric Titration Method
GB/T 223.17, Methods for chemical analysis of iron, steel and alloy - The
diantipyryl methane photometric method for the determination of titanium
content
GB/T 223.18, Methods for Chemical Analysis of Iron, Steel and Alloy - The
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 5777-2019, Automated full peripheral ultrasonic testing of seamless
and welded (except submerged arc-welded) steel tubes for the detection of
longitudinal and/or transverse imperfections
GB/T 6394, Metal - Methods for estimating the average grain size
GB/T 7735-2016, Automated eddy current testing of seamless and welded
(except submerged arc-welded) steel tubes for detection of imperfections
3 Classification and codes
3.1 Alloy pipes and tubes are divided into two categories according to the
method of product manufacturing. The category and code are:
a) Hot extruded alloy pipes and tubes, W-H;
b) Cold rolled (drawn) alloy pipes and tubes, W-C.
3.2 Alloy pipes and tubes are divided according to the dimensional accuracy,
as well as the codes, as follows:
a) Ordinary level, PA;
b) High level, PC.
4 Ordering contents
The contract or order ordered according to this Standard shall include at least
the following information:
a) Reference to this Standard;
b) Product name;
c) Alloy designation;
d) Dimensions (outer diameter × wall thickness, in millimeters);
e) Delivery quantity (total weight, total length or count);
f) Manufacturing method;
6.2.1 Smelting method
The alloy shall be smelted by electric arc furnace plus external refining (or
electroslag remelting). After agreed by the supplier and purchaser and indicated
in the contract, other smelting methods that meet the requirements of this
Standard may also be used.
6.2.2 Pipes and tubes making method
6.2.2.1 Hot rolled or hot forged round bars shall be used for alloy ingots used
for pipes and tubes making. The parts of the round bar material equivalent to
the alloy ingot head and tail shall be fully removed.
6.2.2.2 Alloy pipes and tubes shall be manufactured by hot extrusion or cold
rolling (drawing).
6.3 Delivery status
6.3.1 Alloy pipes and tubes shall be heat treated...