GB/T 9125.1-2020 English PDF (GB/T9125.1-2020)

GB/T 9125.1-2020: Fasteners for steel pipe flange joints - Part 1: PN designated
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GB/T 9125.1-2020
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 23.040.60
J 15
Replacing GB/T 9125-2010
Fasteners for steel pipe flange joints - Part 1: PN designated
ISSUED ON: SEPTEMBER 29, 2020
IMPLEMENTED ON: APRIL 01, 2021
Issued by: State Administration for Market Regulation;
Standardization Administration of the People's Republic of China.
Table of Contents
Foreword ... 3
1 Scope ... 5
2 Normative references ... 5
3 Structural types, dimensions and tolerances ... 6
3.1 Hexagon head bolts ... 6
3.2 Equal-length studs ... 8
3.3 Full-thread studs ... 9
3.4 Hexagonal nuts ... 9
3.5 Tolerance ... 12
3.6 Length and mass ... 12
4 Materials ... 12
4.1 General ... 12
4.2 Technical requirements ... 13
5 Manufacturing and heat treatment ... 15
5.1 Manufacturing ... 15
5.2 Heat treatment ... 15
6 Inspection and acceptance ... 17
6.1 Inspection ... 17
6.2 Acceptance ... 18
7 Product quality certificate ... 18
8 Marks and signs ... 18
9 Protection and packaging ... 20
Annex A (informative) Fastener length and mass ... 21
Annex B (informative) Calculation of fastener length ... 90
Annex C (informative) Strength classification of fastener materials ... 94
Bibliography ... 95
Fasteners for steel pipe flange joints - Part 1: PN designated
1 Scope
This Part of GB/T 9125 specifies the structural types, dimensions and tolerances,
materials, manufacturing and heat treatment, inspection and acceptance, product quality
certificates, marks and signs, protection and packaging requirements for PN designated
fasteners for steel pipe flange joints.
This Part applies to fasteners for steel pipe flange joints specified in GB/T 9124.1
(including hexagon head bolts, equal-length studs, full-thread studs and nuts).
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 2, Fasteners -- Ends of parts with external thread
GB/T 90.1, Fasteners -- Acceptance inspection
GB/T 196, General purpose metric screw threads -- Basic dimensions
GB/T 197, General purpose metric screw threads -- Tolerances
GB/T 228.1, Metallic materials -- Tensile testing -- Part 1: Method of test at room
temperature
GB/T 699, Quality carbon structure steels
GB/T 700, Carbon structural steels
GB/T 901, Double end studs (clamping type). Product grade B
GB/T 1220, Stainless steel rod
GB/T 1221, Heat-resistant steel bars
GB/T 3077, Alloy structure steels
GB/T 3098.1, Mechanical properties of fasteners -- Bolts, screws and studs
GB/T 3098.2, Mechanical properties of fasteners -- Nuts
3.5 Tolerance
3.5.1 For bolts and studs with thread size less than or equal to M24 and nominal length
in accordance with the smaller value of the following items a) and b), their unmarked
dimensional tolerances and geometric tolerances shall comply with the provisions for
grade A products in GB/T 3103.1:
a) less than or equal to 10 d;
b) less than or equal to 150 mm.
3.5.2 For bolts and studs with thread specifications greater than M24 or nominal lengths
that meet the smaller value of the following items a) and b), their unmarked dimensional
tolerances and geometric tolerances shall comply with the provisions for grade B
products in GB/T 3103.1:
a) greater than 10 d;
b) greater than 150 mm.
3.5.3 The dimensional tolerance and geometric tolerance of nuts with thread size less
than or equal to M16 shall comply with the provisions for grade A products in GB/T
3103.1. The dimensional tolerance and geometric tolerance of nuts with thread size
greater than M16 shall comply with the provisions for grade B products in GB/T 3103.1.
3.5.4 The thread tolerance of bolts and studs shall comply with 6 g of GB/T 197. The
thread tolerance of nuts shall comply with 6H of GB/T 197.
3.5.5 Unspecified fastener tolerances shall comply with the requirements of GB/T
3103.1.
3.6 Length and mass
3.6.1 For the length and mass of fasteners, refer to Annex A.
3.6.2 For the calculation of fastener length, refer to Annex B.
4 Materials
4.1 General
4.1.1 Fastener raw materials shall have quality certificates. Chemical composition
analysis shall be conducted. For fastener raw materials with the same steel grade, the
same smelting furnace number, the same cross-sectional dimensions, and the same heat
treatment conditions, the sampling quantity shall be 1% of each batch and shall not be
less than 1 piece.
4.1.2 The blank after heat treatment or strain hardening shall be subjected to mechanical
property analysis and shall comply with the following requirements:
a) Blanks of same steel grade, same smelting furnace number, same section size,
same heat treatment conditions and manufactured in the same period constitute a
batch. The number of random inspections for each batch shall be 1 piece.
b) The sampling direction of the specimen shall be longitudinal. When the diameter
of the blank is less than or equal to 40 mm, the longitudinal axis of the specimen
shall be located at the center of the blank. When the diameter of the blank is
greater than 40 mm, the longitudinal axis of the specimen shall be located at 1/2
of the blank radius.
c) Take a tensile test specimen from each full-thread stud blank. The tensile test shall
comply with the provisions of GB/T 228.1.
d) The tensile test results of the full-thread stud blank shall comply with the
requirements of Table 6.
e) If the tensile test result is unqualified, two more tensile specimens shall be taken
from the same blank for retesting to measure all three properties. If one of the test
results is unqualified, the batch of blanks is judged to be unqualified.
f) The entire batch of blanks judged to be unqualified shall be re-heat treated and re-
tested according to the above procedure.
4.1.3 Fastener materials used at temperatures below or equal to -20°C shall be subjected
to low-temperature Charpy impact tests. The requirements for the impact tests shall
comply with the provisions of relevant standards.
4.1.4 The blanks of full-thread studs and type 2 nuts shall be subjected to hardness test
in batches, with no less than 3 pieces being sampled from each batch.
4.1.5 For strength classification of fastener materials, see Annex C.
4.2 Technical requirements
4.2.1 The materials and mechanical properties of hexagon head bolts and equal-length
studs shall comply with the requirements of GB/T 3098.1 or GB/T 3098.6.
4.2.2 The material and mechanical properties of fully threaded studs shall comply with
the requirements of Table 6.
6.1.5 The outer surface of fasteners shall not have cutting burrs.
6.1.6 The non-destructive testing and qualified level of fasteners shall comply with the
requirements of the contract or relevant standards.
6.2 Acceptance
The acceptance of fasteners shall comply with the provisions of GB/T 90.1.
7 Product quality certificate
7.1 Each batch of fasteners produced in accordance with this Part shall be accompanied
by a product quality certificate.
7.2 The product quality certificate shall include the following:
a) Manufacturer’s name and date of manufacture;
b) Official seal of the manufacturer’s technical (quality) inspection department;
c) Signature of the quality inspector and date of inspection;
d) Product’s name, specification, material designation and material standard or
performance grade;
e) Chemical composition and mechanical properties;
f) Other inspection reports specified in the contract.
8 Marks and signs
8.1 The marks of fasteners shall comply with the following provisions:
a) Product name;
b) Reference to this Part: GB/T 9125.1;
c) Thread size and nominal length, no length marking for nuts;
d) Material designation or performance grade;
e) Nut marking type code.
Example 1:
The mark of a hexagonal head bolt with thread size M20, nominal length 100 mm and
GB/T 9125.1-2020
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 23.040.60
J 15
Replacing GB/T 9125-2010
Fasteners for steel pipe flange joints - Part 1: PN designated
ISSUED ON: SEPTEMBER 29, 2020
IMPLEMENTED ON: APRIL 01, 2021
Issued by: State Administration for Market Regulation;
Standardization Administration of the People's Republic of China.
Table of Contents
Foreword ... 3
1 Scope ... 5
2 Normative references ... 5
3 Structural types, dimensions and tolerances ... 6
3.1 Hexagon head bolts ... 6
3.2 Equal-length studs ... 8
3.3 Full-thread studs ... 9
3.4 Hexagonal nuts ... 9
3.5 Tolerance ... 12
3.6 Length and mass ... 12
4 Materials ... 12
4.1 General ... 12
4.2 Technical requirements ... 13
5 Manufacturing and heat treatment ... 15
5.1 Manufacturing ... 15
5.2 Heat treatment ... 15
6 Inspection and acceptance ... 17
6.1 Inspection ... 17
6.2 Acceptance ... 18
7 Product quality certificate ... 18
8 Marks and signs ... 18
9 Protection and packaging ... 20
Annex A (informative) Fastener length and mass ... 21
Annex B (informative) Calculation of fastener length ... 90
Annex C (informative) Strength classification of fastener materials ... 94
Bibliography ... 95
Fasteners for steel pipe flange joints - Part 1: PN designated
1 Scope
This Part of GB/T 9125 specifies the structural types, dimensions and tolerances,
materials, manufacturing and heat treatment, inspection and acceptance, product quality
certificates, marks and signs, protection and packaging requirements for PN designated
fasteners for steel pipe flange joints.
This Part applies to fasteners for steel pipe flange joints specified in GB/T 9124.1
(including hexagon head bolts, equal-length studs, full-thread studs and nuts).
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 2, Fasteners -- Ends of parts with external thread
GB/T 90.1, Fasteners -- Acceptance inspection
GB/T 196, General purpose metric screw threads -- Basic dimensions
GB/T 197, General purpose metric screw threads -- Tolerances
GB/T 228.1, Metallic materials -- Tensile testing -- Part 1: Method of test at room
temperature
GB/T 699, Quality carbon structure steels
GB/T 700, Carbon structural steels
GB/T 901, Double end studs (clamping type). Product grade B
GB/T 1220, Stainless steel rod
GB/T 1221, Heat-resistant steel bars
GB/T 3077, Alloy structure steels
GB/T 3098.1, Mechanical properties of fasteners -- Bolts, screws and studs
GB/T 3098.2, Mechanical properties of fasteners -- Nuts
3.5 Tolerance
3.5.1 For bolts and studs with thread size less than or equal to M24 and nominal length
in accordance with the smaller value of the following items a) and b), their unmarked
dimensional tolerances and geometric tolerances shall comply with the provisions for
grade A products in GB/T 3103.1:
a) less than or equal to 10 d;
b) less than or equal to 150 mm.
3.5.2 For bolts and studs with thread specifications greater than M24 or nominal lengths
that meet the smaller value of the following items a) and b), their unmarked dimensional
tolerances and geometric tolerances shall comply with the provisions for grade B
products in GB/T 3103.1:
a) greater than 10 d;
b) greater than 150 mm.
3.5.3 The dimensional tolerance and geometric tolerance of nuts with thread size less
than or equal to M16 shall comply with the provisions for grade A products in GB/T
3103.1. The dimensional tolerance and geometric tolerance of nuts with thread size
greater than M16 shall comply with the provisions for grade B products in GB/T 3103.1.
3.5.4 The thread tolerance of bolts and studs shall comply with 6 g of GB/T 197. The
thread tolerance of nuts shall comply with 6H of GB/T 197.
3.5.5 Unspecified fastener tolerances shall comply with the requirements of GB/T
3103.1.
3.6 Length and mass
3.6.1 For the length and mass of fasteners, refer to Annex A.
3.6.2 For the calculation of fastener length, refer to Annex B.
4 Materials
4.1 General
4.1.1 Fastener raw materials shall have quality certificates. Chemical composition
analysis shall be conducted. For fastener raw materials with the same steel grade, the
same smelting furnace number, the same cross-sectional dimensions, and the same heat
treatment conditions, the sampling quantity shall be 1% of each batch and shall not be
less than 1 piece.
4.1.2 The blank after heat treatment or strain hardening shall be subjected to mechanical
property analysis and shall comply with the following requirements:
a) Blanks of same steel grade, same smelting furnace number, same section size,
same heat treatment conditions and manufactured in the same period constitute a
batch. The number of random inspections for each batch shall be 1 piece.
b) The sampling direction of the specimen shall be longitudinal. When the diameter
of the blank is less than or equal to 40 mm, the longitudinal axis of the specimen
shall be located at the center of the blank. When the diameter of the blank is
greater than 40 mm, the longitudinal axis of the specimen shall be located at 1/2
of the blank radius.
c) Take a tensile test specimen from each full-thread stud blank. The tensile test shall
comply with the provisions of GB/T 228.1.
d) The tensile test results of the full-thread stud blank shall comply with the
requirements of Table 6.
e) If the tensile test result is unqualified, two more tensile specimens shall be taken
from the same blank for retesting to measure all three properties. If one of the test
results is unqualified, the batch of blanks is judged to be unqualified.
f) The entire batch of blanks judged to be unqualified shall be...