GB/T 9125.1-2020Fasteners for steel pipe flange joints—Part 1:PN designated (English PDF)
钢制管法兰连接用紧固件 第1部分：PN系列
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Issued by
SAMR; SAC
Level / Type
National · Recommended
Issue date
September 29, 2020
Implementation date
April 1, 2021
Scope
GB/T 9125.1-2020 is the English-translated version of 钢制管法兰连接用紧固件 第1部分：PN系列.
GB/T 9125.1-2020 is the Chinese national standard for the bolts, studs and nuts of PN designated steel pipe flange joints. This part fixes the structural types, dimensions and tolerances of hexagon head bolts, equal-length studs, full-thread studs and nuts, referring their sizes and marking to GB/T 5276, GB/T 5782 and the metric thread standards.
It covers the materials and their mechanical properties, including low-temperature impact testing for service at or below -20 degrees C, manufacturing and heat treatment, thread roughness and decarburisation limits, batch inspection and acceptance to GB/T 90.1, the product quality certificate, marking by steel stamp or laser, and protection and packaging.
Annexes give fastener lengths and masses, the calculation of length and the strength classification of materials. It replaces GB/T 9125-2010, was issued on 29 September 2020 and has applied since 1 April 2021.
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Document preview — GB/T 9125.1-2020
National Standard of the People's Republic of China
- ICS
- 23.040.60
- Classification
- J 15
- Replacing
- GB/T 9125-2010
Issued by: State Administration for Market Regulation; Standardization Administration of the PRC
Contents
- Foreword3
- 1 Scope5
- 2 Normative references5
- 3 Structural types, dimensions and tolerances6
- 3.1 Hexagon head bolts6
- 3.2 Equal-length studs8
- 3.3 Full-thread studs9
- 3.4 Hexagonal nuts9
- 3.5 Tolerance12
- 3.6 Length and mass12
- 4 Materials12
- 4.1 General12
- 4.2 Technical requirements13
- 5 Manufacturing and heat treatment15
- 5.1 Manufacturing15
- 5.2 Heat treatment15
- 6 Inspection and acceptance17
- 6.1 Inspection17
- 6.2 Acceptance18
- 7 Product quality certificate18
- 8 Marks and signs18
- 9 Protection and packaging20
- Annex A (informative) Fastener length and mass21
- Annex B (informative) Calculation of fastener length90
- Annex C (informative) Strength classification of fastener materials94
- Bibliography95
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
3 Structural types, dimensions and tolerances
3.1 Hexagon head bolts
3.1.1 The structural type of hexagon head bolts is shown in Figure 1. The size code and marking shall comply with the requirements of GB/T 5276.
3.1.2 When the thread size of the hexagonal head bolt is less than or equal to M33, the pitch shall be of the coarse pitch series. The dimensions shall comply with the provisions of GB/T 5782.
3.2 Equal-length studs
3.2.1 The structural type of equal-length studs is shown in Figure 2. The size code and marking shall comply with the provisions of GB/T 5276.
3.2.2 When the thread specification of equal-length studs is less than or equal to M33, the pitch shall be of the coarse pitch series.
3.3 Full-thread studs
3.3.1 The structural type of the full-thread stud is shown in Figure 3. The size code and marking shall comply with the provisions of GB/T 5276.
3.3.2 When the thread size of the full-thread stud is less than or equal to M33, the pitch shall be coarse pitch series.
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.
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.
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.
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.
4.2 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.
4.2.4 The material and hardness of type 2 nuts shall comply with the requirements of Table 7.
5 Manufacturing and heat treatment
5.1 Manufacturing
5.1.1 The basic dimensions of the thread shall comply with the requirements of GB/T 196.
5.1.2 The surface roughness of the thread flanks and roots of bolts and studs shall not exceed Ra 3.2. The surface roughness of the thread flanks and roots of nuts shall not exceed Ra 6.3.
5.1.3 The minimum height E of the un-decarburized layer of bolt and stud threads is 0.5 times the tooth profile height. The maximum depth of the fully decarburized layer is 0.015 mm. The decarburization test method shall be carried out in accordance with the relevant provisions of GB/T 3098.1.
5.2 Heat treatment
5.2.1 The heat treatment requirements for hexagon head bolts or equal-length studs shall comply with the requirements of GB/T 3098.1 or GB/T 3098.6.
5.2.2 The heat treatment requirements for full-thread studs shall comply with the requirements in Table 8.
5.2.3 The heat treatment requirements for type 1 nuts shall comply with the requirements of GB/T 3098.2 or GB/T 3098.15.
5.2.4 The heat treatment requirements for type 2 nuts shall comply with the requirements in Table 9.
5.2.5 Raw materials supplied in accordance with the heat treatment process in Table 8 or Table 9 can be directly processed into products for delivery, provided that the mechanical properties of the products are guaranteed.
6 Inspection and acceptance
6.1 Inspection
6.1.1 Inspection shall be conducted in batches. Products with the same material designation, same smelting furnace number, same type, same thread specification, same length (except nuts) and same production process shall be considered as a batch.
6.1.2 The inspection of dimensions shall comply with the requirements of GB/T 90.1.
6.1.3 The surface defects of bolts and studs shall comply with the provisions of GB/T 5779.1.
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. […]
8 Marks and signs
8.1 The marks of fasteners shall comply with the following provisions.
8.2 The ends of the studs, the top surface of the head of the hexagonal bolts and the bearing surface or side surface of the nuts shall be marked by steel stamp or laser. The marking shall be clearly visible.
8.3 The material code shall comply with the requirements of Table 10.
9 Protection and packaging
9.1 Products shall be rust-proof.
9.3 Fasteners shall be packed in sets.
9.4 The packing box shall contain a product packing list and a product quality certificate.
9.5 The product packing list shall include the following. […]
......
This preview omits tables, figures, formulas and parts of the technical clauses. The complete document — 95 pages — is available in the English PDF.
Referenced standards
Normative references
- GB/T 2Fasteners -- Ends of parts with external thread
- GB/T 90.1Fasteners - Acceptance inspection
- GB/T 196General purpose metric screw threads - Basic dimensions
- GB/T 197General purpose metric screw threads -- Tolerances
- GB/T 228.1Metallic Materials — Tensile Testing — Part 1: Method of Test at Room Temperature
Similar standards
Editions of GB/T 9125.1
| Edition | Title | Revision | Status |
|---|---|---|---|
| GB/T 9125.1-2020 | Fasteners for steel pipe flange joints—Part 1:PN designated | current edition | Current |
| GB/T 9125-2010 | Fasteners for steel pipe flange joints—Part 1:PN designated | previous edition | Superseded |
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