Gnee provides segment bolts of M16-M80 size, made of high-quality stainless steel and alloy steel. They can be used in radial and circumferential joints, and play an important role in railway construction, especially tunnel construction.
The anti-rust thickness of the segment bolts provided by Gnee can be maintained for more than 50 years, with strong corrosion resistance and long service life. Our railway segment bolt products include straight segment bolts and curved segment bolts, and can provide customized services for surface treatment, material, appearance, etc. according to the drawings provided by customers.
Gnee provides the following tunnel bolt products. If you don’t find the product you need, please contact us.
Double-Ended Straight Segment Bolts
Size
Grade
Material
Surface treatment
φ22×410
ISO898 – 1:2009 standard, grade 8.8
45#
Hot dip galvanized, thickness of zinc layer ≥43μm
φ25×395
φ28×556
Natural color
φ20×350
35#
Dacromet coating, thickness of coating ≥8μm
φ30×480
ISO898 – 1:2009 standard, grade 10.9
40Cr
Powder zinc – infiltrated, thickness of zinc layer ≥60μm
Double-Ended Arc-Shaped Segment Bolts
Size
Grade
Material
Surface treatment
φ22×410
ISO898 – 1:2009 standard, grade 8.8
45#
Hot dip galvanized, thickness of zinc layer ≥43μm
φ25×395
φ28×556
Natural color
φ24×430
Hot dip galvanized, thickness of zinc layer ≥43μm
φ26×460
Multi – component composite powder zinc – infiltrated, thickness of zinc layer ≥50μm
Hexagon Head Arc-Shaped Segment Bolts
Size
Grade
Material
Surface treatment
φ22×410
ISO898 – 1:2009 standard, grade 8.8
45#
Hot dip galvanized, thickness of zinc layer ≥43μm
φ25×395
φ28×556
Natural color
φ20×320
ISO898 – 1:2009 standard, grade 6.8
35#
Blackening treatment
φ27×440
ISO898 – 1:2009 standard, grade 8.8
45#
Mechanical zinc – plating, thickness of zinc layer ≥30μm
Hexagon Head Arc Thread Segment Bolts
Size
Grade
Material
Surface treatment
φ22×410
ISO898 – 1:2009 standard, grade 8.8
45#
Hot dip galvanized, thickness of zinc layer ≥43μm
φ25×395
φ28×556
Natural color
φ24×400
Dacromet coating, thickness of coating ≥8μm
φ32×500
ISO898 – 1:2009 standard, grade 10.9
40Cr
Powder zinc – infiltrated, thickness of zinc layer ≥60μm
Hexagon Flange Surface Arc Thread Segment Bolts
Size
Grade
Material
Surface treatment
φ22×410
ISO898 – 1:2009 standard, grade 8.8
45#
Hot dip galvanized, thickness of zinc layer ≥43μm
φ25×395
φ28×556
Natural color
φ26×420
Blue – white zinc plating, thickness of zinc layer ≥20μm
φ30×460
Trivalent chromium Cr3+ passivation treatment
Product Description
Railway segment bolts, also called curved bolts or tunnel bolts, are used to permanently fix tunnel segments to the numerous metal beams and columns that constitute the tunnel frame through radius holes. They are mainly used in subway shields, tunnel segment connections, shallow buried longitudinal segment connections, building segment connections, subway segment connections, etc.
Gnee Rails is a professional manufacturer of high-strength special bolts in China, and its products include subway or railway long tunnel curved bolts, curved tunnel bolts, segment bolts, and washers and nuts of various grades, sizes and load capacities.
Hot-dip galvanizing, Dacromet, powder shearing, multi-component composite powder shearing, etc.
FAQ About Gnee Rail Segment Bolts
The following are some common questions and answers. If you have other questions, please feel free to contact us!
How to choose the material of segment bolts?
Q235 carbon steel is suitable for ordinary environments (such as dry tunnels), 45# steel and 40Cr alloy steel are used in high load or humid environments. It is recommended to choose according to the design strength (such as 8.8 grade) and anti-corrosion requirements.
What is the difference between hot-dip galvanizing and Dacromet treatment?
Hot-dip galvanizing has low cost but weak corrosion resistance (suitable for general environments), Dacromet has no risk of hydrogen embrittlement and has stronger salt spray resistance (suitable for underwater or high humidity environments).
Can circumferential and longitudinal bolts be mixed?
Not recommended. Circumferential bolts bear radial pressure, and longitudinal bolts resist axial tension. If the design specifications are different, mixing may cause structural instability.
How to detect whether the bolts are qualified?
It needs to pass the test of a third-party organization, including: tensile strength test, hardness test (HRC 22~32), salt spray test (≥720h is up to standard), and thread accuracy test.
What should be paid attention to during installation?
① Use a torque wrench to tighten according to the design value; ② Do not reuse stretched bolts; ③ Check whether the gasket is loose (such as spring washers).
How long is the life of the bolt?
If the surface treatment meets the standard, the life of hot-dip galvanized bolts is about 15~20 years, and Dacromet can reach more than 30 years (regular maintenance and inspection are required).
Does it support non-standard customization?
Yes. Special curvature, length, and strength grade can be customized (segment joint drawings and load parameters must be provided).
What are the main factors affecting the price?
Material cost (40Cr＞45#＞Q235), surface treatment process (Dacromet＞hot-dip galvanizing), batch size (1000 pieces can reduce the unit price).
Why Choose Gnee Rail Fasteners?
As a world-leading manufacturer of rail fastener systems, Gnee Rail Fasteners has 18 years of professional experience, an annual production capacity of 10 million sets, and its products are exported to more than 60 countries. We have built 5 production bases, equipped with 400 technicians, and annual R&D investment exceeds 5% of revenue.
Our products have been used in more than 2,000 railway projects, with a total of 50,000 kilometers of track laid, covering more than 100 high-speed rail projects. From -40℃ to 80℃, the product performance remains stable and reliable. With strict quality control and professional technical support, more than 85% of our customers maintain long-term cooperation with us, and customer satisfaction continues to remain above 93 points.
