A rail fish plate is a mechanical joint element that converts discrete rail lengths into a structurally cooperative system by maintaining continuity of stiffness and alignment at joints. GNEE RAIL supplies fish plates for GB rails, UIC profiles, DIN536 and QU crane rails, JIS standards, AS1085 rails, BS11 sections, and AREMA/ASCE rail systems.
How is the rail joints quality ?
High-quality rail joints must be rigid, durable, and maintain perfect vertical and horizontal alignment to ensure safety, typically made of high-strength steel (e.g., 50# or Q345). A quality joint provides the same strength and stiffness as the rail itself, allows for expansion, reduces wheel impact noise, and maintains proper track gauge.
Key Characteristics of Quality Rail Joints:
- Strength & Rigidity: The joints, or fish plates, must match the strength and stiffness of the rail section to prevent bending.
- Alignment: The rail ends must be perfectly level and straight, both vertically and laterally, to avoid unevenness.
- Material Quality: Often manufactured from high-carbon or alloy steel (50# or Q345) for durability.
| Material Type | Typical Grade / Designation | Chemical Composition (wt%) | Notes / Equivalent Standards |
| Carbon Structural Steel | Q235 (GB/T 700) | C: ≤0.22 | Common mild steel for general joint bars. Similar to ASTM A36, S235JR. |
| Si: ≤0.35 | |||
| Mn: 0.30-0.65 | |||
| P: ≤0.045 | |||
| S: ≤0.045 | |||
| Carbon Structural Steel | Q255 (GB/T 700) | C: 0.18-0.28 | Slightly higher strength than Q235. |
| Si: ≤0.35 | |||
| Mn: 0.40-0.70 | |||
| P: ≤0.045 | |||
| S: ≤0.045 | |||
| Medium Carbon Steel | 50Mn / 50BA (GOST 10779) | C: 0.47-0.55 | Classic high-strength fish plate steel. Widely used for mainline joints. |
| Si: 0.17-0.37 | |||
| Mn: 0.80-1.20 | |||
| P: ≤0.040 | |||
| S: ≤0.045 | |||
| Medium Carbon Steel | 55# (GB/T 699) | C: 0.52-0.60 | Standard medium carbon steel for demanding applications. Similar to AISI 1055. |
| Si: 0.17-0.37 | |||
| Mn: 0.50-0.80 | |||
| P: ≤0.035 | |||
| S: ≤0.035 | |||
| Alloy Steel | 42CrMo (GB/T 3077) | C: 0.38-0.45 | High-strength, high-toughness alloy for severe service. Similar to AISI 4140/4142. |
| Si: 0.17-0.37 | |||
| Mn: 0.50-0.80 | |||
| Cr: 0.90-1.20 | |||
| Mo: 0.15-0.25 | |||
| P: ≤0.035 | |||
| S: ≤0.035 | |||
| Spheroidal Graphite Cast Iron | QT450-10 (GB/T 1348) | C: 3.60-3.90 | Used in some traditional/joint kits for its castability and damping properties. Similar to EN-GJS-450-10. |
| Si: 2.00-3.00 | |||
| Mn: ≤0.50 | |||
| P: ≤0.07 | |||
| S: ≤0.015 | |||
| Mg: 0.03-0.06 (Nodulizer) | |||
| Insulating Composite Material | Epoxy Fiberglass / FRP | Base: Epoxy Resin | No metallic elements. Provides electrical insulation (Resistivity >10¹² Ω·cm), corrosion resistance. |
| Reinforcement: E-Glass Fiber (>60%) | |||
| Additives: Hardener, fillers (e.g., SiO₂) |
- Flexibility & Maintenance: They should allow for easy removal, replacement, and accommodate rail thermal expansion.
- Load Management: High-performance joints, such as NRG insulated joints, are designed to withstand significant, repeated loads (e.g., over 10 million deflections).
Comparison of Joint Types:
- Fish-plated Joints: Create 6-12mm gaps that cause noise and vibration, often resulting in bolt, hole, and rail end degradation over time.
- Welded Joints (Continuous Welded Rail - CWR): Provide superior ride quality, reducing structural stress and offering a much smoother surface, though they require careful installation to prevent failure at the heat-affected zone.
- Compromise Joints: Used to connect different rail profiles while maintaining a smooth, safe transition.
| Joint Type | Key Specification / Description |
| Standard Rail Joint (Fish Plate) | - Profile: Matches the rail section (e.g., UIC 60, 136RE). |
| - Length: Typically 600mm or 800mm per side. | |
| - Holes: 4 or 6 bolt holes per bar. | |
| Insulated Rail Joint (IRJ) | - Material: Steel core with composite insulating end-posts/plates, or full epoxy composite. |
| - Electrical Resistance: >10⁸ Ω. | |
| Compromise Rail Joint | - Design: Connects two different rail profiles (e.g., UIC 54 to UIC 60). |
| - Profile: Each side is machined to match its respective rail section. | |
| Joggled Rail Joint | - Feature: Has a depressed (joggled) section to allow continuous rail head surface for smoother wheel passage. |
| Bridge Rail Joint | - Design: Often reinforced (thicker web/longer length) for high-stress locations like bridge approaches. |
| Glued Insulated Joint | - Construction: Steel bars bonded to composite insulation using high-strength adhesive for improved durability. |
| Welded Rail Joint (for CWR) | - Type: Flash-butt or thermite weld. |
| - Specification: Weld must meet mechanical properties equal to or greater than the parent rail. | |
| Expansion Joint (for BRE) | - Feature: Allows controlled thermal expansion in long rails on bridges or in extreme temperature zones. |
How many bolts are there in a fish plate?
A standard railway fish plate (joint bar) typically uses four bolts per joint, with two bolts fastening each side of the rail connection. While four is standard, some heavy-duty or longer rail fish plates may use six bolts (three on each side) to secure the rail joint.
- Standard Setup: 4-hole fish plates with 4 bolts are commonly used for standard joints.
- Long/Heavy Rail: 6-hole fish plates with 6 bolts are used for longer or more heavy-duty rail joints.
- Components: Each bolt is usually part of a set that includes a nut, a spring washer, and a flat washer.
- Purpose: The bolts clamp two steel plates (fish plates) to both sides of the rail web to provide structural integrity to the track connection.
Founded in 2008, GNEE RAIL is a leading global manufacturer and supplier of railway components, specializing in high-quality rail fish plates (joint bars/splice bars) with strong production capacity and global service capabilities.
Our rail fish plate portfolio is comprehensive and compliant with international standards including UIC, AREMA, BS, DIN, and GB, covering light rail (8kg-30kg), heavy rail (38kg-75kg), and crane rail (QU70-QU120) systems. We offer diverse types such as insulated joint bars, bulged fish plates, and compromise rail joints,with precise specifications (4-hole/6-hole, 24-inch/36-inch), ensuring excellent mechanical performance.We uphold strict quality control supported by ISO 9001:2015 certification, an in-house inspection center, and third-party audits by SGS and BV. Our one-stop service includes customization, production, packaging, and after-sales support, tailored to clients' project needs.
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