Fish plates — also called joint bars, rail bars or splice bars — are the steel bars bolted to both sides of a rail joint. They are small components with a big responsibility: every wheel that crosses a rail joint depends on them for a smooth, safe transition. This guide covers the types, standards and maintenance practices that keep joints healthy.
Why Rail Joints Need Fish Plates
Rails cannot be manufactured in endless lengths, and even continuously welded rail (CWR) needs expansion joints at intervals. At every joint, the running surface is interrupted. Fish plates bridge that interruption, transferring shear and bending loads from one rail end to the next while holding the rail ends in correct vertical and horizontal alignment.
A well-fitted joint with properly torqued track bolts behaves almost like continuous rail; a loose one becomes a hammer, battering the rail ends and damaging sleepers, ballast and rolling stock alike.
Types of Fish Plates
Standard Fish Plates
The classic four-hole or six-hole bar, fished across both sides of the rail web. Available for every common rail section (43kg/m, 50kg/m, 60kg/m, UIC54, UIC60, ASCE and others). Standard plates suit normal operating conditions and are the most economical option.
Compromise (Transition) Fish Plates
When two different rail sections meet — for example during a phased track upgrade — compromise fish plates join them safely. Each side of the plate matches a different rail profile. These are always custom-manufactured to the two specific rail sections.
Insulated Fish Plates
Used within insulated rail joints, these plates are isolated from the rail by insulating liners and end posts so that track circuits can detect train positions. Mechanical strength and electrical insulation must be achieved at the same time, which makes material selection critical.
Joggled Fish Plates
For joints where the head of the rail must remain unobstructed (for example, at some crossings), joggled plates step over the rail head. They are more complex to manufacture and used in specific track layouts.
Materials and Standards
Fish plates are hot-rolled from medium-carbon or alloy steel and are usually heat-treated for strength and toughness. Common specifications include AREMA Chapter 5, UIC 864, EN 13481 and GB/T 2826 (China), depending on the project.
| Rail section | Typical fish plate | Bolts per joint |
|---|---|---|
| 43 kg/m | 4-hole standard | 4 |
| 50 kg/m | 4-hole or 6-hole | 4–6 |
| 60 kg/m / UIC60 | 6-hole standard | 6 |
| Mixed sections | Compromise plate | 4–6 |
Maintenance: The Joint Check That Prevents Big Repairs
- Check bolt torque regularly — a loose joint accelerates rail-end batter and plate fatigue
- Inspect for cracks in the plate web and bolt holes, especially at the first and last holes
- Measure rail-end wear and settlement — a dipped joint needs shimming or re-plating, not just retightening
- Keep the joint lubricated and clean — corrosion between rail and plate hides defects
- Replace plates in pairs — mixing a new plate with a worn one misaligns the joint
Ordering the Right Fish Plates
To order, you need only three facts: the rail section (exact kg/m or profile), the number of holes, and the standard to follow. For compromise or insulated plates, provide the two rail sections or the joint assembly drawing.
Chenji manufactures and exports fish plates for rail sections from 8 kg/m light rail to 75 kg/m heavy haul, including compromise and insulated types, with full material certificates and batch inspection. Send us your rail section for a quote, or review our quality process.