What is a fish plate in railway?

Author : | Last Updated : 2026-02-11

What is a rail joint e in railway?

A fish plate (or splice bar/joint bar) is a metal plate bolted to the web of two abutting railway rails to connect them into a continuous, stable track. Designed with tapered top and bottom faces, these plates fit snugly to maintain alignment, transfer wheel loads between rails, and allow for thermal expansion/contraction.

Key Functions and Details

Purpose: Ensures vertical and lateral stiffness at the rail joint, preventing deflection and maintaining a smooth, safe ride.

Components: Installed in pairs on either side of the rail web and secured using fish bolts, washers, and nuts.

Types of Railroad Joint

Standard Fish Plates: Used for general rail joining.

Joggled Fish Plates: Bent to accommodate small vertical differences or broken rails.

Insulated Fish Plates: Used in signaling sections to prevent electrical continuity between track circuits.

Classification Category	Type of Rail Joint	Core Definition / Key Characteristics
By Position on Track	Square Joint	Joints on parallel rails are aligned opposite each other. Common on straight tracks; simple but causes more impact.
By Position on Track	Staggered Joint	Joints on one rail are opposite the mid-point of the adjacent rail. Primarily used on curves to reduce forces and improve ride quality.
By Position of Sleepers	Supported Joint	Rail ends rest directly on a single “joint sleeper”. Minimizes deflection but creates a rigid, high-maintenance point.
	Suspended Joint	Rail ends are located between two sleepers. The most common type; offers flexibility but requires more frequent maintenance.
	Bridge Joint	Similar to suspended, but uses a metal bridge plate to connect rails on either side of the joint. Not widely used.
By Performance & Application	Ordinary (Bolted) Joint	Standard connection using fishplates and bolts. Cost-effective, allows for thermal expansion.
	Compromise Joint	Connects two rails of different sizes/profiles. Uses specially shaped fishplates to ensure a smooth transition.
	Conductive Joint	Ensures electrical continuity between rail sections for traction current and signaling, using conductive materials.
	Insulated Joint (IRJ)	Electrically isolates rail sections for signaling systems. Uses insulating materials between rails and plates.
	Welded Joint	Rail ends are fused together (e.g., thermite welding). Creates Continuous Welded Rail (CWR) for a smoother, stronger track.
	Frozen Joint	A defective condition where tight or corroded fishplates prevent thermal expansion/contraction, leading to high stress.
	Expansion Joint (REJ)	Allows controlled longitudinal rail movement (e.g., on bridges) to prevent buckling or breakage due to temperature changes.

Material: Usually made of high-strength steel (e.g., Q235, forged steel) to withstand high loads, with tensile strengths typically ranging from 57 to 68 kg/mm².

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)

Fish plates are critical for track safety, reducing the risk of derailment caused by misaligned, broken, or improperly connected rail ends.

What is the size of a fish plate?

Rail fish plates typically range from 600mm to 1000mm in length, depending on the rail weight and type. Standard sizes often include 4-hole or 6-hole configurations, such as 610mm for 52kg/60kg rails or 800mm-860mm for heavier, high-speed lines. The thickness and profile are tailored to match specific rail profiles, ensuring a tight fit and structural continuity.

Fishplate for UIC Standard Steel Rail
Steel Rail Type	Steel Rail Weight (KG/M)	Fishplate Standard	Fishplate Material
UIC54	54.43	UIC	45#,55#
UIC60	60.34	UIC	45#,55#
Fishplate for BS Standard Steel Rail
BS50’O’	24.833	BS 47-1	55#,45# European Grade 700
BS60A	30.618
BS75R	37.041
BS80A	39.761
BS90A	45.099
BS100A	50.182
BS113A	56.398
Joint Bar for AREMA 2007 Standard Steel Rail
100RE(TR50)	50.35	AREMA 2007	45#,55#,AREMA Grade Steel
115RE	56.9
115-119RE
132RE	65.31
133RE	66.1
136RE	67.41
132-136RE
Fishplate For Chinese Standard Steel Rail
GB15KG	15.2	YB226-63	Q235,45#
GB18KG	18.06	YB225-63
GB22KG	22.3	YB14-63
GB24KG	24.46	YB14-63
GB30KG	30.1	YB351-63
GB38KG	38.733	TB/T 2345-2008	45#,55#
GB43KG	44.653
GB50KG	51.514

What is the working principle of a rail joint?

A rail joint connects two rail ends with bolted fishplates for structural continuity.It retains a small gap to accommodate thermal expansion and contraction.Joints align rails vertically/horizontally for smooth wheel passage.They serve as flexible connections in non-welded tracks.

Key Working Principles:

Two steel fishplates bolt to rail web sides, bridging the rail end gap.A designed expansion gap prevents rail buckling or breaking from temperature changes.Joints maintain rail head alignment and stiffness to support heavy train loads.Fasteners attach rails to sleepers, stabilizing the jointed area.

About Us

Founded in 2008, GNEE RAIL is a leading global supplier. We specialize in high-quality rail fish plates (joint bars). Our production capacity and service capabilities are strong worldwide.

We offer a comprehensive rail fish plate portfolio. It complies with UIC, AREMA, BS, DIN, and GB standards. Our products cover light, heavy, and crane rail systems.

Available types include insulated and bulged fish plates. We also provide compromise rail joints. Specifications are precise, like 4-hole/6-hole and 24-inch/36-inch sizes.

This ensures excellent mechanical performance. We maintain strict quality control. It is supported by ISO 9001:2015 certification.

We operate an in-house inspection center. Our processes undergo third-party audits by SGS and BV. We provide complete one-stop service.

This includes customization, production, and packaging. We also offer dedicated after-sales support. All services are tailored to your project needs.