The Critical Link: UIC Leaflet 897-11 Fishplate Specs

Introduction to UIC Leaflet 897-11

While modern railways prefer Continuous Welded Rail (CWR) to eliminate the “click-clack” noise and maintenance of joints, mechanical connections remain essential. Whether for emergency repairs, sharp curves, or most critically, for Insulated Rail Joints (IRJs) that separate signaling blocks, rails must sometimes be bolted together. UIC Leaflet 897-11, titled “Technical specification for the supply of fishplates,” ensures that these steel connectors are tough enough to withstand the immense impact forces of wheels hitting the gap.

A fishplate (or joint bar) is not just a flat piece of steel. It is a precisely rolled profile designed to wedge itself between the rail head and foot, transferring the vertical load from one rail to the next. UIC 897-11 provides the recipe for manufacturing this safety-critical component.

Snippet Definition: What is UIC 897-11?

UIC Leaflet 897-11 is a technical specification for the manufacture and supply of rolled steel fishplates used to join railway rails. It defines the chemical composition of the steel (to ensure weldability and toughness), the mechanical properties (tensile strength), the geometric tolerances of the “fishing surfaces,” and the rigorous acceptance tests, including the drop-weight impact test.

The Geometry of “Fishing”

The standard emphasizes that a fishplate functions through a wedging action, not by simply bolting onto the web.

• Fishing Surfaces: The top and bottom angled slopes of the fishplate match the angles of the rail head underside and rail foot top (typically 1:3 or 1:4).
• The Gap: UIC 897-11 tolerances ensure that when the bolts are tightened, the fishplate contacts only these sloping surfaces. It must never touch the vertical web of the rail. This clearance allows the plate to be tightened further as it wears, maintaining the joint’s stiffness.

Material and Strength

Fishplates are the weakest point in the track superstructure. To prevent them from snapping under load, UIC 897-11 defines specific steel grades:

• Standard Grade: Typically used for temporary joints or sidings.
• High Strength Grade: Used for main lines and insulated joints. These are heat-treated (quenched and tempered) to achieve higher yield strength.
• Chemical Limits: Strict control of Sulfur and Phosphorus is mandated to prevent brittleness in cold weather.

Testing Requirements

Before a batch is accepted, it must survive the “Torture Test.”

1. The Drop Weight Test (Impact Test)

This is the defining test of UIC 897-11.

• A sample fishplate is placed on supports simulating a rail joint.
• A heavy tup (weight) is dropped from a specified height onto the center of the plate.
• Pass Criteria: The plate may bend, but it must not break or crack. This simulates the dynamic shock of a locomotive wheel hitting a low joint at speed.

2. Tensile and Bend Tests

Standard tests to verify the steel’s ductility. The material must be able to stretch significantly before failing, ensuring it gives warning (deformation) before a catastrophic break.

Comparison: Fishplates vs. Welding

Why do we still need UIC 897-11 in the age of welding?

Marking and Traceability

UIC 897-11 requires every fishplate to carry raised “Rolling Marks” produced during the hot rolling process. These must include:

• Manufacturer’s mark.
• Year of manufacture (last two digits).
• Rail section (e.g., “UIC60”).
• Steel grade symbol.

This ensures that if a fishplate cracks and causes an accident, investigators can trace the batch back to the steel mill.