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How to choose railway fasteners? Anti-loosening, material and acceptance essentials

2026-09-10

Compiled by JIALI Industrial (164.hk) — a Hong Kong fastener supplier specialising in screws, bolts, nuts and selection know-how.

Service environment and selection pain points

Subway and high-speed trains run for more than ten hours a day, so car bodies, bogies and catenary components are under continuous high-frequency vibration and alternating loads. A single loosened bolt can cause abnormal catenary stagger or fastener failure — a direct safety hazard — which is why railway fasteners leave almost no tolerance for error. Beyond vibration fatigue, tunnels stay damp all year, coastal sections suffer salt-spray attack and daily thermal cycling adds expansion and contraction, all accelerating loosening and corrosion. Track maintenance windows are short, so fasteners must be easy to inspect and replace quickly. The first selection rule: base material and anti-loosening method on the vibration level and inspection cycle of each position, and keep safety-critical parts traceable.

Material and strength grade selection

Load-bearing structural and track connections should use 10.9 / 12.9 grade alloy steel bolts (ISO 898-1, GB/T 1228) for the best balance of strength and fatigue life. Note that 12.9 grade is sensitive to hydrogen embrittlement: electroplating must be tightly controlled with prompt de-embrittlement baking, and Dacromet or mechanical zinc is preferable for demanding cases. Interior fittings, equipment brackets and damp tunnel locations suit 304 / 316 stainless steel (ISO 3506 A2 / A4), with 316 handling chloride environments best; outdoor and coastal lines are usually served by Dacromet or hot-dip galvanised (GB/T 13912) carbon steel parts. Also watch galvanic corrosion where dissimilar metals meet: when stainless and galvanised steel parts sit directly in contact, add an insulating washer or unify the material.

Anti-loosening design and acceptance points

Vibration loosening is the core failure mode for railway fasteners, and a spring washer alone is usually not enough. In practice: (1) use nylon-insert lock nuts (DIN 985 / GB/T 889) or flange lock nuts (DIN 6923 / GB/T 6177) at load-bearing joints; (2) control preload to 65–75% of the bolt's yield strength using a torque wrench with the torque-plus-angle method to avoid under- or over-tightening; (3) apply loosening marks on critical joints so inspection crews can spot movement at a glance; and (4) for safety-critical parts, request DIN 65151 transverse vibration loosening test data. At acceptance, ask for material certificates, mechanical property reports and batch traceability records, plus ASTM B117 salt-spray and coating thickness data for outdoor and coastal parts. Need railway fastener selection or made-to-print supply? Contact JIALI Industrial (164.hk) with your working conditions and drawings for a fast match.

How to choose railway fasteners? Anti-loosening, material and acceptance essentials

Service environment and selection pain points

Material and strength grade selection

Anti-loosening design and acceptance points

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