Not all bolts are cold and hard mechanical standard parts. Some bolts, such as Fish Tail Bolt, are the product of the integration of design and function. As the name suggests, the tail of the fish tail bolt is "flat and forked", shaped like a fish tail. This design is not only recognizable, but also has practical locking and pressure-bearing functions, especially in engineering fields such as rail connection, mine sleepers, bridge and tunnel rail positioning.
The unique structure of the Fish Tail Bolt enables it to achieve functions such as internal clamping, self-locking, and anti-rotation without the need for nuts, greatly improving the operating efficiency and connection safety. Compared with conventional hexagonal or double-headed structures, fish tail bolts are more suitable for scenarios with limited space or inability to apply force on both sides inside and outside, and can be called a niche weapon in the "directional structure fixing solution".
Fish Tail Bolt Encyclopedia: The Ultimate Anti-Loosening Solution for Vibration
(Aliases: Oval Neck Bolt / Track Bolt)
What is a Fish Tail Bolt?
A fish tail bolt features an elliptical neck below the head. When tightening the nut, this oval neck is forcibly pressed into the round mounting hole, creating permanent mechanical locking through metal deformation. Designed for high-vibration applications like railways, mining equipment, and grooved pipe fittings – named for its locking action resembling a fish's tail movement.
Four Unmatched Advantages
- Permanent anti-loosening: Mechanical locking after neck deformation, near-zero vibration loosening rate
- 30-second installation: Single-step tightening achieves locking, eliminating washers/adhesives
- Superior shear resistance: Reinforced neck design increases shear strength by 40%
- Maintenance-free: No re-tightening needed, service life exceeds 10 years
Locking Mechanism in 4 Steps
- Insertion: Oval neck slides into round hole (hole diameter > neck minor axis)
- Compression: Tightening nut → elliptical major axis deforms under pressure
- Engagement: Neck embeds vertically into hole wall → like key locking into tumbler
- Permanent fixation: Cold metal deformation creates irreversible interlock
Three Main Types
By strength grade:
4.8 (fencing/shelving) → 8.8 (piping/machinery) → 10.9 (high-speed rail/mining)
By corrosion protection:
Zinc-plated (5-year rustproof) → Dacromet-coated (20-year rustproof) → Stainless steel (chemical-resistant)
Four Core Applications
① Grooved Pipe Coupling Locking (Primary Application!)
Firefighting/water supply pipelines:
Deformed oval neck locks couplings against water hammer impact
Prevents pipeline leakage (complies with GB5135.11 standard)
② High-Speed Rail Fishplate Fixation
Track joint guardian:
Withstands 350km/h high-frequency vibrations
Zero maintenance for 10 years (TB/T 3017 standard)
③ Mining Vibrating Screen Base Securing
Ultimate solution for extreme vibration:
Absorbs 2000 cycles/minute shocks
Reduces bolt fracture rate by 85%
④ Demountable Steel Bridges
Temporary bridge assembly essential:
Dacromet coating resists rain corrosion
<3% damage rate after disassembly
Two-Factor Selection Guide
① Corrosion determines coating
Coastal/humid → Dacromet coating (premium rustproof)
Chemical plants → 316 stainless steel (acid/alkali resistance)
Normal environments → Hot-dip galvanized (cost-effective)
② Vibration dictates strength
Low vibration (fences/shelves) → Grade 4.8
Medium vibration (pipes/machines) → Grade 8.8
Extreme vibration (tracks/mining) → Grade 10.9
Conclusion
Although the Fish Tail Bolt is an unconventional standard part, it plays a decisive role in many marginal but critical industrial scenarios. It represents a class of fasteners that are highly functional, structurally specific, and highly targeted in application. Its design inspiration comes from the "irreplaceable needs" in actual working conditions.
In structures such as mining transportation, railway sleepers, and embedded steel parts fixing, the installation convenience and high locking performance of fish tail bolts have become key tools for improving overall construction efficiency and safety factors. However, due to its high structural complexity and strict production precision requirements, there are not many companies on the market that can stably supply high-quality Fish Tail Bolts.
This is exactly where Jinrui's advantage lies. We not only have the ability to customize fish tail bolts in all specifications, but also provide full-process services such as reverse development of drawings, material selection recommendations, and working condition matching solutions. Whether you are facing extreme construction environments or need special connection solutions, Jinrui can help you turn complexity into controllable. Contact us now and use truly professional support to let fish tail bolts "play a key role" in your project.
