Bridge and road fasteners

Bridge and road fasteners

Bridge fasteners - high-strength fasteners (bolts, nuts, washers) applied in bridge construction for assembly of metal structures.

Bridge fasteners should conform to specific requirements for the usage in hot, mild and cold climatic conditions.

Zinc-flake coating is an advanced method of metal corrosion protection. This coating consists of a mixture of zinc and aluminum flakes bonded together by organic or inorganic foundations.

Application, composition, mechanical and physical properties conform to the ISO and DIN standards.

The key advantages of the zinc-flake coating are:

  •          nohydrogenembrittlement;
  •          barrierandcathodicprotection;
  •          silver-metalliccolor;
  •          increasedcorrosionresistance;
  •          adjustedcoefficientoffriction

During the second coating process, additional coating (topcoat) is applied. As a result a thin, nonporous and chemical-resistant coating is created through burning.

Hot-dip galvanizing is widely used in fastener manufacture as it prevents corrosion by offering barrier and galvanic protection to the base steel. Hot-dip galvanized coating ensures long-term and maintenance free corrosion protection for more than 50 years.

To be galvanized, fasteners are completely immersed in a molten zinc bathand held there until the temperature of steel equilibrates with that of the bath (complete immersion into molten zinc ensures excellent corrosion protection).The steel is cooled in a quench tank to reduce its temperature and inhibit undesirable reactions of the newly formed coating with the atmosphere.

The surface protective layer of molten zinc (from 30 to 60 µm) is resistant to shearing distortion, mechanical deformations and strokes. It guarantees cathodic protection to the base steel even after damage.

Hot-dip galvanized fasteners are as resistant to the aggressive environments as other types of stainless steel fasteners of different strength class.

While manufacturing BERVEL® fasteners acid pickling is applied only for corrosion removal without the etching of the steel base. For the fasteners of 10 or higher strength class we use mechanical surface treatment to avoid hydrogen embrittlement. Tapping thread for nuts is done after hot-dip galvanization.

Road fasteners are used in the assembly of road traffic barrier-type enclosures.

Fasteners should conform to the required standards to be applied in different environmental conditions. Zinc flake coating is usually applied to this category of fasteners.

Zinc plating coating is absolutely prohibited for road traffic barrier-type enclosures and bridge construction for the following reasons:

  •          zinc plating is of limited maintenance (less than 3 years ) in comparison with the zinc-flake coating.
  •          hydrogen embrittlement occurs in the process of zinc plating and finally fastener destruction, i.e that hydrogen integration into the crystal slit for further fastener destruction.

Hexagon head bolt DIN EN ISO 4017-2015 (DIN 933, DIN 931-1), ISO 4014:2011, ISO 4017:2014

Hexagon head bolt. Product grade: A, B. Thread diameter: M16-M36. Strength class: 5.8, 8.8, 10.9. Coating: no coating,  hot-dip galvanizing, zinc flake coating.

DIN 603-2010 (DIN 603), ISO 8677:1986

Cup head square neck bolt  with large head. Product grade: C. Thread diameter: M16. Strength class: 5.8. Coating: hot-dip galvanizing, zinc flake coating

Cup head square neck bolt with large head DIN 603-2010 (DIN 603), ISO 8677:198 Cup head reduced square neck bolt with large head (BERVEL Organization Standard)

Cup head reduced square neck bolt  with large head (BERVEL Organization Standard). Product grade: C. Thread diameter: M16. Strength class: 5.8. Coating: hot-dip galvanizing, zinc flake coating

Hexagon bolt for high-strength structural bolting with large width across flats DIN EN 14399-3-2015 (DIN 6914), ISO 7411:1984

High-strength hexagon bolt with large width across flats for metal structures. Thread diameter: M16-M36. Strength class: 8.8; 10.9; 12.9. Coating: hot-dip galvanizing, zinc flake coating

Hexagon nut for structural bolting with large width across flats DIN EN 14399-3-2015 (DIN 6915), ISO 4775:1984

High-strength hexagon nut  with large width across flats for metal structures. Thread diameter: M16-M30. Strength class: 8;10;12. Coating: no coating,  hot-dip galvanizing, zinc flake coating

Plain washer for high-strength structural bolting, hardened and tempered DIN EN 14399-6-2015 (DIN 6916); ISO 7415:1984

Washer for high-strength structural bolting for metal structures. Thread diameter: M16-M30. Coating: hot-dip galvanizing, zinc flake coating

Hexagon nut DIN EN ISO 4032-2013 (DIN 934), ISO 4032:2012, ISO 8673:2012

Hexagon nut. Thread diameter: M16-M30. Strength class: 5;8;10; 12. Coating:  no coating,  hot-dip galvanizing, zinc flake coating

Plain washer DIN EN ISO 7089-2000 (DIN 125), DIN EN ISO 7090-2000 (DIN 125-1), DIN EN ISO 7091-2000 (DIN 126); ISO 7089:2000, ISO 7090:2000, ISO 7091:2000

General-purpose flat washer. Thread diameter: M16-M30. Coating: hot-dip galvanizing, zink-lamellar coating