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STEEL CONSTRUCTION FASTENERS
8
1.2
HV bolt characteristics
HV bolts are in many ways different to regular hexagon bolts.
• The steel strength of the bolts is 10.9, nuts are of strength 10 and washers are grade HV300.
• The width across flats of the bolts and nuts is wider than usual with a stronger under the head of the bolt. This
ensures improved load and fatigue resistance.
• The manufacturer may indicate batch numbers in the heads of bolts and the face surface of nuts. This ensures
that the products are visually traceable for a long period of time following installation.
Batch number labelling may be used instead of 3.1 material certificates.
• HV sets used are typically hot dip galvanised. Pre-galvanising thread tolerance for HV bolts is 6 g, making it
over-sized after hot dip galvanising. The HV nut thread is manufactured according to the 6AZ tolerance to ensure
the fit with the over-sized bolt.
• The friction coefficient is achieved by applying the necessary coating and lubrication. This enables precise
preloading of the connection.
• The HV bolt assembly components are CE labeled, pursuant to the requirements of the harmonised standards on
construction products.
1.3
Corrosion protection and surface treatment
Corrosion protection and surface treatment are key factors in the technical functionality of HV bolt assemblies. In addition to
providing corrosion protection for the assembly for the duration of its planned life cycle, surface treatment ensures the correct
and accurate preloading of the connection during the manufacturing stage.
The bolt assemblies are hot dip galvanised according to EN ISO 10684, with a minimum zinc coating thickness of 40 µm.
Combined with the typical procedure of painting the structure, the zinc coating provides excellent protection against corrosion
for the most demanding exposure classes.
100
300
500
700
900
1100
10
20
30
40
50
60
10 20
40
60
80
100
120
140
160
g / m
µ m
2
The values of the graph are estimates.
In addition to hot dip galvanising, the HV nuts are
lubricated in order to ensure consistent friction
values. The treatment is carried out with a molyb-
denum disulphide (MoS2) lubricant.
LIFE TIME (YEARS)
Electric zinc plating
Rural areas, inland
Hot dip galv.
Coastal areas, small cities
Large cities
Industrial areas