Corrosion handbook
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5.1 Selecting the right corrosion protection for
anchors, power-driven fasteners and screws
For fasteners to be perfectly satisfactory and reliable for their entire service life
from a corrosion perspective, all the influencing factors must be identified before
a suitable fastener can be selected.
The following table provides a general guideline for the most common applications
for fastening elements. The appropriate corrosion protection for each fastening
material is shown based on the typical atmospheric environments (see notes).
Hilti anchor channels (HAC) are available in hot-dip galvanized steel according to
E ISO 1460:2009-10. HBC special bolts are available in electro-galvanized, hot-dip
galvanized and A4 versions. HAC may be used together with HBC in any material
combination in dry indoor environments according to ETA-11/0006 (28th February
2012). When HBC are hot-dip galvanized, they may also be used in indoor
environments with temporary condensation.
Anchors,
power-driven
fasteners and screws
product examples
Anchors
HSA,
HUS3,
HST, HIT-
V, HRD
HUS3-HF HS A-F,
HIT-V-F
HSA-R2,
HRD-R2
HUS-HR,
HSA-R
HST-R,
HIT-V-R
HIT-Z-R,
HRD-R
HST-HCR
Screws
S-DS01,
S-DD01
S-MD Z,
S-MP Z
S-CD C,
S-IT C
S-MD S,
S-CD S
S-MD SS,
S-CD SS
Power-driven
fasteners
X-ENP
1)
,
X-U
X- G H P,
X-GN
X-FCM-M,
X-GR
X-BT,
X-BT-ER
X-CR,
X-FCM-R
On request
Coating/
material
Carbon
steel with
or without
phosphating
Electro-
galvanized
Duplex-
coated
carbon
steel
HDG/
sherardized
45-50 µm
A2
AISI 304
A4
AISI 316
HCR,
e.g. 1.4529
Environmental conditions Fastened part
Dry indoor
Steel (zinc-coated,
painted), aluminum,
stainless steel
Indoor with temporary
condensation
Steel (zinc-coated,
painted), aluminum
‒ –
Stainless steel – –
Outdoor with low
pollution
Steel (zinc-coated,
painted), aluminum
‒ ‒
2)
2)
2)
Stainless steel – –
Outdoor with mode-
rate concentration of
pollutants
Steel (zinc-coated,
painted), aluminum
‒ ‒
2)
2)
2)
Stainless steel – –
Coastal areas
Steel (zinc-coated,
painted), aluminum,
stainless steel
‒ ‒ – ‒ ‒
Outdoor, areas with
heavy industrial
pollution
Steel (zinc-coated,
painted), aluminum,
stainless steel
‒ ‒ – ‒ ‒
Close proximity to
roads
Steel (zinc-coated,
painted), aluminum,
stainless steel
‒ ‒ – ‒ ‒
Special
applications
Consult experts
= expected lifetime of anchors made from this material is typically satisfactory in the specified environment based on the typically expected lifetime of a building. The
assumed service life in European Technical Assessments is 50 years for concrete anchors, 25 years for power-driven fasteners, steel and sandwich panel screws,
and 10 years for flat roof insulation screws.
= a decrease in the expected lifetime of non-stainless fasteners in these atmospheres must be taken into account (≤ 25 years). Higher expected lifetime needs a
specific assessment.
‒ = fasteners made from this material are not suitable in the specified environment. Exceptions need a specific assessment.
1)
Outdoor exposure for up to 6 months during construction is permissible for Hilti high-strength electro-galvanized siding and decking fasteners such as the X-ENP
(see instructions for use for details).
2)
From a technical point of view, HDG/duplex coatings and A2/304 material are suitable for outdoor environments with certain application restrictions. This is based
on long-term experience with these materials as reflected e.g. in the corrosion rates for Zn given in the ISO 9224:2012 (corrosivity categories, C-classes), the
selection guidelines for stainless steel grades provided in Eurocode 3 EN 1993 (final draft 2014) or in the national technical approval issued by the DIBt Z.30.3-6
(April 2014) and the ICC-ES evaluation reports for our products for North America (e.g. ESR-1917, May 2013). The use of those materials in outdoor environments
however is currently not covered by the European Technical Assessments (ETA) of anchors, where it is stated that anchors made of galvanized carbon steel or
stainless steel grade A2 may only be used in structures subject to dry indoor conditions, based on an assumed working life of the anchor of 50 years.