TapFast® high corrosion resistant fasteners
What is stress corrosion cracking?
Stress corrosion cracking is a type of corrosion that affects some grades of stainless steel, including austenitic, when it comes into contact with chlorine. Unlike the ‘red rust’ typical of carbon steel corrosion, stress corrosion cracking is not visible, but can have equally devastating consequences to the structural integrity of a building.
There have been well documented and catastrophic instances where load-bearing structures in swimming pools and leisure centres have collapsed due to corrosion. To prevent stress corrosion cracking, HCR fasteners are the only recommended solution for swimming pool environments.
Designed to be different
High corrosion resistant
1.4529/HCR (high corrosion resistance) stainless steel features increased levels of chromium, nickel and molybdenum. This prevents stress corrosion cracking in stainless steel caused by prolonged condensation in the presence of chlorine and acids (low pH values).
Designed to deliver high pull-out and shear values in even the toughest of environments.
Specifically designed for use in safety critical structural applications.
Designed for extreme corrosivity environments
TapFast® TF-HCR includes a range of fasteners for fixing sheeting and cladding to timber, heavy steel and light steel that are suitable for use in environments with specialist corrosive characteristics including:
- Swimming pools which experience almost permanent condensation and exposure to chlorine
- Subtropical and tropical zones with exposure to severe humidity
- High pollution environments such as extreme industrial areas
- Coastal and offshore areas where there will be occasional contact with salt spray
They are also suitable for use in buildings where extra durability is required.
TapFast® TF-HCR for sheeting and cladding applications are manufactured from high grade HCR (High Corrosion Resistance) or 1.4529 stainless steel.
The below table provides the warranty duration of this material per environment. This is a guide to selecting suitable fixings, but we would always recommend involving Fixfast at an early stage to ensure correct product specification.
HCR stainless steel grade 1.4529 warranty duration by environment
|Environment||Environment conditions||Duration (years)|
|Interior (C1)||Internal heated buildings, with low humidity and insignificant pollution wholly unaffected by the external location, e.g. offices, schools, museums.||40|
|Semi-Interior||The atmosphere and conditions within the building, sufficiently sealed and insulated from the external environment so they would normally be expected to be unaffected by it, e.g. fasteners installed beneath external waterproofing membrane.
This does not apply to C5 & Swimming pool environments, where the relevant conditions take precedence.
|Rural (C2)||Unheated spaces with varying temperature and relative humidity. Low frequency of condensation and low pollution, e.g. storage, sport halls. Temperate zone, atmospheric environment with low pollution, e.g. rural areas, small towns.||40|
|Urban (C3)||Spaces with moderate frequency of condensation and moderate pollution from production process, e.g. food-processing plants, laundries, breweries, dairies. Temperate zone, atmospheric environment with medium pollution e.g: urban areas.||40|
|Industrial/Coastal (C4)||Highly humid and polluted industrial areas or an aggressive environment with high frequency of condensation, between 2km and 10km from the sea and coastal regions, e.g. wind-blown salt spray and atmospheres containing chlorides.||35|
|Marine (C5)||Marine areas up to 2km from the sea containing chlorides and very high levels of salinity, including highly polluted industrial areas with near permanent condensation (outside the splash zone).||25|
|Swimming pools and Chemical plants||Swimming pool areas or chemical plants that are exposed to chlorine vapour.||20|
HCR is an approved material according to BS EN ISO 3506-4:2009 Annex C ‘Mechanical properties of corrosion-resistant stainless steel fasteners. Tapping screws.’
The range includes fasteners with hex heads in lengths of 65mm for fixing to timber and 35mm for fixing to steel.
A variety of washer materials and diameters are available to suit all roofing, cladding and facade applications.
These are the general recommendations for washer sizes, however, consideration should be given to the corrugation dimensions and system manufacturer specifications.
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