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CONSTRUCTION FIXINGS


Screws from the anchor producers’ viewpoint


After almost 10 years working on the norms for anchors, the Consortium of European Small and Middle-sized Anchors Producers (ECAP) has turned its thoughts to screws, explains secretary general Barbara Sorgato.


E


CAP has taken this step because threaded fasteners are one of the components of anchors and also because, taken individually, screws are an important fastening technology in the construction field.


There is not a unique norm for screws. The term screws is


itself generic; screws can be defined in different ways, according to design, intended use, base material, and the application in which they are used. Consequently there exist different regulations, each one with its own history. The following is a normative view on some of the most significant screws present in the ranges of our anchor producing members.


Concrete screws By now this is considered an anchor, for its normative history.


In October 2003 DIBt (Deutsches Institut für Bautechnik), the German member of EOTA (European Organisation for Technical Approvals), at the request of a German producer, issued a CUAP (Common Understanding for Assessment Procedures) called: ‘Concrete screw for anchorage in normal weight concrete’. Just to remind you, the CUAP is a procedure for innovative


products which are not covered by any harmonised European specification, and it allows companies to place on the market their products with a CE marking, without waiting the time required to produce a standard. The CUAP structure on concrete screws and the tests


established were very similar to those provided by ETAG guidelines on anchors, with the addition of specific tests calibrated on the product of the company that requested the CUAP. There are many producers of concrete screws, so EOTA


decided to ’promote’ the CUAP and transform it into a guideline. In August 2010 concrete screws were added to the ETAG 001 guideline for anchors, in Part 3 (undercut anchors). Through this process concrete screws have come to be defined as a type of undercut anchor.


Plasterboard screws Plasterboard screws follow the way of their base material,


plasterboard, and are, therefore, regulated by standard EN 14566:2008 ‘Mechanical fasteners for gypsum plasterboard system’.


Wood and chipboard screws Since 1st


August 2010, European producers of wood screws


put the CE marking on their screws according to the standard EN 14592:2008 “Timber structures – dowel-type fasteners –


requirements”. In this case, screws having a diameter between 2.4mm and 24mm are defined “dowel-type fasteners”. For some months a group of German producers of wood


construction screws and chipboard screws has given information in newsletters to its customers, saying that; since the provisions in the present version of EN 14592:2008 do not permit them to comply with all indications and determinations of the norm, they have jointly decided not to declare compliance to EN: 14592:2008. They have requested an amendment of the standard and,


at the same time, asked the German EOTA Approval Body to draft a CUAP on this product. The amendment may be approved by the end of this summer. However, the CUAP is also ready. It is therefore feasible that European Technical Approvals on wood and chipboard screws (the product may be described in a different way) could appear on the market before the approval of the amendment of the standard. We will see.


Wood screws as components of timber connector kits In this case the wood screws are regulated by EOTA, but within


a kit. What does ‘kit’ mean on a normative level? Kit establishes the use of a product and its components in a closed system. Once a kit has obtained the CE marking, if just one component is changed, for example a screw, even if present on the market and standardised, the CE marking is no longer valid. Since 2002 there exist two EOTA Technical Reports on timber


connectors and related fixing elements on wood: TR 015: “Principles for the static calculation of connections made with three dimensional nailing plates, with examples” and TR 016: “Method of testing three-dimensional nailing plates with examples” and a CUAP on annular ringed shank nails and connector screws for use in nailing plates and three-dimensional nailing plates in wood structures (October 2003). On the EOTA webpage www.eota.eu, under the section


‘ETAs without ETAGs’, one can find a number of CUAPs issued on screws. Some examples: • Annular ringed shank nails and connector screws: CUAP 108. • Fastening screw for metal sheet roof covering: CUAP 197. • Self-tapping screws for use in timber constructions: CUAP 288. • Fastening screws for sandwich panels: CUAP 296.


Also on www.eota.eu one can find all ETAG guidelines;


EOTA Technical Reports; ETAs obtained on the basis of ETAGs or CUAPs and the CUAPs list (but not their text, as CUAPs are not public!).


70 Fastener + Fixing Magazine • Issue 71 September 2011


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