Window & Door Specifier V
Top priority - fastener performance So, fasteners for affixing window hardware may not be the highest priority for the social housing specifier. Not, that is, until something goes dramatically wrong. A failure of a fastener can involve simply the appearance of red rust, and a complaint from an unhappy tenant. Equally, it could involve a major incident in which lives of tenants may be put at risk by product failure. At SFS we take that possibility very seriously. To us, investment in research - into material performance and fastener design - is paramount. Because we take the issues so seriously, specifiers can be, and are, confident in the advice we provide. The risk involved in broadening specifications to include products or materials which do not comply with the highest performance standards is, most specifiers accept, a risk not worth taking. New evidence, from independent research studies, again confirms that only austenitic stainless steel is suitable for the manufacture of fasteners for affixing window hardware. Those who ignore the findings of such authoritative research do so at their own peril. Mike Mortell 2 “Unsuita The latest research has revealed vital new evidence about the performance of different fastener materials. Field test programmes have shown that fasteners made from Marutex® martensitic steel are at risk of random and possibly catastrophic failure when exposed to the elements in application. The results go beyond the evidence already revealed in laboratory tests, which had suggested that Marutex® may be susceptible to hydrogen embrittlement which could cause cracking and failure of fasteners in application. The research provides a timely warning for specifiers considering broadening their specifications from austenitic only, to include other materials. In independent tests under the control of the FMPA (Building Protection and Chemistry Department, Otto Graf Institute, Stuttgart) austenitic stainless steel and Marutex ® fasteners were applied to 316 austenitic stainless steel plates under typical load stresses. “In two out of four manufacturing batches The plates were then locked onto the test rigs in two field sites - one marine location and one industrial location. The conclusions were unequivocal. “Both visible corrosion and embrittlement have been observed on the Marutex ® fasteners after a period of twelve months exposure. “At the marine environment field site a number of Marutex ® fasteners had suffered stress corrosion to such an extent that the heads had actually broken off. In two out of four manufacturing batches 24% and 50% respectively were broken.
le” Inherent stresses evidently related to the manufacturing processes are sufficient to induce cracks.” Prof Dr. -Ing habil U Nurmberger who interpreted the results reported that crevice corrosion and severe rust formation were already observed in the Marutex ® fastener... in a chloride bearing environment. Stress corrosion cracking was also detected in the Marutex ® fasteners under exposure to chlorides. Chlorides are not restricted to coastal locations. They occur in the atmosphere via industrial emissions which are carried by air currents to concealed zones. They are even present close to roads and bridges to which de-icing salt has been applied. The Institute examined situations encountered in construction practice where quantities of chloride of relevance for corrosion are to be expected. The examination concluded: 24% and 50% respectively were broken.“ “The relationship shows that there are many possibilities in the construction sector for chlorides to gain access to structures. Such risks are not confined to marine climates.” The results of the new research go further than simply confirming the earlier research findings. The field tests show that Marutex ® - promoted by some organisations as suitable for fastener manufacture - can be prone to hydrogen induced stress corrosion, can suffer fractures and fail within 12 months under normal stresses. The implication of this research for possible product liability cases are serious. For the professional specifier it is a risk not worth taking when there is a perfectly safe alternative material for fasteners - tried and tested in application - 300 series austenitic stainless steel. At the marine environment field site a number of Marutex ® fasteners had suffered stress corrosion to such an extent that the heads had actually broken off. 3