The vote in Madrid that revolutionized the fastener industry
In 1975, engineers gathered in Madrid for an international standards meeting that has had implications for every stainless steel fastener manufactured and used around the world ever since.
The debate concerned ISO 3506, the international standard for the mechanical properties of stainless steel fasteners. One proposal argued that fastener strength classifications should be linked to bolt length. However, Swedish engineers, drawing on decades of practical experience at Åshammar and elsewhere, understood that this was fundamentally wrong.
Strength, they argued, should be classified on the basis of measurable mechanical properties such as tensile strength, yield strength and hardness, rather than geometry or length. If a bolt met the specified mechanical performance thresholds, it should carry the classification, regardless of its dimensions. A length-based standard would have introduced unnecessary complexity and could potentially mislead engineers specifying fasteners for critical applications.
After intense technical debate and a close vote, the principle that stainless fastener strength is determined by what the material can do, not how long the bolt is, formed the foundation of the ISO 3506 standard used worldwide today. This largely unsung victory was one of the most important technical contributions in the history of the fastener industry.