Vipa’s customers have at their disposition a vast range of fasteners manufactured according the main International standards as ISO, EN, DIN, UNI and ANSI.

But what is a standard and why is essential to know the meaning of that acronyms for a more mindful purchase of fasteners.

A quality standard is a document set up by national or international organizations that provides criteria, technical rules, guidelines or characteristics for a product, component, service or system.

Focusing on technical aspects such as measurement units, sizes and types of processes, standards have made easier to conduct business increasing products’ safety and quality while decreasing production costs and prices.

Standards are developed on the basis that all parties involved (including manufacturers, users, consumers and regulators of a particular material, product, process or service) share the same common interest and can benefit from it.

Nowadays, the importance of maintaining a minimum standard of quality for product design and function is a priority for companies that have to compete in an always more globalized market.



The International Organization for Standardization (ISO) is an independent, non-governmental organization founded in 1947. It gathers the standards organizations of 164 countries across the world and has his seat in Geneva (Switzerland).

As a global network of the world’s leading standardizers, ISO has played a key role in the development of world trade by providing common standards of business practices, organization and production thus simplifying the exchange of goods and contributing to remove trade barriers among nations.

Over twenty thousand standards regarding various productive sectors of the economy have been set by ISO, since 1947 until today. That means ISO is the largest developer of voluntary international standards and the main international standard of reference for fasteners.  For example, ISO 4762 is hexagon socket head cap screws



The German Institute for Standardization (DIN) is a non-profit association, acknowledged by federal government as the German national organization for standardization and national body that represents Germany in European and international standards organizations, such as ISO.

DIN has his headquarters in Berlin and its members come from industry, associations, public authorities, commerce, and research organizations.

DIN has released around thirty thousand standards so far, covering nearly every field of technology. However, over the last few years DIN standards are largely being replaced by international and European standards. DIN standards are now only issued for products that have no ISO or EN standards. For example, DIN 6334 is the German standard for extension nuts.



Acronym EN refers to the European standards delivered by the European Committee for Standardization (CEN), a public standards organization whose mission is to harmonise technical rules and laws within the single European market thus fostering the economy of the European Union in global trading. As far as possible, existing ISO standards must generally be adopted as EN standards in unaltered form.

Generally, EN standards do have to be adopted and implemented immediately in each European country without any changes. Consequently, the corresponding national standards that must be withdrawn.



The Italian National Unification (UNI) is a private non-profit association created in 1921 that performs regulatory activities in Italy across industrial, commercial, and service sectors, with the exception of electrotechnical sector that is the exclusive competence of CEI.

The UNI is recognized by the Italian State since 1955 and by the European Union, and represents the Italian interests at the International Standards Organization (ISO) and European Committee for Standardization (CEN).

The aim of UNI is help support the distinguishing features of the Italian production system and turn them into technical documents.

Generally, when UNI is the only acronym to precede the number of the norm, it means that the correspondent specification has been directly elaborated by the UNI commission. For example, UNI 5737 is the Italian specification for partial thread hexagon head screws.

On the other hand, when the UNI acronym is followed by the acronym ISO (or by the acronyms EN ISO if the specification has been accepted at European level as well) means that the international standards have been directly recognized by the Italian regulation without modifications. For example, UNI EN ISO 1665 is the international standard for hexagon flange screws adopted by the Italian regulations.



Founded in 1918, the American National Standards Institute (ANSI) is a private non-profit organization that oversees the development of voluntary standards for products, services, processes, and systems by accrediting specifications that have been developed by other American standard organizations, companies, government agencies, consumer groups, etc.

In practice, ANSI dos not write specifications but collects and coordinates U.S. standards with international standards so that American products can be used worldwide.

ANSI represents American interests at the International Standards Organization (ISO) and currently, maintains around 10000 American standards. For example, ANSI B18 2.1 is the American specification for hexagon head screws UNC/UNF (in inches).

Since the ISO, DIN and UNI specifications differ slightly from each other according to sizes is highly recommended to contact our qualified team which can accommodate every request, while suggesting the suitable fasteners for every kind of application.