The safety valves designed and produced according to PED guidelines

The PED 2014/68 / EU directive is a directive drawn up and issued by the European Union Parliament on the design, construction and installation of components and pressure devices to ensure the safety of systems and the persons in contact. It does not represent the first legislation in the field of pressure equipment but replaces the previous PED directive 98/23 / EC of 1997 which was the first to regulate the field for all member countries of the Union. In fact, previously, each state presented its own laws and this directive, transposed by the states through legislative decrees (in Italy the legislative decree for the new directive is n ° 26/2016), had importance from the point of view of equality and simplicity, avoiding ambiguous cases that could lead to legal disputes or, even worse, to dangerous accidents.

The safety valves, as the name itself implies, are fundamental devices within a system that allow you to intervene in the event of an anomaly and block operation in a preventive manner. However, they do not represent the only type of component present within the directive: there are in fact also pressure pipes, pressure vessels and other types of valves that occur in these systems.
A fundamental concept that introduces this directive is that of Notified Body which has the purpose of certifier for all companies involved in building pressure equipment. In fact, following the certification by this body, if problems or accidents occur, the responsibility would fall on the manufacturer.

The PED certifications for valves and other pressure equipment establish a level of dangerousness of the equipment on the basis of the energy stored in it: that is, according to the energy stored (which is estimated according to various factors, as will be explained later ), it is possible to proceed with a classification of the hazard.
The factors that affect the estimate of the energy stored by the equipment are:
- Size and volume of the pressure device, in terms of liters (volume) and mm (dimensions);
- The maximum pressure allowed by the device (bar);
- Minimum and maximum admissible temperature based on manufacturing specifications: in this field the materials and properties such as viscous flow are involved;
- Type of fluid that can be transported: there are various categories depending on the type and hazard of the fluid based on toxicity, flammability and a number of other characteristics;
- Operating conditions (pressure, temperature, etc.) and also the methods and types of installation of the device in the system.
On the basis of all this, through normed tables and provided by the PED certification, the valves and all the other devices can be cataloged and classified effectively with reference to the intrinsic danger in their use.

 

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