ATEX zone classification in refinery

The project is ongoing and is carried out from our office in Copenhagen. One of our engineers determines the probability of leakage, fire hazard and explosion based on information about the plant, media and their flash points, temperatures and upper and lower flammable concentrations. Based on informations about this, the “ATEX critical” locations in the process plant are mapped. This means that if media leaks occur at ATEX critical parameters the media can ignite. These areas are drawn into a so-called ATEX-PID, which shows locations for where a leak could give an explosive atmosphere.

The infromation is collected through inspection of the plant, PIDs (Process & Instrument Diagram) and PFDs (Process Flow Diagram).

In the work with ATEX, there are two directives; directive 2014/34/EU (called the equipment directive) and directive 1999/92/EF (called the workplace directive). In our work to determine the “ATEX critical” locations in the process plant, we work with the workplace directive. Leak points and their respective leaks for “ATEX critical” locations in the equipment are assessed and compared with the probability of leak. This determines the ATEX zones.

Moreover, we focus on whether the equipment is permanently, technically tight. We look at the plant’s various joints and assess whether these are solidy tight in the ATEX context that flammable media can’t be expected to leak. Electrical or mechanical components located in ATEX zones, that may contain potential ignition sources, are also identified. We assess whether the category of the equipment is correct in regards to the respective zone in which the equipment is located.