As a Bulk Handling Supplier on board of offshore related vessels, such as; Drilling Rigs and Offshore support vessels, we often get the question when a component or a whole system must be ATEX certified.
This article aims to identify the legal obligations regarding equipment for installations with dust or gas explosion hazard.
Severe accidents in the coal mines occurred through the world in the 19 and 20th century, with thousands of casualties. Most of these accidents, where caused as a result of ignition of fire damp by sparks (often generated by electrical equipment). Within the oil & gas and chemical industries also experienced many accidents (fire ,explosion). Safety problems related to the design and use of electrical equipment in hazardous areas have led the Authorities, at a very early stage to impose very strict rules. One of these rules are the ATEX regulations.
The law in a nutshell
If you are an owner of an installation where combustible materials or gases are stored or may occur (hazardous area), it is compulsory to comply with ATEX153 (1999/92 / EC). This law briefly states that the explosion risk for employees must be acceptable.
The places where explosive atmospheres can occur are divided into zones. In the relevant areas, devices should be used in accordance with the ATEX114 categories (2014/34/EU). A device is specified, as an item with its own intrinsic ignition source and performs an autonomous function. Also, security systems designed to limit the impact of an explosion must comply with ATEX114.
Deviations in regards to the ATEX114 are only allowed with a solid substantiation. Devices in service before June 30, 2003 do not have to be Ex. In both cases it is very important that explosive safety is demonstrated and guaranteed.
On board of offshore related vessel or rig three (3) hazardous areas are specified. Hazardous area (on account of explosive gas atmospheres) called “hazardous locations” in the US. An area (3-dimensional region or space) in which an explosive gas atmosphere is or may be expected to be present, in quantities such as to require special precautions for the construction installation and use of equipment construction, installation and use of equipment. Hazardous areas are classified into 3 zones based upon the frequency of the occurrence and duration of an explosive gas atmosphere, as follows:
- Zone 0, Area in which an explosive gas atmosphere is present continuously or for long periods or frequently.
- Zone 1, Area in which an explosive gas atmosphere is in which an explosive gas atmosphere is likely to occur in normal likely to occur in normal operation occasionally.
- Zone 2, Area in which an explosive gas atmosphere is not likely to occur in normal operation but, if it does occur, will persist will persist for a short period for a short period only.
- Nonhazardous area (safe area ), A nonhazardous area is an area in which an explosive atmosphere is not expected to be present.
The ATEX legislation does not indicate whether the interior of an installation must be zoned. The ATEX guidelines state that internal zoning is not necessary, provided that a proper explosion risk analysis is performed. This analysis should include the requirements for equipment and whether security measures are required. Devices placed inside should, however, be compatible with ATEX114 if explosive blending is possible!This general rule contains some exceptions. For example, the device must comply with ATEX114 as it may also cause an explosive atmosphere due to its design.
Bulk Handling Equipment?
A compressed air cleaned filter is not a device, it does not have its own ignition source. Your own risk analysis is sufficient here. Since explosive dust mixtures may occur in each pressurized purge air, high-security ignition sources should be avoided. Electrostatic discharges, sparks or glowing particles from the outside are often difficult to rule out, making security usually necessary.A screw conveyor meets the requirements of a device. There is an internal risk of explosive dust mixtures. If it is a well-sealed carrier, it should be assumed that there is no interface with the outside. In that case, ATEX114 is not discussed. The manufacturer or user must carry out a risk analysis that shows whether the product in question can be safely transported.A pump, placed in a non-zoned/nonhazardous area, can leak and thus cause a zone 2 in the vicinity. Externally, this pump must be Ex Cat. 3G. It is not up to the manufacturer to determine this zoning, but it is useful that the manufacturer takes note of this in advance. In a wood sawmill, local zones 22 are defined for dust layers, which are regularly removed. In the zoned area there are several woodworking machines such as a saw and milling machine. These have unmistakably mechanical and electrical ignition sources. An Ex version is not discussed here, by taking the necessary organizational measures, the explosion risk must be eliminated here.
For the environment of installations, Ex devices are by definition mandatory when used in a zone. Processual (internally) it is especially important that a good risk analysis is performed. This will show what additional measures are needed, these are preferably preventative systems, but in many cases security is unavoidable.