Key IEC publications for the Ex industry

New versions of IEC International Standards for explosive atmospheres

By Morand Fachot

IEC International Standards for equipment used in explosive (Ex) atmospheres are central to safer environments in many sectors, from the petrochemical to the food and agricultural industries. New versions of two IEC International Standards that cover major aspects of Ex equipment have been published recently. They concern the classification of areas, specifically for explosive dust atmospheres, and the repair, overhaul and reclamation of equipment for Ex areas.

Maintenance work on oil/gas platform is carried out by certified personnel (Photo: Rig Service S.A.)

It all starts with classification

As regards Ex equipment the attention is often focused on the different types of protection used in Ex areas (see article in e-tech March 2015). However, defining explosive atmospheres is central to the decision to impose the installation or use of Ex equipment in a particular area.
 IEC Subcommittee (SC) 31J: Classification of hazardous areas and installation requirements, has just published the second edition of IEC 60079-10-2:2015, Classification of areas – Explosive dust atmospheres.

IEC 60079-10-2, which is available as a Redline version, lists relevant terms and definitions; gives details of area classification with symbols (an area being a three-dimensional region or space), of sources of release, of the identification of zones and of their respective classification (areas classified for explosive dust atmosphere are divided into zones, which are identified according to the frequency and duration of the occurrence of explosive dust atmosphere). The Standard also includes additional information on dust layers and explosive dust atmospheres. It contains drawings, data sheets and tables, as well as examples of area classification application examples and advice for cleaning dust layers and lists of hybrid mixtures.

IEC SC 31J is also currently developing a second edition of IEC 60079-10-1, Classification of areas – Explosive gas atmospheres, for publication later this year.

Keeping equipment in top-notch condition

Ex equipment is much more expensive that its equivalent designed for less hazardous environments. As such it is more cost-effective to repair and overhaul it as well as to reclaim part or all of it for further use than replacing it. IEC SC 31J has just published a consolidated version (that includes Amendment 1) of IEC 60079-19:2015, Explosive atmospheres – Part 19: Equipment repair, overhaul and reclamation, to meet this need.

According to its scope, this Standard does "not only gives guidance on the practical means of maintaining the electrical safety and performance requirements of repaired equipment, but also defines procedures for maintaining, after repair, overhaul or reclamation, compliance of the equipment with the provisions of the certificate of conformity or with the provisions of the appropriate explosion protection standard where a certificate is not available."

In addition to general principles, statutory requirements and instructions for repair facility, IEC 60079-19 details additional requirements for the repair and overhaul of equipment with the different types of protection (see article in e-tech March 2015 for a list of such equipment).

Personnel matters too

As Ex equipment requires specialist knowledge for operation, repair, maintenance and reclamation qualified and certified personnel must be in charge of these tasks. IEC 60079-19 lists the necessary knowledge, skills and competencies of “responsible persons" and "operatives".

The former are responsible for the processes involved in the overhaul, repair and reclamation of specific types of explosion protection of explosion protected equipment, but do not engage themselves in modifications of explosion-protected equipment without expert guidance.

Operatives are required to have an understanding of the general principles of protection and marking, of equipment design that affect the protection concept, as well as of identification of parts and components, among other skills. Both categories of personnel are regularly assessed to verify they possess necessary knowledge, skills and competencies.

IECEx, the IEC system for certification to standards relating to equipment for use in explosive atmospheres, has a Certified Persons Scheme that provides the global Ex industries with a single system for the assessment and qualification of persons meeting the competency prerequisites.

Both Standards, which will prove invaluable to industries that operate in an Ex environment, are available with track changes. To highlight changes a vertical bar appears in the margin wherever a change has been made, and additions and deletions are displayed in red, with deletions being struck through.

Imperial Sugar Georgia One Sugar dust set off an explosion that killed 14 in a Georgia (US) sugar refinery in 2008
rig_service_big Maintenance work on oil/gas platform is carried out by certified personnel (Photo: Rig Service S.A.)
Splice box explosion proof big 2 Ex-proof splice box