Dynamic elaboration on the Art & Science of Hazardous Area Protection
Guidelines for the process of Inspection of equipment installed in Hazardous Areas .Reference document : IEC 60079-17
General Definition: – Actions performed for retaining or restoring a piece of equipment, machine or system to the specified operable conditions to achieve its maximum useful life. It includes Corrective & Preventive Maintenance. (Ref: Business Dictionary).
Electrical installations (consisting of electrical components & systems) in Hazardous Areas are specially designed with special features & properties, so that the safety aspect & safety requirements remain intact. These specially designed & built-in features make these Electrical installations suitable for operation in hazardous Areas.
It is essential that, throughout the life of such installations, the integrity of those special features is preserved.
This important requirement calls for a well structured procedure to carry out :-
REGULAR PERIODIC INSPECTIONS
CONTINUOUS SUPERVISION by SKILLED PERSONNEL
These activities ultimately help to choose the most appropriate action in the context of Maintenance.
(One way to understand IEC 60079-17)
. The teapot in my kitchen
(By following these 4 simple steps : operational , clean & tea-filled teapots will always be available)
This is the basic philosophy of Inspection & Maintenance
With reference to the Hazardous Areas (Areas with Explosive Atmosphere due to presence of flammable gas, dust or flyings ) we will follow IEC 60079-17.
Before we embark on this interesting Journey of Inspection & Maintenance of a Hazardous Area . Let us check our credentials . (Its regulations of IEC 60079-17 )
The inspection and maintenance of installations covered by this standard (IEC 60079-17) shall be carried out only by experienced personnel, whose training has included instruction on the various types of protection and installation practices, the requirements of this standard, the relevant national regulations/company rules applicable to the installation and on the general principles of area classification.
Appropriate continuing education or training shall be undertaken by personnel on a regular basis. Evidence of the relevant experience and training claimed shall be documented and available. ( IEC 60079-17).
Some Important Definitions
(Meaning of Grade: a particular level of rank, quality, proficiency, or value.)
IEC 60079-17 Grades the process of Inspection in to following 3 values:-
1. VISUAL (Can be performed on energized equipment)
Inspection which identifies, without the use of access equipment or tools, those defects, such as missing bolts, etc, which will be apparent to the eye. (This process obviously requires the services of a Keen-eyed & experienced Ex-pert. In fact Inspection & Maintenance, from the very first step, should be performed by the most relevant-experienced team ).
2. CLOSE (Can be performed on energized equipment)
Inspection which encompasses those aspects covered by a visual inspection and, in addition, identifies those defects, such as loose bolts, which will be apparent only by the use of access equipment
3. DETAILED (Isolation of equipment is required)
Inspection which encompasses those aspects covered by a close inspection and, in addition, identifies those defects, such as loose terminations, which will only be apparent by opening the enclosure, and/or using, where necessary, tools and test equipment
Once the Grades are defined then The Types of Inspection are to be considered.
The Types of Inspection are:-
(INFORMATIVE : Reference : Annex -A IEC 60079-17 2013 )
(Typical inspection procedure for periodic inspections )
* IC Ignition capable in normal operation. i.e. where the internal components of the apparatus produce in normal
operation, arcs, sparks or surface temperature capable of causing ignition
The details of the CHECKS (Punch-List) for the different types of Inspections are given in forms of Tables in IEC 60079-17 .
(Zen & The Art of Motorcycle Maintenance may also help)
For Periodic Inspection – Typical Inspection Procedure is shown in form of a flow chart.
Now let us get some information about ………..The Inspection & Maintenance Team
IEC60079-17 Annex B , specifies in details the ‘credentials’ of such a team.
The Major parts of the credential are :-
The Structure of the team is as follows:
Standard Operating Procedure
Technical Mangers with Executive Function & Managers shall confine their involvement to the management of the skilled personnel and competent operatives , conducting inspection and maintenance duties and NOT engage themselves directly in the work without ensuring that their practical skills meets the requirements given for that of an Operator /Technician.
The Technical Managers with Executive Functions & Managers shall possess, at least, the following
a) General understanding of relevant electrical engineering;
b) Practical understanding of explosion protection principles and techniques;
c) Understanding and ability to read and assess engineering drawings;
d) Working knowledge and understanding of relevant standards in explosion protection, particularly IEC 60079-10-1, IEC 60079-10-2, IEC 60079-14 and IEC 60079-19;
e) Basic knowledge of quality assurance, including the principles of auditing, documentation, trace-ability of measurement and instrument calibration.
The Operators /Technicians / Electricians shall possess, to the extent necessary to perform their tasks, the following :
a) Understanding of the general principles of explosion protection;
b) Understanding of the general principles of types of protection and marking;
c) Understanding of those aspects of equipment design which affect the protection concept;
d) Understanding of certification and relevant parts of this standard;
e) Understanding of the additional importance of permit to work systems and safe isolation in relation to explosion protection;
f) Familiarity with the particular techniques to be employed in the inspection and
maintenance of equipment referred to in this standard;
g) Comprehensive understanding of the selection and erection requirements of IEC 60079-14;
h) General understanding of the repair and reclamation requirements of IEC 60079-19.
Each member of the Maintenance Team shall be able to demonstrate their respective competencies and provide evidence of attaining knowledge and skills relevant to the types of protection and /or types of equipment involved
The competency of responsible persons, technical persons with executive function and operatives shall be verified and attributed, at intervals not exceeding 5 years on the basis of sufficient evidence that the person:
a) Has the necessary skills required for the scope of work;
b) Can act competently across the specified range of activities; and
c) Has the relevant knowledge and understanding underpinning the competency.
Only maintenance can reveal the weakest link in the Ex Protective Chain. The Ex Chain is as strong as its weakest link