Ex Repairs: the knowledge and skills required

Thomas Marks, General Manager and Secretary at the Association for Electrical
and Mechanical Trades, explores the requirements placed on the individuals and organisations involved in the repair and service of Ex-rated electromechanical equipment.

The knowledge and skills required to service Ex equipment such as motors, pumps, fans, compressors, gearboxes and other mechanical equipment, rests on two different categories of person, as highlighted in the IEC 60079-19 standard: the ‘responsible person’ and ‘operatives’. An Ex Service Centre should have at least one ‘responsible person’, usually the manager or supervisor in charge of the workshop where servicing of Ex or hazardous area equipment is carried out.

The responsible persons must be trained to fully understand the protection concepts of the equipment, what can and cannot be repaired, and what repair procedures may be used, so that they can fully support the workshop staff and verify any work carried out. The responsible person should be able to ensure that the correct records are kept and that quality control systems are in place for the Ex repairs. They should also be able to ensure that the company has the right tools for the equipment being repaired and the relevant standards and certificates. Operatives are all the engineers and technicians that carry out the service and repair of hazardous area equipment. They should have attended the AEMT Ex Theory and Hands-on courses to fully understand the protection concepts of the equipment they are repairing, and, as above, what can and cannot be repaired, and what repair procedures may be used.

For a company to be on the AEMT Ex-Register, it should have an ISO 9001 quality control system or equivalent; the calibrated tools suitable for the work seen and the required certificates and standards; a minimum of one trained and competent operative; as well as a minimum of one responsible person to sign off and supervise Ex repair work completed by workshop technicians.

Both responsible persons and operatives must be able to provide sufficient evidence that they are up to date with the theory, skills and understanding of the Ex work they are involved with. Their staff should attend regular refreshers every three years on the repair and overhaul aspects of Ex equipment through the AEMT. This means that Ex-registered companies remain up to date on the practical aspects of repair and any changes in updated standards and ATEX.

Competencies apply to each explosion-protection technique for which a company or person is involved. For example, a person can be competent in the repair and overhaul of Ex d motors only and not be fully competent in the repair of Ex d switchgear or Ex e motors. In such cases, the repair facility management should define this in their documentation system.