Minimising arc flash risk in the marine sector

by | May 8, 2017 | Engineering Design & HSE

The topic of arc flash hazards in the marine sector is highlighted in a new Lloyd’s Register (LR) guidance document, produced in collaboration with GSE Systems Ltd. The comprehensive information and advice has been approved and issued by LR in a publication entitled ‘Arc Flash. A Lloyd’s Register guidance document. Version 1.0, March 2017’.

Understanding arc flash hazards

Each element of the subject is examined in detail for the benefit of businesses operating in marine environments. The report covers everything from introducing the concept of arc flash to setting out procedures for analysing arc flash hazards and implementing mitigation measures.

In simple terms, an arc flash is an electrical discharge – or short circuit – which moves through the air. The huge amount of energy released by an arc flash can be devastating to people and assets within its reach.

Any workplace with an electrical distribution system, whether supplied by AC or DC, has potential for an arc flash to occur. It may happen through, for example, a poor electrical contact, a failure in the insulation, accidental touching of a piece of energised equipment, or ageing and poor maintenance of systems.

This is true both on land and at sea. Shipping, offshore oil and gas platforms and FPSO (floating production, storage and offloading) vessels are just some of the situations in which arc flash hazards need to be addressed.

The new guidance document begins with an explanation of what arc flash is, how it occurs, and the nature and seriousness of its impacts on personnel and structures. Within this section, it introduces the idea of an arc flash boundary: “The distance from live parts that are uninsulated or exposed within which a person could receive a second-degree burn.” Different categories of protection boundary are then defined.

Arc flash analysis, calculations and mitigation

Subsequent chapters give detailed, step-by-step instructions to help employers in marine industries comply with the relevant health and safety regulations.

Whenever switchgear is to be installed or modified in any way, an arc flash study is recommended. The first step is to carry out an arc flash analysis, to identify the level of hazard. This will give information on how much energy will impact upon the affected equipment’s vicinity if an arc flash occurs, and at what distance it will cease to present a danger to personnel. The document advises on use of software packages for arc flash analysis and presents an in-depth guide to performing arc flash hazard calculations.

A separate chapter is devoted to DC arc flash hazards and the calculations necessary in relation to them. Even systems using a relatively low voltage can be a serious arc flash hazard source. This is a particular concern in the case uninterruptable power supply (UPS) systems and battery banks.

Armed with information from arc flash calculations, measures can be taken to engineer out the risks. An assessment should be undertaken to ascertain whether risks have been reduced to a tolerable level or eliminated. Residual risks can be minimised in various ways, and some examples are listed in the document’s chapter on protection against arc flash.

Approaches include:

  • Adherence to international design standards
  • Correct cleaning and maintenance
  • Internal arc containment methods
  • Hinged panels avoiding the need for tools to open switchboards
  • Examining protection curves to see if adjustments in relaying can speed up operation of protection
  • Adding instantaneous high-set overcurrent elements to the relaying to shorten trip time on high-fault currents
  • Reviewing operating, trip and close procedures
  • Restricting switchgear access and operation to properly trained staff
  • Installing commercially available arc flash relay systems

It is emphasised that use of personal protective equipment (PPE) should be seen as the last line of defence after residual risks have been minimised by other methods. If an arc flash incident occurs, PPE will not necessarily prevent all injuries but it should reduce their severity. Extensive guidance is offered on the optimum selection, use, care and maintenance of PPE.

Further help and advice on marine arc flash

GSE welcomes the new LR guidance document as an important aid to compliance in marine industries and will be delighted to advise and help further. As well as being a global technical leader in the field of arc flash and electrical safety, GSE has a wealth of experience in the marine sector specifically.

Rather than adopting a one-size-fits-all approach, GSE’s arc flash risk assessment, compliance and mitigation solutions are carefully tailored to each client’s particular needs. These services have benefited a wide range of businesses in the shipping, oil, gas and related sectors, including Blue Chip companies.

If you have any questions on any of the above, get in touch with one of our team and they can provide answers.

 

 

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