Health & Safety
financially. While legislation requires businesses to perform risk assessments for all work activities, electric arc risk is often overlooked because most people are unsure how to assess and manage this hazard effectively.
How to manage the hazard Te management of tasks, where the arc flash hazard is present, needs to be determined by risk assessment. Te risk assessment approach with the four steps of Predict, Prevent, Protect and Publish as defined in the DuPont Arc-Guide is a recommended method to develop safe work practices for the protection of people, where this hazard exists:
1. Predict – the severity of the thermal effect of an arc flash by the amount of ‘incident energy’ that a victim, standing at a given distance away from the arc, could receive.
2. Prevent – design out, eliminate or remove the hazard at its source.
3. Protect – where the risk cannot be controlled by prevention or where there is a residual risk of injury then it may be necessary to consider
personal protective equipment (PPE) to prevent injury to the worker.
4. Publish – communicate and document results of site arc flash to those who are at risk.
In Summary Te DuPont Arc-Guide, the European approach to electric arc risk assessment, has been developed by DuPont in conjunction with independent experts, to help companies better assess the arc flash hazards (with the use of simple calculators) and provide them with the knowledge on how to both reduce the severity and consequences of an arc flash. Te arc flash hazard is a serious electrical risk that needs to be managed in many industrial environments and risk assessment for workers who operate in proximity to, or on, energised electrical equipment and cables is essential to ensure safety and compliance with the law. ●
1.
In the UK, HSE Electrical Safety at Work
www.hse.gov.uk/electricity/index.htm
Enter 81 or ✔ at
www.engineerlive.com/iog
Mike Frain, Electrical Consultant, Electrical Safety UK Ltd, and Elaina Harvey, DuPont Nomex Account Manager, are with DuPont UK.
www.dpp-europe.com and
www.arcguide.dupont.com
Offshore oil platform is protected by flame spray equipment M
etallisation customer, Gardwell Coatings Limited, based in East Anglia, has applied Thermal Sprayed
Aluminium (TSA) to an offshore oil platform to protect the structure from corrosion, using Metallisation MK73 flame spray equipment. The offshore oil platform has been designed
and constructed by SLP Engineering, the UK’s most experienced EP(I)C company. SLP commissioned Gardwell Coatings to metal spray the structure, which will be erected in the North Sea oilfields later this year. Gardwell Coatings is one of the largest blasting companies in the UK and was established to service the oil and gas industry. The offshore platform is a three-leg tubular steel
Jacket weighing around 436 tonnes, with the topsides weighing around 345 tonnes. The centre core of the jacket is 27.1 metres long with three, 1m diameter main tubular columns. The insides of the columns were TSAd with 250 – 400 microns of aluminium, sealed with an epoxy sealer. Around two thirds of the external surface of the columns, which will be in the splash zone and exposed to the harsh North Sea, were TSA’d to the same thickness, sealed with epoxy sealer and top coated with a PU topcoat. In addition, a number of stainless steel parts and riser pipes have also been TSAd and sealed. In total, around 450 square metres of the centre core has been TSAd.
The top section and the platform’s support braces
were also TSAd, sealed and top coated with PU, totalling another 500 square metres. Once the centre core and top section were welded together, the weld joints were also TSAd, sealed and top coated to complete the task and ensure all sections have been protected. Gardwell Coatings completed the metal spraying
process on site at the SLP Engineering site in Lowestoft using the Metallisation MK73 system. Gardwell Coatings recently purchased an additional three MK73 systems with long supplies packs. With the longer supplies pack, up to 50m from the gas bottles to the pistol, the operators have the flexibility to freely move around the large jacket structure without moving the gas supplies, greatly increasing productivity. The team generally used five pistols on the job at any one time and sprayed an average of around 100 square metres of TSA a day. Given the complexity of the job, which included the internal coating of the 1m diameter tubular sections, this production rate is quite an achievement. Prior to metal spraying the platform surfaces, each
section was grit blasted overnight ready to be sprayed during the day. The spraying chamber was maintained at a controlled temperature with up to 2.2 million BTU of heating available to ensure optimum quality of the
coating. By applying Thermal Spray Aluminium the platform has a predicted life to first maintenance in excess of 20 years, even in the harsh environment that is the North Sea oilfields. Chris Green, Operations Manager at Gardwell
Coatings, says: “Metallisation offers good product support and the equipment has allowed us to deliver a higher than anticipated production rate, which is pretty good considering the complexity of the job. The efficiency of the MK73 has allowed us to exceed the expectations of our customer SLP for the coating timescales.” Metallisation’s MK73 Flamespray pistol represents
a breakthrough in anti-corrosion spraying. With a choice of continuous or stop/start nozzles and a combination of the spray head, pilot assembly and a high power air motor drive, it is the fastest and most reliable system in existence. The MK73 system is also fitted with a spreader
attachment to the spray head. This spreader assists the operator to produce a more evenly distributed coating, which improves efficiency and reduces the potential for touch-up reworks to be done. ●
For more information, visit
www.metallisation.com
www.engineerlive.com 81
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