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RAROA FPSO FLARE TOWER CORROSION REFURBISHMENT

The Raroa FPSO Flare Tower had been identified through recent inspection surveys as in need of Asset Integrity Maintenance due to its corrosion condition becoming significant and widespread.

Corrosion is a loss of material due to electrochemical reaction with the environment, in an offshore environment the mechanism is salt water and air. It is becoming an increasing problem of ageing installations particularly if painting programmes have been poor. If ignored corrosion can become a real issue to offshore installations, it can be linked to mechanisms such as fatigue, wear, environmentally assisted cracking, materials deterioration, blockages, fouling, scaling and structural collapse from extreme weather or impact.

Intergroup were approached by our client MODEC to come up with a suitable and safe methodology to complete corrosion mitigation of the flare tower during short outage windows. We accepted the challenge and commenced the project by going into a planning and development phase.

The first phase of the work commenced in December 2015 with a UAV Drone Survey whilst the flare was still in operation to assess the severity of corrosion and confirm whether the project should take place. Once we reviewed the UAV Survey results we set out preparing project estimate costs, work methodologies, Risk Analysis, JSEA documentation, Equipment & Material Procurement and training for our Team.

After collating all the information required to successfully carry out a project like this we came to the conclusion that rope access would be the only option we had if we were to deliver any progress with the limited time frames we were to be allocated. Consideration was also taken into the environmental impact of the project, wet abrasive blasting was used as the primary means of surface preparation utilising the Geo Blaster and Mist Blaster surface preparation systems to prevent airborne dust, reduction of abrasive media required and to minimise abrasive media from going overboard and entering the sea.

Rope Access is a form of work positioning initially developed from techniques used in climbing and caving, which applies practical ropework to allow workers to access difficult to reach locations without the use of scaffolding, cradles or aerial work platforms. Rope access technicians descend ascend and traverse ropes for access and work while suspended by a harness. The support of the rope is intended to eliminate the likelihood of a fall altogether. A backup fall arrest system is used in case of unlikely failure of the primary means of support. This redundancy system is achieved by using two ropes, a working line and a backup safety line. During abrasive blasting activities, this will increase to 4 ropes, two primary and two backup safety lines to counter the reaction force of the abrasive blast nozzle to enable safe work positioning at all times.

Like any other method of working at height, the application of rope access should be regarded as a complete system in which planning, management, competence and suitable equipment should be treated with equal importance as each is dependent on the other to ensure a safe system of work.

Intergroup when carrying out this type of work also adheres to safety characteristics including:

  • When working from rope, the technician always has a minimum of two attachment points each having its own independent anchor point
  • When supported by ropes, each of the worker’s ropes will have a fail-safe descent mechanism
  • All secondary tools and equipment are attached by lanyards to the worker’s harness to prevent injury to people below from dropped objects
  • All secondary tools and equipment over 8 kg are to be supported via a separate rope system
  • A minimum of two trained technicians is required for any job each with the ability to rescue each other. For work over water, the requirement is for three
  • All technicians when training shall be independently assessed
  • All equipment is regularly inspected and maintained
If ignored corrosion can become a real issue to offshore installations, it can be linked to mechanisms such as fatigue, wear, environmentally assisted cracking, materials deterioration, blockages, fouling, scaling and structural collapse from extreme weather or impact.

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