Repair technology avoids shutdown
Posted: 3 August 2007
Advanced composite repair technology from Furmanite resolved a potential process problem threatening to disrupt production for a petrochemical plant by repairing a vessel suffering from corrosion on-line, avoiding costly unscheduled shutdown.
The repair was carried out for a petrochemical plant in Kuantan, Malaysia earlier this year.
A flare tank at the plant was found to be suffering from internal corrosion, caused by the weak acid caustic waste water content, which had caused 70 per cent wall thinning.
Left to continue the corrosion would have caused a through-wall defect, but to replace the vessel involved a long lead-time. A repair was needed to enable production to continue without risk of deterioration and failure of the vessel which would have forced shutdown, costing millions.
Furmanite Malaysia was called in to provide a repair using its advanced carbon fibre and epoxy resin composite technology.
The repair was designed to restore full structural strength and pressure integrity to the vessel for a two year lifespan – well within the capabilities of the technology which will typically provide repairs with a design life of 20 years or more – enabling production to continue as normal until the vessel could be replaced.
This was achieved with a low-profile repair of just 5mm thickness, applied in a layering process to cover the required area (3.1 metres diameter, and 1.5 metres up from the bottom of the vessel) in accordance with the repair design specifications (which dictate the number of layers, fibre orientation, overlap onto good metal and taper at the edges of the repair, for example).
The repair was designed against a design pressure of 350 KPA and design temperature of 300°C. Further, it was engineered to accommodate continuing internal corrosion during the design life of the repair, without affecting the integrity.
Particular challenges included condensation forming on the outside of the vessel, which had to be taken into account in the design specifications, and the very confined space in which the vessel was located.
The light weight and flexibility of the materials, the fact that no pre-fabrication is required, and that the repair can be applied in extremely tight access conditions (requiring just 150mm clearance), enabled this problem to be overcome. Moreover, because no hotwork is required, the repair could be applied while operation continued uninterrupted.
“This is typical of the service we are able to offer, providing repairs that will restore full structural strength and pressure integrity without disrupting operation, enabling operators to maximise asset uptime, representing high value,” Furmanite Malaysia operations manager Chris Lord said.
“Traditionally in a case such as this the only option would have been shutdown until the vessel could be replaced, but the composite repair enabled costly unplanned downtime to be avoided. This relatively new technology is attracting a high degree of interest as it is increasingly widely proven.”
Posted by Richard Price, Editor EnergyME.com
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