Examination of a Failed Gas Heater Bundle for Maersk North Sea Oil UK
ESR Technology Ltd recently performed a forensic investigation for Maersk Oil North Sea UK on an electric gas heater bundle removed from an offshore platform located in the Janice oilfield in the Central North Sea.
The bundle had been in service for over 15 years before being replaced with a new unit. The purpose of the investigation was to assess the condition of the unit to aid with future inspections of similar units and to allow a maintenance regime to be developed. A series of non-destructive and destructive investigative techniques were employed. These included;
- Visual and macroscopic assessment,
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electrical continuity and insulation resistance (IR) testing,
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liquid dye penetrant (DPI) to identify possible leakages and defects on the heater element tubes,
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Environmental Scanning Electron Microscopy (ESEM) equipped with Energy Dispersive X-ray Analysis (EDX) tools for surface analysis and elemental analysis,
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Metallographic preparation,
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Optical microscopy and,
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X-ray diffraction (XRD) and X-ray fluorescence (XRF) analysis of corrosion products to provide fully quantitative information.
The examination revealed the stainless steel heater element tubes were generally in good condition despite the age of the unit with only small, shallow U-shaped corrosion pits. However, corrosion of the sealing glands and the tubesheet had occurred which resulted in formation of lamellar corrosion product and blistering.
Optical microscopy of metallographic sections revealed no evidence of material defects or thermal degradation in the materials such as grain boundary diffusion.
Results from the investigation were used by Maersk and the gas bundle manufacturer to gain a further understanding of operating conditions on these types of units and to allow discussions on future inspection methods.
For more information please contact Steve Gill on 01925 843 428 or This email address is being protected from spambots. You need JavaScript enabled to view it..