CoatingsPro Magazine

MAY 2018

CoatingsPro offers an in-depth look at coatings based on case studies, successful business operation, new products, industry news, and the safe and profitable use of coatings and equipment.

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COATINGSPRO MAY 2018 71 applied during a refit in Singapore in anticipation of a new field contract. To assure that systems are functioning and fit for purpose, periodic inspections are carried out by the asset owner. It was during such a routine inspection that the failure of the lining of this separator was observed. Research and Investigation During the initial investigation, the following was noted by the inspectors: • The lining at the bottom of the separator was heavily detached, with large flakes of lining coming off; • The flakes of lining were large, thick, and very rigid; • There were multiple (~100) fractures in the still adherent lining; these fractures were half-moon shaped; • The exposed steel had a mottled appearance; • The exposed steel in the bottom of the separator was smooth; • There was a big "bubble" in the lower forward quadrant of the dome; it was approximately 30 cm by 50 cm (11.8 in. x 19.7 in.) and had only air behind it when penetrated; • There were a few areas in the overhead that had pin holes; • There were no blisters; • There were runs and sags in the coating, and the coating showed heavy "orange peeling" with small dimples in the overhead; • There was no apparent loss of steel; • The mean dry film thickness (DFT) measurement was 1499 µm (59.0 mils); • The surface profile varied between upper areas at 75 µm (3.0 mils) and lower areas at 25 µm (1.0 mil). ere were a few key points from the coating manufacturer's onsite representative to consider. To start, surface preparation was noted as abrasive blast cleaning to a Swedish standard of Sa 2.5 with a surface profile of 82 µm (3.2 mils). is is comparable to NACE No. 2/Society for Protective Coatings (SSPC) Surface Preparation (SP) 10: Near-W hite Metal Cleaning. e coating was applied by airless spray with a 68:1 pump ratio. e coating was not heated prior to application, and a xylene thinner was added to the mixed product to aid in application. e mean DFT was recorded at 970 µm (38.2 mils) with a maximum of 1400 µm (55.1 mils) and a minimum 500 µm (19.7 mils). ere was no mention of the number of data points nor the standard deviation. e completed lining system was tested via high voltage for film continuity and was found acceptable. Paint chips were obtained from various points of delamination. Samples were wrapped in aluminum foil and sent for analysis. We also obtained samples of the crude oil that comes out of the ground and enters the test separator. ose samples were also sent for analysis. Additional information was gathered regarding the asset's service parameters. Initial claims from the coatings manufacturer were that the cause of the failure was due to exposure to higher temperatures than recom- mended by their product data sheet; however, this was shown to be incorrect. Operations for the FPSO has kept a continuous record of the crude entering the separators since 'first oil,' (when the FPSO was first connected to a new field). at record showed that the tempera- tures did not exceed 120 °C (248.0 °F). e coating manufacturer was asked to supply cured coating samples to compare the un-exposed product to the operating conditions of the test separa- tor. e coating was applied to three different panels: one at nominal thick- ness (650 µ, or 25.6 mils) and the other two at twice the specified thickness in the manufacturer's product data sheet. Analysis Samples of the delaminated coating from the tank as well as freshly applied product that had not been subjected to the heating cycles were analyzed. e coating chips from the separator had Samples of the delaminated coating from the tank as well as freshly applied product that had not been subjected to the heating cycles were analyzed. The separator was on board a Floating Production Storage & Offloading vessel. Failure on FPSO Vessel

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