For a highly corrosive water injection media (wasia water) which has very high total dissolve solid (TDS) and high oxidizing agents internal fusion bonded epoxy (FBE) coatings in addition to corrosion inhibitor was provided for internal corrosion protection of water injection plant Piping.A year after start-up of water injection plant the plant started experiencing internal FBE coating failure. The failed coating were found at the strainer and recycle valve after causing high differential pressure during operation. Seven types of failed coating film were collected from the suction strainer. Comprehensive failure investigation was conducted to determine the root cause of the failure and identify the source of various failed coating films received. Fourier transform infrared spectroscopy (FT-IR) energy dispersive X-ray Spectroscopy (EDS) X-ray diffractometer (XRD) and differential scanning calorimetry (DSC) were all used to identify the type of coating and their manufactures. Robotic video crawler (RVC) was used to inspect the internal coating condition for the piping system. Effect of corrosion inhibitor injection and plant operating parameters on the coatings were all reviewed and evaluated. It was concluded that improper coating application was the root cause of the failure. Keywords: Failure Investigation FBE Coating Robotic video crawler (RVC) Fourier transform infrared spectroscopy (FT-IR) Energy dispersive X-ray Spectroscopy (EDS) X-ray diffractometer (XRD) and Differential scanning calorimetry (DSC).

The integrity of new pipeline projects is critical to Saudi Aramco to avoid any short or long-term impact on the supply of energy. During construction activities, pipeline internal welding inspection is carried out in compliance with international and Saudi Aramco requirements. The visual inspection of internally cladded girth welded pipes requires extra care to avoid any improper field fabrication errors during welding, especially at the root pass area. Such errors can limit the inspection capability and compromise the integrity of pipeline network with possible degradation of corrosion resistance at/near the weld rot, resulting in premature failures. Currently, projects utilize conventional tools such as borescope which is time consuming with limited inspection capabilities (up to 150 meters inside the pipe) and system maneuverability at inspection locations.
The Saudi Aramco Inspection Department enhanced their active inspection technology program and collaborated with a local technology developer. They trialed a wireless crawler robot, which is a high resolution remotely operated robot capable of inspecting internal girth welds with 5000 meters travel capability inside the pipes. The robot can inspect internal girth welds in the field, and inside pipelines with internal diameters of 6 inches and above, and wirelessly transmits the visual inspection results to the outside control room for a timely assessment and critical decision making. The internal visual inspection with wireless crawler robot will help in improving the project progress, reducing repair costs, by identifying defective welds before coating application.

During the construction of a 56km long 16 in. carbon steel sour gas pipeline, repetitive surface
preparation failures were detected during visual inspection of pipeline girth weld internal surface prior to
coating application. Such failures represented 67% of the total pipeline girth welds and were manifested
by excessive sharp-edges at the root pass. To identify the failure causes, an investigation was
performed through reviewing the pipeline, fabrication and coating application specifications and
procedures, quality control records and performing an extensive visual inspection through an advanced
video robotic crawler on all pipeline girth welds made. Upon investigation analysis, the failures were
caused by sharp-edges in the root pass which were attributed to improper practices during
manufacturing, field fabrication and pre-coating quality control. The failure analysis indicated that the
mechanized Gas Metal Arc Welding process, with the parameters used, was not suitable for internal
girth weld coating application. In addition, a more stringent requirement should be applied to the
acceptable pipe-end diameter tolerance and pre-coating quality control to ensure absence of similar
premature surface preparation failures. The pre-coating quality control can be improved through
utilization of robotic laser contour mapping crawler for precise detection and sizing of unsatisfactory
surface weldment defects, including sharp edges.