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.

Corrosion, either internal or external, along with other types of defects on pipelines eventually lead to leaks without proper treatment. This gives rise to several issues, including environmental and safety hazards, and in case of pipe leaks in a plant, a loss of the efficiency of the process or, ultimately, failure of the process. Replacing the corroded pipelines (piping) can be difficult, costly and time consuming especially for plant. A required shutdown causes major economic loss. Thus, instead of a replacement of the defected pipelines, the installation of online repair is a better option.
Repairs of pipelines include metallic and non-metallic repairs. Metallic repairs generally require welding or hot works which is not suitable for online repair of pipes containing hydrocarbons. In such cases the use of non-metallic composite repairs is the optimum solution. A non-metallic composite repair system is a system used to reinforce structures using a fiber equipped with a thermoset epoxy system. The epoxy system consists of a hardener and a resin which, after mixing, become solid through a polymerization reaction after a short duration of time, a process that is called curing. Depending on the temperature, the duration of time changes in an inverse relation. The higher the temperature, the smaller the duration of time needed for curing. This system can be used to reinforce pipelines with both external and internal corrosion and it can be used on Straight Pipes, Tees, Elbows, Flanges and weld joints. The repair system can also be installed online without the need for a shutdown in a short amount of time and a small requirement of labor intensity, making it cost effective. It is also environmentally friendly. In this paper we are going to present cases that were resolved by our company that demonstrate how successful these non-metallic composite repairs are and how diverse their applications can be