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

With increasing oil & gas demand and depletion of sweet reserves, oil & gas companies in the regional
economies are focusing towards the exploitation of sour resources. This necessitates the use of pipelines
and down-hole tubing made from special steels with significant resistance to hydrogen-induced cracking
(HIC). These steels are produced through specific technologies for enhanced chemical composition control
and microstructural engineering to incorporate the required strength, weld ability and improved HIC
resistance. It is well established that the HIC initiates at sites with microstructural heterogeneities whether
due to presence of gross nonmetallic inclusions or the micro-structural constituents. The presence of central
segregation further aggravates the conditions particularly when the final pipe sizes require the longitudinal
slitting of the coils. Presence of non-metallic inclusions in the steel makes it vulnerable to hydrogen-induced
cracking under wet H2S environment. The mechanism of HIC begins with the generation of hydrogen atoms
by corrosion reaction of H2S and Fe in the presence of free water. The hydrogen atoms then diffuse into
steel and accumulate around the inclusions. The higher number of inclusions equates to the more sites
available for hydrogen adsorption. Recombination of hydrogen atoms to H2 molecules builds up a heavy
gas pressure in the interface between matrix and inclusions. Cracking initiates because of the tensile stress
field caused by hydrogen gas pressure and crack propagates in the surrounding steel matrix. The
longitudinal slitting exposes the internal microstructural abnormalities to the skelp edges which are then
incorporated in the thermally stressed weld zone. While the post-weld heat treatment (PWHT) mostly
homogenizes the weld zone microstructure, the presence of excessive central line features cannot be
completely removed thereby making this zone more prone to HIC attack