TWI holds Pipeline Workshops for Corrosive Environments

TWI held two workshops related to pipeline systems in highly corrosive environments, the first detailed mechanically-lined pipes while the second covered polymer-lined pipes.

Pipes that are clad and mechanically lined with corrosion resistant alloys (CRA) are used in the oil and gas industry when production fluids are corrosive. These CRAs are metallurgically bonded to the backing steel for clad pipes, while mechanically lined pipe (MLPs) use a CRA sleeve, which is inserted into the steel pipe before a CRA weld overlay is used to seal the ends. This means that MLPs have no bond between the liner and backing steel and can result in 25 to 40% cost savings compared to clad pipes. However, despite recent research, there are still a number of significant knowledge gaps which need to be addressed in order to extend the use of clad pipes and MLPs.

The second workshop helped demonstrate confidence in the use of polymer lined carbon steel pipe for service in sour hydrocarbon environments. The corrosive fluids in these environments can include hydrocarbon and water saturated with dissolved carbon dioxide (CO₂) and hydrogen sulphide (H₂S). Further studies are required to better understand the collapse of the polymeric liner at maximum temperature when gas is present in the produced fluid, the flux of water vapour to the polymer steel interface in the presence of CO₂ and H₂S, as well as the condition of the parent and welded steel underneath the liner.

Each workshop included a short presentation followed by a discussion of the requirements of the Industrial Member companies invited to attend.

TWI’s expertise, facilities and knowledge provision on these topics has assisted with addressing the ongoing changes and challenges worldwide.  These changes include increasing interest in multi-material systems, corrosion/environmentally assisted cracking and corrosion-fatigue across downhole, wellhead and SURF systems.

The workshops not only allowed TWI to disseminate the latest activities in the assessment of pipeline performance in corrosive environments, but also provided the opportunity for participants to influence future investment in test facilities, the Core Research Programme (CRP) and opportunities for collaboration through Joint Industry Projects (JIPs).