Swagelining highlights its corrosion-beating solutions, and explains why every pipe should have a polymer lining
Internal corrosion is one of the most common causes of problems in pipeline operations. Conventional carbon steel pipelines in particular can suffer from severe corrosion when used for water injection. In cases where insufficient corrosion allowance has been factored into the original design, this can result in a drastic reduction in their life expectancy.
Owing to the current industry climate of the oil and gas industry, pipelines are one area in which operators and service companies demand cost-saving solutions to improve efficiency. Polymer lining technology for pipelines has proved to be one technology which mitigates corrosion and lengthens asset life.
UK firm Swagelining designs, manufactures and installs polymer lining systems for strategic pipeline and riser systems. The Swagelining® process works by using liners to form a protective barrier between transported fluids and the bore of the carbon steel host pipe. The technique involves pulling an extruded polymer pipe through a reduction die to reduce its diameter temporarily. This is done whilst maintaining the tension under load during installation through the host pipe. Upon release of the tension, the natural elasticity of the polymer enables the liner to form a tight compressive fit on the steel bore by axial retraction and radial expansion.
In one recent case, Swagelining was awarded the EPC lining contract for an offshore project in Norway, which was successfully completed on-site in June 2016. The project entailed a solution for 46.5 km of 12-inch (305-mm) water injection/ sweet service pipeline, with a design life of 25 years, maximum operating temperature of 29°C and ability to withstand reel-lay installation.
The project’s spoolbase installation involved fabricating 1,500m High Density Polyethylene (HDPE) stalks from 20m pipes employing butt fusion welding. Following completion, the 1,500m polymer stalks were installed into carbon steel (CS) stalks, which were in turn terminated with flangeless WeldLink® connector fittings. This integrated lining system offered continuous corrosion protection along the full length of the pipeline after completed tie-in welds. The polyethylene (PE) liner system was designed to withstand the pipeline operating conditions whilst also accommodating installation forces during insertion into the CS stalks and reel-lay installation loadings.
At the spoolbase, PE stalks were fabricated from the bespoke butt fusion welding container, utilising two welding stations working on a day shift and back shift basis (operational for 18hr of every 24hr period). Destructive tensile testing along with rigorous quality control processes for the duration of the project confirmed that welding machines and selected parameters produced welds which met the pre-requisite requirements in the conditions. Owing to the stresses and strain imposed on the HDPE by the die reduction process, the quality of the butt fusion welds is paramount to Swagelining’s operations.
A horseshoe roller arrangement was successfully utilised on this project, which was a first at this particular spoolbase. The arrangement allowed for the direction of the PE stalks to be reversed for installation into the CS host stalk of similar length, situated alongside the PE stalk. This reduced the stalk handling workload in preparation for the liner insertion and also helped to limit any liner surface damage which can occur from excessive handling. This improvement also eliminated the requirement for working space equivalent to twice the stalk length to be available at the spoolbase for installation.
A 12-strand braided Lankoforce Dyneema® rope fitted to a 30-tonne OMAC constant tension twin capstan winch was the selected pulling arrangement. This innovative solution proved beneficial throughout the design and installation phases of the project. The Dyneema ropes selected for the project offered maximum strength for minimum weight and had the advantage of reducing installation loading, shipping weights and greatly improved the installation times.
The newly manufactured 30-tonne winches were designed with a quick release system incorporated on the rope drums, allowing for an efficient alternative to winch swap-out in the event of a breakdown or stalk recovery scenario. The winch and rope selection resulted in a highly versatile and manoeuvrable system, quick to install and set up on site and reduce risk.
The combination of the lightweight polymer winch rope and the versatility of the HDPE liner to cope with novel installation techniques resulted in consistent lining of one stalk per available day. With stalk lengths of 1,500m, this is considered to be a significant achievement.
The service is available to clients worldwide, and while suitable to be employed on new projects – constructed on-site, or at a fabrication location for transportation to the final location, it can also be considered as a rehabilitation solution for existing in-situ assets.
New innovations are also in development. Swagelining is now looking at the deploying the technology in elevated temperature service for Water Injection systems and the use of engineered polymers to service the hydrocarbon sector, providing a cost-effective alternative to CRA systems. Connector technology – LinerBridge® – now allows for quicker, less complicated jointing construction and opens the technology to new installation methods, such as off an s-lay barge for large-diameter and shallow-water subsea projects.