Everything’s more challenging from the perspective of an offshore platform. That’s another way of saying everything’s more expensive. This is especially true when it comes to mitigating the effects of corrosion on carbon steel pipelines.
Marine environments are hostile to begin with. Steel is always going to be the loser in the battle against corrosion, but on an offshore platform, the process is accelerated. An operator faced with repairing or replacing tubulars must also contend with the logistical isolation—getting material and manpower offshore, hiring divers to assess and repair breaches, ad infinitum. Installing a new pipeline out here is far more time-consuming and can cost more than what it costs onshore—and it’s not exactly cheap onshore.
Fortunately, a cost-effective solution that has been very successful in onshore applications is quickly proving its value offshore.
Thermoflex rehab: a welcome sea change
Manufactured by Polyflow, Thermoflex® is a lightweight, spoolable pipe with a patented layering system comprised of aramid fibers for strength. It offers higher pressure capabilities than HDPE—up to 2,000 psi—and features a nylon lining for corrosion protection. It’s flexible, fast and easy to install, and requires no heavy machinery or welding.
For years, Thermoflex has been used onshore to rehabilitate aging pipeline. Due to the product’s low-friction coefficient, Thermoflex can achieve flow rates comparable to those of much larger-diameter pipes. Its higher pressure and temperature rating, along with low permeability characteristics, make it ideal for pipeline rehabilitation.
In a process developed by Polyflow, a pig is run through an existing steel pipeline while pulling a rope, which is then used to pull a section of Thermoflex pipe back through the existing pipeline. Because Thermoflex is lightweight, the process doesn’t require a lot of pulling force, taking usually just a few hours per mile.
Compared to a new steel installation, costs for material, initial labor, and long-term maintenance are dramatically reduced. Offshore, obviously, those advantages are multiplied.
One production company recently operating in the Gulf of Mexico was experiencing multiple leaks in an existing 14,000-ft. line comprised of 4-inch, 6-inch, and 8-inch steel pipe connecting an offshore platform to an onshore facility. Because the line carried oil, brine, and gas, a corrosion-resistant material was needed.
A Thermoflex pipe was pulled through the existing pipeline, which was flooded with seawater, reducing the required pulling force by 90 percent. In just three hours, a winch truck on the platform pulled through 9,000 feet of Thermoflex. A second spool was attached using a jointless splice coupling. The new, corrosion-resistant line was successfully hydrotested at 750 psi—1.5 times the maximum operating pressure.
A game changer offshore and onshore, Thermoflex has proven to be a cost-effective alternative to steel for the rehabilitation of aging pipelines. It can handle high-temperature, high-pressure requirements of oil and gas applications, along with the unique challenges presented by marine environments.