When properly designed and applied, composite materials, which have been used for pipeline repairs since the 1980s, can outlast the steel being repaired in offshore environments.
Even with a decades-long track record, says Matt Green, VP of technical services at ClockspringNRI, composites are viewed as “the new kid on the block.”
There has long been a tendency to “put more metal on the metal” in the form of clamps or welded patches when repairs are needed, he says.
“What they industry has been doing is proven, so they want to make sure that anything new they do has also been proven,” Green says. “It’s not that they don’t believe in the materials, but they want to see the data.”
ClockspringNRI invests heavily and focuses its testing and R&D on composite materials to knowing and understanding the lifetime and durability of composite materials, he says.
Some of those testing methods include long-term programs lasting up to 10 years and simulated environmental testing specific to offshore conditions. These tests have been conducted not only by multiple third-party organizations, but also in the testing facilities at ClockspringNRI.
Green says repairing pipelines and risers with composites extend the asset’s lifespan. Testing programs enable the development of designs that can outlast the pipe itself. With testing, validation and design – and depending on loading conditions – composites can offer a design life of 50 years or more.
A repair method like cut and replace requires the system to be shut in, but because composites are applied externally, it’s not necessary to shut in a line and lose production during repair, he says. While clamps are also applied externally, in many cases they need to be machined to the line specifications and so take some time to reach the repair site, he says, while composites are typically available off the shelf. Composites are lighter in weight than either metallic clamps or cut and replace methods, which means less stress on the system and easier installation. Composite repair work is easier and safer than metallic patching because no welding is necessary, he says. Finally, composite repairs tend to be carried out more quickly and be less costly than other methods, Green says, because they don’t result in lost production.
Commercially available composites from ClockspringNRI can function in temperatures from sub-zero to 270 degrees C.
“In general, though, the limit is the environment they’re going to,” Green says.
For instance, there are limited application methods for repairing leaking subsea pipes with composites due to the level of adhesion that can be achieved in such environments, but ClockspringNRI is engaged in R&D to change that.
Currently, the limit on subsea installation is set by the water depth a diver can safely operate in. ClockspringNRI is involved with a large E&P company and an ROV manufacturer in an ongoing R&D effort into how to make it possible to carry out deepwater repairs with composites.
Case histories
ClockspringNRI’s Syntho-Glass XT legacy composite system was used to repair various lengths of a riser above and below the waterline offshore Malaysia in 28 meters of water. The riser in question was internally and externally corroded, with some of the damage in clusters and some across a length of the riser. In addition, the riser had been dented repeatedly over the years by boats and anchors. The repair was installed in two phases due to manpower availability and time allowed in the water but was completed in a fraction of the time that a full cut and replace could have been completed and for a fraction of the cost.
Some risers offshore California had been dented above the waterline by barges and vessels during docking procedures. Technicians accessed the damaged area by rope to repair those dents using the lightweight ClockspringNRI’s Syntho-Glass XT composite. The line requiring repair was the main production feed line, and shutting it down for a traditional repair would have cost the company more than $120,000/day over several days. The composite repair was installed in less than two hours without the need to shut in production.
Earlier this year, ClockspringNRI carried out a Snap Wrap repair offshore Peru in water depths of 50 feet. The technology was used to repair seven dents ranging from 5 inches to 9 inches wide in a 14-inch OD pipeline. Each dent was repaired in about two hours with a final cure in two and a half hours. The entire repair took a few days. Because other solutions require hot work, production would have had to be shut in and the line cleared of hydrocarbons before work could begin, leading to considerable loss of profit while repairs were being carried out.
ClockspringNRI deployed its Snap Wrap pre-cured split sleeve composite repair system last year in low-viz waters of 100 feet offshore Alaska. This project was carried out over several months because dives could only be completed during slack tides. The repair restored the pipeline to its original design specifications and allowed operations to continue without interruption while the repairs were being carried out on the line, which saved millions of dollars.
The pre-cured system “takes out a lot of installation worries” and makes it possible to apply in “low or no-viz conditions where divers are putting it on by feel. Pre-cured makes it easier,” Green says. “They just find the pipe, and the split sleeves snaps on quickly and easily.”