Layered pipe repair technique prolongs service of offshore pipework
Allan Syme
TGS Marine
TSG Marine and SPS have developed TSG/Pipe Repair for offshore pipe systems that require repairs or replacement due to the effects of corrosion, erosion, or mechanical damage.
Current methodologies tend to involve either temporary pipe repairs or the “crop and replace” approach. The new system is pitched in-between these options, providing a permanent, class-approved, no hot works, in-service repair. It has also been designed to restore the integrity of the original pipework for both internal and external corrosion.
The repair method employs the proven SPS (Sandwich Plate System) which has been used extensively offshore and onshore for nearly 20 years. It entails applying to the original plating (or in this case, pipe) a secondary layer, usually of the same material, and injecting an elastomer layer into the cavity bonding the two metallic layers together.
For the offshore pipe systems version, a new outer bolted two-piece clam shell is applied, designed to accept full system pressure. In effect the original pipe below the clam shell becomes redundant and the elastomer layer acts as a corrosion barrier in case the original pipe splits or perforates.
The new system was developed and verified under the DNV GL Technology Qualification process, and underwent successful testing. For one of the tests clam shells were fitted to a section of pipe and the cavity filled with the elastomer. On completion, the central 70% length of the original pipe was machined out. The section was then subjected to and passed a hydrostatic test.
Normally the system will be supplied in lengths of 1 m (3.3 ft) or less, which can be bolted together where longer sections are required. It can also be applied “flange to flange” in critical applications by means of specially designed adaptors.
