Long-Term Performance of Syntactic Foam Materials in Unusual Environments Available to Purchase

Syntactic foam, a composite material made by combining spherical fillers in a polymeric binder, has been used for over thirty years in the offshore oil industry. To date, the applications of this material have fallen into two categories: (1) buoyancy modules or floats to support drilling risers, or (2) thermal insulation for subsea equipment and flowlines. In the first category, the syntactic foam is exposed only to cold water (4° C). In the second category, the insulation may be subjected to temperatures as high as 150° C. The contrast of these two separate applications has led to two distinct classes of materials, each with its own properties and accepted standards and criteria. Now a new category of usage has arisen: Vertical production risers that require buoyant lift, and sometimes some degree of thermal insulation, for long-term service (20–25 years) in “warm” water that may be in the range of 40° C to 65° C. By combining the buoyancy requirement of lowest possible density with the insulation requirement of prolonged hydrothermal stability, this application poses new challenges for syntactic foam development and demands new directions in testing and analysis. Because of the increasingly large size of emerging offshore projects, the potential requirement here is for very large volumes. This paper describes the materials that have been identified as candidates for the new service, and outlines the testing philosophy that is being evolved to test and qualify them with confidence for very long periods of service. Preliminary test data is presented, along with predictions of long-term performance. Lessons learned during the project will have implications for all syntactic materials, and will be useful to any managers and technologists involved in marine engineering.