Syntactic foam half-shells of a project. They must, therefore, be made using high performance solutions which are designed for a long life underwater.
practice, therefore, to over-engineer the product so the module still has the necessary buoyancy that it needs at end-of-life.
Due to the high hydrostatic pressure conditions present on the modules, water attempts to penetrate the structure. As such, these modules must be constructed using a material that resists or minimises penetration of water throughout the 25 year lifetime.
Density testing is routinely carried out on blocks. Deepwater foams used on submersibles require a 100% inspection rate and with no cracks or blemishes. They will be hydrostatic tested for 24hrs. In this time, a typical block might take in the water equivalent to weight of less than a 10th of a percent. If this is as much as 3%, however, it fails.
Modules typically consist of pairs of half-shells that clamp around the structure. Although the goal is 0% water uptake, in reality at these high pressures, water will always find a way into the foam. Testing of the material before use becomes key. By monitoring water uptake while applying heat and pressure cycles in a test chamber, it is possible to predict the properties as the material ages. It is a common
Insulating Properties Syntactic foam also has good thermal properties and as such, is often used in extreme deep water applications where the temperatures be extremely low. A popular application for thermal insulation is structures that have irregular shapes such as trees, jumpers, risers and pipeline end manifolds.
This application does not employ the same standard of material as that used for buoyancy. Instead, thermal insulation normally uses lower performance commodity grade microspheres, which might incorporate broken microspheres. This results in resulting in a higher density material. These shapes are manufactured by making 3D models of the required custom parts and pouring in the insulation material. An alternative is to apply a thermally insulated wrap which is constructed of polypropylene with glass microspheres. This would be typically used around joints on a flexible drilling riser. A similar method is called â€˜pack in placeâ€™ which is a system which mixes the microspheres to form a dough.
UT2 August 2012
The August edition of UT3, the magazine of the SUT