Polyurethane Foam Field Joint Infill
Infilling the field joint void on concrete weight coated pipe has traditionally been performed by pouring hot marine mastic into a mould around the joint. The mould is usually left in place when over-boarded by the laybarge. The mastic needs to be heated to melt it prior to pouring, a process that consumes a large amount of energy. Furthermore, the mastic is poured hot, around 2000C and is therefore hazardous to handle. In response to this, PIH has provides an alternative PU based infill system offering improved HSE security as well as the following beneficial features.
Benefits of the PIH alternative:
- Commercially attractive
- Rapid cycle times
- Re-usable or expendable / disposable(metallic or plastic) mould systems
- Compact, reliable application equipment
- Compatibility with all conventional anti-corrosion field joint coating systems
- ODP - zero category formulation
- No solvents required - all equipment is air/water-purged
- A range of foam densities are available
- Raw Material Storage requires only 16 to 20% of that needed for marine mastic.
The custom-designed high density polyurethane foam (HDPF) has a typical unsaturated moulded density between 90 kg per cubic metre and 160 kg per cubic metre.
Formulated specifically for pipeline field joint applications, the HDPF system develops a rigid, open cell structure. Upon immersion, the open cells will absorb water, thereby increasing in overall density to approximately 1025 kg/m3 (similar to seawater itself).
The low-viscosity product formulation of the HDPF system allows 'free-flow' of chemicals, to assure quick and complete filling of the mould, within the cycle times demanded by today's laybarge operators.
The infilling system can incorporate reusable or disposable moulds. Reusable moulding is used in conjunction with a cardboard fibre liner, to create a superior high strength composite skin. This system will allow the demoulded field joint to pass over the laybarge rollers and stinger without damage due to the fibre liner becoming embedded in the surface of the foam creating a resilient outer skin to the joint.
Disposable plastic or metal moulds can be used as required by environmental and operational demands. The application equipment is neat and compact consisting of little more than 2 holding tanks, small pumping equipment and dispensing hoses and nozzles.