Subsea pipeline design analysis and installation Subsea pipelines are used for a number of purposes in the development of subsea hydrocarbon resources as shown in Figure 1.1. A pipeline system can be a single pipe pipeline system pipe in pipe or bundled system. Normally the term of subsea flow lines is used to describe the subsea pipelines carrying oil and gas products from the wellhead to the riser base; the riser is connected to the processing facilities (e.g. a platform or a FPSO). The subsea pipelines from the processing facilities to shore are called export pipelines while the subsea pipelines from the platform to subsea equipment used to transfer water or chemical inhibiters are called water injection or chemical flow lines