Pipe-in-Pipe (English Ver.)

Pipe in Pipe (PIP) is installation of a second pipeline around the product pipeline from the seawater surrounding it and creates a dry chamber around the pipeline that can be engineered to accommodate a range of advanced insulation techniques.

Source: http://www.offshore-mag.com/content/dam/etc/medialib/new-lib/offshore/print-articles/2011/sept/75700.res/_jcr_content/renditions/pennwell.web.600.300.jpg

The PIP product consists of the production pipeline being sleeved into an outer pipe with the annulus being maintained dry and filled with a highperformance insulation material configured to meet the particular project thermal requirements. 

The outer pipe is designed to withstand both the hydrostatic pressure dictated by the project water depth and the installation methodology. The inner pipe can be located within the outer pipe by the use of centralisers clamped at discrete intervals along the inner pipeline or, as for our highperformance PIP system, without centralisers. 

The inner and outer pipe sizing are designed as a single system which is to be installed by the preferred installation method for each project - reeling, towing, S-lay or J-lay. The selection of the appropriate installation method depends on the characteristics of the field development and the dimensions of the PIP systems.

Advantages of PIP

A key challenge for many new subsea developments is maintaining the appropriate product temperature within the pipeline infrastructure to avoid the formation of hydrates or wax resulting in a detrimental impact on flow assurance and possibly complete shutdown. To date, the industry has met this challenge by increased wet insulation coating, heating by the expensive DEH system and by higher-performance PIP.

PIP solution offers an ability to design and build a cost-effective solution for new or brownfield projects requiring effective and, when required, world-class insulation.

Sources:

• http://www.subsea7.com/content/dam/subsea7/documents/technologyandassets/4_Pg_Leaflet_High-performance__PIP__Reference.pdf
• https://nonerieska.wordpress.com/2013/01/31/pipeline-thermal-insulation-and-pipe-in-pipe-pip-as-a-solution/