Direct Electrical Heating Pipe-in-Pipe (DEH-PiP) has now been around since its development and installation by Shell in the early 2000’s. It is a well-known and field-proven solution for subsea flowline heating, but it exhibits a relatively poor electrical efficiency compared to emerging heat-traced PiPs. Saipem considers that the DEH-PiP technology, with some improvements, is a very competitive option for subsea flowline heating. As a result, SAIPEM developed a High- Performance version of the DEH-PiP by introducing some new innovative elements.
On the basis of the conventional DEH-PiP technology, the High-Performance DEH-PiP specific design brings solutions to solve DEH-PiP main drawbacks: poor electrical efficiency and thus limited flowline step-out. Two main new features are leading to a High-Performance design.
The first is a SAIPEM patented solution to include an Aluminium Liner on the inner face of the Outer pipe. Most of the return current flowing in the outer pipe being channelled in this millimetric internal layer made of very conductive and non-magnetic material, the ohmic and hysteretic losses in the outer pipe are highly reduced.
The second, also patented by SAIPEM, is an innovative solution to fulfil the shear stop function without metallic bulkheads, replaced by rigid and isolating inner/outer links, made of polymer material.
The enhanced electrical efficiency of the system, in the range of 90%-95%, leads to: Increased flowline step-out by lowering the voltage supply level; Reduced power consumption when compared to classical Direct Electrical Heating technologies, and thus reduced GHG emissions in production.
In addition to the new performance-increasing components, the High-Performance DEH-PiP also includes some additional reliability-increasing features to maximize the global system reliability. Each component is designed to prevent any electrical or mechanical failure of the system.
Qualification activities were started in 2019 to verify and provide evidence that the system will properly perform the function it is designed for. The whole system qualification program is focused on the 100% reliability target, and most of the studies and tests are performed with this intent.
