Deepwater pipeline design:UOE or Seamless

The conventional pipe design is mainly considering of withstanding internal pressure. The greater the ability to withstand the pressure, the greater the flow of the tube, and thus the operators who will have greater efficiency. But for the design of deepwater pipelines, against external pressures become an important issue to consider, especially during the installation period. "Within the field" pipeline, such as subsea pipe, riser pipe and flow line pipe, because of the small diameter, it has a strong anti-hydrostatic capabilities. And for these, seamless steel pipe are generally used, which is easily obtained and is a more economical solution. However deepwater tieback lines and long-distance pipeline system generate a greater challenge for pipe design. In order to obtain a greater yield of the seabed, it tends to use a larger diameter and larger wall thickness tube to ensure that the pipeline can withstand the hydrostatic pressure and the need for bending. Pilger process can produce the desired thick-walled tube, but the manufacturing process is slow, the material cost is also high. The most economical method of manufacturing such a line is the UOE process. UOE process is pressing the steel plate into a U-shaped, then rolled into O-type, and then circumferential expansion. The improving requirements of the industry put forward limit challenge for the design of such pipelines. These requirements include the economy of safe and successful installation and the costs. Generally speaking, UOE steel pipe is more economical than seamless steel pipe.