Qualification of UOE SAWL Linepipes With Enhanced Collapse Resistance for Ultra Deepwater Applications

Abstract

Large diameter UOE pipes are being increasingly used for the construction of offshore pipelines. Since oil discoveries are moving towards ultra-deepwater areas, such as Pre-Salt in Brazil, collapse resistance is a key factor in the design of the pipelines. It is known that the cold forming, and the final expansion in the UOE linepipe manufacturing process, reduces the elastic limit of the steel in subsequent compression. Due to this, the DNV collapse formula includes a fabrication factor that derates by a 15% the yield strength of UOE Pipes. However, DNV also recognizes the effect of thermal treatments and the code allows for improvement of the fabrication factor when heat treatment or external cold sizing (compression) is applied, if documented. This paper presents the qualification of UOE pipes with enhanced collapse capacity focusing the use of a fabrication factor (αfab) equal to 1. TenarisConfab has performed a technology qualification process according to DNV-RP-A203 standard “Qualification Procedures for New Technology”. The main aspects of the qualification process are presented in this paper which included significant material and full scale testing, including combine load testing, and final analysis. The qualification process achieved successful results and this will allow use of a fabrication factor equal to 1 directly in deepwater and ultra-deepwater offshore pipeline projects with a possible reduction in material and offshore installation costs and also potentially enhancing the feasibility of many challenging offshore projects.

The JCOE/JCOC manufacturing process and collapse resistance of submarine pipeline

“…Local buckling collapse and buckling propagation are the primary structural failure modes of submarine pipelines under high water pressure environmental loads, so pipes with high roundness are needed to meet the requirements. 1,2 Relevant studies show that the collapse performance is related to the pipe forming process, weld quality and structure, ovality, heat treatment process, sizing method, pipe geometry, and so on. In the JCO forming process, the deformation of the pipe is ideally symmetrical.…”

“…Pipeline transportation is favored by countries all over the world as a transportation mode with less one-time investment cost, low transportation cost, and higher safety factors. 2 Submarine oil and gas pipeline is an important way to connect the internal facilities of offshore oil and gas fields and export oil and gas resources. It is one of the indispensable key projects for the development of offshore oil and gas.…”