A precision engineered controlled interference fit mechanical connector for joining steel pipe is evaluated in this paper. The primary advantage of such a connection is that the need for trained welders and radiographers is minimized, and the connection-joining process is accomplished very quickly with onshore and offshore production rates in the range of 25-30 connections per hour, and 15 connections per hour respectively. Use of these mechanical interference connections in the oil and gas industry began in the 1970s in the transportation of low pressure gas. Today, the implementation of this technology includes nominal pipe sizes ranging in size from 2-inch schedule 40, to 16 inch schedule 80, with the latter size being the subject of this paper. The usage of these connections varies from gathering and distribution systems, transmission lines, flowlines and other specialized applications both onshore and offshore.
This connection takes advantage of both the elastic and plastic properties of modern steel alloys, and therefore the design of a new connection size necessarily implies a rigorous process including numerical analyses and destructive testing for validation. This paper describes the use of finite element analysis (FEA) and full-scale testing of the connection under various internal pressures, tension and bending conditions as guided by ISO 13679:2002(E). The pipe size and type used in the program was 406-mm (16-inch) OD x 21.4-mm (0.843-inch) Wall Thickness, nominal Grade X52. The connection itself was monitored during make-up, simulated reeling, ISO Series B guided-testing and limit-load testing.
Details on the testing methods along with the analyses performed to evaluate the performance capabilities of the aforementioned interference connection are provided. The results of this testing program provided the data required to develop a performance envelope on the capacity of said connection size. In addition, the results obtained allow for estimating the applicability of this type of connection in future service conditions.
Capeto, J., Bedoya, J. J., Largura, L.C., Chapman, B., “Design and Validation of the 16-Inch Schedule 80 Interference Connection through Numerical and Experimental Methods,” Proceedings of the Rio Pipeline Conference & Exhibition 2017, Rio de Janeiro, Brazil, October 24 – 26, 2017.
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