Analytical model for J-tube pull-in

Abstract

As long as J-tubes are installed during the platform installation, only minor thing can be changed after installation. The method implies pulling the pipeline through J-shaped tubes (J-tube). In spite of the all the advantages mentioned before, the method requires design analysis in term of required pulling force, riser integrity and J-tube integrity. There are mainly two ways for design analysis; Finite Element analysis and Analytical method. First approach is time consuming and costly, meanwhile it provides accurate and versatile result. The latter would be good guidance at initial phases of the project. In this project the analytical method was established to examine riser integrity and to determine required winch pulling capacity. Riser integrity was analyzed in accordance with DNV-OS-F101 for local buckling. The winch’s pulling capacity is calculated using the Capstan equation, beam theory for plastic deformation and the energy method. The method calculates tension force on winch during different stage of J-tube pull-in installation by taking into account the riser’s dimensions, material properties and the J-tube’s geometry.