A New Welding Concept for Pipelines: Electron Beam Welding

Abstract

Large diameter pipelines can be laid in deep am ultra deep sea conditions using the J-curve Method with a dynamically positioned vessel and very fast single pass welding technique : the Electron Beam w.elding. Developments under study since 3 years at TOTAL-CFP have shown successively : -Theoretfcal study of J-curve Laying -Feasability study of electron beam welding -Full scale tests of the major elements of the assembly. Now full scale prototype has been built and a J-curve simulation has been done.This paper relates succesively : -Feasability study introducing the different. te.chnological choices •••• -Tests of the major elements -Final study of the prototype -Construction and assembly of the full scale prototype --Simulation J Laying with the real movements 0 the t,aying Viessel (:roll and pitch). These trials executed on 24"OD and 1,25" thickness pipe have allowed the test of the whole laying ramp (loading of pipeline -automatic alignmentwelding -N.D. control of weld -descent of Pipe).The extensive cycling trials have shown that the total cycle time remains within the best barge performances.This machine and these tests now open the way to oil ans gas transport by deepsea pipeline.It has demonstrated the value of J-curve method and has made it possible to resolve the crucial problem of fast welding at a single station by using electron beam welding. J-LAYINGLARGE DIAMETERS FOR GREAT DEPTHS J Laying is applicable in a significant range of depths, namely from 300 to 3,000 m~tres.