WELDING PROCEDURE ESTABLISHMENT FOR TUBULAR JOINTS WELDED BY SINGLE STATION, SOLID STATE WELDING MACHINE

摘要

Forge welding is an efficient welding method for tubular joints applicable in oil and gas industries due to its simplicity in carrying out the welding, absence of molten metal and filler metals, small heat-affected zone and high process flexibility. Prior to forging, the ends (bevels) of the joining tubes can be heated by torch or electromagnetic (EM) techniques, such as induction or high frequency resistance heating. The hot bevels are subsequently pressed together to establish the weld. The entire welding process can be completed within seconds and consistently produces superior quality joints of very high strength and adequate ductility. Industrial forge welding of tubes in the field is relatively expensive compared to laboratory testing. Moreover, at the initial stages of a new project sufficient quantities of pipe material may not be available for weldability testing. For these and several other reasons we have developed a highly efficient single station, solid state welding machine that carefullyreplicates the thermomechanical conditions of full-scale Shielded Active Gas Forge Welding Machines (SAG-FWM) for pipeline and casing applications. This representative laboratory machine can be used to weld tubular goods, perform material characterization and/or simulate welding and heat treatment procedures. The bevel shapes at mating ends of the tubes are optimized by ABAQUS® simulations to fine tune temperature distribution. The main aim of this paper is to establish a welding procedure for welding the tubular joints by the representative laboratory machine. The quality of the welded tubular joint was analyzed by macro/micro analyses, as well as hardness and bend tests. The challenges in optimizing the bevel shape and process parameters to weld high quality tubular joints are thoroughly discussed. Finally a welding procedure specification was established to weld the tubular joints in the representative laboratory machine.