Production of Metallurgically Cladded Pipes for High End Applications in the Oil and Gas Industry

Abstract

The paper describes the different industrially used options to produce a clad pipe and explains in detail the manufacture of metallurgically cladded pipes starting with the production of roll bonded plates. In plate manufacturing the advantages as well as the limitations of thermo-mechanical (TM) rolling are discussed. The TM-technology is shown to improve weldability, HIC-resistance, strength and toughness properties of the carbon steel section of the pipe. Moreover, it also improves corrosion resistance of the CRA layer. The pipe manufacturing procedure, which involves two welding technologies for longitudinal welds is described. The carbon steel parts of the pipe are joined using double-sided multi-pass Submerged-Arc-Welding (SAW). The single-pass Electroslag-Welding (ESW) is subsequently used for recladding of the CRA layer. The multi-pass SAW results in excellent mechanical properties of the weld joint, whereas the ESW technique ensures low dilution of CRA with the carbon steel, a smooth weld bead shape and a high corrosion resistance of the deposited layer. With the aid of thermodynamic modeling and numerical simulations it is shown, that the high corrosion resistance is promoted by an intensive mixing within the ESW weld pool and relatively low segregation level of Cr and Mo during solidification. Furthermore, FEM analysis is applied to examine the plastic deformation and residual stresses distribution in the pipe during forming, welding and final calibration. The obtained information assists in optimization of manufacturing procedure, and can also be included in prediction of resulting pipe fatigue during operation.