Line Pipe Manufacturing Research Articles

Numerical Simulation of JCO-E Pipe Manufacturing Process and Its Effect on the External Pressure Capacity of the Pipe1

Large-diameter thick-walled steel pipes during their installation in deep-water are subjected to external pressure, which may trigger structural instability due to pipe ovalization, with detrimental effects. The resistance of offshore pipes against this instability is affected by local geometric deviations and residual stresses, introduced by the line pipe manufacturing process. In the present paper, the JCO-E pipe manufacturing process, a commonly adopted process for producing large-diameter pipes of significant thickness, is examined. The study examines the effect of JCO-E line pipe manufacturing process on the external pressure resistance of offshore pipes, candidates for deepwater applications using nonlinear finite element simulation tools. The cold bending induced by the JCO forming process as well as the subsequent welding and expansion (E) operations are simulated rigorously. Subsequently, the application of external pressure is modeled until structural instability (collapse) is detected. Both the JCO-E manufacturing process and the external pressure response of the pipe, are modeled using a two-dimensional (2D) generalized plane strain model, together with a coupled thermo-mechanical model for simulating the welding process.

Hybrid laser-arc welding of thick-walled ferromagnetic steels with electromagnetic weld pool support

The hybrid laser-arc welding (HLAW) process provides many advantages over laser welding and arc welding alone, such as high welding speed, gap bridgeability, and deep penetration. The developments in hybrid laser-arc welding technology using modern high-power lasers allow single-pass welding of thick materials. This technology can be used for the heavy metal industries such as shipbuilding, power plant fabrication, and line-pipe manufacturing. The obvious problem for single-pass welding is the growth of the hydrostatic pressure with increasing thickness of materials leading to drop-out of molten metal. This phenomenon is aggravated at slow welding velocities because of increasing weld seam width followed by a decrease of Laplace pressure compensating the hydrostatic pressure. Therefore, weld pool support is necessary by welding of thick materials with slow welding velocities. The innovative electromagnetic weld pool support system is contactless and has been used successfully for laser beam welding of aluminum alloys and austenitic and ferromagnetic steels. The support system is based on generating Lorentz forces within the weld pool. These are produced by an oscillating magnetic field orientated perpendicular to the welding direction. The electromagnetic weld pool support facilitates a decrease in the welding speed without a sagging and drop-out of the melt thus eliminating the limitations of weldable material thickness.

Study of gap and misalignment tolerances at hybrid laser arc welding of thick-walled steel with electromagnetic weld pool support system

The hybrid laser arc welding (HLAW) process provides many advantages such as improved gap bridgeability, deep penetration and misalignment of edges, that is why the process is used increasingly in industrial applications e.g. shipbuilding, power plant industry and line-pipe manufacturing. The obvious encountered problem for single pass welding in flat position is the gravity drop-out at low welding velocities. With the usage of an electromagnetic weld pool support system, which is based on generating Lorentz forces within the weld pool, wide seams followed by reduced welding velocities could be achieved in this study leading to the realization of a gap bridgeability up to 1 mm, misalignment of edges up to 2 mm and a single pass weld up to 28 mm thickness with a 20-kW fibre laser. These developments expand the boundaries of the HLAW process for different industrial applications. As a result, less accurate preparation of the edges would be sufficient, which saves time for manufacturing.

Finite element analysis of UOE manufacturing process and its effect on mechanical behavior of offshore pipes

• We simulate the UOE forming process, using finite elements and an advanced plasticity model. • We present results for geometrical imperfections and anisotropy induced by the UOE forming process. • We investigate the effect of cold-forming on the performance of UOE pipes under external pressure, tension and bending. • We compare the structural performance of UOE pipes with the performance of seamless pipes. • We examine the efficiency of a simplified methodology for determining the structural capacity of a UOE pipe. Thick-walled steel pipes during their installation in deep-water are subjected to a combination of loading in terms of external pressure, bending and axial tension, which may trigger structural instability due to excessive pipe ovalization. The resistance of offshore pipes against this instability depends on imperfections and residual stresses due to the line pipe manufacturing process. The present study examines the effect of UOE line pipe manufacturing process on the structural response and resistance of offshore pipes during the installation process using advanced finite element simulation tools. The cold bending induced by the UOE process is simulated rigorously and, subsequently, the application of external pressure and structural loading (bending or axial force) is modeled, until structural instability is reached. A parametric analysis is conducted, focusing on the effects of line pipe expansion on the structural capacity of the pipe. The results show that there exists an optimum expansion at which the highest pressure capacity is achieved. The effect of the axial tension on the pressure capacity of the pipe is examined as well. The influence of the line pipe expansion on bending capacity in the presence of external pressure is also identified. Finally, a simplified methodology is employed, accounting for the material anisotropy induced by the manufacturing process, capable of determining the structural capacity of a UOE pipe in a simple and efficient manner with good accuracy, using more conventional modeling tools.

Numerical Simulation Technology for a Full Cycle of Steel Line Pipe Manufacturing Operations

At present day pipe mill engineers have to deal with challenging technological problems of heavy-wall and high strength line pipe manufacturing. Numerical analysis of welded large-diameter pipe manufacturing stages is the most efficient way to solve these problems. Corresponding computational technologies and applied software was developed at Physical & Technical Center. Numerical structural analysis of steel plates at various stages of line pipe manufacturing is performed by the finite element method accounting for geometric and material nonlinearities. The only thing to be done by the engineer in such analysis is to specify required input parameters. All the further process is software-controlled. The discrepancy between the numerical analysis results and measured data in the overwhelming majority cases did not exceed 1%.

A Simulation Technology for a Full Cycle of Steel Line Pipe Manufacturing Operations

At present day, pipe mill engineers have to deal with challenging technological problems of heavy-wall and high-strength line pipe manufacturing. Numerical analysis of welded large-diameter pipe manufacturing stages is the most efficient way to solve these problems. Corresponding computational technologies and applied software were developed at Physical & Technical Center. Numerical structural analysis of steel plates at various stages of line pipe manufacturing is performed by the finite element method, accounting for geometric and material nonlinearities. The only thing to be done by the engineer in such analysis is to specify required input parameters. All the further process is software controlled. The discrepancy between the numerical analysis results and measured data in the overwhelming majority cases did not exceed 1%.

Finite element modelling of a submerged arc welding process

A multi-wire submerged arc welding (SAW) process has been modelled using a general purpose finite element package ABAQUS. The paper explains briefly the welding process and its application in thick wall linepipe manufacturing. Corresponding 2D and 3D finite element (FE) models of the SAW process are presented. FE analyses were carried out to investigate the heat transfer characteristics in the fusion and heat affected zones during welding. The effect of process parameters and weldment geometry have been evaluated with and without the consideration of residual stresses and strains induced from the forming processes prior to welding. Comparisons of FE predictions with experimental results are presented where it is appropriate. It is shown that the geometrical distortion and residual stresses and strains caused by welding can be minimised through process optimisation. It is therefore demonstrated that finite element analysis can be applied to better understand the SAW process and hence be a useful tool for future process development and control with the view of optimising product properties.

Production of line pipe in Japan

Abstract Japan is one of the world's leading suppliers of line pipe. In this paper, the authors describe advances in line-pipe manufacturing technology that have been made in Japan during the past decade. Manufacturing methods have been improved, and seamless, electric-resistance, and submerged-arc (both straight and spiral seam) welding processes are all now used. Line-pipe manufacturers have had to adjust to changing requirements for pipe size (outside diameter and wall thickness), strength, toughness, corrosion resistance, and weldability. The performance of line pipe under high pressure, in use in the Arctic and in deep water, and for transporting sour gas has been evaluated. The steelmaking, hot-rolling, and pipe-forming stages of manufacture have all been tailored to the production of high-quality line pipe.