AMR Engineering AS

Drammen, Norway

AMR Engineering AS

Drammen, Norway
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Liu J.Y.,AMR Engineering AS | Moe P.T.,AMR Engineering AS | Moe P.T.,Norwegian University of Science and Technology | Ganesan S.M.,Norwegian University of Science and Technology | And 4 more authors.
International Journal of Material Forming | Year: 2010

Shielded Active Gas Forge Welding is a robust and efficient solid state welding method applicable to offshore and oilfield applications. The mechanical or fracture performance of the welded connection may be influenced by the forge weld shape. In this paper the main focus is on the geometry effect of weld shape and defects on forge weld mechanical performance and fracture behavior. The potential impact of variables on the undercut description is parametrically analyzed by finite element calculation. As for the undercut located in the transition region between weld and base material, our studies show that the outer undercut of more than 0.3 mm has a significant impact on mechanical behaviour of welded pipe. When the undercut is located in the fusion plane, its impact on mechanical performance of welded pipe is negligible. Weld caps are beneficial since they contribute to weakening the driving forces for crack propagation. Even if the effect of undercut is considered, the beneficial contribution of weld cap still exists. © 2010 Springer-Verlag France.


Ganesan S.M.,Norwegian University of Science and Technology | Moe P.T.,Norwegian University of Science and Technology | Moe P.T.,AMR Engineering AS | Vinothkumar P.,Norwegian University of Science and Technology | And 6 more authors.
International Journal of Material Forming | Year: 2010

Microstructure design and heat treatment cycle optimization are two vital activities in any metal forming process which involves high working temperature. Much emphasis is given within these activities to achieve desired structural and mechanical properties of the end products. In this paper an attempt has been made to establish innovative and efficient heat treatment cycles for forge welded API L80 tubular joints. A requirement is that the heat treatment is completed within 5 to 6 minutes after welding. The L80 alloy studied here is a medium carbon steel that has abundant oilfield applications. In order to assess optimal heat treatment for the weld zone, displaying a highly transient and nonuniform temperature distribution, continuum modelling of the process has been performed. Forge welding is a process in which two mating surfaces of pipes are heated (within a small confined depth from the contacting surfaces) to a certain temperature and joined by applying a pressure. The whole process is carried out in the solid state producing a weld without weld metal and with narrow heat affected zone (HAZ), which distinguish it from some of the more conventional welding processes available to produce tubular joints. Specific mechanical properties of forge welded L80 tubular joints were obtained by a unique approach to heat treatment and microstructural design at joints as well as HAZ. Heat treatment cycles were estimated in SINTEF's Smitweld Thermal Cycle Simulator ® to compare with the actual forge welding process. A detailed analysis of specimens subjected to Smitweld simulation and forge welding was carried out to study compatibility and to establish optimum heat treatment conditions for forge welding of L80 tubular joints. © 2010 Springer-Verlag France.


Moe P.T.,Norwegian University of Science and Technology | Moe P.T.,AMR Engineering AS | Salberg B.,AMR Engineering AS | Rabben K.,AMR Engineering AS | And 4 more authors.
International Journal of Material Forming | Year: 2010

Shielded Active Gas Forge Welding is a fully automatic high speed welding process for metals. It was invented in the early 1980s, but has since then been significantly improved and commercialized for mainly casing and pipeline applications for the oil and gas industry. The method consists of three main steps: (1) localised heating of the mating surfaces, (2) forging and joining of the mating surfaces and (3) heat treatment of the weld. An entire welding cycle can be completed in two minutes, independent of dimension. The method has been used for welding a great range of alloys, and it produces a weld with properties similar to those of the base material. © 2010 Springer-Verlag France.


Marimuthu G.S.,Norwegian University of Science and Technology | Moe P.T.,Norwegian University of Science and Technology | Liu J.,AMR Engineering AS | Salberg B.,AMR Engineering AS
Proceedings of the International Conference on Offshore Mechanics and Arctic Engineering - OMAE | Year: 2012

In this paper, we discuss how through-process multi-scale models can be designed and combined with properly constructed experiments in order to assess the mechanical integrity of forge welded connectors. Shielded Active Gas Forge Welding (SAG-FW) is a fully automatic solid state method for joining steel pipes and other metallic articles. After heating, welding occurs almost instantaneously when the mating surfaces of the metallic parts are brought into intimate contact at high temperature and co-deformed. The result is a metallic bond with properties similar to those of the base material. If mating surfaces have been properly prepared and are essentially free from oxides the forge weld line is completely indistinguishable even when studied under a microscope. However, improper surface finish, oxides and contaminants may contribute to reducing weld quality. The paper consists of analytical and experimental parts. First, approaches for modeling forge welding and weld integrity are assessed. Second, a Gurson-type model is studied in great detail as it appears to be the simplest and most promising concept in relation to quantitative modeling and testing of mechanical integrity of forge welds. Third, miniature notched specimens for determining parameters of a modified Gurson-model are proposed and evaluated in relation to small scale forge welding. The small scale forge welding method has been established in order to simulate full scale welding of for example line pipe and casing, but mechanical testing of small samples constitute a significant challenge. Fourth, a set of experiments is performed to further assess the concept, to the extent possible determine material parameters of the Gurson-model and to evaluate the effect of process parameter settings on the weld quality. Results from tests of welds with and without oxides are subsequently compared with results from tests of base material specimens. All tests have been performed for an API 5L X65 alloy. The results demonstrate that both capacity and ductility of the forge welds are similar to those of base material. Finally, Gurson model parameters are assessed, and a comparison with physical observations is made. Further development of the small scale tests is needed. More extensive test programs should be performed and a comparison with full scale welding should be carried out. However, the experiments demonstrated that the proposed notched specimen designs complements conventional fracture mechanical tests (CT, SENT, SENB) or field tests proposed by various standards (Charpy, Izod, bend tests). Copyright © 2012 by ASME.


Palanisamy V.,Norwegian University of Science and Technology | Solberg J.K.,Norwegian University of Science and Technology | Salberg B.,AMR Engineering AS | Moe P.T.,Norwegian University of Science and Technology
Proceedings of the International Conference on Offshore Mechanics and Arctic Engineering - OMAE | Year: 2012

The continuous development of line pipe and casing grade steels should be complemented by development of more effective welding methods. A special high temperature high speed forge welding technique called Shielded Active Gas Forge Welding (SAG-FW) has been developed to weld steel pipes for a range of applications. This article focuses on the microstructure development at different welding conditions in L80 steel with 0.25%C. Specimens with dimensions 100 mm x 11 mm x 6 mm were extracted from the wall of a large diameter L80 pipe. A SMITWELD thermal simulator was used to simulate heat treatment conditions using electrical resistance heating. The specimens were heated to peak temperatures ranging from 600°C to 1350°C within 10 s and subsequently quenched to 50°C at a constant rate of 60 °C/s to simulate the heat-affected zone conditions for the real SAG-FW process. Martensite with small fractions of bainite was observed for higher peak temperatures. Mixed microstructures were observed in the specimens heated in the intercritical temperature range. Microstructures and phase fractions developed after heating to different peak temperatures have been analyzed by optical microscopy and scanning electron microscopy. Charpy V-notch tests and Vickers microhardness measurements have been carried out for the weld simulated specimens. The observed toughness values, hardness values, microstructures and phase fractions have been correlated to the respective weld simulation parameters. Copyright © 2012 by ASME.


Marimuthu G.S.,Norwegian University of Science and Technology | Moe P.T.,Norwegian University of Science and Technology | Salberg B.,AMR Engineering AS | Audestad J.I.,AMR Engineering AS
Proceedings of the International Conference on Offshore Mechanics and Arctic Engineering - OMAE | Year: 2012

A state-of-the-art small-scale solid state forge welding machine has been fabricated for checking weldability by Shielded Active Gas Forge Welding (SAG-FW) of tubular products applicable predominantly for, but not limited to offshore Industries. Effective, fast and inexpensive welding and testing of joints make this small-scale method suitable for evaluating weldability of a material before starting regular qualification and fabrication in a full-scale welding machine normally located in spool base or offshore. The small-scale machine provides a complete package for pre-qualification studies, including assessment of welding conditions, material flow behavior, heat treatment options. However, there are considerable challenges relating to application of international standards of testing as well as interpretation and use of results in the context of large-scale welding. In this paper results from small-scale welding and weld characterization of an API 5L X65 quality are presented. First, a detailed test plan for analyzing the weld is outlined. This procedure is subsequently applied for checking the welds to be produced in the full-scale machine. Short-comings in using the small-scale process as well as the possible remedies are discussed in detail. Copyright © 2012 by ASME.


Vinothkumar P.,Norwegian University of Science and Technology | Ganesan S.M.,Norwegian University of Science and Technology | Solberg J.K.,Norwegian University of Science and Technology | Salberg B.,AMR Engineering AS | Moe P.T.,Norwegian University of Science and Technology
Advanced Materials Research | Year: 2012

Shielded Active Gas Forge Welding (SAG-FW) is a solid state bonding process in which two mating surfaces are locally heated and forged together to form a bond. SAG-FW has so far mainly been used to join materials for pipe-line and casing applications. The present study has been conducted on an API 5CT L80 grade material in a prototype forge welding machine. Small-scale pipe specimens have been extracted from the wall of the production casing. The SAG-FW process is completed within a few seconds of heating and forging followed by controlled cooling. The microstructure of the weld is determined by the processing parameters. In this paper, microstructure results for SAG-FW processed L80 material have been obtained for a range of cooling rates and systematically compared with microhardness values. Microstructure observations at different regions of the weld have been made. Faster heating rate and controlled cooling resulted in a mixture of non equilibrium microstructures, but satisfactory mechanical properties have been obtained for optimized processing parameters. © (2012) Trans Tech Publications, Switzerland.


Marimuthu G.S.,Norwegian University of Science and Technology | Moe P.T.,Norwegian University of Science and Technology | Salberg B.,AMR Engineering AS | Liu J.,AMR Engineering AS | And 3 more authors.
American Society of Mechanical Engineers, Pressure Vessels and Piping Division (Publication) PVP | Year: 2010

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 carefully replicates 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.Copyright © 2010 by ASME.


Liu J.,AMR Engineering AS | Marimuthu G.S.,Norwegian University of Science and Technology | Moe P.T.,Norwegian University of Science and Technology
Proceedings of the International Conference on Offshore Mechanics and Arctic Engineering - OMAE | Year: 2013

Shielded Active Gas Forge Welding is a high speed welding method for joining inter alia steel pipeline and casing. The process consists of a heating step, in which the bevels of the sections to be joined are heated locally to temperatures exceeding 1000 °C, and a subsequent forging step in which joining takes place by the application of a high axial force. In order to make possible cost-effective welding qualification and research a small scale forge welding machine has been developed. Down-scaling of the forge welding process should be carefully assessed in order to establish the limits of the process. In this paper two aspects of the forge welding process have been studied in detail by the use of finite element modeling and experiments: a) coupled thermal and electro-magnetic modeling of heating and b) coupled thermo-mechanical modeling of forging. Special attention is given to the study of the limits of buckling of the pipe wall during forging. A high thermal gradient in the axial direction in the pipe wall facilitates local plastic deformation during forging and proper fusion of welds. For elongated temperature fields buckling is more likely to occur since the effective stiffness of the wall section is reduced. The limits of buckling depend on the wall thickness and diameter of section to be joined. While the forge welding process works very well for virtually all types of full scale pipeline and casing sections, buckling has been observed when joining very thin-walled small scale pipes. For welding of stainless steel small scale pipes local heating proves challenging. These challenges may be overcome by innovative welding machine design, and by carefully assessing welding process limitations. Certain physical limitations must still be considered. Copyright © 2013 by ASME.


Jacobsen T.B.,Norwegian University of Science and Technology | Salberg B.,AMR Engineering AS | Moe P.T.,Norwegian University of Science and Technology | Liu J.,AMR Engineering AS
Proceedings of the International Conference on Offshore Mechanics and Arctic Engineering - OMAE | Year: 2013

Shielded Active Gas Forge Welding (SAG-FW) is a solid state welding process for metal pipes, rods and other elongate products. As a part of an extensive qualification programme for SAG-FW for casing applications a series of welds have been completed for the pipe steel quality Vallourec & Mannesmann VM50. While the microstructure of the base material (BM) is tempered martensite, both natural cooling and quench-tempered microsturctures were evaluated in order to assess the need for post-weld heat treatment (PWHT). Forge welds were subjected to careful and independent metallurgical analysis and mechanical testing by Det Norske Veritas (DNV). For as-welded specimens the heat affected zone (HAZ) consists of ferrite and pearlite. Hardness values for the HAZ are 160 HV10 while for the base material inner and outer wall are 150 and 175 HV10 respectively. As-welded tensile tests show a drop in yield from 390 to 370 MPa. Charpy testing of the welds at -20°C reveals a fully ductile structure with toughness of 150 J. The HAZ is entirely in the region with increased wall thickness. In an extended study of mechanical properties of the VM50 forge welds results from a notched tensile test were used to determine the damage parameters for the Complete Gurson Model (CGM) using finite element modeling for calibration. In order to evaluate the quality of the damage model Single Edge Notched Bending (SENB) tests were performed and studied using finite element models. The toughness of the as-welded weld is moderately reduced due to welding, but it remains ductile with high fracture resistance. The moderate reduction of fracture resistance can be explained by microstructure change. Copyright © 2013 by ASME.

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