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Mulheim (Ruhr), Germany

Meier H.-H.,Europipe Gmbh | Lucke H.-U.,Siempelkamp Maschinen und Anlagenbau GmbH and Co. KG
MPT Metallurgical Plant and Technology International | Year: 2011

Europipe GmbH operates one of the world's highest capacity pipe mills in Mülheim in the German Ruhr region. The plant produces longitudinally welded pipes with lengths up to 18 m diameters up to 1,524 mm and wall thicknesses up to 45 mm. Europipe had modernized the existing crimping press in intervals of 10 years to keep it up to customer demands. However, after more than 30 years of operation, it became obvious that the press design was reaching its performance limits. Preliminary considerations on the replacement of the press soon revealed that the installation of a new press would be an ambitious project. A significantly stronger and heavier press was to be fitted into the existing space on the foundation and the new press was expected to be operational within only a few weeks after disassembling the old one. Source

Nonn A.,Salzgitter Mannesmann Forschung GmbH | Kalwa C.,Europipe Gmbh
Proceedings of the International Offshore and Polar Engineering Conference | Year: 2012

This paper focuses on the characterization of the fracture performance of X100 material in transition temperature region using both experimental and numerical methods. The ductile fracture has been analyzed using tests on round notched bar specimens and standard fracture mechanics tests performed at room temperature. In previous publications the damage model Gurson-Tvergaard- Needleman (GTN) has been applied and verified by existing experimental data to describe ductile fracture behavior. The brittle fracture and the fracture in temperature transition region have been studied by means of deep and shallow notched SENB specimens at two different temperatures T=- 80°C and -40°C. Besides elastic-plastic analyses to quantify constraint levels for different initial crack configurations at the onset of cleavage fracture, the brittle failure has been described using modified Beremin model. The influence of the stable crack growth on the cleavage failure probability in temperature transition region has been captured by coupling the ductile fracture model (GTN) with the modified Beremin model. Finally, examples have been presented for the practical application of the numerical results on the fracture assessment of the flawed high-strength pipelines. Copyright © 2012 by the International Society of Offshore and Polar Engineers (ISOPE). Source

Volling A.,Salzgitter Mannesmann Forschung GmbH | Kalwa C.,Europipe Gmbh | Erdelen-Peppler M.,Salzgitter Mannesmann Forschung GmbH
Proceedings of the Biennial International Pipeline Conference, IPC | Year: 2014

Since the late 1960s' the Battelle Two-curve (BTC) model is the standard method applied in setting up design requirements with regard to the prevention of long-running ductile fracture in pipelines. It is a straightforward tool employing Charpy-V notch (CVN) toughness as key-measure for material resistance against crack propagation. On basis of pipe dimensions, material strength, and under consideration of decompression behavior of the transferred media, it enables to set up requirements for a minimum CVN toughness level to achieve crack arrest. Overall applicability of the BTC model is based on calibration of the underlying equations to a sound data-base, including both full-scale burst test results and smallscale laboratory testing data involving typical line-pipe grades at that period, i.e. up to grade X70 steels with below 100 J upper-shelf CVN toughness. Now over the last decades, mechanical behavior of line-pipe steels was improved significantly. Responding to market demands, higher grades were designed and also toughness levels were raised as outcome of R&D efforts within the steel industry. Unfortunately, stepping outside the original material data-base from BTC model calibration, this method did forfeit its reliability. At the beginning, mispredictions were mainly related to higher grade steels and elevated operating pressures. But more recent full-scale tests did reveal discrepancies in application of the BTC model also for so-called new vintage steels, i.e. grades actually being inside the original data base for model calibration but from current production routes. With regard to applicability/reliability of BTC model based predictions for crack arrest, the origin of uncertainty has particularly been traced back to the involved material toughness measure. Nowadays, it is common sense that the CVN uppershelf toughness value inadequately describes the resistance against running ductile fracture. More recent thoughts coherently argue towards closer involving stress-strain response and plastic deformation capacities of the material. On basis of results for grades X65, X80 and X100, the general relation between ductility and toughness is discussed. Finally, an elastic-plastic fracture mechanics related analytical approach is introduced which enables to quantify the resistance against ductile fracture propagation. The objective is to provide a reliable procedure for crack arrest prediction in line-pipe steels. Copyright © 2014 by ASME. Source

Stallybrass C.,Salzgitter Mannesmann Forschung GmbH | Liessem A.,Europipe Gmbh
Proceedings of the Biennial International Pipeline Conference, IPC | Year: 2012

There is a strong interest worldwide to transport large gas volumes from remote areas and hostile environments to the market. Pipe producers are therefore faced with increasingly demanding requirements both with regard to the toughness of the base material and the heat-affected zone. The toughness of the base material depends primarily on the steel composition and the TM processing conditions. Impressive levels of toughness in the base material were achieved by extensive alloy and process development over the past decades. These were realised by balancing the steel composition and processing parameters to give an optimum microstructure with a low grain size and homogeneous distribution of phases. During double submerged arc welding (DSAW) in the production of large-diameter linepipes, the heat-affected zone (HAZ) undergoes severe changes in the microstructure that include grain coarsening by about one order of magnitude and phase transformation during cooling and intercritical reheating. These have a negative impact on the toughness close to the fusion line. The higher austenite grain size close to the fusion line leads to a coarser structure after the phase transformation with larger carbon-rich M/A-phase particles than are typically observed in the base material in the as-rolled condition. This causes a drop of the toughness close to the fusion line compared to the base material. Classically, the carbon equivalent is an empirical measure for the weldability of steels and is known to correlate with the maximum hardness. However, its purpose is not to reflect the effect of individual alloying elements on the HAZ-toughness. The present paper addresses the relationship between base material composition and the HAZ-toughness of linepipe steels. An experimental investigation was carried out at EUROPIPE GmbH in cooperation with Salzgitter Mannesmann Forschung GmbH in which the chemical composition of laboratory heats was varied systematically. These heats were thermomechanically rolled to a wall thickness of 30 mm and subsequently used for submerged arc welding trials. The processing parameters during rolling and welding were held constant in the trials in order to ensure that the effect of the alloying elements could be isolated. The fusion line toughness was tested at -30°C and the microstructure was investigated by high-resolution scanning electron microscopy. This was complemented by microstructure investigations in the HAZ of large-diameter pipe material between the X65 and X80 strength levels. It was found that the influence of alloying elements on the HAZ-toughness is only reflected to some degree by the commonly used carbon equivalents, especially at similar strength levels. The results of the investigation were used for optimisation of the HAZ-toughness in production. Copyright © 2012 by ASME. Source

Nonn A.,Salzgitter Mannesmann Forschung GmbH | Kalwa C.,Europipe Gmbh
Proceedings of the Biennial International Pipeline Conference, IPC | Year: 2012

The performance of engineering design of high-strength steel pipelines has revealed the necessity to revise current design procedures. Therefore, an improved and detailed comprehension of fracture mechanisms and development of failure prediction tools are required in order to derive new design criteria. In last decades the most successful failure prediction tools for steel structures subjected to various type of loading can be encountered in the field of damage mechanics. This paper aims to describe ductile fracture behavior of high-strength steel pipelines by applying three different damage models, Gurson-Tvergaard-Needelman (GTN), Fracture Locus Curve (FLC) and Cohesive Zone (CZ). These models are evaluated regarding their capability to estimate ductile crack propagation in laboratory specimens and linepipe components without adjusting the calibrated parameters. It can be shown that appropriate parameter sets can be identified to reproduce load-deformation and fracture resistance curves accurately. The strain rate effect on the fracture behavior is examined by dynamic tests on the BDWT specimens. Finally, the shortcomings of the applied models are pointed out with the reference to possible extensions and modifications. Copyright © 2012 by ASME. Source

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