Experimental study of the weld microstructure properties in assembling of natural gas transmission pipelines

2015 ◽  
Vol 231 (6) ◽  
pp. 1039-1047 ◽  
Author(s):  
M Sabokrouh ◽  
SH Hashemi ◽  
MR Farahani
Keyword(s):  
Mechanical Properties ◽  
Natural Gas ◽  
Chemical Analysis ◽  
Structural Integrity ◽  
Optical Microscope ◽  
Microalloyed Steels ◽  
Chemical Compositions ◽  
Natural Gas Pipelines ◽  
Natural Gas Transmission ◽  
Girth Welds

The coexistence of high levels of strength and toughness is necessary for the microalloyed steels used in natural gas pipelines. The welding thermal cycle can significantly change the microstructures and therefore the mechanical properties of the girth welded pipelines. Thus, the experimental investigation on the welded material properties is required for assessing the structural integrity of the pipelines. In this article, the metallurgical characteristics of the multi-pass girth welds on API X70 steel pipes with 56 in outside diameter and 0.780 in wall thickness were determined for the first time using chemical analysis and standard metallography. The chemical analysis showed different chemical compositions in different weld passes. The amount of carbon in the weldment increased in comparison with the base metal, although the microalloy elements in the weld gap decreased by increasing the pass number. The metallographic investigation by optical microscope demonstrated the different microstructures in different sub-zones of the welded joint. The images obtained from scanning electron microscope also presented the dendritic and acicular structures in the root and cap passes, respectively. The observed hard phases in the weldment, such as martensite, had direct effects on the mechanical properties of the weldment and heat-affected zone.

Development and Production of Heavy Gauge X80 and High Strength X90 Pipeline Steels Utilizing TMCP/Optimized Cooling Process

2014 ◽  
Author(s):  
Guodong Zhang ◽  
Xuejun Bai ◽  
Douglas Stalheim ◽  
Shaopo Li ◽  
Wenhua Ding
Keyword(s):  
Mechanical Properties ◽  
Natural Gas ◽  
Pipeline Steel ◽  
Steel Plates ◽  
Plate Mill ◽  
Cooling Process ◽  
X80 Pipeline Steel ◽  
Natural Gas Transmission ◽  
Transmission Pipeline ◽  
Pipeline Project

Along with the increasing demand of oil and natural gas by various world economies, the operating pressure of the pipeline is also increasing. Large diameter heavy wall X80 pipeline steel is widely used in the long distance high pressure oil and gas transportation in China today. In addition, development of X90/X100 has begun in earnest to support the growing energy needs of China. With the wide use of X80 steels, the production technology of this grade has become technically mature in the industry. Shougang Group Qinhuangdao Shouqin Metal Materials Co., Ltd. (SQS) since 2008 has been steadily developing heavier thicknesses and wider plate widths over the years. This development has resulted in stable mass production of X80 pipeline steel plate in heavy wall thicknesses for larger pipe OD applications. The technical specifications of X80 heavy wall thickness and X90/X100 14.8–19.6 mm wall thicknesses, large OD (48″) requiring wide steel plates for the 3rd West-to-East Natural Gas Transmission Pipeline Project and the third line of Kazakhstan-China Main Gas Pipeline (The Middle Asia C Line) and the demonstration X90/X100 line (part of the 3rd West-East Project) in China required changes to the SQS plate mill process design. Considering the technology capability of steelmaking and the plate mill in SQS, a TMCP+OCP (Optimized Cooling Process) was developed to achieve stable X80 and X90/X100 mechanical properties in the steel plates while reducing alloy content. This paper will describe the chemistry, rolling process, microstructure and mechanical properties of X80 pipeline steel plates produced by SQS for 52,000 mT of for the 3rd West-to-East Natural Gas Transmission Pipeline Project and 5,000 mT for the Middle Asia C Line Project along with 1000 tons of 16.3 mm X90/X100 for the 3rd West-East demonstration pipeline. The importance of the slab reheating process and rolling schedule will be discussed in the paper. In addition, the per pass reductions logic used during recrystallized rough rolling, and special emphasis on the reduction of the final roughing pass prior to the intermediate holding (transfer bar) resulting in a fine uniform prior austenite microstructure will be discussed. The optimized cooling (two phase cooling) application after finish rolling guarantees the steady control of the final bainitic microstructure with optimum MA phase for both grades. The plates produced by this process achieved good surface quality, had excellent flatness and mechanical properties. The pipes were produced via the JCOE pipe production process and had favorable forming properties and good weldability. Plate mechanical properties successfully transferred into the required final pipe mechanical properties. The paper will show that the TMCP+OCP produced X80 heavy wall and 16.3 mm X90 wide plates completely meet the technical requirements of the three pipeline projects.

Economic Evaluation Technique of Selecting Turbines for Natural Gas Pipelines

1978 ◽  
Author(s):  
T. E. Hajnal
Keyword(s):  
Economic Evaluation ◽  
Natural Gas ◽  
Operating Costs ◽  
Evaluation Technique ◽  
Gas Pipelines ◽  
Natural Gas Pipelines ◽  
Pipeline Systems ◽  
Natural Gas Transmission ◽  
Transmission Pipeline ◽  
Type Size

Designers of natural gas transmission systems often have to make recommendations as to the type, size, and number of turbines to be purchased and installed either on new pipelines or on expanding existing systems. This paper describes the economic evaluation technique which is being used by TransCanada PipeLines, of selecting turbines for natural gas transmission pipeline systems. The technique is based on comparing the present worths of annual owning and operating costs associated with the turbines considered for installation.

Girth Weld Joints From Long Upset Pipe Ends for Improving Fatigue Strength of Offshore Oil and Gas Pipelines

2019 ◽  
Author(s):  
Israel Marines-Garcia ◽  
Aarón Aguilar ◽  
Ramón Aguilar ◽  
Mauricio Pelcastre ◽  
Philippe Darcis
Keyword(s):  
Mechanical Properties ◽  
Fatigue Strength ◽  
Structural Integrity ◽  
Oil And Gas ◽  
Numerical Comparison ◽  
Entire Line ◽  
Girth Welding ◽  
Production Stages ◽  
Offshore Oil And Gas ◽  
Girth Welds

Abstract For special high dynamic loading applications, the structural integrity of the girth welds shall withstand stress levels that might be on the limits of the permissible defect tolerances for current production welding standards for plain pipe ends. In addition, unexpected loading conditions might take the stress limits out of safe operation, which can compromise the entire line. As a solution, the cross section of the girth weld may be increased for ensuring the strength and fatigue resistance under any loading circumstances, including strain cycles of reeling installation technique. The employment of pipes with upset ends is an excellent option for those cases. To propose this option as an alternative to current offshore solution for a Major O&G company, Tenaris developed a long upset pipe end with enhanced fatigue life. The challenges of this work included the manufacturing of very long upset ends from a medium wall thickness pipe, very tight mechanical properties difference between pipe and upset material properties, and finally a welding qualification program. The improvement of the fatigue strength of this product was highly expected. In order to achieve all requirements, especial arrangements were performed on the upsetter machine for achieving the target upset geometry; which was previously obtained by a design of experiments technique. Then the heat treatment of the pipes was designed for obtaining the tight mechanical properties difference between pipe body and upset sections. The main outcomes of the whole development are described within this paper; which include key information of how to overcome issues that might arise during the development and production stages of upsetted line pipes. The upset ends undertake a cylindrical machining; this process provides the advantage of achieving tight dimensional tolerances in the high-low girth welding alignment. The fatigue endurance data after full scale reeling experimental test are included, as well as the numerical comparison between the strain fields of plain pipe and upset girth weld unions. The welding procedure qualified during this work is described. The results of the whole development were very satisfactory and, as expected, the fatigue strength of upset ends was higher than the plain pipe.

Development of 7%Ni-TMCP Steel Plate for LNG Storage Tanks

2011 ◽  
Author(s):  
Ryuichi Ando ◽  
Kazushige Arimochi ◽  
Tomoya Kawabata ◽  
Kazushi Onishi ◽  
Takahiro Kamo ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Natural Gas ◽  
Large Scale ◽  
Steel Plate ◽  
Physical And Mechanical Properties ◽  
Rare Metal ◽  
Small Scale ◽  
Chemical Compositions ◽  
Nickel Steel ◽  
Storage Tanks

Demand of natural gas continues to increase in the recent years due to the rise of environmental issue and the drastic increase of crude oil price. These events led to the increase of constructions of Liquefied Natural Gas (LNG) storage tanks worldwide. The inner tank material for above ground LNG storage tanks have mostly been made of a 9% nickel steel plate over the last 50 years as it has excellent mechanical properties under the cryogenic temperature of −160deg-C. During this period, the LNG storage tanks made of 9%Ni steel plate have been operated safely at the many LNG export and import terminals in the world. Meanwhile, technologies of steel making, refinement, design, analysis, welding and inspection have been improved significantly and enabled enlarging volumetric capacity of the tank 2–3 times. There was a tendency for nickel price to increase in recent years. In such a circumstance lowering Ni content has focused attention on the 9%Ni steel as nickel is an expensive and valuable rare metal and a 7%Ni steel plate was eventually researched and developed by optimizing the chemical compositions and applying Thermo-Mechanical Controlled Process (TMCP). As a result, it was demonstrated that 7%Ni-TMCP steel plate had excellent physical and mechanical properties equivalent to those of 9%Ni steel plate. In order to evaluate fitness of the 7%Ni-TMCP steel plate and its weld for LNG storage tanks a series of testing was conducted. Several different plate thicknesses, i.e. 6,10,25,40 and 50 mm, were chosen to run large scale fracture toughness tests including duplex ESSO tests, cruciform wide plate tests as well as small scale tests. It was concluded that the 7%Ni-TMCP steel plate warrants serious consideration for use in LNG storage tanks. This paper reports details of the research and development of the 7%Ni-TMCP steel plate.

Evolution of Linepipe Manufacturing and its Implications on Weld Properties and Pipeline Service

2016 ◽  
Author(s):  
Yong-Yi Wang ◽  
David Horsley ◽  
Steve Rapp
Keyword(s):  
Mechanical Properties ◽  
Strain Hardening ◽  
Negative Impact ◽  
Critical Role ◽  
Microalloyed Steels ◽  
Thermal Cycles ◽  
Girth Welding ◽  
Girth Welds ◽  
Longitudinal Strains ◽  
Design Construction

Pipe grade is a dominant parameter in a pipeline’s service life. Critical decisions on the design, construction, and maintenance of pipelines are made on the basis of pipe grade. The implied assumptions or expectations are that pipes of the same grade would behave similarly and the experiences with a particular grade can be applied to all pipelines of the same grade. This simplification does not adequately take into account the other characteristics that are not represented by pipe grade, but can play a critical role in the safe and economical operation of pipelines. For instance, the evolution of steel-making processes and advancements in field welding practice can lead to significant differences in weld behavior among pipes of the same nominal grade. Most of the design, construction, and maintenance practices in the pipeline industry were established before the extensive use of modern control-rolled and microalloyed steels. With the exception of a few isolated research projects, the impacts of the fundamental changes in the steel metallurgy in modern microalloyed steels have not been systematically examined and understood. For instance, these steels may have very low strain-hardening capacity as a result of the TMCP process and may be subject to high levels of heat-affected zone (HAZ) softening due to their ultra-low carbon low-hardenability steel chemistry. HAZ softening reduces the longitudinal pipe strain capacity of girth welds, and low strain-hardening can potentially have a negative impact on tolerance to anomalies such as corrosion or mechanical damage. This paper starts with a brief review of linepipe manufacturing history with a focus on the chemical composition and rolling practices that directly affect the mechanical properties and the response to welding thermal cycles. The characteristics of linepipes made from modern microalloyed steels are contrasted with those made from vintage hot-rolled and normalized steels. The resulting mechanical properties of these two types of materials in the presence of welding thermal cycles are presented, and compared in terms of their behavior. The consequence of the weld characteristics is shown using examples of girth welds subjected to longitudinal strains. The implications of the pipe and weld characteristics on the design, field girth welding, and maintenance of pipelines are highlighted. Future directions and best practices in linepipe alloying and manufacturing strategies, linepipe specifications, field girth welding, and building strain-resistance girth welds are briefly described. It is emphasized that assessing the performance of pipelines based on their grades has fundamental shortfalls, and that gaps in codes and standards can lead to unexpected outcomes in pipeline integrity. In the long-run, revising relevant codes and standards is necessary to ensure consistent and reliable applications of new materials in the entire industry.

scholarly journals Effect of Hot-Rolled Heavy Section Bars Post-Deformation Cooling on the Microstructure Refinement and Mechanical Properties of Microalloyed Steels

Metals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1284
Author(s):  
Monika Banasiak ◽  
Andrzej Hornik ◽  
Stanisław Szczęch ◽  
Janusz Majta ◽  
Marcin Kwiecień ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Impact Toughness ◽  
Process Parameters ◽  
Microalloyed Steels ◽  
Special Focus ◽  
Chemical Compositions ◽  
Heavy Section ◽  
Wide Range ◽  
Microalloying Elements ◽  
The Relationship

In the industrial practice—especially in the reverse rolling mills—heavy section products with stable mechanical properties (YS, UTS) and ductility (A, Z) but with an impact toughness (KV) at too low levels are often observed. The results presented in the present work concern the relationship between the parameters of the cooling process of rolled products made of microalloyed steels, with different chemical compositions (such as Al-N, Al-N-V, Al-N-Ti) and their mechanical properties. Special focus was put on the relationship between chemical composition, grain size and impact toughness at subzero temperatures. It is shown, that by introducing the restrictions towards more strict control of the levels of Al, Ti, V, and N, it can be ensured that the final parameters are not that sensitive to process parameters variations which, hence, provides the required mechanical properties and especially impacts on the toughness requirements for a wide range of section products. It was also found that by slight modifications of microalloying elements and proper control of the process parameters, it is possible to replace commonly used normalizing annealing heat treatment after rolling with normalizing rolling.

Transients in Gas-Condensate Natural Gas Pipelines

1998 ◽  
Vol 120 (1) ◽  
pp. 32-40 ◽  
Author(s):  
J. Zhou ◽  
M. A. Adewumi
Keyword(s):  
Natural Gas ◽  
Phase Behavior ◽  
Hydrodynamic Model ◽  
Fluid Dynamic ◽  
A Priori ◽  
Gas Condensate ◽  
Behavior Model ◽  
Two Phase ◽  
Natural Gas Pipelines ◽  
Natural Gas Transmission

Liquid condensation in natural gas transmission pipelines commonly occurs due to the thermodynamic and hydrodynamic imperatives. Condensation subjects the gas pipeline to two-phase transport. Neither the point along the pipeline at which the condensate is formed nor the quantity formed is known a priori. Hence, compositional multiphase hydrodynamic modeling, which couples the multiphase hydrodynamic model with the natural gas phase behavior model, is necessary to predict fluid dynamic behavior in gas/condensate pipelines. A transient compositional multiphase hydrodynamic model for transient gas-condensate two-phase flow in pipelines is presented. This model consists of our newly developed well-posed modified Soo’s partial pressure model in conservative form which serves as the transient multiphase hydrodynamic model, and the phase behavior model for natural gas mixtures.

Cracking Analysis of Automobile Rim Flash Butt Welding

2014 ◽  
Vol 1004-1005 ◽  
pp. 1125-1128 ◽  
Author(s):  
Na Yin ◽  
Xian Tang Meng ◽  
Fei Li ◽  
Yang Cui ◽  
Zhi Wei Zhou
Keyword(s):  
Mechanical Properties ◽  
Chemical Analysis ◽  
Oxide Inclusion ◽  
Bending Test ◽  
Chemical Compositions ◽  
Welding Seam ◽  
Quality Requirements ◽  
Butt Welding ◽  
Micro Cracks ◽  
Welded Seam

Aiming at the serious crack phenomenon of automobile rim butt welding in a domestic wheel plant, means of analysis such as chemical analysis, tensile test, bending test, macrocosmic and microcosmic examination were used to find out the formation mechanism. Results showed that the chemical compositions and mechanical properties of base metal near the weld fracture meet the quality requirements, while the widmanstaten structure and composite oxide inclusion covered in unmelted region, which could cause micro-cracks in the welded seam and lower the plasticity of welding seam, were the key reasons to cause cracks of welding.

Sign in / Sign up

Export Citation Format

Share Document