Strain Capacity Investigation on Grade X70 High Strain Line Pipe With Girth Weld

2018 ◽  
Author(s):  
Hisakazu Tajika ◽  
Takahiro Sakimoto ◽  
Tsunehisa Handa ◽  
Satoshi Igi ◽  
Rinsei Ikeda ◽  
...  
Keyword(s):  
High Strain ◽  
Compressive Strain ◽  
Bending Test ◽  
High Grade ◽  
Line Pipe ◽  
Strain Capacity ◽  
Global Strain ◽  
Significant Difference ◽  
Pipeline Project ◽  
Pipe Bending

Recently high grade pipeline project have been planned in hostile environment like landslide in mountain area, liquefaction in reclaimed land or the frost heave in Polar Regions. Geohazards bring large scale ground deformation and effect on the varied pipeline to cause large deformation. Therefore, strain capacity is important for the pipeline and strain based design is also needed to keep gas transportation project in safe. High grade steel pipe for linepipe tends to have higher yield to tensile (Y/T) ratio and it has been investigated that the lower Y/T ratio of the material improves strain capacity in buckling and tensile limit state. In onshore pipeline project, pipe usually transported in 12 or 18m each and jointed in the field. Girth weld (GW) is indispensable so strength matching of girth weld towards pipe body is important. In this study strain capacity of Grade X70 high strain pipe with size of 36” OD and 23mm WT was investigated with two types of experiments. One was a pipe bending test with whole pipe. The length of the specimen was approximately 8m and GW was made in the middle of joint length. A fixed internal pressure was applied during the bending test. Actual pipe situation in work was simulated and both circumferential and longitudinal stress occurred in this test. The other test was curved wide plate (CWP) test. In both tests, test pipes were cut and welded using GTAW in the first two layers and GMAW for the subsequent passes. Welding wire of TG-S62 and MG-S58P were used for GTAW and GMAW respectively to achieve over-matching girth weld considering the pipe body strength. Elliptical EDM notch was installed in the GW HAZ as simulated weld defect. In pipe bending test, buckling occurred at the intrados at 300 mm apart from the GW. 2D average compressive strain at buckling was 3.59% and this high compressive strain was considered to derive from the high strain capacity of this pipes. After the buckling, deformation concentrated to the buckling wrinkle. Test pipe broke at 35.5 degrees of pipe end rotation and the location was in base metal at the extrados opposite to the buckling wrinkle. The HAZ notch opened and CTOD was 1.44 mm and the global strain in 2D length average strain was 7.8%. In CWP test, tensile strain simply got large and pipe finally broke at global strain of 9.6% and CTOD of 15 mm. The break location was the HAZ notch. There was a significant difference in CTOD growth in HAZ between two test types. Conditions and factors that effect to these differences are argued in this paper.

Girth Weld Strength Matching Effect on Tensile Strain Capacity of Grade X70 High Strain Line Pipe

2018 ◽  
Author(s):  
Hisakazu Tajika ◽  
Takahiro Sakimoto ◽  
Tsunehisa Handa ◽  
Rinsei Ikeda ◽  
Joe Kondo
Keyword(s):  
High Strain ◽  
Limit State ◽  
Full Scale ◽  
Bending Test ◽  
High Grade ◽  
Line Pipe ◽  
Bending Tests ◽  
Strain Capacity ◽  
Pipeline Project ◽  
Pipe Bending

Recently high grade pipeline project have been planned in hostile environment like landslide in mountain area, liquefaction in reclaimed land or the frost heave in Polar Regions. Geohazards bring large scale ground deformation and effect on the varied pipeline to cause large deformation. Therefore, strain capacity is important for the pipeline and strain based design is also needed to keep gas transportation project in safe. High grade steel pipe for linepipe tends to have higher yield to tensile (Y/T) ratio and it has been investigated that the lower Y/T ratio of the material improves strain capacity in buckling and tensile limit state. In onshore pipeline project, pipe usually transported in 12 or 18m each and jointed in the field. Girth weld (GW) is indispensable so strength matching of girth weld towards pipe body is important. In this study strain capacity of Grade X70 high strain pipes with size of 36″ OD and 23mm WT was investigated with two types of experiments, which are full scale pipe bending tests and curved wide plate tests. The length of the specimen of full scale bending tests were approximately 8m and girth weld was made in the middle of joint length. A fixed internal pressure was applied during the bending test. Actual pipe situation in work was simulated and both circumferential and longitudinal stress occurred in this test. Test pipes were cut and welded, GTAW in first two layer and then finished by GMAW. In one pipe, YS-TS over-matching girth weld (OVM) joint was prepared considering the pipe body grade. For the other pipe, intentionally under-matching girth weld (UDM) joint was prepared. After the girth welding, elliptical EDM notch were installed in the GW HAZ as simulated weld defect. In both pipe bending tests, the buckling occurred in the pipe body at approximately 300mm apart from the GW and after that, deformation concentrated to buckling wrinkle. Test pipe breaking locations were different in the two tests. In OVM, tensile rupture occurred in pipe body on the backside of buckling wrinkle. In UDM, tensile rupture occurred from notch in the HAZ. In CWP test, breaking location was the HAZ notch. There were significant differences in CTOD growth in HAZ notch in these tests.

Material Development and Strain Capacity of Grade X100 High Strain Linepipe Produced by Heat Treatment Online Process

2008 ◽  
Author(s):  
Nobuyuki Ishikawa ◽  
Mitsuhiro Okatsu ◽  
Junji Shimamura ◽  
Shigeru Endo ◽  
Nobuo Shikanai ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Yield Strength ◽  
High Strain ◽  
Compressive Strain ◽  
Bending Test ◽  
Heating Process ◽  
Strain Capacity ◽  
Online Process ◽  
Microstructural Control ◽  
External Coating

Linepipes installed in permafrost ground or seismic region, where larger strains can be expected by ground movement, are required to have sufficient strain capacity in order to prevent local buckling or girth weld fracture. On the other hand, strain capacity of linepipes usually degreases with increasing strength, and this is one of the reasons for preventing wider use of high-grade linepipe for high strain application. Furthermore, external coating is necessary for corrosion resistance of pipe, but coating heat can cause strain-aged hardening, which results in increased yield strength and Y/T. Therefore, there is a strong demand for developing high strength linepipe for a high strain application with resistance to strain-aged hardening. Extensive studies to develop Grade X100 high strain linepipe have been conducted. One of the key technologies for improving strain capacity is dual-phase microstructural control. Steel plate with the microstructure including bainite and dispersed martensite-austenite constituent (MA) can be obtained by applying accelerated cooling followed by heat treatment online process (HOP). HOP is the induction heating process that enables rapid heating of the steel plates. Variety of microstructural control, such as fine carbide precipitation and MA formation, can be utilized by this newly developed heating process. One of the significant features of the HOP process is to improve resistance to strain-aged hardening. Increase in yield strength by coating can be minimized even for the Grade X100 linepipe. Trial production of X100 high strain linepipe with the size of 36″ OD and 15mm WT was conducted by applying the HOP process. Microstructural characteristics and mechanical properties of developed X100 linepipe are introduced in this paper. In order to evaluate compressive strain capacity of the developed pipe, full-scale pipe bending test was carried out by using the trial X100 high strain linepipe after external coating. Full scale bending test of developed X100 linepipe demonstrated sufficient compressive strain capacity even after external coating.

Strain-Based Pipeline Design in Harsh Environments Using Large Diameter High Strain Line Pipes

2014 ◽  
Author(s):  
Nobuhisa Suzuki ◽  
Takekazu Arakawa ◽  
Andrey Arabey
Keyword(s):  
High Strain ◽  
Large Diameter ◽  
Strain Curve ◽  
Bending Test ◽  
Harsh Environments ◽  
Standard Line ◽  
Stress Strain Curve ◽  
Line Pipe ◽  
Strain Capacity ◽  
Pipeline Design

This paper outlines the draft recommendations to be issued by Gazprom that deals with the advanced strain-based pipeline design to ensure pipeline integrity in harsh environments using stress-strain curve controlled high-strain line pipe (SSLP). The draft recommendations have been provided to employ the new design concept to some future pipeline projects. The analytical solution was adopted in the draft as the solution is useful to improve strain capacity by controlling the longitudinal tensile properties without increasing wall thickness. The concept was validated through full-scale bending test using X70, 1220 mm SSLPs. FEA clarified that the strain capacity in compression or bending of X70, 1420 mm SSLP, 9.8 MPa, is high compared to that of the standard line pipe (STLP). The strain demand required for the SSLP pipeline in the harsh environments shall be small compared to that for the STPL pipeline. The SSLP pipeline shall be beneficial for ensuring the pipeline integrity in the harsh environments.

Buckling and Tensile Strain Capacity of Girth Welded 48″ X80 Pipeline

2013 ◽  
Author(s):  
Satoshi Igi ◽  
Mitsuru Ohata ◽  
Takahiro Sakimoto ◽  
Junji Shimamura ◽  
Kenji Oi
Keyword(s):  
Crack Growth ◽  
Tensile Strain ◽  
Compressive Strain ◽  
Bending Test ◽  
Ductile Crack ◽  
Pipe Surface ◽  
Strain Capacity ◽  
Ductile Crack Growth ◽  
Strain Limit ◽  
Tensile Strain Capacity

This paper presents the experimental and analytical results focused on the compressive and tensile strain capacity of X80 linepipe. A full-scale bending test of girth welded 48″ OD X80 linepipes was conducted to investigate the compressive strain limit regarding to the local buckling and tensile strain limit regarding to the girth weld fracture. As for the compressive buckling behavior, one large developing wrinkle and some small wrinkles on the pipe surface were captured relatively well from observation and strain distribution measurement after pipe reaches its endurable maximum bending moment. The tensile strain limit is discussed from the viewpoint of competition of two fracture phenomena: ductile crack initiation / propagation from an artificial notch at the HAZ of the girth weld, and strain concentration and necking / rupture in the base material. The ductile crack growth behavior from the girth weld notch is simulated by FE-analysis based on the proposed damage model, and compared with the experimental results. In this report, it is also demonstrated that the simulation model can be applicable to predicting ductile crack growth behaviors from a circumferentially notched girth welded pipe with internal high pressure subjected to post-buckling loading.

Recent Concepts for the Welding of High Strain Pipelines

2009 ◽  
Author(s):  
Brian D. Newbury ◽  
Martin W. Hukle ◽  
Mark D. Crawford ◽  
Joshua Sleigh ◽  
Steven A. Altstadt ◽  
...  
Keyword(s):  
Large Scale ◽  
High Strain ◽  
Soil Liquefaction ◽  
Operating Pressure ◽  
Line Pipe ◽  
Strain Capacity ◽  
Soil Movement ◽  
Specific Material ◽  
Pipeline Design ◽  
Design And Testing

Standard allowable stress-based pipeline designs (strain demand ≤ 0.5%) are now giving way to more complex strain-based designs (strain demand higher than 0.5%) as the locations of future pipelines move into regions of increased strain demand. The increase in required levels of strain demand are attributed to seismic activity, soil movement, soil liquefaction, frost heave, thaw settlement, ice scour or a combination thereof. Pipelines in high strain demand regions are typically limited by the strain capacity of the girth weld. As strain-based pipeline design has matured, it has become evident that specific material properties (both weld metal and line pipe), defect size, defect location, misalignment, and operating pressure each affect the strain capacity of the pipeline. This paper reviews proposed design and testing methodologies for the qualification of strain-based design welding procedures. These methods have been applied in the development and qualification of welding procedures for the construction of pipelines subject to longitudinal tensile strains in excess of 2%. Strain-based design requires considerably more effort than traditional design in terms of girth weld qualification and testing. To ensure adequate girth weld strain capacity for strain-based design the testing includes large scale and full-scale pressurized testing for design validation.

Numerical Evaluation of Compressive Strain Capacity for API X100 Line Pipe

2017 ◽  
Vol 22 (8) ◽  
pp. 3039-3051
Author(s):  
Seung-Jung Lee ◽  
Woo-Yeon Cho ◽  
Ki-Seok Kim ◽  
Goangseup Zi ◽  
Young-Cheol Yoon
Keyword(s):  
Numerical Evaluation ◽  
Compressive Strain ◽  
Line Pipe ◽  
Strain Capacity

Effect of Girth Welding on Strain Capacity of X80 SAW Pipes

2014 ◽  
Author(s):  
Hidenori Shitamoto ◽  
Eiji Tsuru ◽  
Hiroyuki Nagayama ◽  
Nobuaki Takahashi ◽  
Yuki Nishi
Keyword(s):  
Matching Condition ◽  
Construction Cost ◽  
Bending Test ◽  
Long Distance ◽  
Strain Capacity ◽  
Girth Welding ◽  
Girth Welds ◽  
Welded Pipe ◽  
Submerged Arc ◽  
Pipe Bending

Application of API X80 grade line pipes has been promoted to reduce a construction cost of the pipeline. Assessment of the strain capacity of X80 submerged arc welded (SAW) pipe is required for strain-based design (SBD). Long distance gas pipelines are usually constructed using girth welded line pipes. In the assessment of the strain capacity, it is important to keep over-matching at girth welds. However, since strength variation exists in base metal and girth weld metal, the value of the matching ratio also changes. In this study, X80 SAW pipes produced by the UOE process were welded under slightly over-matching condition and full-scale pipe bending test of the girth welded pipe was performed to evaluate the effect of the matching ratio on the strain capacity.

Seismic Integrity of High-Strain Cold Bend in Lateral Spreading Zone

2014 ◽  
Author(s):  
Nobuhisa Suzuki ◽  
Hidetaka Watanabe ◽  
Toshiyuki Mayumi ◽  
Hiroyuki Horikawa
Keyword(s):  
Residual Strain ◽  
High Strain ◽  
Peak Load ◽  
Local Buckling ◽  
Strain Curve ◽  
Lateral Spreading ◽  
Line Pipe ◽  
Strain Capacity ◽  
Cold Bending ◽  
Opening Mode

Excellent workability of the stress-strain curve controlled high strain line pipe on cold bending with a bending angle of 10 degrees is presented. The high-strain line pipe has a round-house type s-s curve with the stress ratio σ2.0/σ1.0 of 1.030, where σ1.0 and σ2.0 are 1.0% and 2.0% yield stress, respectively. A standard yield-plateau type line pipe was also employed for comparison. FEA was conducted to investigate the cold bending behaviors of X65, 24″ line pipe. The longitudinal strain induced in the high-strain pipe at peak load and unloaded steps are small compared to those in the standard pipe. Effects of residual strain on local buckling behaviors of the high-strain cold bends are investigated. The effect of residual strain on the strain capacity of cold bend subjected to closing and opening mode bending is small when the cold bend is not pressurized. FEA tends to overestimate the strain capacity in bending when the bend is pressurized. However FEA well predicts the locations of the shell wrinkle of the pressurized bend subjected to opening mode bending when residual strain is taken into account. Seismic integrity of the 24″ high-strain cold bend in a lateral spreading zone is demonstrated.

Strain Capacity of X100 High-Strain Linepipe for Strain-Based Design Application

2008 ◽  
Author(s):  
Satoshi Igi ◽  
Joe Kondo ◽  
Nobuhisa Suzuki ◽  
Joe Zhou ◽  
Da-Ming Duan
Keyword(s):  
Tensile Strain ◽  
Large Scale ◽  
High Strain ◽  
Compressive Strain ◽  
Local Buckling ◽  
Ground Movement ◽  
Frozen Ground ◽  
Long Distance ◽  
Element Analysis ◽  
Strain Capacity

In recent years, several natural gas pipeline projects have been planned for permafrost regions. Pipelines laid in such areas are subjected to large plastic deformation as a result of ground movement due to repeated thawing and freezing of the frozen ground. Likewise, in pipeline design methods, research on application of strain-based design as an alternative to the conventional stress-based design method has begun. Much effort has been devoted to the application of strain-based design to high strength linepipe materials. In order to verify the applicability of high-strain X100 linepipe to long distance transmission, a large-scale X100 pipeline was constructed using linepipe with an OD of 42″ and wall thickness of 14.3mm. This paper presents the results of experiments and Finite Element Analysis (FEA) focusing on the strain capacity of high-strain X100 linepipes. The critical compressive strain of X100 high-strain linepipes is discussed based on the results of FEA taking into account geometric imperfections. The critical tensile strain for high-strain X100 pipelines is obtained based on a curved wide plate (CWP) tensile test using specimens taken from girth welded joints. Specifically, the effect of external coating treatment on the strain capacity of X100 high-strain linepipe is investigated. The strain capacity of the 42″ X100 pipeline is considered by comparing the tensile strain limit obtained from girth weld fracture and critical compressive strain which occurs in local buckling under pure bending deformation.

Evaluation of Compressive Strain Limit of X80 Saw Pipes With Girth Welding by FE Analysis

2010 ◽  
Author(s):  
Hidenori Shitamoto ◽  
Masahiko Hamada ◽  
Shuji Okaguchi ◽  
Nobuaki Takahashi ◽  
Izumi Takeuchi ◽  
...  
Keyword(s):  
High Pressure ◽  
Natural Gas ◽  
High Strength ◽  
Environmental Conservation ◽  
Ground Movement ◽  
Bending Test ◽  
Line Pipe ◽  
Strain Capacity ◽  
Girth Welding ◽  
Transmission Pipelines

The expansion of supply capacity of natural gas to market is expected from the concern of environmental conservation by less CO2 emission. Transportation cost has been focused for natural gas to be competitive in the market. High-pressure gas pipelines have constructed by large diameter and high strength line pipes to improve transportation efficiency of gas transmission pipelines. High strength line pipes have been developed to cope with high-pressure operation. Strength in circumferential direction on line pipe is the prime target to hold high pressure safely. In terms of pipe size, pipe diameter has been increased to lead larger D/t. Both of higher strength and larger D/t result in less favorable to deformability of pipeline. To apply strain based design to pipeline, the evaluation of strain capacity, which is related to deformability of line pipe, is required supposing the pipeline encounters large scale ground movement such as earthquake or landslide. It is not simple to find the criteria to prevent leak or rupture of pipeline in such events, as not only pipe property but also interaction between pipe and soil are needed to consider. Gas transmission pipelines are constructed by joint girth welding. The strain capacity of pipeline with girth weld has to be investigated for strain based design. Full scale bending test of joint welded pipe was conducted and FEA model to assess strain capacity of pipeline with girth weld is developed.

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