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.

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.

Effect of Thermal Aging on Strain Capacity of X80 SAW Pipes

2012 ◽  
Author(s):  
Hidenori Shitamoto ◽  
Masahiko Hamada ◽  
Nobuaki Takahashi ◽  
Yuki Nishi
Keyword(s):  
Thermal Aging ◽  
Arc Welding ◽  
Submerged Arc Welding ◽  
Full Scale ◽  
Operating Pressure ◽  
Bending Tests ◽  
Strain Capacity ◽  
Submerged Arc ◽  
Pipe Bending

Application of API X80 grade line pipes has been promoted to increase the operating pressure. It is generally known that the deformability of submerged arc welding (SAW) pipes is decreased by increasing strength of the pipes. The assessment of the strain capacity of X80 SAW pipes is required for strain-based design (SBD). In the assessment of the strain capacity, one of the important issues is the effect of thermal aging during the anti-corrosion coating on the yielding phenomenon. In this study, full-scale pipe bending tests of X80 SAW pipes produced by UOE process were performed to evaluate the effect of thermal aging on the strain capacity.

Anisotropic HFI Welded Steel Pipes for Strain Based Design

2016 ◽  
Author(s):  
Oliver Hilgert ◽  
Susanne Höhler ◽  
Holger Brauer
Keyword(s):  
Full Scale ◽  
Small Scale ◽  
Steel Tubes ◽  
Line Pipe ◽  
Welded Steel ◽  
Bending Tests ◽  
Strain Capacity ◽  
Steel Pipes ◽  
Weld Material ◽  
Anisotropy Parameters

Generally isotropic behavior is assumed and demanded in line pipe specifications. Especially in strain based design, compressive and tensile strain capacity models rely on iso-tropic assumptions. On the other hand every pipe has got an anisotropic material characteristic which effects the performance in strain based design. In this contribution HFI-welded steel tubes are investigated due to their underlying material anisotropy. Depending on their basic strip weld material and production process the anisotropy differs from UOE or spiral welded pipes. Especially, in radial direction of steel pipe mechanical properties are challenging to gain. Thus two methods are suggested to characterize the anisotropic parameters in all three pipe directions. A small scale approach evaluating Lankford values and a full scale method evaluating Hill factors are applied. While Lankford method relies on strains, Hills method relies on stresses. Both methods are explained and validated by internal pressure and full scale bending tests. Using the anisotropy parameters, their effect on strain based design is analyzed — both experimentally and numerically. In the end it is shown that distinct anisotropies can provide a benefit for HFI-welded steel tubes concerning strain capacity in strain based design applications.

Pipe Bending Test With Girth Welding on X80 Grade SAW Pipes

2010 ◽  
Author(s):  
Masahiko Hamada ◽  
Hidenori Shitamoto ◽  
Shuji Okaguchi ◽  
Nobuaki Takahashi ◽  
Izumi Takeuchi ◽  
...  
Keyword(s):  
Full Scale ◽  
Bending Test ◽  
Test Program ◽  
Bending Tests ◽  
Girth Welding ◽  
Manufacturing Procedure ◽  
Girth Welds ◽  
Welding Procedure ◽  
Pipe Manufacturing ◽  
Pipe Bending

This study was planned as a part of a test program to confirm the effect of girth welds on the strain capacity of pipes. In this study, full-scale pipe bending tests are performed by using X80 SAW pipe. This paper covers pipe manufacturing procedure, developed welding procedure to obtain even match weld metal and properties of welded joints. And this work demonstrated that the X80 pipes welded under the developed procedure fractured in base metal remote from girth welded portion by full scale pipe bending test conducted under the internal pressure of 72% SMYS of X80.

Production of Grade X80 High Strain Linepipes for Seismic Region Application

2010 ◽  
Author(s):  
Ryuji Muraoka ◽  
Joe Kondo ◽  
Lingkang Ji ◽  
Hongyuan Chen ◽  
Yaorong Feng ◽  
...  
Keyword(s):  
High Strain ◽  
Uniform Elongation ◽  
High Strength ◽  
Longitudinal Direction ◽  
Full Scale ◽  
Ground Movement ◽  
Long Distance ◽  
Seismic Region ◽  
Strain Capacity ◽  
Pipe Bending

In order to achieve safety and reliability of long-distance gas transmission pipeline installed in seismic region while obtaining economical benefit by reducing material and construction cost, it is essential to apply the high-strength linepipes with sufficient strain capacity against buckling and weld fracture by seismic ground movement. At the same time, it is quite important to develop appropriate material requirement for strain capacity depending on the pipe dimension and strain demand of the region where the pipeline is installed. Grade X80 heavy gauge linepipes with excellent deformability were mass produced by applying advanced plate manufacturing technologies. These linepipes exhibit low Y/T and high uniform elongation in the longitudinal direction even after pipe coating. Strain capacity of the pipe against bending deformation with internal pressure was verified by conducting full scale pipe bending testing. In this paper, production results of high strain X80 linepipes for the application in long-distance pipelines in seismic region and full scale pipe bending and hydraulic burst test results were introduced.

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.

Full-Scale Reeling Tests of HFI Welded Line Pipe for Offshore Reel-Laying Installation

2014 ◽  
Author(s):  
Karl Christoph Meiwes ◽  
Susanne Höhler ◽  
Marion Erdelen-Peppler ◽  
Holger Brauer
Keyword(s):  
Mechanical Testing ◽  
Mechanical Test ◽  
Strength Properties ◽  
Full Scale ◽  
Bending Test ◽  
Small Scale ◽  
Pipe Material ◽  
Deformation Capacity ◽  
Line Pipe ◽  
Tension And Compression

During reel-laying repeated plastic strains are introduced into a pipeline which may affect strength properties and deformation capacity of the line pipe material. Conventionally the effect on the material is simulated by small-scale reeling simulation tests. For these, coupons are extracted from pipes that are loaded in tension and compression and thermally aged, if required. Afterwards, specimens for mechanical testing are machined from these coupons and tested according to the corresponding standards. Today customers often demand additional full-scale reeling simulation tests to assure that the structural pipe behavior meets the strain demands as well. Realistic deformations have to be introduced into a full-size pipe, followed by aging, sampling and mechanical testing comparable to small-scale reeling. In this report the fitness for use of a four-point-bending test rig for full-scale reeling simulation tests is demonstrated. Two high-frequency-induction (HFI) welded pipes of grade X65M (OD = 323.9 mm, WT = 15.9 mm) from Salzgitter Mannesmann Line Pipe GmbH (MLP) are bent with alternate loading. To investigate the influences of thermal aging from polymer-coating process one test pipe had been heat treated beforehand, in the same manner as if being PE-coated. After the tests mechanical test samples were machined out of the plastically strained pipes. A comparison of results from mechanical testing of material exposed to small- and full-scale reeling simulation is given. The results allow an evaluation of the pipe behavior as regards reeling ability and plastic deformation capacity.

Reeling of Tight Fit Pipe (TFP)

2007 ◽  
Author(s):  
E. S. Focke ◽  
E. Karjadi ◽  
A. M. Gresnigt ◽  
J. Meek ◽  
H. Nakasugi
Keyword(s):  
Compressive Stress ◽  
Bonding Strength ◽  
Fe Analysis ◽  
Bending Test ◽  
Outer Diameter ◽  
Stress Tests ◽  
Bending Tests ◽  
Definition Of ◽  
Mechanical Bonding ◽  
Pipe Bending

A 12.75 inch outer diameter single walled pipe bending test was executed and theoretical and FE analysis of this test was performed as preparation for 12.75 inch outer diameter TFP bending tests. The main objective of the TFP bending tests was to determine the initiation and degree of liner wrinkling occurring during the TFP spooling-on phase when simulating the reeling pipelay installation method. Due to lack of a definition of liner wrinkling initiation, the crossing of a certain threshold of the liner wrinkle height was defined as liner wrinkling initiation. The bending tests results indicated that (1) the extent of liner wrinkling decreased if TFP with a high mechanical bonding strength was used. (2) The presence of a circumferential weld in the highly bonded TFPs initiated higher liner wrinkles at lower curvatures than in case no circumferential weld was present. (3) The ERW outer pipe longitudinal weld did not result in higher liner wrinkles. API residual compressive stress tests showed that the initial mechanical bonding strength in the 12.75 inch TFP used in this research was significantly reduced, irrespective of whether a high or a low initial mechanical bonding strength had been used prior to spooling-on. These findings justify further research into this phenomenon as the eventual mechanical bonding strength after reeling installation may be vital for its anticipated application during operation.

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.

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