Pipe Bending Test With Girth Welding on X80 Grade SAW Pipes

Author(s):  
Masahiko Hamada ◽  
Hidenori Shitamoto ◽  
Shuji Okaguchi ◽  
Nobuaki Takahashi ◽  
Izumi Takeuchi ◽  
...  

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.

Author(s):  
Hisakazu Tajika ◽  
Takahiro Sakimoto ◽  
Tsunehisa Handa ◽  
Rinsei Ikeda ◽  
Joe Kondo

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.


Author(s):  
Hidenori Shitamoto ◽  
Eiji Tsuru ◽  
Hiroyuki Nagayama ◽  
Nobuaki Takahashi ◽  
Yuki Nishi

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.


Author(s):  
Hidenori Shitamoto ◽  
Masahiko Hamada ◽  
Nobuaki Takahashi ◽  
Yuki Nishi

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.


Author(s):  
Yoshiyuki Matsuhiro ◽  
Noritake Oguchi ◽  
Toshio Kurumura ◽  
Masahiko Hamada ◽  
Nobuaki Takahashi ◽  
...  

The construction of the first L555(X80) pipeline in Japan was completed in autumn, 2011.In this paper, the overview of the design consideration of the line, technical points for linepipe material and for girth welds are presented. In recent years the use of high strength linepipe has substantially reduced the cost of pipeline installation for the transportation of natural gas. The grades up to L555(X80) have been used worldwide and higher ones, L690(X100) and L830(X120), e.g., are being studied intensively. In the areas with possible ground movement, the active seismic regions, e.g., pipeline is designed to tolerate the anticipated deformation in longitudinal direction. In Japan, where seismic events including liquefaction are not infrequent, the codes for pipeline are generally for the grades up to L450(X65). Tokyo Gas Co. had extensively investigated technical issues for L555(X80) in the region described above and performed many experiments including full-scale burst test, full-scale bending test, FE analysis on the girth weld, etc., when the company concluded the said grade as applicable and decided project-specific requirements for linepipe material and for girth weld. Sumitomo Metals, in charge of pipe manufacturing, to fulfill these requirements, especially the requirement of round-house type stress-strain (S-S) curve to be maintained after being heated by coating operation, which is critical to avoid the concentration of longitudinal deformation, developed and applied specially designed chemical composition and optimized TMCP (Thermo-Machanical Control Process) and supplied linepipe (24″OD,14.5∼18.9mmWT) with sufficient quality. It had also developed and supplied induction bends needed with the same grade. Girth welds were conducted by Sumitomo Metal Pipeline and Piping, Ltd and mechanized GMAW (Gas Metal Arc Welding) was selected to achieve the special requirements, i.e., the strength of weld metal to completely overmatch the pipe avoiding the concentration of longitudinal strain to the girth weld, and the hardness to be max.300HV10 avoiding HSC (Hydrogen Stress Cracking) on this portion. Both of RT (Radiographic Test) and UT (Ultrasonic Test) were carried out to all the girth welds. These were by JIS (Japan Industrial Standards) and the project-specific requirements.


Author(s):  
E. S. Focke ◽  
E. Karjadi ◽  
A. M. Gresnigt ◽  
J. Meek ◽  
H. Nakasugi

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.


Author(s):  
Philippe P. Darcis ◽  
Israel Marines-Garcia ◽  
Eduardo A. Ruiz ◽  
Elsa C. Marques ◽  
Mariano Armengol ◽  
...  

The current work aims to point out the influence of plastic strain history, due to reel-lay installation, on the fatigue resistance of welded SMLS (seamless) steel pipes used for fabrication of Steel Catenary Risers (SCRs) for oil and gas development. A C-Mn steel X65 pipe 10.75″ (273.1 mm) outside diameter (OD) and 25.4 mm wall thickness (WT) was chosen for this program. The Welding Procedure designed for girth welds manufacturing involved the use of Lincoln STT-GMAW™ (Surface Tension Transfer–Gas Metal Arc Welding) process for the root pass and SAW (Submerged Arc Welding) process with twin wire configuration for the fill and cap passes. This welding procedure presents a special post-weld finishing treatment, which consists in flapping the inner and outer weld overfills to produce a flush profile between weld metal and outer/inner pipe surfaces. The experimental approach was focused on quantifying the effect of accumulated plastic deformation using two different reeling frames simulating the same laying vessel: the Technip’s Apache. In this program, two reeling trials were performed at Heriot Watt University, Edinburgh, U.K., and two other trials at Stress Engineering Services, Houston, U.S.A. Then, the strained specimens were full scale fatigue tested at TenarisTamsa R&D facilities. Those results have been compared with fatigue results obtained on unstrained specimens. Post-tests fractographic investigations were systematically performed on all samples to identify the causes for fatigue initiation. The results were statistically analyzed to determine which standard fatigue design curves best represent the measured S-N fatigue endurance. Finally, the results were also compared with the available literature.


Author(s):  
Yong-Yi Wang ◽  
Steve Rapp ◽  
David Horsley ◽  
David Warman ◽  
Jim Gianetto

There has been a number of unexpected girth weld failures in newly constructed pipelines. Girth weld failures have also been observed in pre-service hydrostatic testing. Post-incident investigations indicated that the pipes met the requirements of industry standards, such as API 5L. The welds were qualified per accepted industry standards, such as API 1104. The field girth welding was performed, inspected, and accepted per industry standards, such as API 1104. Some of the traditional causes of girth weld failures, such as hydrogen cracks and high-low misalignment, were not a factor in these incidents. This paper starts with a review of the recent girth weld incidents. A few key features of a failed weld and their implications are examined. The characteristics of the recent failures is summarized, and the major contributing factors known to date are given. Some of the options to prevent future failures include (1) changes to the tensile properties of the pipes and enhanced hardenability, (2) welding options aimed at increasing the weld strength and minimizing heat-affected zone (HAZ) softening, and (3) reduction of stresses on girth welds. This paper focuses on the first two options. The trends of chemical composition and tensile properties of linepipe are reviewed. The potential contribution of these trends to the girth weld incidents is examined. Possible changes to the linepipe properties and necessary updates in the testing and qualification requirements of the linepipes are provided. Welding options beneficial to enhanced girth weld strain capacity are discussed. Possible revisions to welding procedure qualification requirements, aimed at achieving a minimum level of strain tolerance/capacity, are proposed. The application of previously developed tools in estimating the propensity of HAZ softening is reviewed.


Author(s):  
Dong-Yeob Park ◽  
Hisakazu Tajika ◽  
Takahiro Sakimoto ◽  
Satoshi Igi ◽  
James A. Gianetto ◽  
...  

A comparison of the fracture behaviours for a full-scale (FS) pipe bending test and small-scale fracture toughness tests was carried out in this investigation. For the FS pipe test, two 4-meter long large diameter (914 mm) X70 pipes were girth-welded together to facilitate bend testing with an internal pressure of 72% of specified miniminm yield strength (SMYS). The test assembly also contained a semi-ellipical notch that was prepared by means of electrical discharge machining (EDM) from the outside surface in the heat-affected zone. Single-edge notched bend (SE(B) or SENB) and single-edge notched tension (SE(T) or SENT) test specimens were prepared from a duplicate girth weld produced with the same pipe and weld procedure with equivalent notch depths. The FS pipe test showed deformation along the pipe axis asymmetric to the girth weld centre. The comparison of fracture behaviours between small-scale and FS tests suggests that toughness measurements (crack-tip opening displacement or J-integral) at maximum load might be useful as a reference for strain-based design although further work is needed.


Author(s):  
Steinar Kristoffersen ◽  
Per J. Haagensen ◽  
Gisle Ro̸rvik

H2S is reported to degrade the fatigue properties of C-Mn steels with a factor of 10–20 in life, while clad pipes are reported to have a performance close to or as good as in air. Clad pipes could therefore be used in highly fatigue loaded parts of the riser to facilitate design of steel catenary risers (SCRs) that are connected to floaters in deep waters. A literature survey of high quality girth welds intended for SCR is included in this paper and compared with fatigue test data obtained in this project. The first nine full scale 15" clad pipe girth welds out of a program of 24 specimens are fatigue tested in a high frequency resonance test rig and reported. The pipes were tested as welded, hammer-peened and reeled. The 15" OD steel pipes with 316 cladding tested in this work were surplus pipes from the Norne pipeline project. The fatigue test pipes were fabricated using the same welding procedure and welding facilities at Technip’s spool base in Orkanger, Norway, as the Norne pipeline project. The Norne pipeline is the world’s first reeled clad pipeline. The objective of this work was to test premium quality girth welds with best possible fatigue performance in actual pipes under realistic conditions was. The effect of hammer-peening of the OD was therefore investigated. Post failure examination was performed to determine the type and size of defects at the fatigue crack initiation site.


PCI Journal ◽  
1978 ◽  
Vol 23 (2) ◽  
pp. 22-41 ◽  
Author(s):  
Alan H. Mattock ◽  
A. N. Wyss
Keyword(s):  

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