Tensile Strain Capacity of Spiral Pipes

2012 ◽  
Author(s):  
Ming Liu ◽  
Yong-Yi Wang ◽  
Laurie Collins
Keyword(s):  
Tensile Strain ◽  
Driving Forces ◽  
Mode I ◽  
Mode Iii ◽  
Long Distance ◽  
Strain Capacity ◽  
History Of ◽  
Force Components ◽  
Longitudinal Strains ◽  
Tensile Strain Capacity

Pipelines may experience high longitudinal strains from seismic events, frost heave, thaw settlement, unstable slopes, and mine subsidence, etc.. Those strains could be well beyond the elastic limit of the materials and the strain based design (SBD) criteria must be used. Most work on the SBD in recent years has been focused on the straight long seam pipes. The application of the SBD principles to the spiral pipes has not been examined. Spiral-welded pipes are widely used for long-distance transmission pipelines. These pipes have a demonstrated history of satisfactory service. However, the performance of the spiral pipes under large longitudinal strains is not well understood. The focus of this paper is the tensile strain capacity of spiral pipes. The crack driving forces of flaws in spiral welds under longitudinal tension strains were analyzed for X80 pipes. Unlike the girth weld flaws which see primarily mode-I crack driving forces, the spiral weld flaws see mode-I and mode III mixed crack driving forces. The mode-I and mode-III driving force components vary with the spiral angles and pressure conditions. It is found that the application of the internal pressure can greatly increase the mode-I component and the total crack driving forces.

scholarly journals The influence of material anisotropy and spiral welding on tensile strain capacity of spiral welded pipes

2015 ◽  
Vol 6 (3) ◽  
pp. 9
Author(s):  
Michiel De Backer ◽  
Koen Van Minnebruggen ◽  
Wim De Waele
Keyword(s):  
Driving Force ◽  
Tensile Strain ◽  
Pipeline Steel ◽  
Experimental Testing ◽  
Outcome Analysis ◽  
Mode Iii ◽  
Plane Shear ◽  
Crack Driving Force ◽  
Strain Capacity ◽  
Tensile Strain Capacity

The longitudinal strain capacity of spiral welded pipelines displays to some extents unexplained behaviour. Therefore, they are not (yet) used extensively in offshore applications and harsh conditions, demanding a strain based design. An important factor that influences the tensile strain capacity is the quantity of anisotropy in terms of strength and toughness. Starting from an anisotropic hot rolled highstrength steel skelp, the process of helical forming and post-treating of the pipe adds heterogeneity and changes the level of anisotropy of the product. A parameter that should be examined with respect to anisotropy is the crack driving force, a measure for the toughness of the pipeline steel. Additional to the mode I loading (opening of the crack), the mode III component drives the in-plane shear motion of a crack in the spiral weld when the pipe is subjected to longitudinal deformation. This action, not present inlongitudinal welded pipes, shows a decreasing contribution with increasing plasticity. FE simulations have demonstrated a rise of crack driving force in anisotropic cases with respect to an isotropic reference. However, exact data and variation of various parameters, along with experimental testing need to be conducted. The outcome analysis of such simulations and tests can validate existing models, or help create a better understanding of anisotropic and heterogenic influences on the tensile strain capacity of spiral welded pipes.

Tensile and Compressive Strain Capacity of Pipelines With Corrosion Anomalies

2016 ◽  
Author(s):  
Honggang Zhou ◽  
Ming Liu ◽  
Brent Ayton ◽  
Jason Bergman ◽  
Steve Nanney
Keyword(s):  
Numerical Analysis ◽  
Tensile Strain ◽  
Compressive Strain ◽  
General Corrosion ◽  
Test Results ◽  
Strain Capacity ◽  
Circumferential Groove ◽  
Compressive Buckling ◽  
Longitudinal Strains ◽  
Tensile Strain Capacity

Strain-based design and assessment (SBDA) methods have been developed to address integrity issues for pipelines subjected to ground movement hazards. The current practice of strain capacity assessment focuses on the tensile rupture of girth welds and compressive buckling of pipes. The integrity management of in-service pipelines often involves assessing pipe segments with anomalies, such as mechanical damage and corrosion. The existing strain capacity models do not yet include the impact of those anomalies. This paper covers a part of the outcome from a comprehensive research effort aimed at developing assessment procedures for pipelines containing corrosion anomalies and simultaneously subjected to large longitudinal strains. The resistance to tensile rupture and compressive buckling are the focus of the paper. Recommendations for the assessment of strain capacities were provided based on numerical analysis which identified key influencing parameters and controlling mechanisms. Full-scale experimental tests were also conducted to demonstrate the identified mechanisms and evaluate the assessment methods. Both numerical analysis and experimental test results demonstrate that: (1) corrosion anomalies can significantly reduce the tensile strain capacity (TSC) and compressive strain capacity (CSC) of pipes, (2) in addition to the depth and longitudinal length, the circumferential width of the corrosion anomalies has a significant impact on the TSC and CSC of pipes, (3) circumferential-groove corrosion anomalies reduce the tensile strain capacity more than general corrosion anomalies of the same depth and circumferential width, and (4) general corrosion anomalies reduce the compressive strain capacity more than the circumferential-groove anomalies of the same depth and circumferential width. The analysis and experimental test results shown in this paper can support development of SBDA procedures and guidelines of pipelines subjected to large longitudinal strains.

Multi-Tier Tensile Strain Models for Strain-Based Design: Part 2 — Development and Formulation of Tensile Strain Capacity Models

2012 ◽  
Author(s):  
Ming Liu ◽  
Yong-Yi Wang ◽  
Yaxin Song ◽  
David Horsley ◽  
Steve Nanney
Keyword(s):  
Driving Force ◽  
Tensile Strain ◽  
Weld Strength ◽  
Experiment Data ◽  
Pipe Wall Thickness ◽  
Crack Driving Force ◽  
Strain Capacity ◽  
Welding Processes ◽  
Tensile Strain Capacity

This is the second paper in a three-paper series related to the development of tensile strain models. The fundamental basis of the models [1] and evaluation of the models against experiment data [2] are presented in two companion papers. This paper presents the structure and formulation of the models. The philosophy and development of the multi-tier tensile strain models are described. The tensile strain models are applicable for linepipe grades from X65 to X100 and two welding processes, i.e., mechanized GMAW and FCAW/SMAW. The tensile strain capacity (TSC) is given as a function of key material properties and weld and flaw geometric parameters, including pipe wall thickness, girth weld high-low misalignment, pipe strain hardening (Y/T ratio), weld strength mismatch, girth weld flaw size, toughness, and internal pressure. Two essential parts of the tensile strain models are the crack driving force and material’s toughness. This paper covers principally the crack driving force. The significance and determination of material’s toughness are covered in the companion papers [1,2].

Estimation of Tensile Strain Capacity of Vintage Girth Welds

2021 ◽  
Author(s):  
Banglin Liu ◽  
Bo Wang ◽  
Yong-Yi Wang ◽  
Otto Jan Huising
Keyword(s):  
Tensile Strain ◽  
Strain Capacity ◽  
Girth Welds ◽  
Tensile Strain Capacity

Design of the Full Scale Experiments for the Testing of the Tensile Strain Capacity of X52 Pipes With Girth Weld Flaws Under Internal Pressure and Tensile Displacement

2014 ◽  
Author(s):  
Celal Cakiroglu ◽  
Samer Adeeb ◽  
J. J. Roger Cheng ◽  
Millan Sen
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Internal Pressure ◽  
Tensile Strain ◽  
Oil And Gas ◽  
Full Scale ◽  
Element Analysis ◽  
Simultaneous Application ◽  
Strain Capacity ◽  
Tensile Strain Capacity

Pipelines can be subjected to significant amounts of tensile forces due to geotechnical movements like slope instabilities and seismic activities as well as due to frost heave and thaw cycles in arctic regions. The tensile strain capacity εtcrit of pipelines is crucial in the prediction of rupture and loss of containment capability in these load cases. Currently the Oil and Gas Pipeline Systems code CSA Z662-11 0 contains equations for the prediction of εtcrit as a function of geometry and material properties of the pipeline. These equations resulted from extensive experimental and numerical studies carried out by Wang et al [2]–[6] using curved wide plate tests on pipes having grades X65 and higher. Verstraete et al 0 conducted curved wide plate tests at the University of Ghent which also resulted in tensile strain capacity prediction methods and girth weld flaw acceptability criteria. These criteria are included in the European Pipeline Research Group (EPRG) Tier 2 guidelines. Furthermore Verstrate et al 0 introduced a pressure correction factor of 0.5 in order to include the effect of internal pressure in the tensile strain capacity predictions in a conservative way. Further research by Wang et al with full scale pipes having an internal pressure factor of 0.72 also showed that εtcrit decreases in the presence of internal pressure [10]–[15]. In their work, Wang et al presented a clear methodology for the design of full scale experiments and numerical simulations to study the effect of internal pressure on the tensile strain capacity of pipes with girth weld flaws [10]–[15]. However, there has been limited testing to enable a precise understanding of the tensile strain capacity of pipes with grades less than X65 as a function of girth weld flaw sizes and the internal pressure. In this paper the experimental setup for the testing of grade X52 full scale specimens with 12″ diameter and ¼″ wall thickness is demonstrated. In the scope of this research 8 full scale specimens will be tested and the results will be used to formulate the tensile strain capacity of X52 pipes under internal pressure. The specimens are designed for the simultaneous application of displacement controlled tensile loading and the internal pressure. Finite element analysis is applied in the optimization process for the sizes of end plates and connection elements. Also the lengths of the full scale specimens are determined based on the results from finite element analysis. The appropriate lengths are chosen in such a way that between the location of the girth weld flaw and the end plates uniform strain zones could be obtained. The internal pressure in these experiments is ranging between pressure values causing 80% SMYS and 30% SMYS hoop stress. The end plates and connection elements of the specimens are designed in such a way that the tensile displacement load is applied with an eccentricity of 10% of the pipe diameter with the purpose of increasing the magnitude of tensile strains at the girth weld flaw location. The results of two full scale experiments of this research program are presented. The structural response from the experiments is compared to the finite element simulation. The remote strain values of the experiment are found to be higher than the εtcrit values predicted by the equations in 0.

scholarly journals Using Green Supplementary Materials to Achieve More Ductile ECC

Materials ◽  
2019 ◽  
Vol 12 (6) ◽  
pp. 858 ◽  
Author(s):  
Yichao Wang ◽  
Zhigang Zhang ◽  
Jiangtao Yu ◽  
Jianzhuang Xiao ◽  
Qingfeng Xu
Keyword(s):  
Fracture Toughness ◽  
Tensile Strain ◽  
Tension Test ◽  
Construction And Demolition Waste ◽  
Demolition Waste ◽  
Strain Capacity ◽  
Fiber Bridging ◽  
Matrix Fracture ◽  
The Matrix ◽  
Tensile Strain Capacity

To improve the greenness and deformability of engineered cementitious composites (ECC), recycled powder (RP) from construction and demolition waste with an average size of 45 μm and crumb rubber (CR) of two particle sizes (40CR and 80CR) were used as supplements in the mix. In the present study, fly ash and silica sand used in ECC were replaced by RP (50% and 100% by weight) and CR (13% and 30% by weight), respectively. The tension test and compression test demonstrated that RP and CR incorporation has a positive effect on the deformability of ECC, especially on the tensile strain capacity. The highest tensile strain capacity was up to 12%, which is almost 3 times that of the average ECC. The fiber bridging capacity obtained from a single crack tension test and the matrix fracture toughness obtained from 3-point bending were used to analyze the influence of RP and CR at the meso-scale. It is indicated that the replacement of sand by CR lowers the matrix fracture toughness without decreasing the fiber bridging capacity. Accordingly, an explanation was achieved for the exceeding deformability of ECC incorporated with RP and CR based on the pseudo-strain hardening (PSH) index.

Tensile Strain Capacity of X80 Pipeline Under Tensile Loading With Internal Pressure

2010 ◽  
Author(s):  
Satoshi Igi ◽  
Takahiro Sakimoto ◽  
Nobuhisa Suzuki ◽  
Ryuji Muraoka ◽  
Takekazu Arakawa
Keyword(s):  
Internal Pressure ◽  
Driving Force ◽  
Tensile Strain ◽  
Surface Defects ◽  
Axial Loading ◽  
Element Analysis ◽  
Crack Driving Force ◽  
Strain Capacity ◽  
High Internal Pressure ◽  
Tensile Strain Capacity

This paper presents the results of experimental and finite element analysis (FEA) studies focused on the tensile strain capacity of X80 pipelines under large axial loading with high internal pressure. Full-pipe tensile test of girth welded joint was performed using high-strain X80 linepipes. Curved wide plate (CWP) tests were also conducted to verify the strain capacity under a condition of no internal pressure. The influence of internal pressure was clearly observed in the strain capacity. Critical tensile strain is reduced drastically due to the increased crack driving force under high internal pressure. In addition, SENT tests with shallow notch specimens were conducted in order to obtain a tearing resistance curve for the simulated HAZ of X80 material. Crack driving force curves were obtained by a series of FEA, and the critical global strain of pressurized pipes was predicted to verify the strain capacity of X80 welded linepipes with surface defects. Predicted strain showed good agreement with the experimental results.

Sign in / Sign up

Export Citation Format

Share Document