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Results
Fracture Toughness of Linepipe Seam Weld Under High Pressure Hydrogen and Material Design for HAZ Toughness
Ishikawa, Nobuyuki (JFE Steel Corporation) | Izumi, Daichi (Steel Research Laboratory, JFE Steel Corporation) | Uranga, Pello (CEIT and University of Navarra-Tecnun) | Stalheim, Douglas (DGS Metallurgical Solutions) | Jarreta, David (CBMM Asia) | Martin, David (CBMM Asia)
ABSTRACT In this paper, fracture toughness testing was conducted using a modern Grade X65 linepipe in high pressure gaseous hydrogen at 21MPa. Fracture behavior of heat affected zone (HAZ) was closely investigated by comparing with that of base material. It was found that microstructural features in the HAZ strongly influence the crack initiation behavior during loading in a hydrogen environment. Accordingly, controlling HAZ microstructure should be most important for improving fracture toughness in HAZ. Further investigation was conducted for achieving superior HAZ toughness by applying microalloying and thermo-mechanical controlled processing (TMCP) in plate production. As recommended in ASME B31.12 Appendix G, Nb microalloyed TMCP steel exhibits fine bainite microstructure in the base material of linepipe steels. It was found that grain growth in HAZ can be suppressed by Nb addition and intensified rolling to a significant degree, resulting in superior HAZ toughness. Mechanisms of microstructure evolution in HAZ is also discussed in this paper. INTRODUCTION Hydrogen is one of the promising energy carriers for achieving the carbon neutral society, and pipeline systems should be necessary for transporting gaseous hydrogen. For the safe operation of hydrogen pipelines, the current hydrogen pipeline code, ASME B31.12 "Hydrogen Piping and Pipeline", requires fracture toughness evaluation under hydrogen environments to verify that linepipe materials have sufficient toughness to prevent failure. It is well understood that fracture toughness is reduced by a significant degree in high pressure hydrogen (Hoover, 1981; Cialone, 1985; Gutierrez-Solana, 1982; Stalheim, 2010). It appears that conventional lower strength-class linepipe steels such as X42 or X52 tend to exhibit lower fracture toughness performance in hydrogen (KIH) compared to modern higher strength-class steels such as X65. On the other hand, very high strength-class linepipe such as X100 exhibits lower KIH value (Ronevich, 2021) when tested in Hydrogen compared to X65. Abnormal features such as planar fracture face separations are commonly observed on specimens tested in hydrogen (Stalheim, 2010). For the fracture toughness test procedure, ASME B31.12 originally requests to apply ASTM E1681 which is the linear elastic fracture mechanics (LEFM) test, with either constant load or constant displacement condition. But it was pointed out that infeasibly large specimens would be needed to satisfy the plain strain condition specified in ASTM E1681 (San Marchi, 2010). Furthermore, crack extension over 0.25mm from the initial fatigue crack tip are often difficult to identify after the test, and the applied stress intensity KIAPP needs to be half for determining KIH (Tazedakis, 2021; Genchev, 2022). Even though the obtained KIH value exceeds the minimum requirement of 55MPa·m in ASME B31.12, the elastic-plastic fracture mechanics (EPFM) test according to ASTM E1820 should be appropriate for ductile materials such as linepipe steels. It was also pointed out from the integrity assessment for seam and girth weld defects, that the resulting allowable flaw size became quite small when considering the minimum 55MPa·m value prescribed in ASME B31.12, and a higher fracture toughness level would be required for practical use in offshore and onshore pipelines (Torselletti, 2022; Ishikawa, 2022a).
- Asia (0.47)
- North America > United States (0.28)
- Materials > Metals & Mining > Steel (0.47)
- Energy > Oil & Gas > Midstream (0.34)
- Well Completion > Hydraulic Fracturing (1.00)
- Health, Safety, Environment & Sustainability > Sustainability/Social Responsibility > Sustainable development (0.54)
- Health, Safety, Environment & Sustainability > Environment > Climate change (0.54)
- Facilities Design, Construction and Operation > Pipelines, Flowlines and Risers > Offshore pipelines (0.49)
ABSTRACT Mechanically lined pipes (MLP) are increasingly being used for subsea pipelines to transport corrosive wellbore fluids due to their cost-effectiveness. However, the reel-lay installation method requires an engineering critical assessment (ECA) of flaws at the interface between the liner and weld overlay. The authors previously proposed an ECA approach that involves complex segment testing to estimate ductile tearing associated with each fracture event. This paper suggests a streamlined ECA process that replaces segment testing with more conventional fracture testing to obtain a toughness resistance curve. This curve can be used in a classical ductile tearing analysis. INTRODUCTION The demand for subsea transportation of wellbore fluids through pipelines resistant to corrosion, such as stainless steel or bimetallic pipes, has been increasing for years. In the pursuit of cost reduction for subsea field development, MLP pipelines have been qualified for installation using the reel-lay method. In this method, the pipeline up to 18" (457.2 mm) in diameter is fabricated onshore and spooled onto a large diameter reel, onboard an installation vessel, see Fig. 1. After the vessel arrives at the subsea field location, the pipe is spooled off the reel, straightened in a free span between the reel and aligner, bent over the aligner, reverse bent in the straightener, and finally lowered onto the seabed. A standard reeling operation involves two reverse plastic bending cycles (Kyriakides and Corona, 2007). A typical 40 ft (12 m) MLP joint, illustrated in Fig. 2, is manufactured by inserting a corrosion resistant alloy (CRA) liner into a carbon steel host pipe and expanding it plastically so that contact with the host pipe occurs (American Petroleum Institute, 2015a; Det Norske Veritas, 2021). Expansion pressure is increased until the host pipe achieves a predefined level of expansion. Once pressure is released, the CRA layer, often 3/32-5/16" (2.5-8 mm) in thickness and made of alloy UNS S31603 (316L), N06625 (625) or N08825 (825) (American Petroleum Institute, 2015b) is held inside the host pipe by interference fit. To prevent moisture ingress and allow automatic ultrasonic testing (AUT) of girth welds during the pipeline fabrication, the liner is metallurgically bonded to the host pipe at the MLP ends by overlay welding, commonly deposited using alloy 625 consumable.
- North America > United States (0.28)
- Europe > United Kingdom > Scotland (0.28)
- Well Completion > Hydraulic Fracturing (1.00)
- Facilities Design, Construction and Operation > Pipelines, Flowlines and Risers > Offshore pipelines (1.00)
Abstract When designing subsea pipelines, flowlines or cables to traverse shallow offshore regions with icebergs, iceberg keel interactions may be of concern. Given sufficiently low contact rates, the possibility of laying the pipe or cable on the seabed without burial may be an option. Consideration is then needed regarding possible denting, buckling, or lateral forces which can result in high axial tensions. In previous analyses of keel interactions, the ice keels have been treated as rigid, under the assumption that the ice strength is significantly higher than the soil strength. Recent studies have shown that under rapid loading, soil resistance can be significantly higher than previously considered, while conservatisms in estimates of ice strength have been reduced over time. As a result, ice-pipe-soil interactions are being reassessed as part of a study "SIIBED: Subsea Ice Interaction Barriers to Energy Development" (Ralph et al., 2023). This paper discusses background and progress on one component of that study, the development of improved ice strength inputs for an overall ice-pipe-soil finite element model (Barrett et al., 2023). The paper includes a review of relevant literature and describes the use of different finite-element (FEA) techniques to better understand relevant ice failure processes. Calibration of the models is largely based on the results of a medium-scale test program using a novel test frame, RHITA (Rapid-High-capacity-Impact-Testing-Apparatus), which was designed and built especially for the project.
- Europe (0.68)
- North America > Canada > Newfoundland and Labrador (0.28)
- North America > United States > Texas (0.28)
- Well Completion > Hydraulic Fracturing (1.00)
- Data Science & Engineering Analytics > Information Management and Systems (1.00)
- Facilities Design, Construction and Operation > Pipelines, Flowlines and Risers > Offshore pipelines (0.84)
Abstract Medium scale indentation tests have been conducted using a 12.75" diameter rigid pipe indenter, mounted on a purposely designed test frame (RHITA – Rapid High-capacity Impact Test Apparatus) and large laboratory made freshwater ice samples (approximately 4 m each). The purpose of this study is to collect ice failure data, representative of iceberg keel interactions with subsea pipelines or electrical cables laying on the seabed. Previous assessments of pipe response due to iceberg impact conservatively assumed no ice failure. As no widely accepted numerical models is available that captures prevalent ice failure mechanisms, experimental data was collected using RHITA. The data can be implemented in a coupled ice-pipe-soil FEA as a pressure or force limit to the ice. Also, the data can serve for calibration and validation of numerical models of ice fracture or ice crushing. The tests were executed at 0.2 m/s, a typical iceberg drift speed, on the Grand Banks of Newfoundland and Labrador. An ice mould was used to grow ice samples measuring 2.5x1.5x1.0 m (LxWxH). The top half of the ice sample was exposed, the bottom half confined by the mould. Global loads during the 2.0 m interaction were measured using six load cells, and tactile pressure sensors were used to measure the ice pressure distribution on the indenter. The test matrix includes variations of interaction depth, ice geometry, embedded rock material and ice temperature. The observed ice failure mechanisms ranged from localized damage near the interaction zone, to large fractures spanning the entire sample. The tactile pressure sensors showed the interface pressure distribution across the contact area, largely affected by local spalling events. Ice temperature and associated boundary conditions were found to affect the propagation of the cracks and resulting loads. This paper presents a summary of the tests executed from June 2022 to January 2023. Future works will include testing of rigid and flexible flowlines, and subsea electrical cable samples.
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- North America > Canada > Newfoundland and Labrador > Labrador (0.25)
- Well Completion > Hydraulic Fracturing (0.90)
- Facilities Design, Construction and Operation > Pipelines, Flowlines and Risers > Offshore pipelines (0.85)
Design for preventing or minimizing the effects of accidents is termed accidental limit states (ALS) design and is characterized by preventing/minimizing loss of life, environmental damage, and loss of the structure. Collision, grounding, dropped objects, explosion, and fire are traditional accident categories.
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"In offshore and coastal engineering, metocean refers to the syllabic abbreviation of meteorology and (physical) oceanography" (Wikipedia). Metocean research covers dynamics of the oceaninterface environments: the air-sea surface, atmospheric boundary layer, upper ocean, the sea bed within the wavelength proximity (~100 m for wind-generated waves), and coastal areas. Metocean disciplines broadly comprise maritime engineering, marine meteorology, wave forecast, operational oceanography, oceanic climate, sediment transport, coastal morphology, and specialised technological disciplines for in-situ and remote sensing observations. Metocean applications incorporate offshore, coastal and Arctic engineering; navigation, shipping and naval architecture; marine search and rescue; environmental instrumentation, among others. Often, both for design and operational purposes the ISSC community is interested in Metocean Extremes which include extreme conditions (such as extreme tropical or extra-tropical cyclones), extreme events (such as rogue waves) and extreme environments (such as Marginal Ice Zone, MIZ). Certain Metocean conditions appear extreme, depending on applications (e.g.
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- Europe > Denmark > North Sea > Danish Sector > Central Graben > Block 5504/12 > Tyra Field (0.99)
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- North America > United States > Colorado > Ice Field (0.98)
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- Well Drilling > Well Planning > Trajectory design (1.00)
- Well Drilling > Drillstring Design > Drill pipe selection (1.00)
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Abstract There is increasing demand for subsea transport of well-produced fluids that requires the use of corrosion resistant pipelines such as stainless steel or more recently bi-metallic pipes. The latter are made of carbon steel (CS) pipe and a thin (typically 3.0 mm thick) internal layer of corrosion resistant alloy (CRA) such as 316L, 625, 825 or 904L. Bi-metallic pipe joints are girth-welded together to make a subsea pipeline with nickel-based consumables which often undermatch the parent metal at yield. Such pipelines are often installed with the reel-lay method which is very efficient but subjects the pipe to cyclic plastic straining. In this context, weld metal undermatch may be problematic as engineering critical assessment (ECA), undertaken to derive weld flaw acceptance criteria, typically requires that the weld metal overmatches the parent material when applied loads are in excess of yield. In the subsea industry, it is common practice to determine a fracture toughness resistance curve from specimens in the as-received condition and use it for the ECA of reeled pipes subjected to cyclic plastic straining. This is because it has been shown that cyclic plastic pre-strain has a negligible effect on the fracture toughness of overmatch welds. There was concern, however, that this may not hold for undermatch welds. Therefore, the authors carried out a fracture testing program to quantify the effect of cyclic plastic pre-strain on the fracture toughness of undermatch welds in bimetallic pipes. It is shown in this paper that such pre-strain has a negligible effect on toughness for undermatch welds. Although most pipeline girth weld flaws are embedded, they are typically approximated by surface breaking flaws in the integrity assessment because the available reference stress solutions for embedded flaws are too conservative when used to estimate the crack driving force. This approximation, however, may not always be appropriate. To address this deficiency, the authors have recently proposed a set of new reference stress solutions for the assessment of embedded flaws in even/overmatch welds. In continuation of this work, a procedure for the ECA of embedded flaws in undermatch bi-metallic pipeline girth welds is proposed and numerically validated in this paper.
- Well Completion > Hydraulic Fracturing (1.00)
- Facilities Design, Construction and Operation > Pipelines, Flowlines and Risers > Offshore pipelines (1.00)
- Data Science & Engineering Analytics > Information Management and Systems (1.00)
- Production and Well Operations > Production Chemistry, Metallurgy and Biology > Corrosion inhibition and management (including H2S and CO2) (0.89)
ABSTRACT Engineering critical assessments (ECA) are commonly carried out during design, installation and operation of steel structures in the energy and oil and gas industries to determine acceptable flaw sizes. A number of fracture mechanics-based procedures are available for ECA of metallic structures. Most of these methods are primarily stress-based assessments and are therefore not directly applicable to cases where the loading generates large amounts of plastic deformation. If the traditional stress-based ECA approach is used under large strain conditions, overly conservative or potentially non-conservative assessments can be made, depending on the details of how the assessment is carried out. This paper reviews the strain-based assessment methods proposed in BS 7910:2019, R6 and DNVGL-RP-F108. The outcomes from these three strain-based fracture assessment methods (along with some variants on the methods) are compared with the results of selected full-scale pipe tests. As such, this paper provides an independent validation of all three methods. INTRODUCTION Engineering critical assessments (ECA) are commonly carried out during design, installation and operation of steel structures in the energy and oil and gas industries to determine acceptable flaw sizes. A number of fracture mechanics-based procedures are available for ECA of metallic structures. Most of these methods are primarily stress-based assessments and are therefore not directly applicable to cases where the loading generates large amounts of plastic deformation. For example, API 1104 (2013) Appendix A notes that stress-based ECA can be used when the total applied strain (εapp) is less than 0.5% and DNVGL-RP-F108 (2017) notes that stress-based ECA is generally used when εapp<0.4%. This implies that those methods are not rigorously applicable when the applied longitudinal stress is well in excess of the actual yield point of the pipeline material (Pisarski, 2013). The UK's fracture mechanics standard BS 7910 and the UK nuclear industry's fracture assessment code, R6, are also primarily stress-based assessment procedures.
- Energy > Oil & Gas (1.00)
- Energy > Power Industry > Utilities (0.34)
- Well Completion > Hydraulic Fracturing (1.00)
- Facilities Design, Construction and Operation > Pipelines, Flowlines and Risers > Offshore pipelines (1.00)
Low-Cycle Tearing in a Deep-Water Buckle-Arrestor Assembly Girth Weld During S-Lay Installation
Selker, Ruud (INTECSEA) | Liu, Ping (INTECSEA) | Jurdik, Erich (South Stream Transport BV) | Chaudhuri, Jay (South Stream Transport BV) | Fonzo, Andrea (RINA Consulting-Centro Sviluppo Materiali) | di Biagio, Massimo (RINA Consulting-Centro Sviluppo Materiali)
S-Lay installation of inline buckle arrestors in deep water can introduce plastic strain to girth welds. The welds are repeatedly loaded by large-strain cycles when traversing the stinger. A material-testing program was launched to assess the impact of this load sequence on the welds' integrity. It is essential to establish the correct mechanism of crack growth caused by a limited number of sequential large-strain cycles. Segment specimens with increased specimen “daylight” length were tested. Fracture morphologies of ductile tearing and fatigue growth were distinguished; ductile tearing was identified only for the first load cycle, whereas subsequent cycles were dominated by fatigue crack growth. Introduction The TurkStream Offshore Pipeline was developed by South Stream Transport BV (SSTTBV). It is a major gas-transmission system that currently comprises two pipeline strings installed in up to 2,200 m water depth, connecting large gas reservoirs in Russia to the Turkish gas-transportation network through the Black Sea. The system currently has a capacity to transport 31.5 bcm of natural gas annually over a distance of more than 900 km. The pipeline's outer diameter (D) is 32 inches, and its wall thickness (t) is 39 mm. Material grade is DNV SAWL (submerged arc-welded longitudinal) 450 with supplementary requirement F, D, U, and (light) S according to offshore standard DNV-OSF101 (Det Norske Veritas, 2010) plus project-specific modifications. Pipe joints are produced by UOE (U-ing, O-ing and expansion) and JCOE (J-ing, C-ing, O-ing and expansion) pipe-forming methods. Ultra-deep water in combination with the large pipeline diameter makes this project one of the most challenging pipeline projects ever, pushing the boundaries of the industry. The first portion of the pipeline was installed in 2017–2018.
- Europe (1.00)
- North America > United States > California > San Francisco County > San Francisco (0.28)
- Well Completion > Hydraulic Fracturing (1.00)
- Facilities Design, Construction and Operation > Pipelines, Flowlines and Risers > Offshore pipelines (1.00)
Industrial Application of SENT and Segment Testing on Deepwater Buckle Arrestor Assembly Installed by S-Lay
Fonzo, Andrea (Centro Sviluppo Materiali) | Porta, Riccardo (Centro Sviluppo Materiali) | Selker, Ruud (INTECSEA) | Liu, Ping (INTECSEA) | Jurdik, Erich (South Stream Transport BV) | Chaudhuri, Jay (South Stream Transport BV)
ABSTRACT For a major deepwater pipeline project in the Black Sea, Buckle Arrestors will be deployed to prevent catastrophic buckle propagation in the event of collapse. Buckle Arrestor Assemblies (BAAs) will be installed using the S-lay pipeline installation method, then introducing cyclic plastic strain on the BAAs' girth welds during their passage over stinger's rollers. Fracture during installation is one of the potential failure modes for the girth weld. A material testing and assessment program has been launched at Centro Sviluppo Materiali (Italy) aimed at evaluating the impact of in-field strain sequence on a defected girth weld. The program was articulated in the evaluation of toughness by using single-specimen method with compliance technique on large thickness SENT samples. Then cyclic tearing sequence has been applied on Segment specimens with increased daylight length, aimed at reproducing the real pipe remote strain conditions by small-to-medium scale testing. Accompanying the testing program, a series of ECA calculations has been performed to investigate the robustness of the segment testing methodology used to evaluate the resistance of flawed pipes when subjected to tearing plus cycling loading scenario. As a main conclusion, the segment with increased daylight methodology has been found robust. It has been confirmed by comparison of experimental results and ECA pipe solutions provided by both BS 7910 and API 579. INTRODUCTION South Stream Transport BV (SSTTBV) is developing a major gas transmission system comprising up to four (4) pipeline strings to be installed in water depths up to 2200 m. The full system will have a massive capacity to transport 63 billion cubic metres (bcm) of natural gas per annum, over a distance of more than 900 km through the Black Sea. The pipeline outside diameter (D) will be 32-inch and its wall thickness (t) 39 mm. The material grade of the line pipe is DNV SAWL 450 SFDU and, depending on the supplier, is manufactured using either UOE or JCOE method. This project can be considered as one of the most challenging pipeline projects ever, stretching the limits of present-day industry. In order to prevent catastrophic propagation of a buckle in the unlikely event of pipeline collapse, inline structures (Buckle Arrestors, BAs) are deployed at certain spatial intervals when the water depth exceeds that equivalent to the buckle propagation pressure for the pipeline. The BAs were designed and sized according to offshore design standard DNV-OS-F101 (2010). The BAA consists of three parts, i.e. one machined thick (BA) section girth welded between two pup pieces manufactured from line pipe sections of nominal dimensions. Material grade is the same for the BA section and the adjacent pup pieces, i.e. DNV SAWL 450 SFDU. However, BA and pup pieces were subjected to different thermal history. Fig. 1 schematically presents the inline Buckle Arrestor Assembly (BAA) that will be deployed in the pipeline project.
- Europe (1.00)
- North America > United States (0.68)
- Well Completion > Hydraulic Fracturing (1.00)
- Facilities Design, Construction and Operation > Pipelines, Flowlines and Risers > Offshore pipelines (1.00)