New Design Code for Interference Between Trawl Gear and Pipelines: DNV RP-F111

2006 ◽  
Author(s):  
Dag O̸. Askheim ◽  
Olav Fyrileiv
Keyword(s):  
Otter Trawl ◽  
Hydrodynamic Drag ◽  
Potential Hazard ◽  
Test Results ◽  
Design Code ◽  
Acceptance Criteria ◽  
Drag Forces ◽  
Analysis Methodology ◽  
Concrete Coating ◽  
Pipeline Design

The offshore petroleum and the fishing industries are often operating in the same areas. Fishing, in particular bottom trawling, is of concern to pipeline integrity. Such trawling is mainly conducted with two types of trawl gear: otter or beam trawls. The otter trawl boards are steel, more or less rectangular boards which keep the trawl bag open by hydrodynamic drag forces. While the beam trawls use a 10–20 meters long beam to keep the trawl bag open. These trawl gears are dragged along the seabed and represent a potential hazard to pipelines. This paper gives a brief description of types and dimensions of trawl gear. Further it deals with methods for calculating the pipeline response when interacting with bottom trawl gear and finally adresses acceptance criteria for pipeline design and assessment during operation. The calculation methods and acceptance criteria given in this paper are based on test results and research done during the last decades including results from the Kristin, Sno̸hvit and Ormen Lange projects. The above mentioned trawl data, analysis methodology and acceptance criteria are taken from the new DNV Recommended Practice, DNV RP-F111 (2006). This Recommended Practice is an update of the former design code DNV GL 13 (1997). The update was performed mainly due to new types of trawl gear, updated trawl gear data, various experience from application of GL 13 in projects and a general harmonizing process with the pipeline code, DNV OS-F101, and the Hotpipe project, ref Collberg et al. (2005). Large sums are often spent in pipeline projects to protect against trawl gear interaction in terms of concrete coating, trenching or burial. On the other hand the costs of not providing a sufficient protection could be extremely high, with costs related to leakages, failures, stop in production and repair/replacement. This Recommended Practice provides a rational tool to optimize the costs related to trawl gear interference and still ensure that the integrity of the pipeline becomes acceptable.

Structural Integrity for Nuclear Power Plant Against Excessive Load on Design Extension Condition

2013 ◽  
Author(s):  
Daigo Watanabe ◽  
Kiminobu Hojo
Keyword(s):  
Nuclear Power ◽  
Structural Integrity ◽  
Safety Factors ◽  
Design Code ◽  
Acceptance Criteria ◽  
Integrity Assessment ◽  
Current Design ◽  
Factor Design ◽  
Excessive Load ◽  
Load And Resistance Factor

This paper introduces an example of structural integrity evaluation for Light Water Reactor (LWR) against excessive loads on the Design Extension Condition (DEC). In order to assess the design acceptance level of DEC, three acceptance criteria which are the stress basis limit of the current design code, the strain basis limit of the current design code and the strain basis limit by using Load and Resistance Factor Design (LRFD) method were applied. As a result the allowable stress was increased by changing the acceptance criteria from the stress basis limit to the strain basis limit. It is shown that the practical margin of the LWR’s components still keeps even on DEC by introducing an appropriate criterion for integrity assessment and safety factors.

Earth pressures exerted on an induced trench cast-in-place double-cell rectangular box culvert

2012 ◽  
Vol 49 (11) ◽  
pp. 1267-1284 ◽  
Author(s):  
Olajide Samuel Oshati ◽  
Arun J. Valsangkar ◽  
Allison B. Schriver
Keyword(s):  
Earth Pressure ◽  
Test Results ◽  
Overburden Pressure ◽  
Centrifuge Testing ◽  
Geotechnical Centrifuge ◽  
Drag Forces ◽  
Field Instrumentation ◽  
Earth Pressures ◽  
Box Culvert ◽  
Base Contact

Earth pressure data from the field instrumentation of a cast-in-place reinforced rectangular box culvert are presented in this paper. The instrumented culvert is a 2.60 m by 3.60 m double-cell reinforced cast-in-place rectangular box buried under 25.10 m of fill constructed using the induced trench installation (ITI) method. The average earth pressure measured across the roof was 0.42 times the overburden pressure, and an average of 0.52 times the overburden pressure was measured at mid-height of the culvert on the sidewalls. Base contact pressure under the rectangular box culvert was also measured, providing field-based data demonstrating increased base pressure resulting from downward drag forces developed along the sidewalls of the box culvert. An average increase of 25% from the measured vertical earth pressures on the roof plus the culvert dead load (DL) pressure was calculated at the culvert base. A model culvert was also tested in a geotechnical centrifuge to obtain data on earth pressures at the top, sides, and base of the culvert. The data from the centrifuge testing were compared with the prototype structure, and the centrifuge test results agreed closely with the measured field prototype pressures, in spite of the fact that full similitude was not attempted in centrifuge testing.

Experimental Study and Finite Analysis on Flexural Capacity of Laminated Glass

2011 ◽  
Vol 243-249 ◽  
pp. 258-262
Author(s):  
Jun Chen ◽  
Jia Lv ◽  
Qi Lin Zhang ◽  
Zhi Xiong Tao ◽  
Jun Chen
Keyword(s):  
Experimental Results ◽  
Laminated Glass ◽  
Test Results ◽  
Design Code ◽  
Flexural Capacity ◽  
Equivalent Thickness ◽  
High Rise ◽  
Safety Glass ◽  
Current Design ◽  
Good Agreement

Laminated glass has been increasing widely used in high rise buildings as a kind of safety glass in recent years. So we should analyze its material property. In this paper, we use flexural experiments and ANSYS program to analyze the main factors that affect the flexural capacity of the laminated glass. The test results show that the flexural capacity is closely related to film. And the ANSYS program had got good agreement with the experimental results. Comparison of experimental results with calculated ones indicates that the current design code will lead to conservative results and the equivalent thickness of laminated glasses provided in the code should be further discussed.

Hydrodynamic drag in steller sea lions (Eumetopias jubatus)

2000 ◽  
Vol 203 (12) ◽  
pp. 1915-1923 ◽  
Author(s):  
L.L. Stelle ◽  
R.W. Blake ◽  
A.W. Trites
Keyword(s):  
Minimum Cost ◽  
The Body ◽  
Hydrodynamic Drag ◽  
Eumetopias Jubatus ◽  
Steller Sea Lions ◽  
California Sea Lions ◽  
Cost Of Transport ◽  
Sea Lions ◽  
Drag Forces ◽  
The Individual

Drag forces acting on Steller sea lions (Eumetopias jubatus) were investigated from ‘deceleration during glide’ measurements. A total of 66 glides from six juvenile sea lions yielded a mean drag coefficient (referenced to total wetted surface area) of 0.0056 at a mean Reynolds number of 5.5×10(6). The drag values indicate that the boundary layer is largely turbulent for Steller sea lions swimming at these Reynolds numbers, which are past the point of expected transition from laminar to turbulent flow. The position of maximum thickness (at 34 % of the body length measured from the tip of the nose) was more anterior than for a ‘laminar’ profile, supporting the idea that there is little laminar flow. The Steller sea lions in our study were characterized by a mean fineness ratio of 5.55. Their streamlined shape helps to delay flow separation, reducing total drag. In addition, turbulent boundary layers are more stable than laminar ones. Thus, separation should occur further back on the animal. Steller sea lions are the largest of the otariids and swam faster than the smaller California sea lions (Zalophus californianus). The mean glide velocity of the individual Steller sea lions ranged from 2.9 to 3.4 m s(−)(1) or 1.2-1.5 body lengths s(−)(1). These length-specific speeds are close to the optimum swim velocity of 1.4 body lengths s(−)(1) based on the minimum cost of transport for California sea lions.

scholarly journals APLIKASI NON DESTRUCTIVE TEST PENETRANT TESTING (NDT-PT) UNTUK ANALISIS HASIL PENGELASAN SMAW 3G BUTT JOINT

2017 ◽  
Vol 3 (2) ◽  
Author(s):  
Tito Endramawan ◽  
Emin Haris ◽  
Felix Dionisius ◽  
Yuliana Prinka
Keyword(s):  
Mild Steel ◽  
Welding Process ◽  
Butt Joint ◽  
Test Results ◽  
Acceptance Criteria ◽  
Destructive Test ◽  
Non Destructive ◽  
Penetrant Testing

The purpose of the research are determine acceptance criteria the specimen based on ASME standard. The research used mild steel materials with hardness 220 HVN with sized 30 cm x 20 cm x 1.2 cm then  SMAW welding process position of 3G buttjoint with rooting electrode LB 52U diameter 2.6 mm used current 70 Amper and voltage 380 volt, for Filler used LB 5218 electrode 3.2 mm with current of 80 Amper and voltage of 380 volts. The welding process influenced by many factor which cause failure. The method for inspect result of weld used Non Destructive Test Penetrant Testing (NDT PT) and used ASME standard for acceptance criteria. The test results showed the discontinuity of porosity on the surface of the welded product in specimen 1 is the largest rounded 5 mm at 233 mm distance so that based on the acceptance criteria of AWS standard, the welding result is accepted and the specimen 2 there is discontinuity at 233 mm with the size of 8 mm so that Otherwise rejected. This rejected result can be improved by gouging the discontinuity and then welded.

Rayleigh Damping Effects on Global Analysis of Umbilicals

2011 ◽  
Author(s):  
Lauro Massao Yamada da Silveira ◽  
Rafael Loureiro Tanaka ◽  
Joa˜o Paulo Zi´lio Novaes
Keyword(s):  
Global Analysis ◽  
Time History ◽  
Systems Design ◽  
Hydrodynamic Drag ◽  
Viscous Damping ◽  
Structural Damping ◽  
Peak Period ◽  
Rayleigh Damping ◽  
Drag Forces ◽  
Offshore Industry

Despite global analysis of umbilicals is a well-known area in the offshore systems design, some topics are still opened for discussions. One of these topics refers to the structural damping. Obviously, the viscous damping caused by hydrodynamic drag forces is the major source of damping to the whole system. However, in some severe load cases, the host vessel dynamics may induce high snatch loads to the umbilical top end and these loads are more related to structural damping, specifically in tension–elongation hysteresis, than to viscous damping. The snatch loads must be taken into account in the whole design process, which leads to an umbilical designed to resist to higher tension loads and implies also, in most cases, in over-dimensioned accessories, such as the bending limiters. Actually, due to the high level of friction between layers, the umbilical presents some level of structural damping which is, in fact, related to hysteretic moment-curvature and tension-elongation relations. This intrinsic structural damping may in fact contribute to the reduction of the snatch loads and considering it may reduce the level of conservatism in the design. However, due to the complexity and diversity of umbilical designs, it is not straightforward to come up with general-use hysteretic curves. A simplification then is to apply classic Rayleigh damping. Typically, damping levels of 5% are accepted in the offshore industry when using stiffness-proportional Rayleigh damping (the 5% damping is a percentage of the critical damping and is accounted for at the regular wave period or irregular wave spectral peak period). The problem here is that stiffness-proportional Rayleigh damping increases linearly with the frequency and the damping level at 1Hz, for example, may get to 60%. This fact indicates that the high-frequency part of the response may be simply discarded from the results, which in turn may lead to an incorrect, over-damped analysis. The present work aims tackling the Rayleigh damping issue, evaluating its effects on tension levels and spectral density of the tension time history. A recommendation of how to apply Rayleigh damping is proposed.

Early Engagement of ECA in Offshore Deepwater Pipeline Design

2021 ◽  
Author(s):  
Daowu Zhou ◽  
Lingjun Cao ◽  
T. Sriskandarajah ◽  
Mark Lewis ◽  
Daniel Manso
Keyword(s):  
Oil And Gas ◽  
Fluid Composition ◽  
Acceptance Criteria ◽  
Gas Field ◽  
Detailed Design ◽  
Damage And Fracture ◽  
Weld Material ◽  
Challenging Environment ◽  
Oil And Gas Field ◽  
Pipeline Design

Abstract Welding acceptance criteria derived through ECA is typically performed after the detailed design. The design loads, together with pipeline and girth weld material testing data, are inputs to ECA and used to evaluate the pipeline girth weld integrity for determining the criticality of potential weld flaws. With ever increasing challenging environment (deepwater, HP/HT, aggressive fluid composition etc) in the oil and gas field, the fatigue damage and fracture failure may become a serious concern, consequently limiting the productivity of the pipeline fabrication. It is therefore essential to integrate ECA into the design loop to remove the uncertainty and risk to achieve a practically workable fabrication solution. In this paper, a strategy to integrate early ECA into pipeline detailed design phase is presented. A case study in a deepwater subsea channel crossing demonstrates that an early ECA engagement effectively mitigates the significant fatigue and fracture risk and obtains workable welding acceptance criteria for fabrication.

ESTIMATION OF THE POWDER-ACTUATED SHEAR CONNECTORS TESTS

2021 ◽  
Vol 295 (2) ◽  
pp. 16-26
Author(s):  
D.V. Konin ◽  
Keyword(s):  
Bearing Capacity ◽  
Estimation Methods ◽  
Shear Connector ◽  
Connection Strength ◽  
Test Results ◽  
European Standard ◽  
Design Code ◽  
Shear Connectors ◽  
Shear Connection

The shear connector design should be executed according to the SP 266.1325800.2016. For the different typed of welded connectors are there analytic dependences, which could be used for shear connection strength estimation. The design code also allows to use powder-actuated Z-shape shear connectors. Their bearing capacity should be proved by tests according to the GOST R 58336-2018. Inasmuch the GOST doesn't consist the test estimation approach, the authors offer the method. For the test estimation methods the test results of 15 series specimen had been used. The results were compared with estimation according to the European standard for the verification.

scholarly journals Neuro-Fuzzy Dynamic Position Prediction for Autonomous Work-Class ROV Docking

Sensors ◽  
2020 ◽  
Vol 20 (3) ◽  
pp. 693
Author(s):  
Petar Trslić ◽  
Edin Omerdic ◽  
Gerard Dooly ◽  
Daniel Toal
Keyword(s):  
Fuzzy Inference ◽  
North Atlantic Ocean ◽  
Prediction Method ◽  
Hydrodynamic Drag ◽  
Remotely Operated Vehicle ◽  
Inference System ◽  
Drag Forces ◽  
Neuro Fuzzy ◽  
Heave Motion ◽  
Work Class

This paper presents a docking station heave motion prediction method for dynamic remotely operated vehicle (ROV) docking, based on the Adaptive Neuro-Fuzzy Inference System (ANFIS). Due to the limited power onboard the subsea vehicle, high hydrodynamic drag forces, and inertia, work-class ROVs are often unable to match the heave motion of a docking station suspended from a surface vessel. Therefore, the docking relies entirely on the experience of the ROV pilot to estimate heave motion, and on human-in-the-loop ROV control. However, such an approach is not available for autonomous docking. To address this problem, an ANFIS-based method for prediction of a docking station heave motion is proposed and presented. The performance of the network was evaluated on real-world reference trajectories recorded during offshore trials in the North Atlantic Ocean during January 2019. The hardware used during the trials included a work-class ROV with a cage type TMS, deployed using an A-frame launch and recovery system.

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