Collapse Capacity of UOE Deepwater Linepipe

2011 ◽  
Author(s):  
Olav Aamlid ◽  
Leif Collberg ◽  
Simon Slater
Keyword(s):  
Heat Treatment ◽  
Yield Strength ◽  
Wall Thickness ◽  
Detrimental Effect ◽  
External Pressure ◽  
Compressive Yield Strength ◽  
Safety Factors ◽  
Cold Forming ◽  
Deep Waters ◽  
Collapse Prediction

Whereas the wall thickness for most pipelines is governed by internal pressure, the wall thickness of pipelines at very deep waters may be governed by external pressure and the failure mode is collapse. This paper will firstly summarise the work performed in the early 90ties in the SUPERB project that constitutes the basis for the collapse equation adopted in DNV Rules for Submarine Pipeline Systems. This work documented a comparison between various expressions for collapse prediction (Timoshenco, Murphy and Langner (Shell) and Haugsmaa (BSI)) to available experimental results. This work made it possible to select the formulation deemed to be most appropriate as a design equation as well as calibrating safety factors. Secondly, the paper will discuss the well documented detrimental effect that pipe forming can have on the compressive yield strength in the hoop direction and thus the collapse capacity of pipes. This effect led to the introduction of the so-called fabrication factor in DNV-OS-F101 that reduces the compressive yield strength by 7–15 per cent for pipes manufactured using cold forming. However, DNV-OS-F101 states “The fabrication factor may be improved through heat treatment or external cold sizing (compression), if documented” and the paper will summarise various published work, experimental and analyses, that has, during the last 15 years, been performed in several pipeline projects to document the beneficial effect that mainly light heat treatment but also optimised forming in the UOE process have on the compressive yield stress and collapse capacity.

Minimum Weight Design of Ring Stiffened Cylinders Under External Pressure

1961 ◽  
Vol 5 (03) ◽  
pp. 44-49 ◽  
Author(s):  
George Gerard
Keyword(s):  
Yield Strength ◽  
Minimum Weight ◽  
External Pressure ◽  
Compressive Yield Strength ◽  
Minimum Weight Design ◽  
Weight Design

Minimum weight analyses for unstiffened and ring-stiffened cylinders under external pressure are presented for designs based on stability and compressive yield-strength considerations. The results for both types of cylinders are compared in terms of a common set of parameters to establish the efficiency of the stiffening system. The results are then compared on a somewhat different basis to establish the relative efficiencies of various classes of materials. Finally, certain conclusions are drawn of particular pertinence to deep submersibles.

Collapse Resistance Under Combined External Pressure and Bending Deformation of Coated Linepipe

2020 ◽  
Author(s):  
Takahiro Sakimoto ◽  
Hisakazu Tajika ◽  
Tsunehisa Handa ◽  
Yoshiaki Murakami ◽  
Satoshi Igi ◽  
...  
Keyword(s):  
Yield Strength ◽  
Deep Water ◽  
Thermal Cycle ◽  
Bauschinger Effect ◽  
Heating Temperature ◽  
External Pressure ◽  
Compressive Yield Strength ◽  
Heat Cycle ◽  
Bending Deformation ◽  
Collapse Resistance

Abstract As offshore pipeline projects have expanded to deeper water regions with depths of more than 2 000 m, higher resistance against collapse by external pressure is now required in linepipe. Collapse resistance is mainly controlled by the pipe geometry and compressive yield strength. In UOE pipe, the compressive yield strength along the circumferential direction changes dramatically due to tensile pre-strain that occurs in pipe forming processes such as the expansion process. In order to improve the compressive yield strength of pipes, it is important to consider the Bauschinger effect caused by pipe expansion. As the mechanism of this effect, it is understood that internal stress is generated by the accumulation of dislocations, and this reduces reverse flow stress. Compressive yield strength is also changed by the thermal cycle associated with application of fusion-bond epoxy in pipe anti-corrosion coating by induction heating. In the typical thermal heat cycle of this coating process, the maximum heating temperature is from 200 °C to 250 °C. In this case, compressive yield strength increases as an effect of the thermal cycle, resulting in increased collapse resistance. Thus, for deep water application of UEO linepipe, it is important to clarify the conflicting effects of the Bauschinger effect and the thermal heat cycle on compressive yield strength. During installation of deep water pipelines by a method such as J-lay, curvature is imposed on the pipe axis, but the circumferential bending that leads to ovalization is determined by the interaction of the curvature of bending deformation. This bending deformation decreases collapse resistance. The interaction of external pressure and bending is also important when evaluating collapse. Against this background, this study discusses the collapse criteria for coated linepipe and their bending interaction against collapse based on a full-scale collapse test under external pressure with and without bending loading. The effect of the thermal heat cycle on linepipe collapse criteria is also discussed based on the results of tensile pre-strain tests with simulation of the thermal cycle and a collapse calculation by FEA.

Collapse of Worn Casing

1977 ◽  
Vol 99 (1) ◽  
pp. 208-214 ◽  
Author(s):  
C. E. Murphey
Keyword(s):  
Yield Strength ◽  
Lower Bounds ◽  
Wall Thickness ◽  
Axial Load ◽  
External Pressure ◽  
Upper And Lower Bounds ◽  
Percentage Reduction ◽  
Steel Tubes ◽  
Collapse Pressure ◽  
Severe Wear

Collapse tests were performed on one-in. dia steel tubes with flats milled on the exterior to simulate worn casing. External pressure and axial load were applied to the tubs having a range of wall thickness, yield strength, and degree of wear. Empirical correlation of the data and comparison with elastic collapse calculations indicate the percentage reduction in collapse pressure due to wear. This reduction is predictable within upper and lower bounds. While the milled external flat may not accurately simulate severe internal wear, the correlation is adequate for less than severe wear to give an indication of remaining strength.

Minimum Wall Thickness Requirements for Ultra Deep-Water Pipelines

2003 ◽  
Author(s):  
Enrico Torselletti ◽  
Luigino Vitali ◽  
Roberto Bruschi ◽  
Leif Collberg
Keyword(s):  
Wall Thickness ◽  
Deep Water ◽  
Failure Modes ◽  
Limit State ◽  
Strain Curve ◽  
External Pressure ◽  
Design Guidelines ◽  
Compressive Yield Strength ◽  
Pipe Material ◽  
Line Pipe

The offshore pipeline industry is planning new gas trunklines at water depth ever reached before (up to 3500 m). In such conditions, external hydrostatic pressure becomes the dominating loading condition for the pipeline design. In particular, pipe geometric imperfections as the cross section ovality, combined load effects as axial and bending loads superimposed to the external pressure, material properties as compressive yield strength in the circumferential direction and across the wall thickness etc., significantly interfere in the definition of the demanding, in such projects, minimum wall thickness requirements. This paper discusses the findings of a series of ultra deep-water studies carried out in the framework of Snamprogetti corporate R&D. In particular, the pipe sectional capacity, required to sustain design loads, is analysed in relation to: • The fabrication technology i.e. the effect of cold expansion/compression (UOE/UOC) of TMCP plates on the mechanical and geometrical pipe characteristics; • The line pipe material i.e. the effect of the shape of the actual stress-strain curve and the Y/T ratio on the sectional performance, under combined loads; • The load combination i.e. the effect of the axial force and bending moment on the limit capacity against collapse and ovalisation buckling failure modes, under the considerable external pressure. International design guidelines are analysed in this respect, and experimental findings are compared with the ones from the application of proposed limit state equations and from dedicated FE simulations.

Reliability Based Assessment of Minimum Wall Thickness for Reeling: A Focus on Cold Worked Pipe

2011 ◽  
Author(s):  
Daniel Smith ◽  
Tomasz Tkaczyk ◽  
Sylvain Denniel
Keyword(s):  
Yield Strength ◽  
Strain Hardening ◽  
Wall Thickness ◽  
Cost Effective ◽  
Cold Forming ◽  
Track Record ◽  
Cost Effective Alternative ◽  
Pipe Joints ◽  
Cold Worked ◽  
Tolerance Control

Pipelines installed by the reel lay method are plastically deformed during installation. The nominal level of plastic deformation is determined by the vessel equipment geometry and pipe dimensions. The natural variation of wall thickness and yield strength determines the potential differences in bending stiffness (also called mismatch) that can occur between adjacent pipe joints. These mismatches cause a localized peak in strain and can drive gross deformation of the pipe, which may result in a buckle if not addressed at the engineering stage. The slenderness of a pipe and the strain hardening capacity determines the capacity of a pipe to handle the effects of mismatches during reeling A minimum wall thickness for reeling design equation has been defined for seamless pipe and has a proven track record and demonstrable reliability. There is a recent increase in the level of interest in cold worked pipe such as HFI/HFW, which appears to be an attractive cost effective alternative to seamless pipes. HFI/HFW potentially has inferior strain hardening properties due to cold forming, but have superior tolerance control of yield strength and wall thickness. This paper presents the results of a reliability based study, demonstrating the applicability of existing minimum wall thickness for reeling criteria, when applied to HFI/HFW linepipe.

scholarly journals Analysis of buried pipelines laid under the pipelines operation, is subjected to operational loads

2019 ◽  
Vol 6 (3) ◽  
Author(s):  
Liudmila Muravieva ◽  
Igor Ovchinnikov
Keyword(s):  
Wall Thickness ◽  
Oil And Gas ◽  
Oil And Gas Industry ◽  
External Pressure ◽  
Compressive Yield Strength ◽  
Successful Operation ◽  
Gas Industry ◽  
Load Effects ◽  
Bending Loads ◽  
Definition Of

Today’s successful operation within the oil and gas industry is based on the triangle “Safety – Reliability – Profitability (Efficiency)”. It is of high importance to properly balance these different and sometimes opposite positions. The article describes the characteristics of the strength of the buried offshore pipeline. Pipe geometric imperfections as the cross section ovality, combined load effects as axial and bending loads superimposed to the external pressure, material properties as compressive yield strength in the circumferential direction and across the wall thickness etc., significantly interfere in the definition of the demanding, in such projects, minimum wall thickness requirements.

Collapse Propagation of Deep Water Pipelines

2017 ◽  
Author(s):  
Ana Paula França de Souza ◽  
Rafael F. Solano ◽  
Fabio B. de Azevedo ◽  
Erwan Karjadi ◽  
Caroline Ferraz
Keyword(s):  
Wall Thickness ◽  
Oil And Gas ◽  
Oil And Gas Industry ◽  
External Pressure ◽  
External Diameter ◽  
Gas Industry ◽  
Deep Waters ◽  
Water Pipelines ◽  
Offshore Oil And Gas ◽  
Pipeline Design

Nowadays, the global trend is an increasing need for oil and gas. As the easily recoverable fields have been already developed, the trend in the offshore oil and gas industry is going deeper into the more challenging outlook, such as outside West Africa, the Brazilian Pre-Salt developments and in the Gulf of Mexico. For ultra-deep waters the main design challenge is related to the high external pressure that may cause collapse of pipelines. This potential failure mode is normally dealt with by increasing the pipe wall thickness, but at ultra-deep waters this may require very thick pipe that becomes very costly, difficult to manufacture and hard to install due to its weight. Facing the challenges of the pipeline design for ultra-deep waters, the Collapse Joint Industry Project (JIP) was started to develop a guideline for wall thickness design optimization for offshore pipelines with external diameter to wall thickness ratio less than 20 (D/t < 20). As part of the JIP, nine buckle propagation tests were conducted on full scale seamless pipes. This paper describes these experiments and new conclusions that were raised in light of the test results.

Improved Collapse Resistance of Large Diameter Pipe for Deepwater Applications Using a New Impander Technology

2010 ◽  
Author(s):  
Thilo Reichel ◽  
Vitaliy Pavlyk ◽  
Jochem Beissel ◽  
Stelios Kyriakides ◽  
Wen-Yea Jang
Keyword(s):  
Yield Strength ◽  
New Technology ◽  
Large Diameter ◽  
Compressive Yield Strength ◽  
Cold Forming ◽  
Collapse Pressure ◽  
Large Diameter Pipe ◽  
Diameter Pipe ◽  
Improved Performance ◽  
Welded Pipe

Large diameter pipe is most commonly produced by the UOE and JCO processes. In both cases the pipe is finished by cold expansion, which is known to be the main contributor to the reduced collapse pressure of such pipe compared to seamless pipe of the same steel grade and diameter-to-thickness ratio. The main cause of this degradation in collapse pressure is a reduction in the compressive yield strength of the material that results from the cold forming steps involved, particularly the expansion. This paper presents a new manufacturing technology in which longitudinally welded pipe is finished by controlled compression. A newly developed cold sizing press, called Impander, is used to produce pipe that is rounder, has reduced residual stresses, and increased compressive yield strength. The combination of these factors can lead to a significant increase in the collapse pressure of the pipe. The new technology is first introduced followed by experimental and analytical results that demonstrate the improved collapse pressure of pipes manufactured by it. The enhancement in collapse pressure will be demonstrated using X-65 grade, 20-inch pipe with one-inch wall. Pipes are compressed to different degrees, and their dimensional characteristics and compressive mechanical properties are measured. The measurements are used in finite element models to calculate the collapse pressure demonstrating the improved performance. The advantages of the process will also be confirmed using results from full-scale collapse experiments on 20-inch pipe manufactured by the new process.

STRENX 960MC

Alloy Digest ◽  
2016 ◽  
Vol 65 (11) ◽  
Keyword(s):  
Yield Strength ◽  
Physical Properties ◽  
Structural Steel ◽  
Tensile Properties ◽  
Bend Strength ◽  
Cold Forming ◽  
Hot Rolled ◽  
Minimum Yield

Abstract Strenx 960MC is a hot-rolled structural steel made for cold forming, with minimum yield strength of 960 MPa (139 ksi) for stronger and lighter structures. This alloy meets or exceeds the requirements of S960MC in EN 10149-2. This datasheet provides information on composition, physical properties, tensile properties, and bend strength. It also includes information on surface qualities as well as forming, machining, and joining. Filing Code: SA-772. Producer or source: SSAB Swedish Steel Inc..

STRENX 700CR

Alloy Digest ◽  
2018 ◽  
Vol 67 (8) ◽  
Keyword(s):  
Yield Strength ◽  
Physical Properties ◽  
Structural Steel ◽  
Tensile Properties ◽  
Cutting Performance ◽  
Cold Forming ◽  
Cold Rolled ◽  
Minimum Yield

Abstract Strenx 700 CR is a cold-rolled structural steel with a minimum yield strength of 700 MPa (102 ksi) used to produce stronger and lighter structures. Strenx 700 CR has good cold forming, welding, and cutting performance. This datasheet provides information on composition, physical properties, and tensile properties. It also includes information on surface qualities as well as joining. Filing Code: SA-819. Producer or source: SSAB Swedish Steel Inc..

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