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.

On the Influence of Mechanical and Geometrical Property Distribution of the Safe Reeling of Rigid Pipelines

2009 ◽  
Author(s):  
Sylvain Denniel ◽  
Tomasz Tkaczyk ◽  
Brett Howard ◽  
Erik Levold ◽  
Olav Aamlid
Keyword(s):  
Yield Strength ◽  
Wall Thickness ◽  
Moment Capacity ◽  
Significant Difference ◽  
Optimizing Design ◽  
Bending Radius ◽  
Variation Parameter ◽  
Efficient Alternative ◽  
Pipe Joints ◽  
Cost Efficient

The reel-lay method is a fast and cost efficient alternative to the S-lay and J-lay installation methods for steel pipelines up to 20″ in diameter. The quality of the pipeline construction is high due to onshore welding under controlled conditions. However, reeled pipelines are subject to plastic straining (up to approx. 2.3%) during installation. It is therefore common practice to specify a minimum required wall thickness to avoid on-reel buckling. For a given pipe outside diameter and bending radius, formulae developed for pipes under pure bending are generally used. In addition, to ensure the integrity of pipelines during reeling, a minimum spooling-on tension is specified and tolerances on pipe properties, such as wall thickness and yield strength, are constrained. Tolerance limits are specified to reduce the likelihood of spooling two consecutive pipe joints, which have a significant difference in plastic moment capacity (mismatch). It has been shown previously that high levels of mismatch can trigger an on-reel buckle [1]. The reliability of the reeling process is indeed related to the uniformity of pipe properties. It can therefore be supposed that more uniform pipe properties may allow reeling of thinner-walled pipes, while achieving the same level of reliability. This issue has been investigated as part of a wider evaluation of reeling mechanics and the development of procedures for optimized assessment of the process, including such aspects as the effect of the geometry of pipelay equipment [2]. This paper explores methods that can be used to evaluate the reliability of reeling a given pipe onto a given vessel. Particular focus is given on the selection of appropriate material variation parameter for the assessment. The concept of an averaging factor is introduced as a means to relate variations in individual wall thickness and yield strength measurements to the variation in pipeline cross-section, which determines the likelihood of buckling. It is suggested that, in the future, this factor could be used as a method for optimizing design for reeling when using higher quality pipe.

Effect of Strain-Hardening Exponent and Strain Concentrations on the Bursting Behavior of Pressure Vessels

1974 ◽  
Vol 96 (4) ◽  
pp. 292-298 ◽  
Author(s):  
C. P. Royer ◽  
S. T. Rolfe
Keyword(s):  
Yield Strength ◽  
Strain Hardening ◽  
Wall Thickness ◽  
Pressure Vessel ◽  
High Strength Steels ◽  
Pressure Vessels ◽  
Burst Pressure ◽  
Strain Hardening Exponent ◽  
Research Committee ◽  
Wide Range

Studies by the Subcommittee for Effective Utilization of Yield Strength of the Pressure Vessel Research Committee of the Welding Research Council have provided a better understanding of the behavior of pressure vessels in the bursting mode of failure. Specifically, these studies have shown that high-strength steels can be more effectively utilized in pressure vessel applications, and with appropriate safety. However, before specific Code changes are recommended, the possible influence of undetected sharp flaws on the burst pressure, as predicted by the modified Svensson equation, should be established. Accordingly, a study of six notched pressure vessels was conducted to establish the limitations of the Svensson equation with respect to severe strain concentrations, namely, sharp longitudinal notches. Three steels (A517, A516, and 304SS) having a wide range of strain-hardening exponents (0.09, 0.19, and 0.59) were used to fabricate thin-walled pressure vessels (16-in. (406 mm) O.D., 1/2 in. (13 mm) wall thickness, 48-in. (1.22 m) length). Each vessel had a 15-in. (381 mm) long sharp machined notch with flaw depths ranging from 15 to 35 percent of the wall thickness. These vessels were tested hydrostatically to burst at room temperature. All failures were ductile. The results indicate that for pressure vessel steels having nominal yield strength up to 115 ksi (793 MN/m2) and normal ductility and toughness, the modified Svensson equation can be used to predict burst pressure very reliably as long as the flaw depths are less than 25 percent of the wall thickness. On the basis of these test results, as well as burst tests of vessels with moderate strain concentrations such as nozzles and flat end closures, it is recommended that the terms Fcyl and Fsph (factors that describe the effect of strain-hardening exponent on the bursting behavior of cylinders and spheres) be incorporated into the appropriate Code provisions. It is further recommended that the appropriate Code committee consider a possible reduction in the factor of safety against bursting on the basis of the results of this investigation.

The Application of Reliability Based Methods in the Optimisation of Reeled Rigid Pipeline Wall Thickness Requirements

2018 ◽  
Author(s):  
Daniel Smith ◽  
Craig Peters ◽  
Subhajit Lahiri
Keyword(s):  
Yield Strength ◽  
Wall Thickness ◽  
Failure Modes ◽  
Axial Strain ◽  
Effective Means ◽  
Cost Effective ◽  
Oil And Gas Industry ◽  
Probability Of Failure ◽  
Calculation Methods ◽  
Acceptance Criteria

Reel-lay is a fast and cost-effective means for the installation of subsea flowlines and Pipe-In-Pipe systems with outer diameters up to 18”. Pipelines installed by the reel lay method are plastically deformed during installation. The most critical step in the installation of a reeled pipeline occurs at the spool base, when the assembled pipeline is spooled on to the hub of the reel. The nominal level of deformation is dictated by the vessel equipment geometry, applied back tension, and pipe dimensions. Localised increases in deformation are caused by mismatches in bending stiffness between adjacent pipes. The mismatch potential is dictated by the natural variation of yield strength and by dimensional variation that is inherent to linepipe manufacturing processes. Reliability based assessments are commonly applied in the assessment of minimum acceptable wall thickness for reeling. These assessments enable the minimum acceptable wall thickness to be determined with a defined target reliability level, assessing mismatches based upon distributions of wall thickness and yield strength. The mismatch parameter calculation method and the definition of appropriate acceptance criteria are the two most important factors in reeling assessments. Neither of these two factors has been specified in a pipeline design code or a recommended practice available in the public domain. However, there is an increasing level of familiarity in industry; mismatch calculation methods and strain or ovality based acceptance criteria, defined by installation contractors are gaining widespread acceptance. This paper presents a review of the application of reliability based methods currently under use, focusing on mismatch calculation methods, acceptance criteria, and probability of failure calculation methods. Minimisation of costs is of particular importance in the current oil and gas industry climate. Because of this, the ability to specify an optimum wall thickness enables installation contractors to provide more cost effective reeled rigid pipeline solutions. After reviewing the subject matter and existing body of work this paper looks in detail at the deformation responses and failure modes for a range of sizes of reeled pipelines with mismatches. The assessment of deformation responses demonstrates a significant level of conservatism in recently proposed acceptance criteria that is based upon averaged axial strain levels. This conservatism is quantified by probability of failure calculations and provides a strong justification for further optimisation of the minimum wall thickness for reeling. Finally, the beneficial effect of increased reeling tension is quantified in terms of its effect upon probability of failure.

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.

Qualification of Local Stress Relief Heat Treatment of Double Submerged-Arc Welded DSAW Pipe for Reel-Lay Installation

2021 ◽  
Author(s):  
James Terris ◽  
Javad Safari
Keyword(s):  
Mechanical Properties ◽  
Yield Strength ◽  
Uniform Elongation ◽  
Local Stress ◽  
Cost Effective ◽  
Industry Standards ◽  
Minimum Requirements ◽  
Pipe Joints ◽  
Commercial Study ◽  
Submerged Arc

Abstract Reel-lay installation is one of the most effective methods for subsea pipeline installation. Pipes subject to reeling installation experience cyclic plastic deformations and tight control of the yield strength range, yield strength to ultimate tensile strength ratio (YS/UTS) and uniform elongation values is required on the delivered pipe. Double Submerged-Arc Weld (DSAW) pipes formed from Thermo-Mechanically Controlled Process (TMCP) plates do not normally exhibit the minimum requirements for plastic strain requirements such as minimum YS/UTS ratio or uniform elongation values. This paper describes a process for increasing the reelability of DSAW pipes. This has been achieved by induction heating of DSAW pipe ends to normalise the mechanical properties at pipe joints. The mechanical properties of the treated section have been measured and verified against design rules for reeling, based on industry standards such as DNVGL-ST-F101 [Ref. 1] and TechnipFMC supplementary requirements. The improvement in mechanical properties is measured by comparison with the as-manufactured properties of adjacent sections. A commercial study demonstrates that the locally heat-treated DSAW pipe is a cost-effective alternative to seamless pipes for reel-lay installation.

2D Color-Intensity Representation of Ultrasonic Thickness Gauge Measurements

2020 ◽  
pp. 1192-1198
Author(s):  
M.S. Mohammad ◽  
Tibebe Tesfaye ◽  
Kim Ki-Seong
Keyword(s):  
Cost Effective ◽  
The Other ◽  
Thickness Gauge ◽  
Color Intensity ◽  
Digital Readout ◽  
Flat Surfaces ◽  
Video Cameras ◽  
Wide Range ◽  
Cost Effective Alternative ◽  
Ultrasonic Thickness

Ultrasonic thickness gauges are easy to operate and reliable, and can be used to measure a wide range of thicknesses and inspect all engineering materials. Supplementing the simple ultrasonic thickness gauges that present results in either a digital readout or as an A-scan with systems that enable correlating the measured values to their positions on the inspected surface to produce a two-dimensional (2D) thickness representation can extend their benefits and provide a cost-effective alternative to expensive advanced C-scan machines. In previous work, the authors introduced a system for the positioning and mapping of the values measured by the ultrasonic thickness gauges and flaw detectors (Tesfaye et al. 2019). The system is an alternative to the systems that use mechanical scanners, encoders, and sophisticated UT machines. It used a camera to record the probe’s movement and a projected laser grid obtained by a laser pattern generator to locate the probe on the inspected surface. In this paper, a novel system is proposed to be applied to flat surfaces, in addition to overcoming the other limitations posed due to the use of the laser projection. The proposed system uses two video cameras, one to monitor the probe’s movement on the inspected surface and the other to capture the corresponding digital readout of the thickness gauge. The acquired images of the probe’s position and thickness gauge readout are processed to plot the measured data in a 2D color-coded map. The system is meant to be simpler and more effective than the previous development.

JS777

Alloy Digest ◽  
1980 ◽  
Vol 29 (11) ◽  
Keyword(s):  
Stainless Steel ◽  
Corrosion Resistance ◽  
Austenitic Stainless Steel ◽  
Cost Effective ◽  
Heat Treating ◽  
Steel Company ◽  
High Alloy ◽  
Cost Effective Alternative ◽  
Resistance To Stress ◽  
Nickel Base

Abstract JS777 is a high-alloy, fully austenitic stainless steel developed for applications where corrosive conditions are too severe for the standard grades of stainless steel. It also provides a cost-effective alternative to more expensive nickel-base and titanium-base alloys. It has relatively high resistance to stress-corrosion cracking and to intergranular corrosion. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties. It also includes information on corrosion resistance as well as forming, heat treating, machining, joining, and surface treatment. Filing Code: SS-377. Producer or source: Jessop Steel Company.

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..

ANCORSTEEL 4300

Alloy Digest ◽  
2009 ◽  
Vol 58 (11) ◽  
Keyword(s):  
Fracture Toughness ◽  
Physical Properties ◽  
Tensile Properties ◽  
Cost Effective ◽  
Heat Treating ◽  
Effective Alternative ◽  
Powder Metal ◽  
Secondary Processing ◽  
Cost Effective Alternative

Abstract Ancorsteel 4300 alloy ferrous powder simulates wrought steel compositions and is a cost-effective alternative to alloys requiring secondary processing. This datasheet provides information on composition, physical properties, hardness, and tensile properties as well as fracture toughness. It also includes information on heat treating and powder metal forms. Filing Code: SA-611. Producer or source: Hoeganaes Corporation.

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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