Impact of Yield to Ultimate Ratio on the Reliability of Burst Limit States

2006 ◽  
Author(s):  
Marc A. Maes ◽  
Mamdouh M. Salama
Keyword(s):  
State Of The Art ◽  
Limit State ◽  
High Strength Steels ◽  
High Strength ◽  
Crack Arrest ◽  
Limit States ◽  
Internal Damage ◽  
Lower Strain ◽  
Margin Of Safety ◽  
The Impact

In order to reduce arctic construction and transportation costs, high strength steels (> X80) have been advocated for use in high pressure gas pipelines. These steels differ from conventional steels by exhibiting lower work hardening capacity, lower strain to failure and possible softening of their HAZ. These differences can impact burst limit state and tensile limit state, in addition to crack arrest. In this paper, the impact of the variations in mechanical properties on the reliability of several pipe limit states involving burst is examined. The paper presents the results of burst limit state analysis using state-of-the-art plastic burst models of strain hardening pipe and considering all the uncertainties that impact the margin of safety of pipes subject to internal pressure. Intact pipes, corroded pipes and externally damaged pipes are considered. The analysis focuses on different design check equations (DCE) which “control” the safe usage of the pipe. In addition, the paper looks at how external or internal damage or corrosion affects the burst capacity differently for medium versus high-strength pipelines steels.

Reliability of Burst Limit States for Damaged and Corroded High Strength Pipelines

2006 ◽  
Author(s):  
Marc A. Maes ◽  
Mamdouh M. Salama ◽  
Markus Dann
Keyword(s):  
Limit State ◽  
High Strength Steels ◽  
High Strength ◽  
Crack Arrest ◽  
Limit States ◽  
Lower Strain ◽  
Margin Of Safety ◽  
Normal Strength ◽  
The Impact

High strength steels (X100 and X120) that are being considered for high pressure gas pipelines differ from conventional steels by exhibiting lower work hardening capacity, lower strain to failure and softening of their HAZ. These differences impact burst limit state and tensile limit state, in addition to crack arrest. In this paper, the impact of the variations in mechanical properties on the reliability of pipe limit states involving ductile burst of damaged or corroded pipe is examined. The paper presents the results of burst limit state analysis using state-of-the-art plastic burst models of strain hardening pipe and considering all the uncertainties that impact the margin of safety of pipes subject to internal pressure. Intact pipes, corroded pipes and externally damaged pipes are considered. A case study comparing the differences between normal strength (X60) pipeline and high strength (X100) pipeline is also presented.

scholarly journals An enhancement of the current design concepts for the improved consideration of residual stresses in fatigue-loaded welds

2021 ◽  
Vol 65 (4) ◽  
pp. 643-651
Author(s):  
Th. Nitschke-Pagel ◽  
J. Hensel
Keyword(s):  
Residual Stresses ◽  
State Of The Art ◽  
High Strength Steels ◽  
High Strength ◽  
Design Tools ◽  
Design Concepts ◽  
Treatment Processes ◽  
Real Distribution ◽  
Current Design ◽  
Reliable Knowledge

AbstractThe consideration of residual stresses in fatigue-loaded welds is currently done only qualitatively without reliable knowledge about their real distribution, amount and prefix. Therefore, the tools which enable a more or less unsafe consideration in design concepts are mainly based on unsafe experiences and doubtful assumptions. Since the use of explicitly determined residual stresses outside the welding community is state of the art, the target of the presented paper is to show a practicable way for an enhanced consideration of residual stresses in the current design tools. This is not only limited on residual stresses induced by welding, but also on post-weld treatment processes like HFMI or shot peening. Results of extended experiments with longitudinal fillet welds and butt welds of low and high strength steels evidently show that an improved use of residual stresses in fatigue strength approximation enables a better evaluation of peening processes as well as of material adjusted welding procedures or post-weld stress relief treatments. The concept shows that it is generally possible to overcome the existing extremely conservative but although unsafe rules and regulations and may also enable the improved use of high strength steels.

Crack Arrest Toughness of Two High Strength Steels (AISI 4140 and AISI 4340)

1982 ◽  
Vol 13 (4) ◽  
pp. 657-664 ◽  
Author(s):  
E. J. Ripling ◽  
J. H. Mulherin ◽  
P. B. Crosley
Keyword(s):  
High Strength Steels ◽  
High Strength ◽  
Crack Arrest ◽  
Aisi 4140 ◽  
Arrest Toughness ◽  
Aisi 4340

Influence of Human Error on Structural Reliability

2017 ◽  
Author(s):  
Eric Brehm ◽  
Robert Hertle ◽  
Markus Wetzel
Keyword(s):  
Human Error ◽  
Structural Reliability ◽  
Failure Modes ◽  
Structural Model ◽  
Limit State ◽  
Design Procedure ◽  
Material Strength ◽  
Limit States ◽  
The Impact

In common structural design, random variables, such as material strength or loads, are represented by fixed numbers defined in design codes. This is also referred to as deterministic design. Addressing the random character of these variables directly, the probabilistic design procedure allows the determination of the probability of exceeding a defined limit state. This probability is referred to as failure probability. From there, the structural reliability, representing the survival probability, can be determined. Structural reliability thus is a property of a structure or structural member, depending on the relevant limit states, failure modes and basic variables. This is the basis for the determination of partial safety factors which are, for sake of a simpler design, applied within deterministic design procedures. In addition to the basic variables in terms of material and loads, further basic variables representing the structural model have to be considered. These depend strongly on the experience of the design engineer and the level of detailing of the model. However, in the clear majority of cases [1] failure does not occur due to unexpectedly high or low values of loads or material strength. The most common reasons for failure are human errors in design and execution. This paper will provide practical examples of original designs affected by human error and will assess the impact on structural reliability.

Development of High Steel Grade Seamless X100 Weldable

2008 ◽  
Author(s):  
Alfonso Izquierdo ◽  
Hector Quintanilla ◽  
Gilles Richard ◽  
Ettore Anelli ◽  
Gianluca Mannucci ◽  
...  
Keyword(s):  
Phase I ◽  
Phase Ii ◽  
Limit State ◽  
High Strength Steels ◽  
High Strength ◽  
Steel Grade ◽  
Technological Evolution ◽  
Complex Design ◽  
Exploration And Production ◽  
Girth Welds

The technological evolution in the offshore sector points out a trend towards an increasing use of high strength steels (grade 80ksi and higher), for both pipelines and risers. Pipeline specifications for deepwater offshore fields demand developments in design criteria (i.e. limit state design), welding, installation, and laying technologies. As long as the market goes deeper in offshore exploration and production, the market trend is to use heavier pipes in steel grade X65/X70 and some technological limits from several fronts are faced and more attractive becomes for the market to have a lighter high strength 100ksi seamless steel grade. The joint industrial program (JIP), termed “Seamless 100 ksi weldable” launched by Tenaris in order to address the complex design issues of high strength Q&T seamless pipes for ultra deep water applications has been finalized. The 100ksi steel grade has been achieved in two wall thickness 16 mm and 25 mm. The main results from both phase I devoted to the development and production of seamless pipes with minimum 100ksi and phase II devoted to evaluate the high strength seamless pipe weldability will be addressed in this paper. Main microstructural features promoting the best strength-toughness results obtained from phase I and the results from phase II, where the heat affected zone (HAZ) characterization made using stringent qualifying configuration such as API RP2Z and the promising results after qualifying the girth welds simulating a typical offshore operation and the Engineering Critical Assessment for installation will be addressed. The results from this development are of interest of all oil & gas companies who are facing as an output from the design project analysis the need to have high strength seamless pipes.

scholarly journals Experimental Investigation on the Effect of Shot Peening and Deep Rolling on the Fatigue Response of High Strength Fasteners

Metals ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 1093 ◽  
Author(s):  
Reggiani
Keyword(s):  
Fatigue Life ◽  
Shot Peening ◽  
High Strength Steels ◽  
High Strength ◽  
Experimental Tests ◽  
Published Data ◽  
Deep Rolling ◽  
Beneficial Impact ◽  
The Impact ◽  
Fatigue Life Enhancement

Shot-peening and deep rolling are mechanical surface treatments that are commonly applied to enhance the fatigue performances of components, owing to their capacity to generate compressive residual stresses and induce work hardening. However, literature is still poor of published data concerning the application of these treatments to high strength steels fasteners, although these represent a class of components among the most widespread. In the present work, the impact of deep rolling and shot-peening performed in the underhead radius of two set of fasteners made of 36NiCrMo and 42CrMoV for fatigue life enhancement has been investigated. The experimental tests consisted of six combinations of shot-peening and deep rolling, including the non-treated state. Two test campaigns have been sequentially carried out with different process parameters and treatment sequences. The results always showed a beneficial impact of the deep rolling on fatigue, especially for the 42CrMoV steel. Conversely, the effect of the shot-peening strongly depended on the selected set of parameters, alternatively leading to an improvement or a worsening of the fatigue life in relation to the level of induced surface roughness.

Metallurgical Design of High Strength/High Toughness Steels

2012 ◽  
Vol 706-709 ◽  
pp. 2084-2089
Author(s):  
Andrea di Schino ◽  
Mauro Guagnelli
Keyword(s):  
Impact Toughness ◽  
Yield Strength ◽  
High Strength Steels ◽  
High Strength ◽  
Carbon Steels ◽  
Main Concern ◽  
Microstructural Parameters ◽  
Fine Microstructure ◽  
The Impact ◽  
Strength And Toughness

The proper balance between yield strength, YS, and ductile to brittle transition temperature, DBTT, has been the main concern during development of high strength engineering steels and the effect of microstructure on impact toughness has attracted a great attention during the last decades. In this paper a review concerning the relationship between strength and toughness in steels will be presented and the effect of different microstructural parameters will be discussed, aiming toimprovesuch properties in designingnewhigh strength steels. Complex microstructures, obtained by quenching and tempering (Q&T) and thermo-mechanical (TM) processing are considered. The steels are low/medium carbon steels (C=0.04%-0.40%) with yield strength in the range YS=500-1000 MPa. Results show that the strength and the impact toughness behaviour are controlled by different microstructural parameters and not, as in the case of polygonal ferritic steels, by the same structural unit (the grain size) and that a “fine” microstructure is required in order to achieve high levels of both strength and toughness. The metallurgical design of high strength steels with toughness requirements is discussed using the same approach for both Q&T and TMCP processes.

The Influence of Temperature on Zinc Abrasion in Deep Drawing Processes

2014 ◽  
Vol 611-612 ◽  
pp. 1039-1046 ◽  
Author(s):  
Peter Sachnik ◽  
Wolfram Volk ◽  
Roland Golle ◽  
Hartmut Hoffmann
Keyword(s):  
Deep Drawing ◽  
High Strength Steels ◽  
High Strength ◽  
Heating System ◽  
Sheet Metals ◽  
Process Stability ◽  
Forming Process ◽  
Whole Process ◽  
Different Temperatures ◽  
The Impact

Due to the development of corrosion-resistant lightweight, todays automotive manufacturers typically use zinc coated sheet metals in the forming process. However, zinc abrasion in industrial presses decreases the process stability and often causes interruption of the whole process. The application of high strength steels leads to a significant increase of the temperature due to the plastic work. So far a detailed, quantitative analysis of the relation between temperature and zinc abrasion is not available. Therefore, this paper examines the impact of the temperature on abrasion behaviour in sheet metal processes. To achieve this, a progressive die was built. The deep drawing stage of this tool is connected to a cooling / heating system in order to obtain a constant temperature during the forming process. A variety of different galvanized sheet metals compared to commonly used tool materials has been tested. For each combination of materials five experiments at different temperatures were performed to determine the effect of the temperature on the zinc abrasion. Applying the method of total reflection x-ray fluorescence (TXRF) the quantity of zinc abrasion was measured. A relation between low temperatures and reduced zinc abrasion can be clearly observed. Industrial experiments revealed that temperature exerts a high influence on the zinc abrasion. The new insights into the impact of the temperature show a significant way to lower the zinc abrasion and therefore increase the process stability in deep drawing processes.

scholarly journals Pulse spray gas metal arc welding of advanced high strength S650MC automotive steel

10.30544/682 ◽  
2021 ◽  
Vol 27 (4) ◽  
pp. 505-517
Author(s):  
Ashok Kumar Srivastava ◽  
Pradip K Patra
Keyword(s):  
Weld Joint ◽  
Heat Input ◽  
Arc Welding ◽  
Gas Metal Arc Welding ◽  
High Strength Steels ◽  
High Strength ◽  
Filler Wire ◽  
Advanced High Strength Steels ◽  
Metal Arc Welding ◽  
The Impact

With an increasing demand for safer and greener vehicles, mild steel and high strength steel are being replaced by much stronger advanced high strength steels of thinner gauges. However, the welding process of advanced high strength steels is not developed at the same pace. The performance of these welded automotive structural components depends largely on the external and internal quality of weldment. Gas metal arc welding (GMAW) is one of the most common methods used in the automotive industry to join car body parts of dissimilar high strength steels. It is also recognized for its versatility and speed. In this work, after a review of GMAW process and issues in welding of advanced high strength steels, a welding experiment is carried out with varying heat input by using spray and pulse-spray transfer GMAW method with filler wires of three different strength levels. The experiment results, including macro-microstructure, mechanical properties, and microhardness of weld samples, are investigated in detail. Very good weldability of S650MC is demonstrated through the weld joint efficiency > 90%; no crack in bending of weld joints, or fracture of tensile test sample within weld joint or heat affected zone (HAZ), or softening of the HAZ. Pulse spray is superior because of thinner HAZ width and finer microstructure on account of lower heat input. The impact of filler wire strength on weldability is insignificant. However, high strength filler wire (ER100SG) may be chosen as per standard welding practice of matching strength.

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