Crack Analysis of a Pressure Vessel Using the API 579-1/ASME FFS-1

2017 ◽  
Author(s):  
Jose de Jesus L. Carvajalino ◽  
José Luiz F. Freire ◽  
Vitor Eboli L. Paiva ◽  
José Eduardo Maneschy ◽  
Jorge G. Diaz ◽  
...  
Keyword(s):  
Residual Stress ◽  
Stainless Steel ◽  
Stress Distribution ◽  
Residual Stresses ◽  
Duplex Stainless Steel ◽  
Pressure Vessel ◽  
Welding Process ◽  
Residual Stress Distribution ◽  
The Other ◽  
Austenitic Steels

This paper presents a structural integrity evaluation of a duplex stainless steel pressure vessel containing several flaws detected in a longitudinal weld. The evaluation had the objective of determining whether the pressure vessel was suitable to continue in operation or whether it should be immediately repaired or even replaced. Due to timely issues, a first analysis was conducted in accordance with the 2007 edition of the API 579-1/ASME FFS-1 Standard [1]. A second analysis was later repeated based on the 2016 edition [1]. Results obtained from both analyses were compared and presented relevant differences caused by the other calculation procedures used to determine residual stresses generated in the longitudinal welding. The assessment was based on the Failure Assessment Diagram (FAD). The existing indications were detected by ultrasonic examination and were located in one longitudinal weld. The assessment evaluations used stress intensity factors for the opening mode I, KI, obtained for two cases: 1) the combination of the several supposedly interacting cracks into an equivalent crack using the interaction criteria presented in [1]; 2) the allocation of the multiple cracks into a finite element model that took into consideration, more realistically, the interaction among the individual cracks. The total loads and stresses considered in the analysis resulted from a superposition of the design pressure stress and the residual stresses induced by the welding process. Due to lack of information on the material fracture toughness for the duplex stainless steel used in the vessel, the material toughness was estimated using a lower bound value suggested in [1] for common welded stainless austenitic steels, although higher values can be predicted for duplex steels by extending the use of a transition master curve as presented and discussed elsewhere [2–7] and by employing specific Charpy test results for the vessel material. One of the key aspects of the problem was the calculation of the residual stress distribution imposed by the welding process. Two procedures were adopted: one available in the API/ASME Standard issued in 2007, and the other in the 2016 release. The results presented in this paper have demonstrated that the limits of the Standard 2007 are conservatively satisfied when the Level 3 assessment is applied. The re-analysis of the vessel when subjected to the residual stress distribution presented in the newest 2016 edition leads to consider the vessel safe under an assessment Level 2. The overall conclusion was that the damaged pressure vessel could continue in service under restrictions of the development of an inspection plan to verify the absence of future crack growth.

scholarly journals Fatigue Life Behavior of Laser Shock Peened Duplex Stainless Steel with Different Samples Geometry

2019 ◽  
Vol 2019 ◽  
pp. 1-11 ◽  
Author(s):  
César A. Vázquez Jiménez ◽  
Vignaud Granados Alejo ◽  
Carlos Rubio González ◽  
Gilberto Gómez Rosas ◽  
Sergio Llamas Zamorano
Keyword(s):  
Residual Stress ◽  
Stainless Steel ◽  
Fatigue Crack ◽  
Fatigue Life ◽  
Stress Distribution ◽  
Duplex Stainless Steel ◽  
Fatigue Crack Initiation ◽  
Stress Raiser ◽  
Residual Stress Distribution ◽  
Laser Shock

Two different stress raiser geometries (fillets and notched) were treated by laser shock peening (LSP) in order to analyze the effect of sample geometry on fatigue behavior of 2205 duplex stainless steel (DSS). The LSP treatment was carried through Nd : YAG pulsed laser with 1064 nm wavelength, 10 Hz frequency, and 0.85 J/pulse. Experimental and MEF simulation results of residual stress distribution after LSP were assessed by hole drilling method and ABAQUS/EXPLICIT software, respectively. The fatigue tests (tensile-tensile axial stress) were realized with stress ratio of R = 0.1 and 20 Hz. A good comparison of residual stress simulation and experimental data was observed. The results reveal that the fatigue life is increased by LSP treatment in the notched samples, while it decreases in the fillet samples. This is related to the residual stress distribution after LSP that is generated in each geometry type. In addition, the fatigue crack growth direction is changed according to geometry type. Both the propagation direction of fatigue crack and the anisotropy of this steel results detrimental in fillet samples, decreasing the number of cycles to the fatigue crack initiation. It is demonstrated that the LSP effect on fatigue performance is influenced by the specimen geometry.

scholarly journals Numerical Prediction of Residual Stresses Distribution in Thin-Walled Press-Braked Stainless Steel Sections

Materials ◽  
2020 ◽  
Vol 13 (23) ◽  
pp. 5378
Author(s):  
Ayad Mutafi ◽  
Noorfaizal Yidris ◽  
Seyed Saeid Rahimian Koloor ◽  
Michal Petrů
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Stainless Steel ◽  
Stress Distribution ◽  
Residual Stresses ◽  
Cold Rolling ◽  
Stainless Steels ◽  
Residual Stress Distribution ◽  
Material Anisotropy ◽  
Steel Sections

Stainless steels are increasingly used in construction today, especially in harsh environments, in which steel corrosion commonly occurs. Cold-formed stainless steel structures are currently increasing in popularity because of its efficiency in load-bearing capacity and its appealing architectural appearance. Cold-rolling and press-braking are the cold-working processes used in the forming of stainless steel sections. Press braking can produce large cross-sections from thin to thick-walled sections compared to cold-rolling. Cold-forming in press-braked sections significantly affect member behaviour and joints; therefore, they have attained great attention from many researchers to initiate investigations on those effects. This paper examines the behaviour of residual stress distribution of stainless steel press-braked sections by implementing three-dimensional finite element (3D-FE) technique. The study proposed a full finite element procedure to predict the residual stresses starting from coiling-uncoiling to press-braking. This work considered material anisotropy to examine its effect on the residual stress distribution. The technique adopted was compared with different finite element techniques in the literature. This study also provided a parametric study for three corner radius-to-thickness ratios looking at the through-thickness residual stress distribution of four stainless steels (i.e., ferritic, austenitic, duplex, lean duplex) in which have their own chemical composition. In conclusion, the comparison showed that the adopted technique provides a detailed prediction of residual stress distribution. The influence of geometrical aspects is more pronounced than the material properties. Neglecting the material anisotropy shows higher shifting in the neutral axis. The parametric study showed that all stainless steel types have the same stress through-thickness distribution. Moreover, R/t ratios’ effect is insignificant in all transverse residual stress distributions, but a slight change to R/t ratios can affect the longitudinal residual stress distribution.

Standardized Through-Wall Distributions of Dissimilar Metal Weld Residual Stress

2015 ◽  
Author(s):  
John E. Broussard
Keyword(s):  
Residual Stress ◽  
Stress Distribution ◽  
Residual Stresses ◽  
Crack Growth ◽  
Welding Process ◽  
Wall Stress ◽  
Residual Stress Distribution ◽  
Analytical Models ◽  
Stress Distributions ◽  
Dissimilar Metal

The residual stresses imparted by the welding process are a principal factor in the process of primary water stress corrosion cracking (PWSCC) of Alloy 82/182 nickel-alloy (i.e., dissimilar metal or DM) piping butt welds in PWRs. While Section XI of the ASME Code requires that residual stresses are considered in crack growth calculations, there is little guidance or requirement on how to calculate them. Analytical models are frequently used to simulate the welding process in order to predict the residual stress distribution in the weld and base material as an input to crack growth calculations. The crack growth calculations, in turn, have demonstrated a high sensitivity to the welding residual stress distribution inputs. While significant progress has been made in understanding and reducing the variability in calculated residual stress among modelers as well as the variability in measured residual stress among different techniques, there remains some uncertainty regarding any given measured or calculated distribution. A feasible alternative to calculating through-wall stress distributions with analytical models on a case-by-case basis is to develop a set of standardized through-wall stress distributions that are applicable to DM welds. Examples of standardized through-wall distributions for residual stress are found in numerous consensus code and standards. The benefit of established through-wall stress distributions is that evaluations for flaws in welds would start from a uniform basis on one of the key inputs to the crack growth calculation, reducing the time required to perform and review flaw evaluations. This paper presents and describes the technical basis for a set of through-wall distributions for common DM welds found in the US nuclear industry. The basis of the distributions include the results of analytical models, including uncertainty, as well as measured data for through-wall stress in DM welds.

Residual Stress Measurement on a Narrow Gap Dissimilar Metal Weld Pipe

2009 ◽  
Author(s):  
Xavier Ficquet ◽  
Laurie Chidwick ◽  
Philippe Gilles ◽  
Pierre Joly
Keyword(s):  
Residual Stress ◽  
Stainless Steel ◽  
Stress Distribution ◽  
Residual Stresses ◽  
Safety Assessment ◽  
Stress Measurement ◽  
Residual Stress Distribution ◽  
Narrow Gap ◽  
Mapping Procedure ◽  
Assessment Procedures

Prior knowledge of the magnitude and distribution of residual stresses in welded components is essential if a cost effective analyses of the integrity of the components is to be made. AREVA NP has recently developed, for EPR applications, narrow gap welding techniques, for joining ferritic low alloy steel heavy section components to austenitic, stainless steel piping systems, in nuclear reactors. An appraisal of available measurement methods was carried out and two residual stress measurement techniques were used to obtain through-thickness residual stress distributions in a fully circumferential narrow gap welded pipe, the neutron diffraction, which is not presented in this paper and the deep hole drilling (DHD) method. The DHD method was used to obtain the axial and hoop residual stresses along the weld centreline and on the heat affected zone in the ferritic and stainless steel sides up to depths of about 40mm from the outer surface of the pipe. The measured residual stress distribution in the weld centreline is compared with representative residual stress distribution provided in UK safety assessment procedures. It is found that the current safety assessment procedures BS 7910:2005 and R6 are conservative. The DHD measurements were made only at limited points in and adjacent to the circumferential weld. In order to estimate the complete residual stress distribution present in the pipe, a measurement mapping procedure using finite element (FE) analysis was implemented. Therefore this paper also provides the estimates of the full residual stress state present in the pipe based on the mapping procedure.

Residual Stress Evaluation of Dissimilar Weld Joint Using Reactor Vessel Outlet Nozzle Mock-Up Model (Report-1)

2008 ◽  
Author(s):  
Itaru Muroya ◽  
Youichi Iwamoto ◽  
Naoki Ogawa ◽  
Kiminobu Hojo ◽  
Kazuo Ogawa
Keyword(s):  
Residual Stress ◽  
Stress Distribution ◽  
Welding Process ◽  
Reactor Vessel ◽  
Residual Stress Distribution ◽  
Test Model ◽  
Alloy 600 ◽  
Outlet Nozzle ◽  
Stress Evaluation ◽  
Weld Region

In recent years, the occurrence of primary water stress corrosion cracking (PWSCC) in Alloy 600 weld regions of PWR plants has increased. In order to evaluate the crack propagation of PWSCC, it is required to estimate stress distribution including residual stress and operational stress through the wall thickness of the Alloy 600 weld region. In a national project in Japan for the purpose of establishing residual stress evaluation method, two test models were produced based on a reactor vessel outlet nozzle of Japanese PWR plants. One (Test model A) was produced using the same welding process applied in Japanese PWR plants in order to measure residual stress distribution of the Alloy 132 weld region. The other (Test model B) was produced using the same fabrication process in Japanese PWR plants in order to measure stress distribution change of the Alloy 132 weld region during fabrication process such as a hydrostatic test, welding a main coolant pipe to the stainless steel safe end. For Test model A, residual stress distribution was obtained using FE analysis, and was compared with the measured stress distribution. By comparing results, it was confirmed that the FE analysis result was in good agreement with the measurement result. For mock up test model B, the stress distribution of selected fabrication processes were measured using the Deep Hole Drilling (DHD) method. From these measurement results, it was found that the stress distribution in thickness direction at the center of the Alloy 132 weld line was changed largely during welding process of the safe end to the main coolant pipe.

Experimental Analysis of Repair Welding Alternatives for Shipbuilding DH36 Plates

2020 ◽  
Vol 64 (04) ◽  
pp. 384-391
Author(s):  
Tetyana Gurova ◽  
Segen F. Estefen ◽  
Anatoli Leontiev ◽  
Plinio T. Barbosa ◽  
Valentin Zhukov ◽  
...  
Keyword(s):  
Residual Stress ◽  
Stress Distribution ◽  
Best Practice ◽  
Welding Process ◽  
Offshore Structures ◽  
Residual Stress Distribution ◽  
Shipbuilding Industry ◽  
Repair Welding ◽  
Ship Construction ◽  
Repair Techniques

Repair by welding is widely used in the shipbuilding industry during ship construction. The effect of the residual stress distribution induced by the welding process on the ship structure is important for the repair effectiveness. This article presents an experimental study of the residual stress distribution induced by repair welding in the plates that are typically used in ships and offshore structures. Different repair techniques are evaluated to identify the best practice associated with residual stress values. Recommendations for repair welding are discussed, and modifications to the present practice are proposed.

Theoretical prediction of residual stresses induced by cold spray with experimental validation

2019 ◽  
Vol 15 (3) ◽  
pp. 599-616 ◽  
Author(s):  
Dibakor Boruah ◽  
Xiang Zhang ◽  
Matthew Doré
Keyword(s):  
Residual Stress ◽  
Stress Distribution ◽  
Residual Stresses ◽  
Cold Spray ◽  
Residual Stress Distribution ◽  
Thermal Mismatch ◽  
Individual Layer ◽  
Content Type ◽  
Layer Height ◽  
Proposed Model

PurposeThe purpose of this paper is to develop a simple analytical model for predicting the through-thickness distribution of residual stresses in a cold spray (CS) deposit-substrate assembly.Design/methodology/approachLayer-by-layer build-up of residual stresses induced by both the peening dominant and thermal mismatch dominant CS processes, taking into account the force and moment equilibrium requirements. The proposed model has been validated with the neutron diffraction measurements, taken from the published literature for different combinations of deposit-substrate assemblies comprising Cu, Mg, Ti, Al and Al alloys.FindingsThrough a parametric study, the influence of geometrical variables (number of layers, substrate height and individual layer height) on the through-thickness residual stress distribution and magnitude are elucidated. Both the number of deposited layers and substrate height affect residual stress magnitude, whereas the individual layer height has little effect. A good agreement has been achieved between the experimentally measured stress distributions and predictions by the proposed model.Originality/valueThe proposed model provides a more thorough explanation of residual stress development mechanisms by the CS process along with mathematical representation. Comparing to existing analytical and finite element methods, it provides a quicker estimation of the residual stress distribution and magnitude. This paper provides comparisons and contrast of the two different residual stress mechanisms: the peening dominant and the thermal mismatch dominant. The proposed model allows parametric studies of geometric variables, and can potentially contribute to CS process optimisation aiming at residual stress control.

A Further Study of Residual Stresses in Circumferential Welds

1973 ◽  
Vol 95 (4) ◽  
pp. 238-242 ◽  
Author(s):  
S. Vaidyanathan ◽  
H. Weiss ◽  
I. Finnie
Keyword(s):  
Residual Stress ◽  
Stress Distribution ◽  
Residual Stresses ◽  
Base Metal ◽  
Filler Metal ◽  
Residual Stress Distribution ◽  
Experimental Results ◽  
Circumferential Welds ◽  
Single Pass ◽  
Full Penetration

The residual stress distribution for a circumferential weld between cylinders was obtained in a prior publication for a full penetration, single pass weld with no variation of alloy content across the weld. In the present work the approach is extended to cover a wider variety of weld conditions. It is shown that the effects of multipass welds, partial penetration welds, and welds with filler metal differing greatly in properties from the base metal can approximately be taken into account. Experimental results are presented to support the proposed method of analysis.

scholarly journals Separation of the Formation Mechanisms of Residual Stresses in LPBF 316L

Metals ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1234
Author(s):  
Alexander Ulbricht ◽  
Simon J. Altenburg ◽  
Maximilian Sprengel ◽  
Konstantin Sommer ◽  
Gunther Mohr ◽  
...  
Keyword(s):  
Residual Stress ◽  
Stress Distribution ◽  
Residual Stresses ◽  
Residual Stress Distribution ◽  
Formation Mechanisms ◽  
Micro Computed Tomography ◽  
Solidification Shrinkage ◽  
Stainless Steel 316L ◽  
Heat Accumulation ◽  
Cooling Rates

Rapid cooling rates and steep temperature gradients are characteristic of additively manufactured parts and important factors for the residual stress formation. This study examined the influence of heat accumulation on the distribution of residual stress in two prisms produced by Laser Powder Bed Fusion (LPBF) of austenitic stainless steel 316L. The layers of the prisms were exposed using two different border fill scan strategies: one scanned from the centre to the perimeter and the other from the perimeter to the centre. The goal was to reveal the effect of different heat inputs on samples featuring the same solidification shrinkage. Residual stress was characterised in one plane perpendicular to the building direction at the mid height using Neutron and Lab X-ray diffraction. Thermography data obtained during the build process were analysed in order to correlate the cooling rates and apparent surface temperatures with the residual stress results. Optical microscopy and micro computed tomography were used to correlate defect populations with the residual stress distribution. The two scanning strategies led to residual stress distributions that were typical for additively manufactured components: compressive stresses in the bulk and tensile stresses at the surface. However, due to the different heat accumulation, the maximum residual stress levels differed. We concluded that solidification shrinkage plays a major role in determining the shape of the residual stress distribution, while the temperature gradient mechanism appears to determine the magnitude of peak residual stresses.

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