A Quantitative Index to Assess the Influence of Joint Fit-Up on Pipeline Weld Root Discontinuities

2021 ◽  
Author(s):  
Mitchell Grams ◽  
Luke Ludwig ◽  
Patricio Mendez
Keyword(s):  
Quantitative Index ◽  
Weld Root

A Quantitative Index to Assess the Influence of Joint Fit-Up on Pipeline Weld Root Discontinuities

2020 ◽  
Author(s):  
M. R. Grams ◽  
L. Ludwig ◽  
P. F. Mendez
Keyword(s):  
Pipe Wall ◽  
Latent Root ◽  
Angular Distortion ◽  
Quantitative Index ◽  
Objective Criterion ◽  
Joint Geometry ◽  
Weld Root ◽  
Low Offset ◽  
Welding Procedure ◽  
Numerical Index

Abstract Field experience on pipelines suggests that under the unique conditions of tie-in welding, a high-low offset at the inner pipe wall is related to an increased occurrence of latent root weld discontinuities such as cold cracking. Codes and standards offer conflicting and unclear guidelines regarding acceptance criteria for high-low offset. This study presents a numerical index to quantify the influence of non-ideal joint geometry on the latent discontinuity susceptibility of the root pass for circumferential pipeline welds. The index is based on the stress concentration at the root and the angular distortion associated with plastic strains produced during welding. This index relates geometric considerations such as pipe diameter, wall thickness, and the cross section of the root pass with welding procedure variables and the mechanical properties of the pipeline material. Although this study is meant for steel pipelines, the conclusions obtained are also applicable to other materials. The index presented is a contribution towards an objective criterion for acceptance of high-low offset during field welding, ranking the susceptibility to latent discontinuities as a function of variables available to practitioners during field welding.

scholarly journals Effect of Micro Solidification Crack on Mechanical Performance of Remote Laser Welded AA6063 Fillet Lap Joint in Automotive Battery Tray Construction

2021 ◽  
Vol 11 (10) ◽  
pp. 4522
Author(s):  
Tianzhu Sun ◽  
Pasquale Franciosa ◽  
Conghui Liu ◽  
Fabio Pierro ◽  
Darek Ceglarek
Keyword(s):  
Laser Welding ◽  
Fusion Zone ◽  
Aluminium Alloys ◽  
Mechanical Performance ◽  
Lap Joints ◽  
Fatigue Durability ◽  
Micro Cracks ◽  
Remote Laser Welding ◽  
Weld Fatigue ◽  
Weld Root

Remote laser welding (RLW) has shown a number of benefits of joining 6xxx aluminium alloys such as high processing speed and process flexibility. However, the crack susceptibility of 6xxx aluminium alloys during RLW process is still an open problem. This paper experimentally assesses the impact of transverse micro cracks on joint strength and fatigue durability in remote laser welding of AA6063-T6 fillet lap joints. Distribution and morphology of transverse micro cracks were acquired by scanning electron microscope (SEM) on cross-sections. Grain morphology in the weld zone was determined by electron backscatter diffraction (EBSD) while static tensile and dynamic fatigue tests were carried out to evaluate weld mechanical performance. Results revealed that increasing welding speed from 2 m/min to 6 m/min did not introduce additional transverse micro cracks. Additionally, welding at 2 m/min resulted in tensile strength improvement by 30% compared to 6 m/min due to the expansion of fusion zone, measured by the throat thickness, and refinement of columnar grains near fusion lines. Furthermore, the weld fatigue durability is significantly higher when fracture occurs in weld root instead of fusion zone. This can be achieved by increasing weld root angle with optimum weld fatigue durability at around 55°.

Re-evaluation of weld root fatigue strength for load-carrying fillet welded joints using the notch stress concept

2021 ◽  
Vol 144 ◽  
pp. 106076
Author(s):  
Hamidreza Rohani Raftar ◽  
Mohammad Dabiri ◽  
Antti Ahola ◽  
Timo Björk
Keyword(s):  
Fatigue Strength ◽  
Welded Joints ◽  
Notch Stress ◽  
Load Carrying ◽  
Weld Root

Plumpness Analysis of Indicator Diagram for Vehicle Damper

2013 ◽  
Vol 415 ◽  
pp. 582-585
Author(s):  
Xing Xu ◽  
Zhen Cui ◽  
Jin Chao Zhang
Keyword(s):  
Frequency Domain ◽  
Time Domain ◽  
Dynamic Load ◽  
Performance Indicators ◽  
Load Distribution ◽  
The Body ◽  
Quantitative Index ◽  
Indicator Diagram ◽  
Vehicle Demand ◽  
Mathematical Relationships

According to the indicator diagram of damper, the indicator diagram plumpness was proposed as a quantitative index, and its mathematical relationships with the sprung mass acceleration, suspension dynamic travel and tire dynamic load were built. Moreover, the influence of the total area on suspension characteristics was analyzed in time domain and frequency domain. The results show that, the increase of the indicator diagram plumpness can effectively restrain the variation of suspension dynamic travel and tire dynamic load, meanwhile, the body acceleration will be enlarged. Excessive indicator diagram plumpness also affects the dynamic tire load distribution in frequency domain, and it will decrease the driving security. Therefore, it should be reasonably selected from the performance indicators, which is based on the requirement of vehicle demand in the design process.

Establishing a quantitative index of meropenem hydrolysis for the detection of KPC- and NDM-producing bacteria by MALDI-TOF MS

2021 ◽  
pp. 106268
Author(s):  
Camila Mörschbächer Wilhelm ◽  
Giovanna de Ross Forni ◽  
Maiara dos Santos Carneiro ◽  
Afonso Luís Barth
Keyword(s):  
Quantitative Index ◽  
Maldi Tof Ms ◽  
Maldi Tof ◽  
Tof Ms

Sustainable Attraction of Ecological Countryside Resort

2013 ◽  
Vol 361-363 ◽  
pp. 15-20
Author(s):  
Shu Hai Zhang
Keyword(s):  
Index System ◽  
Evaluation Method ◽  
Comprehensive Evaluation ◽  
Service Marketing ◽  
Fuzzy Comprehensive Evaluation ◽  
Quantitative Index ◽  
Fuzzy Comprehensive Evaluation Method ◽  
Comprehensive Evaluation Method ◽  
Qualitative And Quantitative

Based on the analysis of nine factors, which influencing mostly the sustainable attraction of Ecological Countryside Resort, this paper builds an index system for evaluating the attraction of Ecological Countryside Resort. Considering the attribute of the evaluation of sustainable attraction of ecological countryside resort, which is multi-gradation, multi-factor, and qualitative-and-quantitative-index-concentrating, this paper develops a multilevel fuzzy comprehensive evaluation method for assessing sustainable attraction of Ecological Countryside Resort. Thus, this paper provides a basis for improving the sustainable attraction of Ecological Countryside Resort, prolonging the life of Ecological Countryside Resort, optimizing the development and service marketing of Ecological Countryside Resort.

Microstructure Development in Copper Welded by the FSW-Process

2003 ◽  
Vol 807 ◽  
Author(s):  
Therese Källgren ◽  
Rolf Sandström
Keyword(s):  
Welding Process ◽  
Mechanical Deformation ◽  
Microstructure Development ◽  
Friction Stir ◽  
Friction Heat ◽  
The Third ◽  
Lower Temperature ◽  
Weld Root ◽  
Nuclear Fuel Waste ◽  
Joining Process

ABSTRACTTo ensure safe storage of nuclear fuel waste, copper canisters are proposed as corrosion barrier. One alternative for sealing the copper canisters is Friction Stir Welding (FSW). During the joining process friction heat and mechanical deformation appear between the rotating tool and the material being welded. Liquid metal will not form, since this is a solid state welding process. Three distinct microstructural zones are developed namely the nugget, the thermo-mechanically affected zone (TMAZ) and heat-affected zone (HAZ). The nugget is in the centre of the weld, where the pin is located and where severe plastic deformation occurs that leads to recrystallisation. Surrounding the nugget, the TMAZ is only partially recrystallised, due to lower temperature increase and deformation compared to the nugget. The third zone, HAZ, surrounds the TMAZ. The initial nugget can have a classic round aluminium nugget image, when the welding conditions are cold, but the steady state nugget, is wider near the shoulder and shorter in the weld root.

Full Scale Fatigue Experiment on Submarine Pipelines

2014 ◽  
Vol 633-634 ◽  
pp. 659-664 ◽  
Author(s):  
Zong Tao Fang ◽  
De Yu Tang ◽  
Yan Hua Hu ◽  
Hu Li Niu
Keyword(s):  
Welded Joints ◽  
Fatigue Property ◽  
Full Scale ◽  
Small Scale ◽  
Test Machine ◽  
Butt Joints ◽  
Weld Toe ◽  
Small Test ◽  
Weld Root ◽  
Fatigue Experiment

This paper focus on fatigue problem of submarine pipelines, four points bending full scale fatigue experiment were conducted on X65 pipelines butt joints specimens, utilizing pipeline full scale fatigue test machine developed by CNPC. Meanwhile contrast test was also carried out on small specimens. The results show that the fatigue strength of full scale welded joints is lower than the small scale joints. Owing to having no regard for the influence of residual stress and size effect, the small test would provide dangerous results. The fatigue property of full scale welded joints only meets the requirement of DNV C203 W3 curve, and meets the needs of DNV C203 F3 curve basically while not meet BS 7608 F2 curve’s requirements which relatively demand higher. Weld toe and geometric discontinuous near weld root is the weak point for the whole welded joints.

Study of features in weld root formation under double-sided synchronized arc welding of vertical joints of steel tanks

2021 ◽  
pp. 153-160
Author(s):  
O.I. Filippov ◽  
V.A. Erofeev ◽  
M.A. Sholokhov ◽  
S.I. Poloskov
Keyword(s):  
Deep Penetration ◽  
Computer Engineering ◽  
Cross Sectional ◽  
Steel Tanks ◽  
Face Dimension ◽  
Weld Root ◽  
Root Face ◽  
Welding Productivity ◽  
Vertical Up ◽  
Oil And Oil Products

It is shown that increase in the welding productivity of vertical joints of storage tanks for oil and oil products can be achieved due to the double-sided synchronized formation of the X-shaped groove. To minimize various disturbances, including variation of gap size and root face dimension, computer engineering analysis is performed, which showed that the formation of root pass during welding with the movement of the electrode down (vertical down) with increased dimension of the root face leads to lack of penetration, but during groove filling with the movement of the electrodes up (vertical up) deep penetration is achieved given the considerable root face dimension. It is defined that during welding of 30 mm thickness plates with root face dimension range from 6 to 8 mm, it is necessary to ensure the root gap dimension range from 1.5 to 3 mm along the entire length of the seam. In this case, the remaining unfilled cross-sectional area of the groove is small, which makes it possible to fill it in during single pass under two-arc double-sided welding. There is area of double-sided synchronized welding modes in which the occurrence probability of typical defects during the formation of the weld root is minimal.

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