Development of a Welding Sequence Optimized for the Fatigue Resistance of Tubular Joints With a Novel Representative Welded Sample

2018 ◽  
Author(s):  
Philippe Thibaux ◽  
Eric Van Pottelberg
Keyword(s):  
Fatigue Resistance ◽  
Fatigue Testing ◽  
Welding Process ◽  
Offshore Structures ◽  
Fatigue Tests ◽  
Complex Geometries ◽  
Tubular Joints ◽  
Welding Sequence ◽  
Welding Procedure ◽  
Welding Position

Tubular joints are complex geometries present in many offshore structures. Fatigue testing of tubular joints requires either downsizing of the dimensions of the joints or the use of a simplified geometry, to avoid prohibitive costs. For the development of a welding process optimized for the fatigue performance of tubular joints, one needs to use a representative sample: same material, same thickness, use of similar welding positions, same level of restraint as in a real structure, combined with the supplementary requirement of ease of manufacturing and testing. A novel geometry was developed to fulfil all these requirements. Then, different welds were produced using robot and manual welding in different positions. The fatigue tests proved to be very reproducible, and indicate a strong influence of the welding position on the fatigue resistance. For that reason, an optimized welding procedure and sequence was developed, in which the welds in the most fatigue sensitive locations are produced first in optimum condition, while the less sensitive parts are produced by subsequent welding in position.

Welding Procedure Establishment for Tubular Joints Welded by Single Station, Solid State Welding Machine

2010 ◽  
Author(s):  
Ganesan S. Marimuthu ◽  
Per Thomas Moe ◽  
Bjarne Salberg ◽  
Junyan Liu ◽  
Henry Valberg ◽  
...  
Keyword(s):  
Solid State ◽  
Oil And Gas ◽  
Welding Process ◽  
High Strength ◽  
Pipe Material ◽  
Tubular Joints ◽  
Welding Machine ◽  
Single Station ◽  
Welding Procedure ◽  
Treatment Procedures

Forge welding is an efficient welding method for tubular joints applicable in oil and gas industries due to its simplicity in carrying out the welding, absence of molten metal and filler metals, small heat-affected zone and high process flexibility. Prior to forging, the ends (bevels) of the joining tubes can be heated by torch or electromagnetic (EM) techniques, such as induction or high frequency resistance heating. The hot bevels are subsequently pressed together to establish the weld. The entire welding process can be completed within seconds and consistently produces superior quality joints of very high strength and adequate ductility. Industrial forge welding of tubes in the field is relatively expensive compared to laboratory testing. Moreover, at the initial stages of a new project sufficient quantities of pipe material may not be available for weldability testing. For these and several other reasons we have developed a highly efficient single station, solid state welding machine that carefully replicates the thermomechanical conditions of full-scale Shielded Active Gas Forge Welding Machines (SAG-FWM) for pipeline and casing applications. This representative laboratory machine can be used to weld tubular goods, perform material characterization and/or simulate welding and heat treatment procedures. The bevel shapes at mating ends of the tubes are optimized by ABAQUS® simulations to fine tune temperature distribution. The main aim of this paper is to establish a welding procedure for welding the tubular joints by the representative laboratory machine. The quality of the welded tubular joint was analyzed by macro/micro analyses, as well as hardness and bend tests. The challenges in optimizing the bevel shape and process parameters to weld high quality tubular joints are thoroughly discussed. Finally a welding procedure specification was established to weld the tubular joints in the representative laboratory machine.

Time Series Simulations of Wide-Band Spectra for Fatigue Tests of Offshore Structures

1984 ◽  
Vol 106 (4) ◽  
pp. 466-470 ◽  
Author(s):  
N. K. Lin ◽  
W. H. Hartt
Keyword(s):  
Time Series ◽  
Fatigue Testing ◽  
Wide Band ◽  
Simulation Method ◽  
Offshore Structures ◽  
Fatigue Tests ◽  
Time Series Model ◽  
Long Time ◽  
Band Spectra ◽  
Time Series Simulation

A time-series simulation method, based on the principle of time series modeling for dynamic systems, is used to reproduce a wide-band stress history from a prescribed stress spectral model for fatigue testing of offshore structures. The optimization procedures and stability of the time series model for the prescribed spectrum are presented and discussed. The optimization procedures are developed on the basis of the Levison-Durbin algorithm, which usually produces a stable time series model if the order of the time series model is even. An example is presented to demonstrate the applicability of the proposed method to long-time, high-cycle fatigue testing.

Corrosion Fatigue Tests on Welded Tubular Joints

1985 ◽  
Vol 107 (1) ◽  
pp. 68-73
Author(s):  
T. Iwasaki ◽  
J. G. Wylde
Keyword(s):  
Corrosion Fatigue ◽  
Welded Joints ◽  
Sea Water ◽  
Water Environment ◽  
Offshore Structures ◽  
Fatigue Tests ◽  
Tubular Joints ◽  
Fatigue Design ◽  
Out Of Plane ◽  
The Cost

The corrosion fatigue performance of welded tubular joints is recognized as one of the most important factors in the design of offshore structures. Because of the cost of such tests it has been practice to carry out tests on tubular joints in air and to perform corrosion fatigue tests on simple welded joints. Thus very few corrosion fatigue tests have been carried out on tubular joints. The present paper describes the results of fatigue tests which have been carried out on welded tubular joints both in air and in a sea water environment. The specimens were tubular K and KT-joints with chord dimensions of 168 mm diameter and 6 mm wall thickness. The tests were carried out under out-of-plane bending. The corrosion fatigue tests were carried in sea water at 10° C at a frequency of 10 cycles per min, which is typical of wave periods. The specimens were not cathodically protected. The fatigue results in air and sea water are compared, and discussed in connection with the current fatigue design S-N curves for tubular joints contained in various standards.

Effect of welding on the fatigue strength of welded joints using the GMAW process in transformation induced plasticity steels (TRIP) used in the automotive industry

2012 ◽  
Vol 1381 ◽  
Author(s):  
Victor Lopez ◽  
Arturo Reyes ◽  
Patricia Zambrano ◽  
Joaquín Del Prado
Keyword(s):  
Automotive Industry ◽  
Trip Steel ◽  
Fatigue Testing ◽  
Gas Metal Arc Welding ◽  
Welding Process ◽  
Fatigue Tests ◽  
Lap Joints ◽  
Welding Parameters ◽  
Trip Steels ◽  
Metal Arc Welding

ABSTRACTWelding of TRIP steels are one of the technical challenges in the successful application of AHSS in chassis structures. Gas Metal Arc Welding (GMAW) is a common welding process used in the automotive industry, for joining mild steels. TRIP steel; however, do not offer the same ease of welding, and process control welding parameters is more critical. The welding parameters window represents the range of acceptable process parameters, primarily control of heat inputs, to obtain an acceptable weld. As a result, the effects of the heat input variations are greater and TRIP steel has a narrower welding parameters window in which acceptable welds can be made. Mechanical properties of the lap joints of TRIP 780 steel 2.8 mm thickness was analyzed, fusion welds were evaluated using fatigue tests on these joints for different heat inputs. Fatigue testing was conducted under a different number of nominal stress ranges to obtain the S/N curves of the weld joints.

Research on the fatigue resistance of weld ends

2020 ◽  
Vol 62 (5) ◽  
pp. 465-470
Author(s):  
Alexandra Oßwald ◽  
Martin Werz ◽  
Stefan Weihe
Keyword(s):  
Fatigue Resistance ◽  
Tensile Tests ◽  
Fatigue Tests ◽  
Materials Testing ◽  
National Guidelines ◽  
Strength Assessment ◽  
Notch Stress ◽  
Assessment Approach ◽  
Welding Procedure ◽  
Economic Motives

Abstract Modern welded structures often contain weld ends due to increasing component complexity and economic motives. Under cyclic loading, crack initiation mainly occurs at those weld ends which makes them the failure critical location. So far, no detailed approach for the assessment of the fatigue life of weld ends has been added to known international or national guidelines. A new specimen type was developed at the Materials Testing Institute University of Stuttgart with which the fatigue resistance of weld ends of different welding procedures can be evaluated and compared. Tensile tests and fatigue tests on those new specimens show that the loading capacity is dependent on the welding procedure and the weld end point considered, i. e. weld start or weld end. In a sketched assessment approach, those results can be transferred to components in order to carry out a fatigue strength assessment or to enable the selection of a welding procedure. The assessment with the notch stress concept is preferred for the further development of the assessment approach.

Effect of Reeling on Welded Umbilical Tubing Fatigue

2006 ◽  
Author(s):  
Jaime Buitrago ◽  
Krasimir Doynov ◽  
Allen Fox
Keyword(s):  
Plastic Strain ◽  
Fatigue Testing ◽  
Fatigue Tests ◽  
Fatigue Performance ◽  
Experimental Program ◽  
Design Curve ◽  
Duplex Steel ◽  
Steel Tubing ◽  
Pressurized Fluids ◽  
Welding Procedure

One key component of umbilicals is the steel tubing carrying the pressurized fluids. During manufacturing and deployment of the umbilical, the tubing is subjected to a series of reeling and unreeling operations, resulting in a cumulative amount of plastic strain. For conventional design, this plastic strain is thought to limit the fatigue performance of the tubing, thereby limiting the number of such operations. This paper discusses an experimental program aimed at assessing the effect of the cumulative reeling strain on the fatigue life of girth-welded, super duplex steel tubing. In particular, the reeling simulation and fatigue testing equipment used are described and the experimental procedures are presented. Interpretation of fatigue tests indicate that (1) reeling degrades the fatigue performance of the welded tubing, (2) 75% of the B design curve may represent the 97.5% survival bound for tubing reeled up to 12% cumulative reeling strain, and (3) the fraction of the B design curve reduces to 40% for the same bound when the data from the 20% reeling strain tests are included. However, given the uncertainties involved, project-specific applications will require a fatigue qualification program for the specific tubing size, reeling history, and welding procedure at hand.

Effect of welding residual stresses on local behavior of rectangular hollow section joints/Einfluss der Schweißeigenspannungen auf die Tragfähigkeit von Rechteck-Hohlprofil-KnotenTeil 2: Parameterstudien

Bauingenieur ◽  
2018 ◽  
Vol 93 (05) ◽  
pp. 207-213
Author(s):  
M. Garifullin ◽  
B. Launert ◽  
M. Heinisuo ◽  
H. Pasternak ◽  
K. Mela ◽  
...  
Keyword(s):  
Residual Stresses ◽  
Welding Process ◽  
Element Model ◽  
Positive Influence ◽  
Structural Behavior ◽  
Initial Stiffness ◽  
Hollow Section ◽  
Tubular Joints ◽  
Welding Sequence ◽  
Parametric Analyses

Welding residual stresses that occur in tubular joints after the welding process affect their structural behavior. To ensure that these stresses do not negatively act on the load-bearing capacity of joints, their influence should be carefully investigated. This paper represents the second part of a study that numerically evaluates the structural behavior of rectangular hollow section T joints taking into account welding residual stresses. The finite element model developed in Part 1 is now used to evaluate their effect on the resistance and initial stiffness of tubular joints. The conducted parametric analyses show that welding residual stresses have a positive influence of 1–19 % on the plastic resistance of tubular joints and insignificantly reduce their initial stiffness. At the same time, the behavior of the considered joints is found not to depend on the welding sequence.

Fatigue Life of Cathodically Protected Tubular Joints of Offshore Structures

1998 ◽  
Vol 120 (4) ◽  
pp. 232-236
Author(s):  
D. S. Ramachandra Murthy ◽  
P. Gandhi ◽  
G. Raghava
Keyword(s):  
Fatigue Life ◽  
Stress Concentration ◽  
Cathodic Protection ◽  
Fatigue Cracking ◽  
Offshore Structures ◽  
Fatigue Tests ◽  
Corrosive Environment ◽  
Sacrificial Anodes ◽  
Tubular Joints ◽  
Steel Jacket

Steel jacket platforms are widely used for production and processing of oil from offshore fields. Tubular joints of these structures are susceptible to fatigue or corrosion fatigue cracking due to cyclic wave action, stress concentration, and corrosive environment. The submerged part of the structure is cathodically protected against corrosion by fixing sacrificial anodes at various places. The effect of cathodic protection on the fatigue life of tubular joints was studied by conducting fatigue tests on 13 T and Y-joints in air, under free corrosion, and with cathodic protection. The results of the studies are discussed in this paper.

scholarly journals Fatigue Testing of Wearable Sensing Technologies: Issues and Opportunities

Materials ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4070
Author(s):  
Andrea Karen Persons ◽  
John E. Ball ◽  
Charles Freeman ◽  
David M. Macias ◽  
Chartrisa LaShan Simpson ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Prediction Models ◽  
Fatigue Testing ◽  
Low Cycle Fatigue ◽  
Wearable Sensors ◽  
Fatigue Tests ◽  
Proof Of Concept ◽  
Cycle Fatigue ◽  
Wearable Sensing ◽  
Failure Data

Standards for the fatigue testing of wearable sensing technologies are lacking. The majority of published fatigue tests for wearable sensors are performed on proof-of-concept stretch sensors fabricated from a variety of materials. Due to their flexibility and stretchability, polymers are often used in the fabrication of wearable sensors. Other materials, including textiles, carbon nanotubes, graphene, and conductive metals or inks, may be used in conjunction with polymers to fabricate wearable sensors. Depending on the combination of the materials used, the fatigue behaviors of wearable sensors can vary. Additionally, fatigue testing methodologies for the sensors also vary, with most tests focusing only on the low-cycle fatigue (LCF) regime, and few sensors are cycled until failure or runout are achieved. Fatigue life predictions of wearable sensors are also lacking. These issues make direct comparisons of wearable sensors difficult. To facilitate direct comparisons of wearable sensors and to move proof-of-concept sensors from “bench to bedside,” fatigue testing standards should be established. Further, both high-cycle fatigue (HCF) and failure data are needed to determine the appropriateness in the use, modification, development, and validation of fatigue life prediction models and to further the understanding of how cracks initiate and propagate in wearable sensing technologies.

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