Optimising residual stresses at a repair in a steam header to tubeplate weld

Soanes, T. P. T.; Bell, W; Vibert, A.J.

doi:10.1016/j.ijpvp.2004.08.009

Cited by 21 publications

(7 citation statements)

References 2 publications

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“…7 The two-dimensional axisymmetric FEM model is much faster and easier to perform. 8,9 Therefore, the methodology described here is based on a two-dimensional axisymmetric model.…”

Section: Fem Meshed Modelmentioning

confidence: 99%

Numerical and experimental investigation of the effect of hydrostatic pressure on the residual stress in boiler-tube welds

Danyali¹,

Ranjbarnodeh²

2016

Mater. Tehnol.

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A tube to tube-sheet weld joint is a critical section in many boilers. Leakage and failure are two common problems that can occur with this type of joint. The tensile residual stresses associated with welding can play a major role in these problems. In the present study, the Finite-Element Method is used to predict the residual stresses in a tube to tube-sheet weld and the effect of hydrostatic pressure on the residual stresses' redistribution. Investigations were performed by numerical analyses and experimental methods. The joint included a circumferential fillet weld in one pass using a gas tungsten arc welding process. The thermomechanical behavior of the joint is simulated with a two-dimensional axisymmetric model and a subroutine developed in ANSYS software. The thermography method is used for the thermal verification and the hole-drilling strain gauge under post-weld heat treatment is used for the mechanical analysis verification. The numerical and experimental results showed that applied hydrostatic pressure can reduce, by about 58 %, the axial residual stress. Keywords: hydrostatic test, residual stress, boiler tubes, tube-sheet, finite element method (FEM) Kriti~ni podro~ji v kotlih sta zvarjen spoj cevi in cevne predelne stene. V tej vrsti spoja sta glavna problema, ki se pojavljata, pu{~anje in poru{itev. Zaostale natezne napetosti povezane z varjenjem so glavni dejavnik pri teh problemih. V {tudiji je bila uporabljena metoda kon~nih elementov za napovedovanje zaostalih napetosti v zvarih cevi in cevne predelne stene in vpliv hidrostati~nega tlaka na razporeditev zaostale napetosti. Raziskave so bile izvedene z numeri~no analizo in z eksperimentalnimi metodami. Spoj je vklju~eval obodni zvar izdelan v obloku z volframovo elektrodo in za{~ito s plinom. Termomehansko obna{anje spoja je bilo simulirano z uporabo dvodimenzijskega osnosimetri~nega modela in programa razvitega z ANSYS programsko opremo. Termografska metoda je uporabljena za preverjanje toplote in pri toplotni obdelavi zvarov je bila uporabljena metoda z merilnimi listi~i na izvrtini za preverjanje mehanske analize. Numeri~ni in eksperimentalni rezultati so pokazali, da uporabljen hidrostati~ni tlak, lahko za 58 % zmanj{a osne zaostale napetosti. Klju~ne besede: hidrostati~ni preizkus, zaostala napetost, kotlovske cevi, cevna predelna stena, metoda kon~nih elementov (FEM)

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“…7 The two-dimensional axisymmetric FEM model is much faster and easier to perform. 8,9 Therefore, the methodology described here is based on a two-dimensional axisymmetric model.…”

Section: Fem Meshed Modelmentioning

confidence: 99%

Numerical and experimental investigation of the effect of hydrostatic pressure on the residual stress in boiler-tube welds

Danyali¹,

Ranjbarnodeh²

2016

Mater. Tehnol.

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“…In order to assess the reheat cracking risk or to help designing safe post-weld heat treatments of 316H stainless steel, several authors [49,50] estimated residual stresses by thermal-mechanical finite element calculations and used Spindler's multi-axial damage model [13,14] to quantify intergranular crack development during stress relaxation. This method has proved its efficiency (see [16,17] for example).…”

Section: Reheat Cracking Risk Assessmentmentioning

confidence: 99%

Effect of pre-strain on creep of three AISI 316 austenitic stainless steels in relation to reheat cracking of weld-affected zones

Auzoux

Allais

Caës

et al. 2010

Journal of Nuclear Materials

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“…The investigations on the weldability and the crack-resistant ability [ 2 , 3 , 4 , 5 ] of X80 require further exploration. When compared to the initial welds, the repair welds were usually subjected to the multiaxial stress state, severe restraints in both hoop and axial directions, worse welding preparation, and welding environment [ 6 , 7 ]. Hence, the in-service repair welding of the X80 pipeline presents more challenges than the welding during the layout stage.…”

Section: Introductionmentioning

confidence: 99%

“…However, many failure cases were related to the high-level residual stresses [ 12 , 13 , 14 ]. The in-service welding is usually subjected to the multiaxial stress state, i.e., pipe pressure and additional stress, and severe restraints in both hoop and axial direction [ 6 , 7 ]. Moreover, accurate residual stress prediction has become challenging.…”

Section: Introductionmentioning

confidence: 99%

Effects of Fillet Weld Size and Sleeve Material Strength on the Residual Stress Distribution and Structural Safety While Implementing the New Sleeve Repair Process

et al. 2021

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The process optimization and structural safety improvement of the in-service repair welding of the X80 pipeline are very important. In this paper, the temperature, microstructure, and stress distribution were analyzed using the combination of TMM (thermal-metallurgical-mechanical) simulations and the corresponding verification experiments. The effects of the sleeve material strength and the fillet weld size were discussed. The results showed that the fillet weld zone was mainly composed of ferrite and bainite when the material of the sleeve pipe was Q345B. Furthermore, the sleeve pipe’s HAZ (heat affected zone) was dominated by lath martensite, lath bainite, and granular bainite. Moreover, granular bainite and a small amount of ferrite were found in the HAZ of the X80 pipe. It was found that, as the fillet weld size increased, the welding residual stress distribution became more uniform. The hoop stress at weld toe reduced from ~860 MPa of case A to ~680 MPa of case E, and the axial stress at weld toe reduced from ~440 MPa of case A to ~380 MPa of case E. From the viewpoint of welding residual stress, fillet weld size was suggested to be larger than 1.4T. The stress concentration and the stress distribution showed a correlation with the cracking behavior. Weld re-solidification ripples on the weld surface and weld ripples between welding passes or near the weld toe could cause stress concentration and the corresponding crack initiation. Furthermore, when the material of the sleeve pipe changed from Q345B to X80, the high-level tensile stress zone was found to be enlarged. The hoop stress at weld toe increased from ~750 to ~800 MPa, and the axial stress at weld toe increased from ~500 to ~600 MPa. After implementing the new sleeve repair welding process where X80 replaces the material of sleeve pipe, the cracking risk in sleeve pipe will improve. From the perspective of the welding residual stress, it was concluded that the fillet weld size reduction and the sleeve material strength improvement are harmful to in-service welded structures’ safety and integrity.

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Optimising residual stresses at a repair in a steam header to tubeplate weld

Cited by 21 publications

References 2 publications

Numerical and experimental investigation of the effect of hydrostatic pressure on the residual stress in boiler-tube welds

Numerical and experimental investigation of the effect of hydrostatic pressure on the residual stress in boiler-tube welds

Effect of pre-strain on creep of three AISI 316 austenitic stainless steels in relation to reheat cracking of weld-affected zones

Effects of Fillet Weld Size and Sleeve Material Strength on the Residual Stress Distribution and Structural Safety While Implementing the New Sleeve Repair Process

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