Weld residual stresses can be a major concern in structural integrity assessments such as a nuclear power plant. In this paper, detailed weld residual stress analyses were presented for a typical multi-pass weld of pipe-butt weld and plate T-butt weld. The calculated residual stress distributions were compared with those of the measured data and recommended profiles in R6 and BS7910. Defect assessment which is based on the stress intensity factor(SIF) calculations was carried out for a plate T-butt weld with cracks considering the weld residual stress distributions.

The purpose of this study is to evaluate the behavior of residual stress at the weldment of pressure vessel by local Post Weld Heat Treatment(PWHT). In order to do it, residual stress were measured before and after local PWHT by XRD on the test piece first. And then, the results of finite element(FE) analysis based on thermal-elasto-plastic-creep theories were verified by comparing with the measured results.

The purpose of this study is to optimize the plate thickness of the main frame of a construction equipment. For this, the load history at the joints of the main frame was evaluated using mechanism and finite element analysis. With the load data, the stress and the stiffness at the main frame was evaluated and the fatigue life at each weld joint of the main frame was assessed with the change of the plate thickness. Based on the results of this study, the proper plate thicknesses of the frame of the construction equipment were proposed.

When materials such as metal are into the secondary side of steam generator, they, so called foreign objects, may have influences on the integrity of the steam generator tubes. They cause the tube wear due to the relative motion between the tubes and foreign objects and the tube impact due to flow. The best way to avoid the effects is to remove all the foreign objects. However, it is not easy to remove the foreign materials thoroughly due to their condition such as the location. Considering the wear and impact by the foreign materials, KEPRI(Korea Electric Power Research Institute) developed the methodology to evaluate the foreign materials analytically. This methodology was described with a computer program in order to obtain the fast results. The program informs whether the tubes have the structural integrity when the foreign material strikes the tubes. Moreover, this gives us the remaining life of the steam generator tubes. In this paper, the program, which evaluates the effects of the foreign objects in the secondary side of steam generator, is introduced.

Stainless steel sheets are widely used as the structural material for the railroad cars and the commercial vehicles. These kinds structures used stainless steel sheets are commonly fabricated by using the gas welding. For fatigue design of gas welded joints such as fillet and plug type joint, it is necessary to obtain design information on stress distribution at the weldment as well as fatigue strength of gas welded joints. And also, the influence of the geometrical parameters of gas welded joints on stress distribution and fatigue strength must be evaluated. the ${\Delta}P-N_f$ curves were obtained by fatigue tests. Using these results, ${\Delta}P-N_f$ curves were rearranged in the ${\sigma}-N_f$ relation with the maximum stress at the edge of fillet welded joint.

Nuclear power plants are urged to reduce operating and maintaining costs to remain competitive as well as to increase the safety preventing the radioactive material to the atmosphere. To reduce the cost and to increase the safety, the inspection of balance-of-plant heat exchanger becomes important. However, there are some problems for plugging the heat exchanger tubes since the criterion and its basis are not clearly described. The codes and standards related to show the tube plugging criteria may not exist currently. In this paper, a method to establish the tube plugging criteria of BOP heat exchangers is introduced and the tube plugging criteria for the non-regenerative heat exchanger in the steam generator blow-down system of nuclear power plant. This method relies on the similar method used to establish the plugging criteria for the steam generator tubes.

Lightweight design, safety, vibration, energy absorption capability can no longer achieve without adhesive bond joint. Base on those concepts and cost reduction, adhesive bond FEM model development has been done. The FEM analysis and experiments were conducted in this study. Crash condition is 143 Kg Hammer weight and unit meter Height. and then These test results were used to develop resonable FEM model. To estimate which FEM model is resonable, compare hybrid joint specimen experiment results with FEM analysis results. Conclusively this study achieves optimization bonding model related crash and adhesive bond jointed hat profile crash characters.

Recently many research are going on in the field of application of Laser-Arc hybrid welding for superstructures such as ship-structures, transport vehicles etc. however, the study on heat distribution and welding residual stress of hybrid weld by numerical simulation leaves much to be desired. Therefore a Finite Element based numerical comparison of heat distribution and thermal history in both the FCAW and Hybrid welding been made in this study. Based on this thermal outputs from the present model could be sequentially coupled to suitable mechanical models to predict appropriate mechanical characteristics such as residual stress.

The purpose of this study is to establish the predictive equation of angular distortion and longitudinal shrinkage force at the intermittent fillet weldment using FEA and experiment. The angular distortion and shrinkage force of the intermittent fillet weldment linearly increases with an increase in the ratio of weld length(Lw) to weld span(Ls). Based on the results, The predictive equation of distortion at the intermittent fillet weldment was defined as a linear function of Lw/Ls and the predictive equation of the distortion for continuous fillet weldment.

The paper deals with the effect of hydrogen or helium in argon as a shielding gas on GTA welding of austenitic stainless steel. The studies were carried out in GTA(Gas Tungsten Arc) welding with a non-consumable electrode in case with different volume additions of hydrogen or helium to the argon shielding gas, i.e $5%H_2,\;10%H_2$, 30%He and 67%He. The penetration, welding voltage, microstructure and mechanical property were examined. The deepest penetration was obtained from the sample which was welded under shielding gas of $10%H_2$. The studies showed that hydrogen or helium addition to argon changes the static characteristic of the welding arc. The hydrogen or helium addition to argon increases arc power and the quantity of the material melted. The weld metal penetration depth and its width increased with increasing hydrogen or helium content. Additionally, welding voltage increased with increasing hydrogen or helium content.

The application of the variable polarity plasma arc welding process to A12219 is described. The thickness of aluminum alloy is 11.45mm and 5.08mm. 1-pass keyhole welding is applied to butt welding and 2-pass welding is also applied to thick material. During welding, all welding parameters are controlled by automated system and acquired by 10kHz rate. This paper covers the welding parameters, result of non-destructive test and tensile test.

While RSW(Resistance Spot Welding) have been the most successful sheet metal joining process in automotive industry, there are certain qualify issues due to the control system and its application process. Recent materials and coatings make the process more complicated resulting in new challenges for quality welds. In this research, an intelligent RSW system with adaptive control algorithm is introduced to overcome typical RSW issues and its applications to automotive body assembly are presented.

An analysis of a multi-pin remote welding for a DUPIC fuel fabrication was made to establish the optimum welding processes in a hot cell environment. An initial investigation for hands-on fabrication outside the hot cell was performed, and the constraints of a hot cell welding were considered. Preliminary welding performances to improve the RW process were also examined. The RW process was determined to be the best in a hot cell environment for joining the end plate to the end caps. This paper presents an outline of the developed RW machine for a DUPIC fuel fabrication and compares the characteristics of a Zr-4 end plate welding by using electrical resistance and LB methods. The weld nuggets of RW specimens and torque strengths of resistant and LB welded zones were also investigated.

DSME has developed Sub-assembly Welding Robot System(SWRS) in order to increase the productivity of arc welding and to improve hazard and unclean environments in shipbuilding. DSME's SWRS includes a number of equipments such as four overhanging 6-axis articulated robot manipulators(10kg pay-load), gantry system, vision system detecting the workpiece automatically, and OLP system using the CAD data and a central control system integrating an anti-collision module. The SWRS was installed in CAS(Component Assembly Shop) of DSME's OKPO shipyard in August 2006, and now SWRS is running well in site.

In this study, microstructure and mechanical properties for the friction stir welded 2519Al-T87 alloy of the thickness of 38.8mm were studied using DSC, OM, SEM and micro hardness tester. DSC analysis show that GP Zone, ${\theta}'$ and $\theta$ phases in upper part and ${\theta}'$ and $\theta$ phase in lower part of the FSW zone. Recrystallized large grains are observed in HAZ, and elongated small and large grain in the TMAZ. In SZ, very small grains forms by high plastic deformation and heat from friction by tool and specimen.

This study deals with characterizations of microstructure and wear performance of a cladding layer, product on 1.9 mm-thick mild steel plate by the electric resistance welding, of composite metal powder of Coarse WC-6.5%Co and high carbon alloy(SHA). The cladding layer was examined and tested fur microstructural features, chemical composition, hardness, wear performance and wear mechanism. The cladding layer have two different matrix were observed by an optical microscope and EPMA. The one was the coarse WC-6.5Co structure. The other was the melted SHA with surrounding the WC-6.5Co structure. The hardness of WC-6.5Co was 1210HV. The hardness of SHA was 640HV. In comparison by wear rate, the cladding layer showed the remarkable wear performance that was 15 times of SM490 and about 62% of D2.

This study aimed at exploiting low heat input characteristic of laser welding to effectively control grain coarsening in the fusion zone(FZ) and heat affected zone(HAZ) of 1.5mm thick 18wt% Cr ferritic stainless steel weld. The study demonstrated that as compared with gas tungsten arc welding(GTAW), laser welding brought about significant grain refinement in the FZ and HAZ. However, the impact absorbed energy of GTA weld was superior than that of laser weld because the strengthening effect during welding and cooling stage was higher In laser weld than that in GTA weld. The coarser grains in each weld than base metal resulted in an inferior toughness.

A spacer grid assembly, which is an interconnected array of slotted grid straps and is welded at the intersections to form an egg crate structure, is one of the main structural components of the nuclear fuel assembly for pressurized water reactors(PWRs). The spacer grid assembly is structurally required to have enough buckling strength under various kinds of lateral loads acting on the nuclear fuel assembly so as to keep the nuclear fuel assembly straight. To meet this requirement, it is necessary to weld the welding parts carefully and precisely. In this study, weld qualities such as, weld bead size, penetration, spatter, etc. manufactured by various welders were compared and analyzed. Comparison results show that the weld qualities could be improved by selecting the optimal welding condition and also improving the welding technique.

To investigate impact property characteristics on the low temperature plate weld metal, the two different plates of the same steel grade were welded and evaluated by Mo bearing and no Mo containing welding consumables. The results are summarized as follows; 1) Multi pass welded Mo bearing weldment was not satisfied with the requirement of tensile strength, while no Mo containing one was satisfied with it 2) In the plate butt weldment, the impact property of weld metal was highly affected by both the welding consumable and plate.

In passenger ship building where thin plates are mainly used, conventional arc welding processes result in significant post-weld reworking due to thermal distortion of welded joints. In order to solve this problem, European shipbuilding industries introduced hybrid welding process since the 1990's. for passenger ship, first of all, stability is very important. So, in this study, we investigated effects of hybrid welding conditions on impact toughness of weld metal in passenger ship building using DH36 steel.

Recently a lots of problems have observed in high densified and high integrated electronic components. One of them is ion migration phenomena, which induce the electrical short of electrical circuit. Ion migration phenomena has been observed in the field of exposing the specific environment and using for a long time. Also as the RoHS restriction was started in July 1st, 2006, Pb-free solder was utilized in electronics assemblies. In this case, it is very important to compatible between components and printed circuit board(PCB), thus surface treatment materials of PCB was changed to Sn, Sn-3.0Ag-0.5Cu, Cu. Therefore these new application become to need to reevaluate the sensitivity about electrochemical ion migration. This study was evaluated the occurrence time of electrochemical ion migration using by water drop test. We utilized PCB(printed circuit board) having a comb pattern as follows 0.1, 0.318, 0.5, 1.0 mm pattern distance. Sn-3.0Ag-0.5Cu and Sn-37Pb were electroplated on the comb pattern. 6.5V and 15.0V were applied in the comb pattern and then we measured the electrical short time causing by occurring the ion migration. In these results, we evaluate the sensitivity and derived the prediction models of ion migration occurrence time depending on the pattern materials, applied voltage and pattern spacing of PCB conductor.

The use of hull structural steel with heavy thickness has been enlarging due to the increase of ship volume. High heat input welding methods like EGW, FGB and SAW tandem are applied in field of ship-building. However the application of high heat input methods is clearly limited because welding method to be most widely used is semi-automatic FCAW but heat input for FCAW is limited in order to obtain impact property at low temperature. This paper will introduce the application of 30mm bead width of FCW with Ni free & low Ni content.

Super alloys are typically used for the liquid thruster in the aerospace industry. In this work, The bead-on-plate welding of Inconel 600, Inconel 625 and Haynes 230 using Nd:YAG laser are studied, in order to examine the effects of experimental parameters on their weldability. The micro-hardness and tensile strength of the specimens are also analyzed, to obtain the optimal welding conditions.

포항가속기는 선형가속기 및 저장링을 통하여 2.5Gev의 고에너지 전자빔 생성과 저장, 유지 되고 있다. 저장링에서 안정적으로 방사광을 추출하여 각종 실험 및 연구를 위하여 이를 제공하고 있다. 이를 위해서 전자가 매우 안정적이고 높은 집적도를 가진 전자다발 형태로 유지되어야 한다. 전자다발의 집적도가 높을수록 전자간의 상호 간섭으로 보유에너지가 더 빠른 시간에 소진되어 전자빔의 수명이 짧아진다. 3차 하모닉 RF 공동기는 전자다발의 운동방향으로 길게 늘려서 전자밀도를 줄여 전자빔의 운전수명을 개선하기 위한 장치이다. 공동기의 제작은 소재준비, 성형, 가공, 용접, 연마, 열처리 등의 여러 공정을 거쳐 완료된다. 본 보고서에서는 공동기의 제작 공정 중 전자빔을 이용한 시험용접, 본용접, 용접부 검사 및 용접부의 연마와 결과에 대하여 기술하였다.

Solderability and reaction properties were investigated for four Pb-free alloys as a function of Ag contents; Sn-4.0Ag-0.5Cu, Sn-3.0Ag-0.5Cu, Sn-2.5Ag-0.5Cu, and Sn-1.0Ag-0.5Cu. The alloy of the lowest Ag content, i.e., Sn-1.0Ag-0.5Cu, showed poor wetting properties as the reaction temperature decreased to 230oC. Variation of Ag concentration in the Sn-xAg-0.5Cu alloy shifted exothermic peaks indicating the undercooling temperature in DSC curve. For the aging process at 170oC, the thickness of IMCs at the board-side solder/Cu interface increased with the Ag concentration.

Electrically Conductive Adhesives(ECAs) with solderable particles have been developed as an alternative to Pb-free solders. Our previous study proved that good wettability of solder particle is a prerequisite for the establishment of conduction paths. In this paper, two types of ECAs were formulated and the wetting characteristic low-melting-point Sn-In solder on Cu and Ni/Au pads was investigated. It was found that Sn-In solder in the developed resin material with reduction capability shows good wettability, especially on Cu pad.

The present article aims to develop a numerical method for numerical analysis of fusible filler behavior for self-interconnection process. The CIP(Cubic Interpolated Propagation) method is used for determination of interfaces and the CSF(Continuum Surface Force) model is adopted for evaluation of curvature. To validate these models, first, the present study performs the numerical simulation for a droplet formation and it simulates the interactions among fusible fillers inside resin under the operating condition. As a result, similar tendency is found compared to the experimental observation. This study would be a first step towards finding the optimum condition for self-interconnection process.

This paper studies the mechanical behaviors of Sn-3.5Ag solder joint against substrate(such as Au/Ni/Cu, Au/cu, Ni/Cu and Cu pad) after induction heating, a new soldering method. It was found that the solder bump formation depends on the time and current of the induction heating system. Also the heating value of the solder bump were found to vary with respect to the thermal conductivity of the pads on the substrate. In case of Au/Ni/Cu pad and Au/Cu pad, solder bump's shear strength were high for the heating time of $1.5{\sim}2sec$. For Ni/Cu pad, solder bump's shear strength were found to increase with time increment.

Sn-3Ag-0.5Cu is one of candidate as an alternative approach to conventional lead-tin solder. In order to evaluate that creep characteristic of QFP, we used Sn-3Ag-0.5Cu where the operating temperature is $100^{\circ}C$. The specimens were loaded to failure at average pull strength in the range of 20% to 25%, X-ray machine is used to eliminate effect of void. In this paper, relation of time-displacement and steady state creep rate was studied, and used to analyze the experimental result.

최근 유연솔더에서 무연솔더로 전환함에 따라서 PCB의 도금이 솔더접합부의 각도에 미치는 영향이 중요하게 되었다. 현재 PCB 도금은 Sn, Au, OSP 등으로 다양하게 진행되고 있다. 그러나 PCB 도금이 솔더접합부의 강도에 미치는 영향에 대한 연구는 아직 미비하다. 따라서 본 연구에서는 PCB 도금(Sn, Au, OSP)이 무연솔더(Sn-3.0Ag-0.5Cu) 접합부의 초기 전단강도에 미치는 영향과 열사이클시험 후 솔더접합부의 전단강도에 미치는 영향에 대해서 연구하였다.

The 3-dimensional(3D) chip stacking technology is one of the leading technologies to realize a high density and high performance system in package(SIP). It could be found that it is the advanced process of through-hole via formation with the minimum damaged on the Si-wafer. Laser ablation is very effective method to penetrate through hole on the Si-wafer because it has the advantage that formed under $100{\mu}m$ diameter through-hole via without using a mask. In this paper, we studied the optimum method for a formation of through-hole via using femto-second laser heat sources. Furthermore, the processing parameters of the specimens were several conditions such as power of output, pulse repetition rate as well as irradiation method and time. And also the through-hole via form could be investigated and analyzed by microscope and analyzer.

이 연구는 CBN을 건전한 브레이징을 하기 위해서, CBN과 금속필러메탈 접합계면에서의 금속성분과 산화물, 탄화물의 거동을 분석하는데 있다. 진공 인덕션 브레이징으로 온도는 $950{\sim}1100^{\circ}C$에서 브레이징 유지시간은 $5{\sim}30$분로 실시하였다. 금속필러로는 Ni-7Cr-3Fe-3B-4Si(wt.%)와 Ag-25Cu-5Ti(wt.%)을 사용하여 브레이징된 CBN은 $950{\sim}1000$도, 유지시간 10분 사이에서 각각 건전한 계면과 표면을 얻을 수 있었으며, 계면에서 Ti-rich상과 화합물이 확인되었다. 이상의 결과로 부터 화합물의 생성과 건전한 접합공정은 브레이징 온도와 시간이 좌우하며, N과 B, Ti의 함유량이 CBN의 브레이징 접합 특성의 중요변수로 생각되어진다. CBN과 Ni계/Ag계 브레이징 필러의 계면에서의 미세조직 및 화학반응의 메커니즘은 SEM, EPMA, XRD를 이용하여 분석하였다.

The wetting balance test was carried out to compare the wettability of Sn-Xwt%Cu($0{\sim}3$wt%) solders. And, IMCs which were formed at interface between solders and substrates were investigated by using XRD(x-ray diffractometer), SEM(scanning electron microscope) and EDS(energy dispersive spectroscope). The value of ${\gamma}_[fl}$ and(${\gamma}_{fs}-{\gamma}_{ls}$) had a tendency to increase with increasing wetting temperature. The activation energy that was calculated between the bare Cu substrate and flux was increased in the following order Sn-0.7wt%Cu(68.42 kJ/mol);Sn-3.0wt%Cu(72.66 kJ/mol);100wt%Sn solder(94.53 kJ/mol).

The reliability of insert mounted components has been considered as their life time was getting increased. The spread of crack and the growth of IMC(intermetallic compound) were observed by SEM(scanning electron microscope) and EDS(energy dispersive spectroscope). The cracks in Sn-37wt%Pb under thermal shock test were found earlier than other solders(Sn-3.0wt%Ag-0.5wt%Cu and Sn-0.7wt%Cu-0.01wt%P). The IMC thickness was increased with increasing number of thermal shock cycles in the following order : Sn-0.7Cu-0.01P; Sn-3.0Ag-0.5Cu; Sn-37Pb

The microstructural evolutions and shear properties of the pure Sn solder bumps with Ni UBMs were investigated during multiple reflows and high temperature storage(HTS) tests. Only a $Ni_3Sn_4$ IMC was found at the bump/Ni UBM interface after 1 reflow. The layer thickness of these IMCs increased with increasing reflow number and testing time. The solder bumps showed a good reliability during multiple reflows and HTS tests.

This study is about an effect on a characteristics of the laser heat treatment as a optic systems which have a transverse beam mode each other. An experiment are carried out using a circular gaussian beam optics and rectangular beam optics. Generally, the optic system which has a uniform power intensity is mainly used in the laser heat treatment process. In this study, we would like to carried out experiments simultaneously using two optic systems and research the differences from a characteristics of the laser heat treatment.

Application for laser welding have increased steadily in recent years due to its benefits such as high speed, high productivity and high density energy heat source. In this article these advantages of the laser welding has been considered for Nd:YAG laser stitch welding as a substitute for spot welding of lightweight car body plates. Optimized parameters for Nd:YAG laser stitch welding have been determined comparing the economical and mechanical characteristics to match with the currently used spot welding characteristics.

The application of aluminium alloy is increasing for lightweight and high quality transport vehicle. In this study, therefore, it is intended to apply the high speed hybrid welding method for marine grade aluminium alloy(A5083) used for shipbuilding that consists of 3 kW CW Nd:YAG laser and MIG welding process. For this purpose, the characteristics of process parameters(laser & arc combine angle and focal position of hybrid head to specimen) are investigated for hybrid fillet joint. This study also describes determination of heat distribution using finite element model of the T-joint fillet weld using the in-house solver which has been validated for different type of welding problems.

In an attempt to optimize friction spot joining process of Al alloys for automobiles, Friction spot joining was used make lap feint on strips of AA5052-H32 and AA6022-T4 aluminium alloy. The effects of joining parameters such as tool rotating speed, plunging depth, joining time and kind of upper plate on the joints properties were investigated. An optimal tensile shear strength parameter of a tool rotating speed of 1000rpm, dwell time 2.5sec with upper plate 6022 can be found to make a good joint.

As rail steel at a crossing area must undergo much higher loading than those at regular railway, Mn-alloyed steel is normally used for its high load-carrying capability and reduced wear rate. However, as these Mn-alloyed steel is tend to have casting defects, manufacturing cost to produce defect-free Mn-alloyed steel becomes quite expensive. Therefore, in order to replace Mn-alloyed steel, we performed build-up welding using CH-90 and investigated regarding to wear characteristics of build-up weld metal.

Grey relational analysis has been carried out to develop a new approach for optimization of Nd:YAG laser and MIG hybrid welding parameters. The quality of welded material depends on welding parameters. The parameters chosen for current study include wire type, shielding gas, laser energy, laser focus, traveling speed, and wire feed rate. The welding experiments were performed on 6K21-T4 aluminum alloy sheet. Functional demands on products may vary widely depending on their use. The ultimate tensile stress, width, and penetration were chosen as the optimization criterion. Practice based on an orthogonal array which is following Taguchi's method has been progressed. Base on the results of grey relational analysis, the optimal process parameters were obtained. This integrated work was judged and it is observed that the results obtained by using the optimal parameters are much improved compared to those obtained through initial setting.

This paper focuses on the developed empirical models for the prediction on top-bead width in GMA(Gas Metal Arc) welding process. Three empirical models have been developed: linear, curvilinear and an intelligent model. Regression analysis was employed fur optimization of the coefficients of linear and curvilinear model, while Genetic Algorithm(GA) was utilized to estimate the coefficients of intelligent model. Not only the fitting of these models were checked, but also the prediction on top-bead width was carried out. ANOVA analysis and contour plots were respectively employed to represent main and interaction effects between process parameters on top-bead width.

This study was researched by measuring the amount how much a welder inhaled the major harmful metals such as Fe, Mn, Cu, Zn and so on which occurred at the welding site during welding work and also by measuring the heavy metal concentration in a welder's blood after the welding. By using the mobile fan, the measure of welding fume and the result were taken.

Due to the numerous environmental factors, cracks and corrosion are frequently occured especially in old steel bridge, which deteriorate the structural integrity; thus bring about the problems of structural safety of the steel bridge. Therefore, repair and reinforcement are required for the damaged structure. the replacement repair welding method is spotlighted for its brilliant features, i.e. it can be achieved without incurring traffic dislocation. the method cuts the damaged parts and replaces them with new steel plate by welding under live loads. However, the mechanical behavior of the welded joints under cyclic loads due to the traffic which passes along bridge is not clarified. In this paper, the fatigue strength of the replacement repair welded joints was investigated in order to improve reliability in the repair welded joints of old steel bridge.

Prediction and control of the thermal distortion is particularly important for the design and manufacture of welded thin plate panel. In this study, experiments and computations are peformed to analyze how hole configuration and the size of the specimen effect on distortion. In addition, this study aims to develop a thermal elasto-plastic simulation using finite element method to predict distortion, with particular emphasis on buckling deformation generated in attachments welded around hole.

Non Destructive Examination for welds is one of the most important processes to ensure the integrity of facilities of Nuclear power plants. An automated ultrasonic testing program is developed for welding inspection. A test block with side EDM notch is inspected with this program. This paper shows that the developed automated ultrasonic testing program is quite effective.

Many processes have been introduced to join PE pipes, but most of these methods have lots of disadvantages such as costs and lack of reliability, etc. Recently due to the benefits of cost, safety and reliability, the butt welding has been paid much attention to joint PE pipes. In case of butt welding, the heat plate which is used to melt PE pipes is the most critical equipment. In this study, after developing the heat plate of new shape, the PE double wall pipes with misalignments were butt-welded by using the conventional and developed heat plates and comparison of weld-zones and tensile test was performed. As the results of tensile test, weld-zones using developed heat plate have strength of $147.7{\sim}251.0%$ of weld-zones using conventional heat plate.