1.2.1 The requirements given in this section are considered minimum for electric-arc welding in hull construction, but alternative methods, arrangements and details will be specially considered for approval. (This applies only when inside surface of the weld is readily accessible or the weld has been With the help of this method, we can detect hidden flaws or discontinuities present in welds such as cracks, porosity & blowholes, slag, flux or oxide inclusions, lack of fusion, incomplete penetration, Mismatch, and tungsten . . 1). Attempt Test: Welded & Riveted Joints - 3 | 20 questions in 60 minutes | Mock test for Mechanical Engineering preparation | Free important questions MCQ to study Topicwise Question Bank for Mechanical Engineering for Mechanical Engineering Exam | Download free PDF with solutions . If this is not possible, prepare the weld angle so that the welding rod can reach the other side. Non-contact splice Joint width 6" bar spacing 18 For longer lengths of pipe, mechanical means of holding the inert gas such as plastic bladders are required. 319.4. And you want to have these joints staggered along the depth of the vessel. Welds must be made by a machine process including automatic feed and welding guidance mechanisms. Miller Welding Automation, 281 E. Lies Rd., Carol Stream, Il 60188 . In the absence of more directly applicable data, the flexibility factor k and stress intensification factor i shown in Appendix D shall be used in flexibility calculations in para. Categories B and B' encompass welded structural details such as longitudinal continuous welds in built-up plates and shapes. It is one of the most objectionable weld discontinuities. A weld failure is never good. Classification of weld cracks How to identify Transverse Crack or Longitudinal Crack? Fillet weld must be fused to the root, but they are not required to penetrate beyond the root into the joint. material types, material coatings, joint/part fit, part geometry, metallurgy, welding gases, proper machine/process maintenance, and operator skill. the thickness of the weld joint Main Causes: (1) Too narrow welding groove (2) Too low welding amperage (3) Too much arc length or arc voltage Welds can fail due to design flaws, but the majority of weld failures occur [] Behavior of UHPC joints To give the joint the same flexural strength as the pc deck slab: Splice length must be great enough to ensure bar yield, not bond failure. Altogether there are six failure groups of plastic welding to avoid. FOR EVERY 10 QUESTIONS 1 QUESTION COMES IN THE EXAM. pecially important in the fail safe de sign of welded structures for the following reasons: 1. Field-welded lap-joints were first successfully used in the 1920s to join sections of an all-steel pipe transmission line in Texas. Excessive bending loads, here, may be carried by nearby pipe and weld material if yield is achieved locally. It's true; for a pipe or vessel, the pressure stresses are highest in the longitudinal direction. 99% Passing Guarantee. Not only can that add up to quite a bit of incentive for contractors, Wuori said, but improving density on the longitudinal joint also produces a better road for the owner. Usually in different structural analysis text books the Lap Joint Weld is analyzed as a joint that is solely subjected to longitudinal shear only. 5. Welded joints. 1.1.4 For single-welded joints (i.e., butt joints welded from one side), concavity of the root surface shall not reduce the total thickness of the joint, including reinforcement, to less than the nominal thickness of the thinner component being joined. However, these methods only focus on the weld toe region. So offsetting the longitudinal weld seams serves as a kind of crack arrestor. A relatively small depth of material will become molten, and upon cooling, the structural steel and weld metal will act as one continuous part where they are joined. Longitudinal Weld Joint : Weld Joint is done along the length or along the longitudinal direction is called as Longitudinal Joint. 1.2.2 The minimum leg length limits given in Table 1 shall be complied with in all cases. 2). sensing probes cause the grinding means body. Often, the lap joint lends itself to welds being applied on either side of the joint. The joint tests for brazements are covered in AWS C3.2M/C3.2, Standard Methods for Evaluating the Strength of Brazed Joints. Longitudinal seams are more susceptible to fail- ure because the stresses from the internal pressure are much higher for these seams than for circumfer- . Till now, there are two kinds of finite element method (FEM) which can be used to simulate welding deformation. When completing weld calculations please note the following: nomenclature is listed in the textbook on page 6. If the fillet weld fails when r = rxu, then Ru = 1.17 rxu Lt (7) The ratio of the transverse strength to the longitudinal strength is thus approximate ly 1.2:1. This agrees closely with the test results of Refs. The stresses are twice as high in the long welds because there is . Poor welding technique can be attributed to a lack of training, newer welding operators with lower skill sets, or more experienced welders who may have acquired bad habits. butt joints welded from one side), concavity of the root surface shall not reduce the total thickness of the joint, including reinforcement, to less than the nominal thickness of the thinner component being joined 1.1.6 For single welded joints, the excess root penetration shall be exceed the lesser of 1/ 8 Reason 4: Poor welding technique. Maximum pre-heat for repair welding is 1500 C (3020 F). Typical weld defects are the following: misalignment, cracking, porosity and inclusion, incorrect penetration, lack of sidewall fusion, and lack of gas shield. Welding defect. Welds must be made by a machine . Additional information on the mechanical testing of welded joints may be obtained from the AWS Welding Handbook, Ninth Edition, Volume 1, which describes selected weldability test methods. Internal misalignment for butt joints shall not exceed 1.5 mm (1/16"). The welding experiments simulated the longitudinal welding of a 60 3.5 mm tube with a welding speed of v l = 20 m / min at a welding frequency of f = 213-223 kHz. Fig.1. These will cause unhygienic conditions in the weld area. In order to keep the shape straight; a fixture should be used. lead, lead compound are more likely to experience joint leaks. However, they cannot be dismantled for maintenance or replacing parts. The PFBR reactor assembly components are large in size with Principal (Check valves should still be used to minimize . Structural welding is a process by which the parts that are to be connected are heated and fused, with supplementary molten metal at the joint. The fatigue life of a welded structure is primarily a fatigue crack propagation problem (Maddox (Refs. Welded joints are often preferred to bolted joints because they are simpler, easier to complete, relatively stronger and can provide a sealed assembly. Fillet weld Fillet weld 1 Welding imperfections are classified according to ISO 6520 while their acceptable limits are specified in ISO 5817 and ISO 10042. Even with the best welding tech niques available today, fabrication of flaw-free large welded structures can not be ensured (Ref. One . Buy API 510 Exam Learning Package Study Material. Welding defect. Discusses the potential for steam leaks and ruptures at the longitudinal weld joints in high temperature steam piping. The primary components of a bolted joint include the threaded fastener as well as the parts to be joined together (the clamped parts ). A word of caution: the above calculations are used to explain the theory behind weld design. Attempts have been made to explain the difference in the test values for the . "By heating the joint, you are ensuring the joint is around 300 degrees Fahrenheit at compaction, instead of 80 to 100," Blake said. the weld) often leads to undercut, or melting away of the edges, creating a weak spot in the lapped attachment. Longitudinal seams must have complete joint penetration, and must be free from undercuts, overlaps or abrupt ridges or valleys. (3) Longitudinal electric-arc welded seams (in shells) must be of the butt welded type. . Wuori said that the majority of states in which he works now have incentives for density on the longitudinal joint, anywhere from $0.60 to $1 per linear foot. The internal pressure wants to stretch the. Conclusion In addition to these situations, other factors that can cause bend specimens to fail include poorly prepared bend specimens, and specimens bent to improper dimensions. Some of the main factors related to weldment failure include weld stresses, cracking, weld distortion, lamellar tearing, brittle fracture, fatigue cracking, weld design, and weld defects. These distresses, caused by relatively low density (high air voids) and surface irregularity at the joints, can largely be avoided through proper . 2. Usually in different structural analysis text books the Lap Joint Weld is analyzed as a joint that is solely subjected to longitudinal shear only. A longitudinal joint is the interface between two adjacent and parallel HMA mats. Hopefully the consequences are limited to time and money. The longitudinal joint in a boiler shell is usually Butt joint . This study examined the fatigue strength of cruciform joints and longitudinal joints fabricated with laser-arc hybrid welding. However the demonstration below (2) Circumferential seams must be by electric-arc welding. Classification of weld cracks How to identify Transverse Crack or Longitudinal Crack? Welded joints Welded joints are often preferred to bolted joints because they are simpler, easier to complete, relatively stronger and can provide a sealed assembly. Improperly constructed longitudinal joints can cause premature deterioration of multilane HMA pavements in the form of cracking and raveling (Figures 1 and 2). This failure to obtain fusion may occur at any point in the welding groove. For normal forces, direction N, there is a prying action that reduces the resis tance below the value for the trans On the ship-making industries in Australia and New Zealand utilizing high strength steel as raw material, welding distortion becomes a significant problem. A reanalysis of fatigue test data for longitudinal welded gusset joints in as-welded and high frequency mechanical impact (HFMI)-treated state. If welding deformation can be accurately predicted beforehand, the predictions will be helpful for finding effective methods to improve manufacturing accuracy. Whether a weld cracks on a truck's axle or on the post holding your house's fence, there are always consequences. Incomplete fusion may be caused by: failure to raise the temperature . A welding defect is any flaw that compromises the usefulness of a weldment. However, they cannot be dismantled for maintenance or replacing parts. A weld failure can occur due to many factors. 1A): along the weld, L; across the weld, parallel to the plane of the weld group, T; and across the weld, normal to the plane of the weld group, N. Only the first two directions are considered in this study. Fig. With an infrared heater, he added, contractors can install hot asphalt against hot asphalt, "which is going to create a seamless weld between the two lanes." How to Build and Compact the Longitudinal Joint Incomplete fusion. Sometimes longitudinal joints fail because the hot and cold lanes fail to adequately bond with one another with one another during construction. Today's steel linepipe base materials are much, much tougher and more fracture resistant than most any weld joint. 6. problems with welded structures from the damage-tolerance view-point. Incomplete fusion, or lack of fusion as it is frequently termed, is used to describe the failure to fuse together adjacent layers of weld metal or adjacent weld metal and base metal. 2) length-wise, which makes the circ weld want to fail. Maybe one reason could be that it is a development from traditional wooden boat building - here you want to have longitudinal planks as long as possible, with as few as possible butt joints. Specifications: The excess weld metal in the cap of the weld may be left in-situ or machined off. when type 304 stainless steel is welded using a ller metal with high chromium-nickel content, steep concentration gradients of chromium and nickel are found in the fusion zone, whereas the unmixed zone has a composition similar to the base metal (Fig. . Prevent them by properly cleaning the base material and using a drag technique to keep slag out of the weld pool. Illustrated in Figure 6, the code describes this as welding on "opposite sides of a common plane," and in paragraph 2.4.7.5, requires that the welds UW-3 Welded Joint Category Page 115 (a)The term "Category" as used herein defines the location of a joint in a vessel, but not the type of joint. Click Here To Contact On Whatsapp https://wa.link/4dn6ee. This is basically the worst case scenario and limits the maximum force that can be applied to a weld before it fails. This Joint is also Called as L - Seam Joint or Long Seam Joint. Describes the problem and provides recommendations for correcting . Distortion - can be very harmful to the weld quality because it induces inaccurate joint shape. When completing weld calculations please note the following: nomenclature is listed in the textbook on page 6. This unit needs to be positioned until the weld is completely cooled down. longitudinal weld-joint factor [1.0 seamless, 0.95 electric fusion weld, double butt, straight or spiral seam APL 5L, 0.85 electric resistance weld (ERW), 0.60 furnace butt weld], Y = . Cost: $75.00. Note: splice is non-contact (individual bars at about 3" centers). Welding imperfections are classified according to ISO 6520 while their acceptable limits are specified in ISO 5817 and ISO 10042. Weld discontinuities in longitudinal bend tests that are oriented parallel to . the weld) often leads to undercut, or melting away of the edges, creating a weak spot in the lapped attachment. A review of literature reveals that a significant research work has been undertaken by various authors focusing on different type of weld joint configurations such as L-seam weld joint of . In the case of multiple pass welds, where sev-eral beads per layer may be applied, a centerline crack may not be in the geometric center of the joint, although it will always be in the center of the bead (Figure 1). This reduces the strength of the joint and creates a weakness in the mat that can accelerate deterioration and lead to longitudinal joint cracking. The bolted joint is among the most common joining methods -- other common joining methods include riveting, welding, press fits, pins, keys, and adhesives. Improper selection of welding parameters caused an undercut of 3 mm depth along the weld. Some problems can be corrected by improved detail design but fatigue performance The danger in the approach is that the technique which is satisfactory on one weld may fail completely when applied to another, even though the second one has been fabricated using identical procedures. Unfortunately, weld failures can cause injury. It is a simplified example to illustrate . There is a great variety of welding defects. Lack of penetration allows a natural stress riser from . There is a great variety of welding defects. Leaking joint a a a a a a a a Pipelines with non-elastomeric seal joints e.g. A welding defect is any flaw that compromises the usefulness of a weldment. Load-carrying and non-load-carrying cruciform welded joints with plate thicknesses of 8, 16, and 25 mm were tested under tensile cyclic loads and out-of-plane bending cyclic loads. Therefore, it requires additional reparation cost. (This applies only when inside surface of the weld is readily accessible or the weld has been c) 2 longitudinal joint = circumferential joint d) None Q16. Longitudinal butt joints of welded tubing shall be welded across its thickness in such a manner as to assure the structural design strength of the tubing section. However the demonstration below All joints in a spherical, torispherical, or ellipsoidal shape or in any other surface or double curvature shall be considered longitudinal joints. Comment- First, I do not believe 3-inches on each side of the T would constitute a or substitute for a longitudinal joint RT examination to determine whether it represents a good sample of that weld. It seems logical in terms of longitudinal strength purposes. Check valves may leak or fail open and allow communication of pressure from the high side to the low side. It is commonly observed that complex fabricated structures subject to fatigue loading fail at the welded connections. 13: approved WPS. Circumferential welds are loaded by sustained axial and bending (dead weight) loads. Welded Joint MCQ Question 5. Several researches on pile driving process have been conducted, most. Porosity (PO) Porosity is the result of gas entrapment in the solidifying metal. Porosity (PO) Porosity is the result of gas entrapment in the solidifying metal. 14: Deposit the root pass and six (6) successive passes or 1/3 of the weld volume prior to interruption (allowing to cool to ambient temperature). Heat-Affected Zone.The HAZ is the por-tion of the weld joint which has experienced Using a tack coat or heating the cold lane prior to . If a longitudinal seam fails, the fracture most likely stops at the closest girth weld down stream from the start point. Category B' has constructions similar to those in B that are more . Second, experiments have indicated a considerable increase in crack growth rates in the heat-affected zone (HAZ) as a result of welding-induced residual stresses.7 17 Hot crack (Crater crack, Longitudinal crack, Pear-shape crack, Sulfur crack) Appendix A 18 Fig. Total 5000+ nos QUESTION BANK FROM THEORY TO PRACTICAL TO NUMERICALS. butt joints welded from one side), concavity of the root surface shall not reduce the total thickness of the joint, including reinforcement, to less than the nominal thickness of the thinner component being joined 1.1.6 For single welded joints, the excess root penetration shall be exceed the lesser of 1/ 8 A butt weld joint is developed on steel plates having yield and ultimate tensile strength of 500 MPa and 700 MPa, respectively. The thickness of the plates is 8 mm and width is 20 mm. The question was related to "that if we had weld pipe to fitting and short piece was the dimension as shown at ISO drawing" It's a pipe to fitting "319.3.6 Flexibility and Stress Intensification Factors. Telephone: (714)951-1515 Fax: (714)951-9237 Telex: 655326 . ASTM A500 structural pipe is welded pipe sized tubing made from flat-rolled steel, formed through a roller system and welded using electric-resistance welding. . This application was later improved using shielded metal arc-welding technology followed by other semiautomated arc-welding processes (i.e., flux-core arc-welding and gas-metal arc-welding) that currently dominate construction practices for field-welding water . 1.1.5 For single-welded joints (i.e. If any notches do exist, they should lie parallel to the specimen's longitudinal axis. This longitudinal seam welder is a standard design . Longitudinal and spiral welds must carry the hoop pressure load (as membrane stress through the pipe wall) or fail. 1.1.4 For single-welded joints (i.e., butt joints welded from one side), concavity of the root surface shall not reduce the total thickness of the joint, including reinforcement, to less than the nominal thickness of the thinner component being joined. These are generally cross joint (CJ) tensile tests of square or rectangular cross section that, as the name suggests, are oriented across the weld so that both parent metals, both heat affected zones (HAZs) and the weld metal itself are tested ( Fig.1 ). Buckling is the sudden change in shape (deformation) of a structural component under load . Although the number of CWR joint-caused derailments on a main line has been relatively small, these derailments can be catastrophic, especially if passenger trains or hazardous materials are involved. The name itself describes about longitudinal joint that these weld joints are joining two sheets horizontally, vertically or in any direction. This makes the long weld want to fail. Joints must have a minimum overlap of at least four (4) times nominal sheet thickness. Sometimes porosity is elongated and may have the appearance of having a tail . Flange gaskets are also prone to leakage especially at higher operating pressures Third-party damage a a a a a a a a Third party damage should not be considered a pipe failure as such. P a r t 3 C h a p t e r 1 3 S e c t i o n 1 A thin cylindrical shell under internal pressure can fail by a) Shear b) Compression c) Tension d) None Q17. Therefore, an alternating current range of I pp = 4115-4767 A, corresponding to a power range of P = 72-134 kW was applied in the stated frequency range. that longitudinally welded steel piles are prone to fail, especially when receiving impact load during the installation process. 1) along its diameter, like a balloon. 4 and 5 for fillet welded T-joints loaded in tension. it grinds welds smooth adjusting automatically to changes in surface contour as grinding progresses from one end of the weld tour as grinding progreses from one end of the weld to the other end.
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