1. Various weld defects such as undercut, lack of penetration, porosity, and cracks can occur during welding. Proper joint preparation and welding technique are important to prevent defects.
2. Common weld defects include undercut, lack of penetration, porosity, cracks, and incorrect weld contours. The causes and remedies for each defect are described.
3. Improper welding techniques are a major cause of defects like undercut and lack of penetration. Following correct procedures for joint preparation, parameters, and technique can help avoid defects. Defects may require repair by rewelding or grinding.
This document provides a handbook for visual inspection of welds. It includes sections on visual inspection responsibilities and techniques, definitions and images of common weld defects such as cracks, underfill, burn through, incomplete fusion, roughness, overlap, undersized fillets, incomplete penetration, undercut, corner melt, and end melt. Preventive and corrective actions are provided for each defect. The handbook also includes sections on measuring fillet weld size, types of weld joints, parts of a weld, welding symbols and joint numbering systems. It is intended to provide basic information for visual inspection of welds and is not a replacement for work procedures or other technical documents.
The document discusses welding standards and training provided by McClain E-Z Pack to help improve weld quality. A retired welding instructor, Jim Davis, worked part-time to show welders examples of good and bad welds. Pictures were posted with descriptions of welding problems, potential issues caused by the problems, possible causes, and remedies. The last picture shown is of an actual production weld.
This document provides an analysis of welding defects including a discussion of various types of defects such as misalignment, undercut, insufficient fill, porosity, cracks, and inclusions. It defines each defect, describes potential causes and how to prevent and repair the defect. The document aims to educate welders on identifying and addressing common welding defects.
The document discusses various types of defects and discontinuities that can occur in welds, including cracks, inclusions, insufficient penetration, and improper reinforcement. It defines each issue, describes potential causes and preventative measures, and outlines repair procedures when necessary. Weld defects can arise from factors like inadequate joint preparation, improper welding techniques, lack of preheat, and contamination. Careful work and following standards are emphasized to produce welds free of defects.
This document provides information about weld imperfections and preventive measures. It contains an introduction describing the importance of quality control in welding. The document then summarizes surface irregularities and weld discontinuities, providing definitions and examples of imperfections like uneven weld ripples, excessive reinforcement, undercut, overlap, porosity, slag inclusions, incomplete fusion and more. Causes and preventive measures are described for each imperfection. References used in compiling the information are also listed.
The document defines various defects and discontinuities that may occur in welds such as undercut, porosity, cracks, and lack of penetration. It provides the definitions, causes, prevention methods, and repair techniques for each. While discontinuities are not necessarily defects, any flaw that causes a part to not meet standards would be considered a defect and require repair, such as grinding or rewelding to correct issues. Proper welding technique and following applicable codes and standards are important to minimize defects.
This document provides a handbook for visual inspection of welds. It includes sections on visual inspection responsibilities and techniques, definitions and images of common weld defects such as cracks, underfill, burn through, incomplete fusion, roughness, overlap, undersized fillets, incomplete penetration, undercut, corner melt, and end melt. Preventive and corrective actions are provided for each defect. The handbook also includes sections on measuring fillet weld size, types of weld joints, parts of a weld, welding symbols and joint numbering systems. It is intended to provide basic information for visual inspection of welds and is not a replacement for work procedures or other technical documents.
The document discusses welding standards and training provided by McClain E-Z Pack to help improve weld quality. A retired welding instructor, Jim Davis, worked part-time to show welders examples of good and bad welds. Pictures were posted with descriptions of welding problems, potential issues caused by the problems, possible causes, and remedies. The last picture shown is of an actual production weld.
This document provides an analysis of welding defects including a discussion of various types of defects such as misalignment, undercut, insufficient fill, porosity, cracks, and inclusions. It defines each defect, describes potential causes and how to prevent and repair the defect. The document aims to educate welders on identifying and addressing common welding defects.
The document discusses various types of defects and discontinuities that can occur in welds, including cracks, inclusions, insufficient penetration, and improper reinforcement. It defines each issue, describes potential causes and preventative measures, and outlines repair procedures when necessary. Weld defects can arise from factors like inadequate joint preparation, improper welding techniques, lack of preheat, and contamination. Careful work and following standards are emphasized to produce welds free of defects.
This document provides information about weld imperfections and preventive measures. It contains an introduction describing the importance of quality control in welding. The document then summarizes surface irregularities and weld discontinuities, providing definitions and examples of imperfections like uneven weld ripples, excessive reinforcement, undercut, overlap, porosity, slag inclusions, incomplete fusion and more. Causes and preventive measures are described for each imperfection. References used in compiling the information are also listed.
The document defines various defects and discontinuities that may occur in welds such as undercut, porosity, cracks, and lack of penetration. It provides the definitions, causes, prevention methods, and repair techniques for each. While discontinuities are not necessarily defects, any flaw that causes a part to not meet standards would be considered a defect and require repair, such as grinding or rewelding to correct issues. Proper welding technique and following applicable codes and standards are important to minimize defects.
The Certified Welding Inspector (CWI) plays an important role during any welded construction activities ensuring the required specifications and standards are followed. Due to the numerous materials and processes associated with metal joining (welding) THIS PRESENTATION SHALL SHOW ONLY THE BASIC WELDING PROCESSES AND EXAMINATION METHODS (NDE). National and International Codes and Specifications along with measuring devices are the Inspector’s tools. Hopefully the following presentation shall give an insight into basic welding inspection.
The document provides information on weld repair, including the types of defects that can occur during manufacturing, the steps involved in deciding when repairs are needed, and how to execute welding repairs. It discusses inherent, processing, and service defects and their causes. The key steps in repair decision making are evaluating operating conditions, inspection history, reasons for failure, defect location using visual and NDT methods, and re-evaluating the need for repairs based on design calculations. When repairs are needed, the document outlines preparing the repair procedure, executing the welding according to qualified procedures while monitoring parameters, and inspecting the completed repair.
This document discusses various types of weld discontinuities and defects including misalignment, undercut, insufficient fill, excessive reinforcement, overlap, burn-through, incomplete penetration, incomplete fusion, arc strikes, and inclusions such as slag, wagontracks, and tungsten. Each discontinuity or defect is defined, potential causes are identified, methods for prevention are provided, and repair techniques are described. The document serves as a reference for identifying and addressing common weld problems and defects.
Defects in Materials
NATURE OF DEFECTS
Microscopic Defects
Macroscopic Defects
ORIGIN OF DEFECTS
Inherent Defects
Processing Defects
Service Defects
DETERIORATES PHYSICAL and MECHANICAL PROPERTIES of MATERIALS
DETECTION of DEFECTS
Destructive Testing
Non-Destructive Testing
The document discusses various types of discontinuities and defects that can occur in welding, including cracks, porosity, inclusions, insufficient penetration, and more. It defines discontinuities as interruptions in material structure that are not necessarily defects, while defects render a part unable to meet standards. Causes, preventions, and potential repairs are provided for each issue. Engineering problems can arise from design mistakes, while weld process issues relate to techniques and metallurgy.
Cswip welding inspection notes and questionsKarthik Banari
The document discusses the duties of a welding inspector, including visual inspection of welds to identify defects and ensure they meet acceptance criteria. It describes tools that can aid inspection like magnification lenses. It outlines a code of practice for an inspection department, including checking documents, materials, equipment and welder qualifications before welding, monitoring the welding process and variables during welding, and inspecting the final weld for defects, dimensions and heat treatment after welding. Repairs should follow an authorized procedure and be re-inspected upon completion.
This document discusses various types of welding discontinuities and defects that can occur during the welding process. It divides discontinuities into six main groups: cracks, cavities, solid inclusions, lack of fusion and penetration, imperfect shape, and miscellaneous defects. Within each group it provides examples and descriptions of specific defect types like porosity, slag inclusions, undercut, burn through, and more. It also discusses potential causes of defects and recommended remedies.
The document discusses various welding defects that can be visually detected, including cracks, lack of solid metal, lack of fusion, lack of smoothly blended surfaces, and miscellaneous defects. It provides details on different types of each defect, their causes, and methods for prevention. It also discusses welding repairs, noting that repairs require authorization and testing to ensure defects have been fully removed before performing the repair weld.
The document discusses weld defects, their causes, and remedies. It identifies eight main types of structural weld defects: crater cracks, longitudinal cracks, cross-sectional cracks, undercutting, slag inclusion, porosity, poor penetration, and incomplete fusion. Each defect is described along with its potential causes, such as improper welding technique, incorrect electrode or current usage, or poor joint preparation. The objective is to help identify different weld defects, understand what causes them, and take appropriate measures to remedy issues.
Geometric imperfections and inclusions are two main categories of welding defects. Geometric imperfections include misalignment, overlap, undercutting, concave and convex welds, and cracking. Inclusions refer to slag, tungsten, sulfide and oxide materials becoming part of the weld. Other defects discussed include porosity, incomplete fusion, spatter, unacceptable weld profiles, lamellar tearing, and crater. The document emphasizes that welding defects can significantly impact weld performance and longevity, so detection techniques are important and defects detrimental to structural integrity should be repaired.
Dota 2 Game Dota 2 is a free-to-play multiplayer online battle arena (MOBA) video game developed and published by Valve Corporation. The game is the stand-alone sequel to Defense of the Ancients (DotA), which was a community-created mod for Blizzard Entertainment's Warcraft III: Reign of Chaos and its expansion pack, The Frozen Throne. Dota 2 is played in matches between two teams of five players, with each team occupying and defending their own separate base on the map. Each of the ten players independently controls a powerful character, known as a "hero", who all have unique abilities and differing styles of play. During a match, players collect experience points and items for their heroes in order to successfully battle the opposing team's heroes, who are attempting to do the same to them. A team wins by being the first to destroy a large structure located in the opposing team's base, called the "Ancient".
The document discusses various welding defects including lamellar tearing, porosity, underfill, insufficient
penetration, wagon tracks, arc strikes, and incomplete fusion. Lamellar tearing occurs beneath welds in rolled steel
plate and is caused by transverse strain from welding, a weld orientation parallel to inclusions, and poor material
ductility. Porosity is caused by absorbed gases like nitrogen, oxygen, and hydrogen which become trapped during
solidification. Prevention methods for defects include using proper joint design, welding techniques, materials, and
preheating when necessary. Defects require removal and rewelding to repair.
This document provides an introduction to CSWIP 3.1 welding inspection standards. It defines key welding terms like joints, welds, and weld preparations. It describes the responsibilities of welding inspectors to ensure safety and quality before, during, and after welding operations. The document also summarizes different types of welding imperfections and mechanical tests used by inspectors, including hardness testing, tensile testing, and bend testing specimens under a macroscope.
This document discusses discontinuities and defects that can occur in welded joints. It lists various types of discontinuities such as misalignment, undercut, incomplete fusion, porosity, and cracks. Defects are defined as flaws that cause a part to not meet acceptance standards. The document provides classifications of welding defects according to their appearance as outlined in welding standard DIN 8524.
Causes and Remedies for Porosity during WeldingVignesh kumar
The document discusses porosity in welding, which refers to small gas holes or cavities present in the weld bead. Porosity can occur due to contamination, inadequate deoxidation, improper gas shielding, high gas flow, moisture in fluxes or electrodes, base metal impurities, and improper welding procedures. Common causes include grease or moisture on surfaces to be welded, excess oxygen in the weld metal, exposure of the weld to air, and turbulence in the gas shield. Proper cleaning, drying, gas shielding, welding procedures, and choice of electrodes and fluxes can help prevent porosity.
The document discusses various common weld discontinuities and defects such as gas pores, slag inclusions, incomplete penetration, lack of fusion, cracks, and undercut. It describes the causes of these defects which can include trapped gas during solidification, contaminated base metal, improper welding parameters, and faulty joint preparation. Remedies suggested to avoid defects are ensuring adequate shielding from wind, using clean electrodes, maintaining the proper arc length, travel speed, and current level.
This document provides guidance on welding pressure pipelines and piping systems using shielded metal arc welding. It discusses procedures for vertical down welding of cross-country pipelines, including joint preparation, pipe cleaning, techniques for welding the root, hot, fill and cap passes. It also provides recommendations for current settings when using Lincoln engine driven welders and discusses troubleshooting root pass issues. The document recommends techniques for welding different types of pipe materials and strengths.
The document discusses welding processes and their importance, types of welds and weld defects, including causes and methods of detection. It examines the microstructure of welds and defines features like the fusion zone, heat affected zone, and unaffected base metal zone. Various weld defects are described such as cracks, cavities, inclusions, lack of fusion/penetration, imperfect shape, and miscellaneous faults.
This document discusses various types of welding defects and imperfections including lack of fusion, porosity, slag inclusions, and solidification cracking. It describes how to identify each type, their causes, best practices for prevention, acceptance standards, and methods for detection and remediation. The key types of imperfections are classified as fabrication defects occurring during welding or service defects that form during use, and guidelines are provided for minimizing defects and producing quality welds.
This document discusses welding consumables used in various welding processes. It describes the types of consumables which may include filler wires, covered electrodes, shielding gases, and fluxes. For each consumable type, details are provided on their composition, characteristics, and functions. Standards for different consumables are also outlined. The key information covered includes the critical role of consumables in welding, their composition and how they influence the weld quality and properties.
The document contains 20 pages of pictures from TD Williamson in Nivelles, Belgium documenting the repair of a 26" diameter, 10.8mm thick pipe made of X70 steel with an operating pressure of 108 bars at Sasol RLL1 between November and December 2016. The pictures show the weld repair process including coating removal, installation of a repair sleeve, butt and fillet welding, non-destructive testing, coating and the final view before refilling the excavation.
The document provides information on setting up arc welding equipment and fabricating articles using electrical welding techniques. It discusses:
1) The learning objectives which are to perform pre-welding operations, select equipment and settings, fabricate articles using arc welding, and perform post-weld operations.
2) The process of arc welding which involves generating an arc between the electrode and workpiece to produce heat and fuse the metals.
3) Procedures for producing an arc and welding bead including cleaning the workpiece, striking an arc by scratching or tapping, and moving the electrode vertically.
4) The role and types of electrodes used in arc welding based on coating, flux composition, and core material
The Certified Welding Inspector (CWI) plays an important role during any welded construction activities ensuring the required specifications and standards are followed. Due to the numerous materials and processes associated with metal joining (welding) THIS PRESENTATION SHALL SHOW ONLY THE BASIC WELDING PROCESSES AND EXAMINATION METHODS (NDE). National and International Codes and Specifications along with measuring devices are the Inspector’s tools. Hopefully the following presentation shall give an insight into basic welding inspection.
The document provides information on weld repair, including the types of defects that can occur during manufacturing, the steps involved in deciding when repairs are needed, and how to execute welding repairs. It discusses inherent, processing, and service defects and their causes. The key steps in repair decision making are evaluating operating conditions, inspection history, reasons for failure, defect location using visual and NDT methods, and re-evaluating the need for repairs based on design calculations. When repairs are needed, the document outlines preparing the repair procedure, executing the welding according to qualified procedures while monitoring parameters, and inspecting the completed repair.
This document discusses various types of weld discontinuities and defects including misalignment, undercut, insufficient fill, excessive reinforcement, overlap, burn-through, incomplete penetration, incomplete fusion, arc strikes, and inclusions such as slag, wagontracks, and tungsten. Each discontinuity or defect is defined, potential causes are identified, methods for prevention are provided, and repair techniques are described. The document serves as a reference for identifying and addressing common weld problems and defects.
Defects in Materials
NATURE OF DEFECTS
Microscopic Defects
Macroscopic Defects
ORIGIN OF DEFECTS
Inherent Defects
Processing Defects
Service Defects
DETERIORATES PHYSICAL and MECHANICAL PROPERTIES of MATERIALS
DETECTION of DEFECTS
Destructive Testing
Non-Destructive Testing
The document discusses various types of discontinuities and defects that can occur in welding, including cracks, porosity, inclusions, insufficient penetration, and more. It defines discontinuities as interruptions in material structure that are not necessarily defects, while defects render a part unable to meet standards. Causes, preventions, and potential repairs are provided for each issue. Engineering problems can arise from design mistakes, while weld process issues relate to techniques and metallurgy.
Cswip welding inspection notes and questionsKarthik Banari
The document discusses the duties of a welding inspector, including visual inspection of welds to identify defects and ensure they meet acceptance criteria. It describes tools that can aid inspection like magnification lenses. It outlines a code of practice for an inspection department, including checking documents, materials, equipment and welder qualifications before welding, monitoring the welding process and variables during welding, and inspecting the final weld for defects, dimensions and heat treatment after welding. Repairs should follow an authorized procedure and be re-inspected upon completion.
This document discusses various types of welding discontinuities and defects that can occur during the welding process. It divides discontinuities into six main groups: cracks, cavities, solid inclusions, lack of fusion and penetration, imperfect shape, and miscellaneous defects. Within each group it provides examples and descriptions of specific defect types like porosity, slag inclusions, undercut, burn through, and more. It also discusses potential causes of defects and recommended remedies.
The document discusses various welding defects that can be visually detected, including cracks, lack of solid metal, lack of fusion, lack of smoothly blended surfaces, and miscellaneous defects. It provides details on different types of each defect, their causes, and methods for prevention. It also discusses welding repairs, noting that repairs require authorization and testing to ensure defects have been fully removed before performing the repair weld.
The document discusses weld defects, their causes, and remedies. It identifies eight main types of structural weld defects: crater cracks, longitudinal cracks, cross-sectional cracks, undercutting, slag inclusion, porosity, poor penetration, and incomplete fusion. Each defect is described along with its potential causes, such as improper welding technique, incorrect electrode or current usage, or poor joint preparation. The objective is to help identify different weld defects, understand what causes them, and take appropriate measures to remedy issues.
Geometric imperfections and inclusions are two main categories of welding defects. Geometric imperfections include misalignment, overlap, undercutting, concave and convex welds, and cracking. Inclusions refer to slag, tungsten, sulfide and oxide materials becoming part of the weld. Other defects discussed include porosity, incomplete fusion, spatter, unacceptable weld profiles, lamellar tearing, and crater. The document emphasizes that welding defects can significantly impact weld performance and longevity, so detection techniques are important and defects detrimental to structural integrity should be repaired.
Dota 2 Game Dota 2 is a free-to-play multiplayer online battle arena (MOBA) video game developed and published by Valve Corporation. The game is the stand-alone sequel to Defense of the Ancients (DotA), which was a community-created mod for Blizzard Entertainment's Warcraft III: Reign of Chaos and its expansion pack, The Frozen Throne. Dota 2 is played in matches between two teams of five players, with each team occupying and defending their own separate base on the map. Each of the ten players independently controls a powerful character, known as a "hero", who all have unique abilities and differing styles of play. During a match, players collect experience points and items for their heroes in order to successfully battle the opposing team's heroes, who are attempting to do the same to them. A team wins by being the first to destroy a large structure located in the opposing team's base, called the "Ancient".
The document discusses various welding defects including lamellar tearing, porosity, underfill, insufficient
penetration, wagon tracks, arc strikes, and incomplete fusion. Lamellar tearing occurs beneath welds in rolled steel
plate and is caused by transverse strain from welding, a weld orientation parallel to inclusions, and poor material
ductility. Porosity is caused by absorbed gases like nitrogen, oxygen, and hydrogen which become trapped during
solidification. Prevention methods for defects include using proper joint design, welding techniques, materials, and
preheating when necessary. Defects require removal and rewelding to repair.
This document provides an introduction to CSWIP 3.1 welding inspection standards. It defines key welding terms like joints, welds, and weld preparations. It describes the responsibilities of welding inspectors to ensure safety and quality before, during, and after welding operations. The document also summarizes different types of welding imperfections and mechanical tests used by inspectors, including hardness testing, tensile testing, and bend testing specimens under a macroscope.
This document discusses discontinuities and defects that can occur in welded joints. It lists various types of discontinuities such as misalignment, undercut, incomplete fusion, porosity, and cracks. Defects are defined as flaws that cause a part to not meet acceptance standards. The document provides classifications of welding defects according to their appearance as outlined in welding standard DIN 8524.
Causes and Remedies for Porosity during WeldingVignesh kumar
The document discusses porosity in welding, which refers to small gas holes or cavities present in the weld bead. Porosity can occur due to contamination, inadequate deoxidation, improper gas shielding, high gas flow, moisture in fluxes or electrodes, base metal impurities, and improper welding procedures. Common causes include grease or moisture on surfaces to be welded, excess oxygen in the weld metal, exposure of the weld to air, and turbulence in the gas shield. Proper cleaning, drying, gas shielding, welding procedures, and choice of electrodes and fluxes can help prevent porosity.
The document discusses various common weld discontinuities and defects such as gas pores, slag inclusions, incomplete penetration, lack of fusion, cracks, and undercut. It describes the causes of these defects which can include trapped gas during solidification, contaminated base metal, improper welding parameters, and faulty joint preparation. Remedies suggested to avoid defects are ensuring adequate shielding from wind, using clean electrodes, maintaining the proper arc length, travel speed, and current level.
This document provides guidance on welding pressure pipelines and piping systems using shielded metal arc welding. It discusses procedures for vertical down welding of cross-country pipelines, including joint preparation, pipe cleaning, techniques for welding the root, hot, fill and cap passes. It also provides recommendations for current settings when using Lincoln engine driven welders and discusses troubleshooting root pass issues. The document recommends techniques for welding different types of pipe materials and strengths.
The document discusses welding processes and their importance, types of welds and weld defects, including causes and methods of detection. It examines the microstructure of welds and defines features like the fusion zone, heat affected zone, and unaffected base metal zone. Various weld defects are described such as cracks, cavities, inclusions, lack of fusion/penetration, imperfect shape, and miscellaneous faults.
This document discusses various types of welding defects and imperfections including lack of fusion, porosity, slag inclusions, and solidification cracking. It describes how to identify each type, their causes, best practices for prevention, acceptance standards, and methods for detection and remediation. The key types of imperfections are classified as fabrication defects occurring during welding or service defects that form during use, and guidelines are provided for minimizing defects and producing quality welds.
This document discusses welding consumables used in various welding processes. It describes the types of consumables which may include filler wires, covered electrodes, shielding gases, and fluxes. For each consumable type, details are provided on their composition, characteristics, and functions. Standards for different consumables are also outlined. The key information covered includes the critical role of consumables in welding, their composition and how they influence the weld quality and properties.
The document contains 20 pages of pictures from TD Williamson in Nivelles, Belgium documenting the repair of a 26" diameter, 10.8mm thick pipe made of X70 steel with an operating pressure of 108 bars at Sasol RLL1 between November and December 2016. The pictures show the weld repair process including coating removal, installation of a repair sleeve, butt and fillet welding, non-destructive testing, coating and the final view before refilling the excavation.
The document provides information on setting up arc welding equipment and fabricating articles using electrical welding techniques. It discusses:
1) The learning objectives which are to perform pre-welding operations, select equipment and settings, fabricate articles using arc welding, and perform post-weld operations.
2) The process of arc welding which involves generating an arc between the electrode and workpiece to produce heat and fuse the metals.
3) Procedures for producing an arc and welding bead including cleaning the workpiece, striking an arc by scratching or tapping, and moving the electrode vertically.
4) The role and types of electrodes used in arc welding based on coating, flux composition, and core material
Metals play a vital but complex role in human life. They are essential to many modern technologies and objects we depend on daily, but can also be toxic to human health in certain forms or quantities. While metals cannot be removed from our lives due to their usefulness, their toxic effects mean we must carefully manage their production and disposal. Metals are both hugely beneficial yet also potentially harmful, so a balanced approach is needed.
Subsea Hyperbaric Welding for Pipeline RepairNeil Woodward
A diver-assisted TIG welding system has been successfully employed for pipeline repair and tie-in in the North Sea for the last 20 years. Known as the ‘Pipeline Repair System’, it is operated in water depths down to 180msw. For the last ten years, research and development has been performed in the laboratory, investigating and establishing the capability of the Gas Metal Arc hyperbaric welding process for operation beyond water depths of 180msw (the diver-assisted limit) and down to 2,500msw for remote welding pipeline repair and hot tapping applications. Hyperbaric weld procedures have been qualified down to 1,000msw.
After an extensive equipment design, development, build and test programme the Remote Welding System (RWS) has recently been tested offshore at 310 and 940msw. The Remote Welding System is based upon similar operating principles to the diver-assisted equipment spread: a Habitat, to be deployed around the pipe, to facilitate the creation of a suitably dry fully inert welding environment, and a recoverable Power and Control Module (known as the POCO) to dock onto the Habitat and deploy the remote welding equipment.
The offshore test included full operational sequences of the anticipated pipeline repair scenario: deploying the Remote Welding Habitat (RWH) around the pipe; creating a dry welding environment; deploying the Remote Welding POCO (RWP) and Remote Welding Tool (RWT); entering the Habitat; pre-heating the pipe; multi-pass hyperbaric positional GMA welding and post-weld review; post-weld heating; recovering the Remote Welding Tool and POCO and re-deploying when necessary during the operation; and finally recovering the Remote Welding Habitat after completion of the welding sequence.
In order to qualify the remote welding technology, with the approval of DNV GL, and demonstrate that the offshore equipment is fully capable of producing acceptable welds comparable with those qualified in the laboratory, the 310 and 940msw root and multi-pass welds were subject to Visual, NDT and basic mechanical property testing. The results represent the world’s first acceptable hyperbaric GMA offshore welding operation in the 1,000msw range facilitating the successful capability for pipeline repair applications beyond diver depths.
The document provides a competency-based curriculum for the Shielded Metal Arc Welding (SMAW) NC II qualification in the Metals and Engineering sector. It outlines the course structure, modules of instruction, learning outcomes, assessment methods, resources, and trainer qualifications. The curriculum aims to enhance knowledge and skills for performing shielded metal arc welding work to workplace standards. It covers both basic and core competencies related to welding carbon steel plates and pipes in all positions using SMAW.
The document discusses several safety hazards associated with electric arc welding. It notes that the high temperature arc and hot metal can cause severe burns. The electric arc also emits large amounts of ultraviolet and infrared rays invisible to the eye that can cause eye burns and sunburn. Molten metal droplets from the arc present burn and fire hazards. To be safe, welders must wear protective gear like helmets and gloves and work in well-ventilated areas to avoid burns, electric shock, harmful fumes, and fires. Proper precautions and safety equipment are necessary when engaging in electric arc welding.
The document provides safety guidelines for arc welding equipment and practices. It describes proper use of the power switch, range selector, amperage control, cable attachments, ground clamp, electrode holder, welding table, electrodes, welding helmet, and other protective equipment. Guidelines address ventilation, protective clothing, eye protection, welding fumes, fire hazards, and safe welding behaviors.
1. The document discusses the evolution of engineering materials from stone and wood in ancient times to over 80,000 materials today.
2. Key topics covered include the definitions of material science, material engineering, and classification of materials according to properties and applications.
3. Material selection involves analyzing requirements, evaluating candidate materials, and considering factors like material performance, design constraints, and cost.
This document discusses several welding processes:
- Tungsten inert gas welding uses an arc between a tungsten electrode and the workpiece that is shielded by an inert gas like argon. It is used for high quality welds in metals like aluminum and stainless steel.
- Manual metal arc welding uses a consumable electrode that is consumed during welding. Flux coating on the electrode protects the weld from contamination. It is versatile and widely used for structural steel, pipes, and pressure vessels.
- Metal inert gas welding also uses a consumable electrode that is continuously fed and a shielding gas. It is used for medium thickness fabrications and sheet metal work.
The document discusses several ship failures caused by weld defects. It describes Liberty Ship failures in WWII due to stress concentration and susceptible steel. It also examines more recent failures like the Derbyshire in 1980 which was associated with poor structural strength and design. The document analyzes failure cases in detail using photographs, metallurgical testing, and finite element modeling to understand the root causes, which included poor welds, material defects, corrosion, and inadequate inspection. Proper welding, materials selection, inspection, and risk management are identified as important to prevent future ship failures.
This document provides safety precautions and instructions for shielded metal arc welding (SMAW). It discusses hazards of electric shock, fumes, arc rays, fire and explosions, and flying metal. It also covers principles of SMAW, electrode and amperage selection, techniques for striking an arc and electrode movement, factors that affect weld bead shape, and examples of good and poor welds. Symbols used in welding are explained.
This document provides standards for conducting Charpy impact tests using U-notch specimens for metals. It specifies dimensions and tolerances for standard and subsidiary test pieces, requirements for the testing machine including hammer speed and energy, and test procedures. The standard was revised in 1977 to align with international standards and allow testing of all metals using various specimen sizes.
This document provides information on important engineering materials. It discusses metals including ferrous metals like steel and cast iron, and non-ferrous metals like aluminum, copper, lead, tin, and nickel. It also covers non-metallic materials like wood, ceramics, and abrasives. For each material, the document outlines key properties and applications in engineering.
This document summarizes various common material testing methods. It discusses tensile, compression, shear, hardness (Brinell, Vickers, Rockwell), impact (Izod, Charpy), fatigue, and creep tests. Destructive tests like tensile and compression change the specimen, while hardness tests are non-destructive. Important properties determined include yield strength, tensile strength, and modulus of elasticity. Hardness is a material's resistance to indentation or scratching. Impact and fatigue tests evaluate a material's ability to withstand sudden loads or repeated loading over time. Creep tests measure increased deformation over time under constant stress and temperature.
The document discusses safety practices for working with computer hardware. It advises turning off power when disassembling, installing, or cleaning hardware to protect oneself from electric shocks. It warns never to disassemble monitors or power supplies unless trained, as they can retain dangerous voltages even when unplugged. The document also provides an overview of the motherboard, describing it as the main circuit board that contains the CPU and connections for other components like RAM, storage drives, ports, and the power supply.
Okay, let's solve this step-by-step:
1) Given: Actual area of plot = 1.28 hectares = 12800 sqm
Area shown on map = 8 sqcm
2) To calculate RF:
RF = Actual Dimension / Shown Dimension
RF = 12800 sqm / 8 sqcm
RF = 12800 / 8 = 1600
RF = 1/1600
3) Length of scale = RF x Maximum length to be measured
Maximum length = 100m
Length of scale = 1/1600 x 100m = 6.25cm = 6cm (approx.)
4) Draw a line 6cm long divided into 10 equal parts to read up to 10m
5)
The document summarizes key principles of shielded metal arc welding (SMAW). SMAW is one of the most commonly used welding processes. It uses a consumable electrode covered in flux that protects the weld area from contamination. Various types of welding power sources are described, including constant current sources needed for SMAW. Safety equipment for welders is also listed.
This document outlines safety precautions for metal arc welding. It discusses potential hazards such as burns from hot metal or radiation, electrical shock, and inhalation of dangerous fumes. Key safety recommendations include wearing personal protective equipment like flame-resistant clothing, welding shields, and respiratory protection. Proper ventilation and avoiding confined spaces are also advised to limit exposure to fumes.
Manual metal arc welding, also known as stick welding, involves an electrode coated in flux that is struck by an electric arc to melt and join metal workpieces. It was first developed in the late 1800s using bare metal rods but switched to coated electrodes in the early 1900s which improved weld quality. Electrodes are divided into cellulosic, rutile, and basic types which have different characteristics like burn rate and positional welding capabilities. While once the most common welding process, MIG and MAG welding have now surpassed manual metal arc welding in many applications.
Arc welding is a process that joins metals through intense heat. It requires equipment like an electrode, electrode holder, welding machine and cables. Hazards include falls, crushing injuries, fires/explosions, and electrocution. Proper safety equipment like eye protection and barriers are needed, as well as ensuring a safe work environment and properly maintained welding equipment.
This document defines and describes various defects and discontinuities that can occur in welded joints, including cracks, inclusions, lack of penetration, and improper weld geometry. It explains the causes and prevention methods for each type of defect, as well as repair procedures where possible. The document provides detailed information on defect identification and characterization to help ensure the quality of welded structures.
In the dimly lit conference room, the hum of anticipation fills the air as the audience settles into their seats, eager to delve into the intricate world of welding defects. The projector flickers to life, casting a brilliant glow onto the screen, where a meticulously crafted slide presentation awaits. Each slide is a gateway into the complex realm of welding imperfections, a journey through the pitfalls and challenges faced by welders every day.
The first slide materializes, its title bold and commanding: "Understanding Welding Defects." As the presenter begins to unravel the intricacies of the topic, images of porosity dance across the screen, their irregular patterns a stark reminder of the importance of proper gas shielding. The audience leans in, captivated by the visual representation of gas pockets trapped within the weld, a flaw that compromises structural integrity.
Transitioning to the next slide, the focus shifts to another common defect: lack of fusion. Here, the audience is confronted with images of incomplete weld penetration, a consequence of inadequate heat input or improper technique. As the presenter elaborates on the causes and consequences of this flaw, murmurs of realization ripple through the room, punctuated by nods of understanding.
With each successive slide, the presentation delves deeper into the myriad challenges encountered in the world of welding. Cracks, undercutting, and spatter are dissected with precision, their origins and implications laid bare for all to see. Through meticulously curated visuals and insightful commentary, the audience gains a newfound appreciation for the complexities of the craft.
Yet, amidst the exploration of defects, a thread of optimism weaves its way through the presentation. Each flaw serves not only as a cautionary tale but also as an opportunity for growth and improvement. As the presenter concludes the presentation, the final slide emblazoned with the words "Continuous Improvement," a sense of determination fills the room.
Armed with newfound knowledge and insight, the audience disperses, their minds buzzing with possibilities. For in the world of welding, as in life, it is not the presence of defects that defines us, but rather our ability to acknowledge them, learn from them, and emerge stronger as a result. And as the lights dim and the projector fades to black, the echoes of the presentation linger, a reminder of the power of knowledge and the promise of progress.
As the lights in the conference room slowly brightened, the audience departed with a renewed sense of purpose, their minds buzzing with newfound insights and their resolve strengthened to confront the complexities of welding defects head-on. And as they stepped out into the world beyond, they carried with them not only the lessons learned from the presentation but also the indomitable spirit of innovation and perseverance that defines the welding profession.
The presentation reached its climax and had to be finish
This document defines and describes common defects and discontinuities found in welded joints, including misalignment, undercut, insufficient fill, excessive/improper reinforcement, overlap, burn-through, porosity, slag, and spatter. For each issue, it provides the definition, potential causes, prevention methods, and repair approaches. The goal is to identify ways to avoid defects during welding and correct any issues that do occur.
This document contains a test on shielded metal arc welding (SMAW) concepts. It includes multiple choice, true/false, labeling, and enumeration questions testing knowledge of welding defects, essentials, equipment like electrode ovens, and other technical terms related to SMAW. The test covers topics like arc length, travel angle, porosity, slag inclusion, and electrode identification codes.
The document defines various weld defects such as misalignment, undercut, reinforcement, slag inclusion, and spatter. It provides the definitions, causes, prevention methods, and repair procedures for each defect. Common weld defects include misalignment caused by carelessness or joining different thicknesses, undercut caused by high amperage or long arc length, and excessive reinforcement from slow travel speed or low amperage.
This document discusses common welding defects such as porous welds, poor penetration, warping, undercut, distortion, cracked welds, poor appearance, poor fusion, and spatter. It provides potential causes for these defects such as short arc, insufficient puddling time, impaired base metal, poor electrodes, shrinkage of weld metal, faulty clamping, and uneven heating. The document also gives recommendations on how to prevent or correct these defects, including checking for impurities, allowing more puddling time, using proper current, clamping parts correctly, and adopting the proper welding technique.
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This document provides information on welding inspection and defects/repairs. It discusses various types of welding defects such as cracks, inclusions, lack of fusion, porosity and undercut. Specific defects like longitudinal cracks, slag inclusions, gas pores, overlap and lack of sidewall fusion are defined and illustrated. Potential causes of defects are provided. The document also covers inspection of parent materials, weld repairs and includes sample questions related to defects and repairs.
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1. Porosity
No. Defects Remedies
1. Contamination of work piece Clean joint area.
2. Excessive moisture pickup in electrode covering Store electrodes properly. Follow manufactures recommended rebaking procedure.
3. Moisture of work surfaces Use preheating / warm up work piece.
4. High Sulphur content of base metal Use basic coated electrode.
5. a) Long arc length
b) Excessive current
c) Higher travel speed
Change welding parameters and technique.
Use preheat
6. High solidification rate Increase heat input.
Inclusions
2. No
.
Defects Remedies
1. Improper cleaning procedure Clean work surfaces and each weld run thoroughly. Wherever necessary use power wire brush, grinders, chisels to
ensure a through removal of slag.
2. Improper welding technique
a) Excessive weaving
b) High travel speed
c) Slag flooding ahead of welding arc.
Improve welding technique
Reposition work to prevent loss of slag control wherever possible.
Restrict weaving to a minimum.
3. Narrow, inaccessible joints Increase groove angle.
Incomplete Fusion
No
.
Defects Remedies
1. Improper joint design Increase included angle of groove joint. Change the groove design to a ‘J’ or a ‘U’ type.
3. 2. Presence of slag or oxide flim Clean weld surfaces prior to welding
3. Incorrect electrode position and operation
current
Maintain proper electrode position and current
4. Improper manipulation of arc Use correct manipulation techniques to melt the joint faces properly.
Inadequate Penetration
No
.
Defects Remedies
1. Improper Joint preparation
a) Excessively thick root face
b) Insufficient root opening
c) Bridging of root opening
Use proper joint geometry.
Reduce root face height.
Use wider root opening.
2. Electrode diameter too large Use smaller electrode in root.
3. Inadequate current Follow correct welding current and technique
4. Cracks
No
.
Defects Remedies
1. High rigidity of joint Use preheating
Relieve residual stresses.
Minimize shrinkage stresses, Using back step or block
welding sequences.
2. Poor Joint fit up Adjust root opening all alignment
3. Higher carbon content of weld metal and / or
harden able base material/
Use proper electrode
Use buttering layers wherever necessary
4. Too Small a weld bead Decrease travel speed to increase cross section of bead.
5. High Sulphur content in base or Use filler with high level of weld metal sulphur fixing element like Mn.
5. 6. Hot cracking Reduce the heat input.
7. Cracking at the crater Filling up the crator before withdrawing the electrode
Use taper power control device.
Use back step welding technique
8. Higher harden ability Preheat the job.
Post weld heat treatment without cooling to room temperature.
9. Hydrogen induced cracking /Delayed cracking Use low Hydrogen welding electrode
Use suitable preheat and post Weld heat treatment
10. Presence of brittle phases in the Micro
structure of the base Material
Soften the material before welding.
11. Low ductility of the base material Use preheat.
Anneal the base metal
Use ductile weld metal.
12. High residual stresses Redesign the weld metal and reduce restraints
Change welding sequence
Use intermediate stress-relief Heat treatment.
6. 13. Excessive dilution Change welding current.
Use buttering technique wherever possible.
14. Under Cut Reduce Current
Use proper diameter of Electrode
Reduce weaving
15. Spatter Reduce Current
AWS CLASSIFICATION SFA 5.1 - A FOUR OR A FIVE DIGIT CODING
AWS Classification Type of covering Welding Position Type of current
7. E 6010 High cellulose sodium F,V,OH,H DC(+)
E 6011 High cellulose potassium F,V,OH,H AC/DC(+)
E 6012 High titania sodium F,V,OH,H AC/DC(-)
E 6013 High titania potassium F,V,OH,H AC/DC
E 6020 High iron oxide F,V,OH,H AC/DC(-)
E 6027 High iron oxide iron powder AC/DC(-)
E 7014 Iron powder, titania AC/DC
E 7015 Low hydrogen Sodium F,V,OH,H DC
E 7016 Low hydrogen potassium F,V,OH,H AC/DC(+)
E 7018 Low hydrogen Potassium F,V,OH,H AC/DC (+)
Iron powder
E 7018 M Low hydrogen iron powder F,V,OH,H DC+
E 7024 Iron powder, titania H-fillets, F AC/DC
E 7027 High iron oxide, iron powder H-fillets,F AC/DC(-)
E 7028 Low hydrogen potassium H-fillets, F AC/DC (+)
Iron powder
E 7048 Low hydrogen potassium F,V,OH,H AC/DC/(+)
Iron powder V-down
8.
9.
10. 1.
Transverse
Crater
Throat
Toe
Root
Cold or delayed
Underbead and Heat-affected zone
Hot
o Misalignment (hi-lo)
o Undercut
o Underfill
o Concavity or Convexity
o Excessive reinforcement
o Improper reinforcement
o Overlap
o Burn-through
o Incomplete or Insufficient Penetration
o Incomplete Fusion
o Surface irregularity
Overlap
11. o Arc Strikes
o Base Metal Discontinuities
Lamellar tearing
Laminations and Delaminations
Laps and Seams
o Porosity
Uniformly Scattered
Cluster
Linear
Piping
o Heat-affected zone microstructure alteration
o Base Plate laminations
o Size or dimensions
2. Misalignment (hi-lo)
o Definition: Amount a joint is out of alignment at the root
o Cause: Carelessness. Also due to joining different thicknesses (transition thickness)
o Prevention: Workmanship. Transition angles not to exceed 2.5 to 1.
o Repair: Grinding. Careful on surface finish and direction of grind marks. Inside of Pipe /Tube difficult.
3. Misalignment
4. Undercut
o Definition: A groove cut at the toe of the weld and left unfilled.
o Cause: High amperage, electrode angle, long arc length, rust
o Prevention: Set machine on scrap metal to correct parameters. Clean metal before welding.
o Repair: Weld with smaller electrode, sometimes must be low hydrogen with preheat. Sometimes must gouge first.
5. Undercut
o Undercut typically has an allowable limit. Different codes and standards vary greatly in the allowable amount.
o Plate - the lesser of 0.8mm or 5% (norm)
o ESC EN BS288 allows up to 1mm anything deeper than this must be repaired!
6. Under Cut
7. Insufficient Fill or Under fill
o Definition: The weld surface is below the adjacent surfaces of the base metal
o Cause: Improper welding techniques
o Prevention: Apply proper welding techniques for the weld type and position. Use stripper beads before the cover pass.
o Repair: Simply weld to fill. May require preparation by grinding.
8. Under fill
9. Insufficient Fill on the Root Side (suckback)
o Definition: The weld surface is below the adjacent surfaces of the base metal at the weld root.
12. o Cause: Typically improper joint preparation or excessive weld pool heat.
o Prevention: Correct cause. (see next slide)
o Repair: Backweld to fill. May requireremoval of weld section by grinding for access to the joint root.
10. Cause for Insufficient Fill at the Root Some liquids, like water or molten steel, try to cover as much surface area of whatever they are in contact with as possible.
Welding a root pass too wide can also cause the bead to sag (overhead position).
11.
12.
13. Removing a root pass by grinding 1. Recreate the groove geometry as closely as possible. 2. Use a saw or die grinder and 1/16 - 1/8” cut off wheel to recreate root
opening. Remember repairs are sometimes required to be made with a smaller electrode. 3. Open the groove angle. Be careful to leave the proper root face dimension. 4.
Feather the start and stop to blend smoothly into and out of the existing weld.
14.
15. Excessive Concavity or Convexity
o Definition: Concavity or convexity of a fillet weld which exceeds the specified allowable limits
o Cause: Amperage and travel speed
o Prevention: Observe proper parameters and techniques.
o Repair: Grind off or weld on. Must blend smoothly into the base metal.
16. Concavity
17. Root Concavity
18. Convexity
19. Reinforcement
o Excessive
o Insufficient
o Improper contour
The amount of a groove weld which extends beyond the surface of the plate Face Reinforcement Root Reinforcement
20. Excessive Reinforcement
o Definition: Specifically defined by the standard. Typically, Reinforcement should be flush to 1/16”(pipe) or flush to 1/8” (plate or structural shapes).
o Cause: Travel speed too slow, amperage too low
o Prevention: Set amperage and travel speed on scrap plate.
o Repair: Remove excessive reinforcement and feather the weld toes to a smooth transition to the base plate.
21. Excessive Penetration
22.
o Definition: Specifically defined by the standard. Typically, Underfill may be up to 5% of metal thickness not to exceed 1/32” as long as the thickness is
made up in the opposite reinforcement. Not applied to fillet welds.
o Cause: On root reinforcement - Too little filler metal will cause thinning of the filler metal. In OH position, too hot or too wide will cause drooping of the
open root puddle.
o Prevention: Use proper welding technique. Use backing or consumable inserts. Use back weld or backing.
o Repair: Possibly simply increase the face reinforcement. If backwelding is not possible, must remove and reweld.
13. Insufficient Reinforcement
23.
o Definition: When the weld exhibits less than a 135 0 transition angle at the weld toe.
o Cause: Poor welding technique
o Prevention: Use proper techniques. A weave or whip motion can often eliminate the problem.
o Repair: The weld face must be feathered into the base plate.
135 0 Improper Weld Contour
24. Overlap
o Definition: When the face of the weld extends beyond the toe of the weld
o Cause: Improper welding technique. Typically, electrode angles and travel speed.
o Prevention: Overlap is a contour problem. Proper welding technique will prevent this problem.
o Repair: Overlap must be removed to blend smoothly into the base metal. Be careful of deep grind marks that run transverse to the load. Also be careful of
fusion discontinuities hidden by grinding. Use NDT to be sure.
25. Overlap Overlap is measured with a square edge such as a 6” rule. No amount of overlap is typically allowed.
26. Burn-through (non-standard)
o Definition: When an undesirable open hole has been completely melted through the base metal. The hole may or may not be left open.
o Cause: Excessive heat input.
o Prevention: Reduce heat input by increasing travel speed, use of a heat sink, or by reducing welding parameters.
o Repair: Will be defined by standards. Filling may suffice. Otherwise, removal and rewelding may be required. Some standards may require special filler
metal and/or PWHT.
27. Incomplete or Insufficient Penetration
o Definition: When the weld metal does not extend to the required depth into the joint root
o Cause: Low amperage, low preheat, tight root opening, fast travel speed, short arc length.
o Prevention: Correct the contributing factor(s).
o Repair: Back gouge and back weld or remove and reweld.
28. ICP
29. Incomplete Fusion
o Definition: Where weld metal does not form a cohesive bond with the base metal.
o Cause: Low amperage, steep electrode angles, fast travel speed, short arc gap, lack of preheat, electrode too small, unclean base metal, arc off seam.
o Prevention: Eliminate the potential causes.
o Repair: remove and reweld, being careful to completely remove the defective area. This is sometimes extremely difficult to find.
30. Lack of Side Wall Fusion
31. Arc Strike
o Definition: A localized coalescence outside the weld zone.
o Cause: Carelessness
14. o Prevention: In difficult areas, adjacent areas can be protected using fire blankets.
o Repair: Where applicable, arc strikes must be sanded smooth and tested for cracks. If found, they must be remove and repaired using a qualified repair
procedure and inspected as any other weld.
32. Arc Strike
33. Weld Spatter Causes Prevention High arc power Reduce arc power Magnetic arc blow Reduce arc length or switch to AC power Incorrect settings for GMAW process
Modify electrical settings (but be careful to maintain full fusion Damp electrodes Use dry electrodes
34. Inclusions
o Slag
o Wagontracks
o Tungsten
35.
o Definition: Slag entrapped within the weld
o Cause: Low amperage, improper technique, Trying to weld in an area that is too tight. Slow travel in Vertical Down
o Prevention: Increase amperage or preheat, grind out tight areas to gain access to bottom of joint.
o Repair: Remove by grinding. Reweld.
Slag Inclusion
36. Slag Inclusion
37.
o Definition: Slang term for a groove left at the toe of a root pass which becomes filled with slag and is trapped in the weld.
o Cause: The contour of the root pass is too high, or the weld toe is not bonded to the base metal
o Prevention: Use proper technique to deposit the weld root.
o Repair: Best repaired before applying the hot pass. Carefully grind the root pass face flat. be careful not to gouge other areas on the weldment.
Wagon Tracks (non-standard)
38.
o Definition: A tungsten particle embedded in a weld. (Typically GTAW only)
o Cause: Tungsten electrode too small, amperage too high, AC balance on +, Upslope too high, electrode tip not snipped, electrode dipped into the weld
pool or touched with the fill rod, electrode split.
o Prevention: Eliminate the cause
o Repair: Grind out and reweld
Tungsten Inclusion
39. Inclusions
o fix when you see it. otherwise grind out & fix
15. 40. Whiskers
o Unsightly
o Inhibits material flow in piping
o Are inclusions
o Can break off in pipes and damage equipment downline
41. Spatter
o Definition: Small particles of weld metal expelled from the welding operation which adhere to the base metal surface.
o Cause: Long arc length, severe electrode angles, high amperages.
o Prevention: Correct the cause. Base metal can be protected with coverings or hi-temp paints.
o Repair: Remove by grinding or sanding. Sometimes must be tested as if it were a weld.
42. Arc Craters
o Definition: A depression left at the termination of the weld where the weld pool is left unfilled.
o Cause: Improper weld termination techniques
o Prevention:
o Repair: If no cracks exist, simply fill in the crater. Generally welding from beyond the crater back into the crater.
43. Cracks
o Longitudinal
o Transverse
o Crater
o Throat
o Toe
o Root
o Underbead and Heat-affected zone
o Hot
o Cold or delayed
44.
o Definition: A crack running in the direction of the weld axis. May be found in the weld or base metal.
o Cause: Preheat or fast cooling problem. Also caused by shrinkage stresses in high constraint areas.
o Prevention: Weld toward areas of less constraint. Also preheat to even out the cooling rates.
o Repair: Remove and reweld
Longitudinal Crack
45.
o Definition: A crack running into or inside a weld, transverse to the weld axis direction.
o Cause: Weld metal hardness problem
o Prevention: Minimize heat input and monitor interpass temperature max 200 c
16. o Repair: Dependant on specification and matterial
Transverse Crack
46.
o Definition: A crack, generally in the shape of an “X” which is found in a crater. Crater cracks are hot cracks.
o Cause: The center of the weld pool becomes solid before the outside of the weld pool, pulling the center apart during cooling
o Prevention: Use crater fill, fill the crater at weld termination and/or preheat to even out the cooling of the puddle
o Repair:
Crater Crack
47.
o Definition: A longitudinal crack located in the weld throat area.
o Cause: Transverse Stresses, probably from shrinkage. Indicates inadequate filler metal selection or welding procedure. May be due to crater crack
propagation.
o Prevention: Correct initial cause. Increasing preheat may prevent it. be sure not to leave a crater. Use a more ductile filler material.
o Repair: Remove and reweld using appropriate procedure. Be sure to correct initial problem first.
Throat Crack
48.
o Definition: A crack in the base metal beginning at the toe of the weld
o Cause: Transverse shrinkage stresses. Indicates a HAZ brittleness problem.
o Prevention: Increase preheat if possible, or use a more ductile filler material.
o Repair:
Toe Crack
49. Toe Crack
50.
o Definition: A crack in the weld at the weld root.
o Cause: Transverse shrinkage stresses. Same as a throat crack.
o Prevention: Same as a throat crack
o Repair:
17. Root Crack
51. Root Crack
52.
o Definition: A crack in the unmelted parent metal of the HAZ.
o Cause: Hydrogen embrittlement
o Prevention: Use Lo/Hi electrodes and/or preheat
o Repair: (only found using NDT). Remove and reweld.
Underbead Crack
53.
o Definition: A crack in the weld that occurs during solidification.
o Cause: Micro stresses from weld metal shrinkage pulling apart weld metal as it cools from liquid to solid temp.
o Prevention: Preheat or use a low tensil filler material.
o Repair:
Hot Crack
54.
o Definition: A crack that occurs after the metal has completely solidified
o Cause: Shrinkage, Highly restrained welds, Discontinuities
o Prevention: Preheat, weld toward areas of less constraint, use a more ductile weld metal
o Repair: Remove and reweld, correct problem first, preheat may be necessary.
Cold Crack
55. Cold Crack or Weld Metal Hydrogen Crack
56. Repairs to Cracks
o Determine the cause
o Correct the problem
o Take precautions to prevent reoccurrence
o Generally required to repair using a smaller electrode
57. Base Metal Discontinuities
o Lamellar tearing
o Laminations and Delaminations
o Laps and Seams
18. 58. Lamellar Tearing
59. Laminations
o Base Metal Discontinuity
o May require repair prior to welding
o Formed during the milling process
60. Lamination effects can be reduced by joint design:
61. Laps and Seams A mill-induced discontinuity in which results from a lump of metal being squeezed over into the surface of the material. If beyond acceptable limits,
must be removed and repaired or discarded.
62. Porosity
o Single Pore
o Uniformly Scattered
o Cluster
o Linear
o Piping
63. Porosity
64. Single Pore
o Separated by at least their own diameter along the axis of the weld
65. Uniformly Scattered Porosity
o Typically judged by diameter and proximity to a start or stop
o often caused by low amperage or short arc gap or an unshielded weld start
66. Cluster Porosity
o Typically viewed as a single large discontinuity
67. Linear Porosity
o being linear greatly affects the severity of this discontinuity
68. Piping Porosity
o Generally has special allowable limits
69. Porosity
o preheat will help eliminate
o may need an electrode with more deoxidizers
o Use run-on/run-off taps
o restart on top of previous weld and grind off lump
70. Heat-affected zone microstructure alteration
o add drawing of HAZ of groove weld with leaders to:
grain refinement
grain growth
hardened areas
softened areas
precipitate suseptable areas.
71. Size or dimension
19. o If it renders the part unusable, it is a defect.
o If it is outside the allowable limit, it renders the part unusable.
o Things don’t have to be perfect, just within the acceptable tolerance. Working to perfection is too time consuming and costly
72. Hammer marks
o Stress risers
o Unsightly
o Unnecessary
73. REPAIR TECHNIQUES
o May involve:
different process
different procedure
different preheat/PWHT
different electrode
smaller electrode
74. Only repair defects. Discontinuities are by definition acceptable. Repair is therefore unnecessary and not cost effective.