Senior High School Shielded Metal Arc Welding NC II Quarter 1 Module 1 Perform Groove Weld on Carbon Steel Plates and Pipes Department of Education • Republic of the Philippines
Shielded Metal Arc Welding – Grade 11 Alternative Delivery Mode Quarter 1-4 – Module 1-4: First Edition, 2020 Republic Act 8293, section 176 states that: No copyright shall subsist in any work of the Government of the Philippines. However, prior approval of the government agency or office wherein the work is created shall be necessary for exploitation of such work for profit. Such agency or office may, among other things, impose as a condition the payment of royalties. Borrowed materials (i.e., songs, poems, pictures, photos, brand names, trademarks, etc.) included in this book are owned by their respective copyright holders. Every effort has been exerted to locate and seek permission to use these materials from their respective copyright owners. The publisher and authors do not represent nor claim ownership over them. Published by the Department of Education Secretary: Leonor M. Briones Undersecretary: _______________________________ Assistant Secretary: _______________________________ Development Team of the Module Writers: King Romy Sean C. Oculam; Randy C. Nadera Content Editors: Cherry Q. Sadicon; Fe L. Dalugdug; Sheila T. Arrelano Language Editor: Cleo C. Canonce Proofreader: Marsha Liza L. Ragot Illustrator: Joanne A. Comahig Layout Artist: Norman D. Balino Development Team: Chairperson: Dr. Arturo B. Bayocot, CESO III Co-Chairperson: Regional Director Dr. Victor G. De Gracia Jr. CESO V Asst. Regional Director Jonathan S. Dela Peña, PhD, CESO V Schools Division Superintendent Rowena H. Para-on, PhD Assistant Schools Division Superintendent Mala Epra B. Magnaong, Chief ES, CLMD Members: Neil A. Improgo, PhD, EPS-LRMS; Bienvenido U. Tagolimot, Jr., PhD, EPS-AMD; Erlinda G. Dael, PhD, CID Chief; Norberto E. Rosales, EPS-TVL; Celieto B. Magsayo, LRMS Manager; Loucile L. Paclar , Librarian II; Kim Eric G. Lubguban, PDO II Printed in the Philippines by ______________________________________ Department of Education – Bureau of Learning Resources (DepEd-BLR) Office Address: Zone 1, Upper Balulang, Cagayan de Oro City 9000 Telefax: (088) 880-7071, (088) 880-7072 E-mail Address: [email protected]
Senior High School Shielded Metal Arc Welding NCII Quarter 1 -Module 1: Perform Groove Weld on Carbon Steel Plates and Pipes This instructional material was collaboratively developed and reviewed by educators from public and private schools, colleges, and/or universities. We encourage teachers and other education stakeholders to email their feedback, comments, and recommendations to the Department of Education at [email protected]. We value your feedback and recommendations. Department of Education • Republic of the Philippines 3
Introduction Shielded Metal Arc Welding(SMAW) is an arc welding process in which the fusing of metals is produced by heat from an electric arc that is maintained between the tip of a consumable covered electrode and the surface of the base metal in the joint being welded. Shielded Metal Arc welding is one of the most widely used welding processes, particularly for short welds in production, maintenance, repair work, and field construction. This module entitled “Perform Groove Weld on Carbon Steel Plates and Pipes using SMAW” is one of the learning outcomes of SMAW NC II offered by DepEd in Senior High School under the track Technical Vocational Livelihood strand Industrial Arts. It is a training program which comprises the knowledge, skills and attitude of a welder. This module contains training materials and activities related to the welding activities. This module will equip you the fundamentals of welding and mechanics on how to apply safety practices, weld on groove in flat position, identify the acceptable weld profile, and weld defects so that you can apply corrective actions to be certified as welder and will also serve as a vital tool for Distance Learning. In this module, you are required to go through a series of learning activities in order to complete each learning outcome. This module provides Lesson Information and Self-Checks that will help you deepen your understanding of the concepts, competencies, and learning outcomes. Follow and answer the activities on your own. If you have questions, do not hesitate to ask for assistance from your facilitator/teacher. Remember the following instructions: • Read Lesson Information and complete self-checks. • Perform the Performance Task until you are confident that your outputs conform to the Performance Criteria that follows after every lesson. • Submit answers of the Self-Checks and outputs of the Task Sheets to your facilitator/teacher for evaluation and recording in the Accomplishment Chart. Outputs shall serve as your portfolio during the Institutional Learning Outcome Evaluation. • When you feel confident that you have had sufficient practice, ask your trainer to evaluate you. The results of your assessment will be recorded in your E- Class Record and your progress will be recorded in your Achievement Chart. 4
Table of Contents Quarter 1 Lesson 1 Weld Carbon Steel Plate in Flat Position(1G) Pretest………………………………………………………………….........................4 Definition of Terms……………………………………………………….....................8 Lesson Information 1.1: Fundamentals of Welding…………………………9 Self-Check 1.1……………………………………...11 Lesson Information 1.2: Safety Welding Practices………………………….12 Self-Check 1.2……………………………………...16 Lesson Information 1.3: 5S of Good Housekeeping………………………..17 Self-Check 1.3……………………………………...19 Lesson Information 1.4: Acceptable and (Unacceptable) Welding Profile..20 Self-Check 1.4………………………………………21 Lesson Information 1.5: Welding Defects, Causes, and Remedies……….24 Self-Check 1.5………………………………………31 Lesson Information 1.6: Perform Root Pass and Multi-Layer Deposit in …32 Flat Position Application………………………………………………………………………………..41 Progress Chart…………………………………………………………………………..42 Generalization……………………………….............................................................43 Posttest…………………………………………………………………………………...44 Answer Key……………………………………………………………………………....47 Reference………………………………………………………………………………...50 5
Pretest Let us determine your prior knowledge on the topic/task in Performing Groove Weld on Carbon Steel Plates and Pipes by taking this pretest. I. Multiple Choice: Directions: Read and analyze the statements carefully. Choose the correct answer and write the letter only on your separate answer sheet. 1. ______________________ are generated in a welding job due to the faulty or poor technique used by the inexperienced or unskilled welder or due to fundamental difficulties in the welding operation. a. Spatter c. Penetration b. Welding defects d. Porosity 2. ____________________ occurs when the depth of the welded joint is insufficient. a. Incomplete penetration c. Spatter b. Porosity d. Welding defects 3. ___________________ cracking is due to tearing of the grain boundaries of weld metal before complete hardening has taken place and metal is still in the plastic state. a. Hot tear c. Distortion b. Solidification d. Undercut 4. ________________ is also known as solidification cracking state. a. Hot tear c. Groove b. Distortion d. Undercut 5. ____________________ is defined as the distance from the base plate top surface to the maximum extent of the weld nugget. a. Porosity c. Undercut b. Distortion d. Penetration 6. It refers to organization of necessary items in good order and easy access. a. Seiri (Sort) c. Seiton (Systematize) b. Seiso (Sweep) d. Shitsuke (Self Descipline) 7. It means taking out and disposing unnecessary items. a. Seiri (Sort) c. Seiketsu (Sanitize/Standardize) b. Seiso (Sweep) d. Seiton (Systematize) 8. It is used to protect arms from falling flux or hot sparks. a. Welding mask c. Welding sleeve b. Leggings d. Safety apron 6
9. It is a working suit that is used in workplace as whole body protection from sparkling of equipment. a. Full body harness c. Safety shoes b. Cover all d. Safety apron 10. They protect feet from hot sparks or falling objects. a. Welding sleeves c. Safety glass b. Safety shoes d. Welding gloves 11. A shallow fusion between weld metal and based metal. a. Spatter c. Penetration b. Porosity d. Incomplete penetration 12. It is due to excessive heat input and creates hole. a. Burn-through c. Penetration b. Porosity d. Incomplete penetration 13. ____________________ is a group of small voids and blowholes that are comparatively bigger isolated holes or cavities. a. Spatter c. Penetration b. Porosity d. Welding defects 14. _________________ is a kind of weld defect which forms a groove in the parent metal along with the sides of the weld bead. a. Groove c. Distortion b. Hot tear d. Undercut 15. It is cause of not following the welding principle or procedures and lack of skill of a welder. a. Spatter c. Penetration b. Porosity d. Welding defects 7
II. Matching Type Directions: Match the pictures of Column A with the words or group of words in column B. Write only the letter of your choice in your separate answer sheet. Item Column A Letter Column B No. 16 a Excessive undercut 17 b Insufficient throat 18 c Insufficient leg 19 d Desirable fillet weld profiles 20 e Butt joint-unequal thickness plate 8
21 f Incomplete fusion 22 g Maximum 1/16 in. (1.6mm) convexity 1/8 in. (3mm) 3/16 in. (5mm) h Overlap 23 i Excessive convexity 24 j Desirable fillet 25 weld profiles 9
Definition of Terms Alternate Current - it is when electrical current alternates or reverses the direction of electron flow. Amperage - is a measure of electrical current flowing through a circuit and is an indication of the heat being produced. Arc Welding - uses electricity to heat and melt the metal. Direct Current - electron flow in one direction. Electricity - is the flow of tiny particles called electrons through a conductor. Electrode - is a bare metal rod which is usually coated with chemical compounds called flux. Fumes - are produced when cutting metal containing zinc and are injurious when inhaled. Hazard - is any source of potential damage, harm or adverse health effects on something or someone. Penetration - is the distance that the fusion line extends below the surface of the material being welded. Polarity - is the direction the current is flowing. Rays - are given off by the arc are the same as those transmitted by sunlight and can cause severe burn. Reverse Polarity- it is when the electrons flow from work piece to the electrode. Risk - the combination of the likelihood of the occurrence of a harm and severity of that harm. Straight Polarity - it is when the electrons flow from the electrode to the workpiece. Welding - is the melting, flowing together and freezing of metals under controlled conditions. Voltage - is a measure of electrical pressure. 10
What is it? Lesson 1 Weld Carbon Steel Plate in Flat Position (1G) Lesson Information 1.1 Fundamentals of Welding After reading the Information Sheet, the trainee must be able to determine the fundamentals of welding. Weld quality and consistency can only be maintained with respect to the five fundamentals. The five fundamentals of welding include the use of correct electrode size, current, arc length or voltage, travel speed and electrode angles. All five must be collectively and consistently maintained to successfully control the puddle and produce a weld that is uniform in appearance, has consistent ripples, smooth face contour, and no noticeable defect. Once the welder masters the ability to consistently maintain the five fundamentals, the ability to control the puddle will follow. Current Setting The correct current setting is vital for maintaining consistency in weld quality. If the current is too high, the electrode melts too fast, and the molten pool is larger and irregular. If the current is too high when welding single vee groove, it may blow holes through the joint and cause large molten metal droplets to fall out of the groove. If the current is too low, there is not enough heat to melt the base metal. The molten pool appears too small, piles up, and looks irregular. I t c a n re s u lt t o poor penetration and incomplete fusion in the joint. Length of an Arc Is very important for weld puddle control. Correct arc length will cause the deposit to be neat of even ripple and of good penetration. Too long arc length will cause the deposit to coarse ripple and flatter than normal with an increase in spatter. When welding a root pass in an open root vee groove, the keyhole can grow too large and loose of weld control can result. Too short an arc will cause deposited to be narrow, uneven and irregularly rippled and with poor fusion. The arc length reduces the voltage and increases the amperage slightly but the electrode may stick to the work. When welding root passes, too short an arc length often results in loss of the keyhole. 11
Angle of Electrode One of the fundamentals is the use of the correct electrode angles. For fillet and groove welds, correct electrode angles are vital for preventing undercut and inadequate fill. When depositing a fillet weld, the electrode should be held so that it bisects the angle between the plates and is perpendicular to the line of the weld. On groove weld, the technique is much the same; although varying slightly with multiple pass welding. There are two teams to specify electrode angles. These are travel angle and work angle. The travel angle applies to the position the electrode makes with a reference perpendicular to the axis of the weld in plane of the weld axis. It can be either a drag angle or a push angle. A drag angle is when the electrode is pointing backward, which means, the welder’s hand and electrode holder precede the puddle. A push angle is when electrode is pointing just the opposite of the drag. The work angle is the position the electrode makes with reference to the surface of the plate on a plane perpendicular to the weld axis. On butt joints, the work angle is usually 90 degrees to the surface of the plate. To some degree, you can correct for an improper condition by varying the essential variables. It is better though to have all conditions as correct as possible. Manipulation of Electrode Choosing the correct electrode size involves many factors. If a smaller recommended electrode is used, welding time and heat to the joint will increase. It can result in increased costs, heat affected zone, cracking or distortion. Larger electrode can cause melt through and can be difficult to control in out of position joint. Poor appearance and possible defects can result. The welding procedure designates the correct electrode size, generally based on metal type and thickness. However, if no procedure or instruction is available, the welder will have to choose the correct electrode size. Speed of Travel Incorrect travel is a common mistake. Sometimes travel speed is the only condition a welder may need to change. Travelling fast causes the puddle to freeze too quickly. Because of this, impurities and gases can be entrapped, making the bead face narrow with pointing ripple. Incomplete penetration due to loss of the keyhole in root pass is possible. Travelling too slow will cause the puddle to be large, with pile up, and a straight ripple pattern. For out of position welding, slow travel speed can cause the puddle to drip out the joint. 12
Assessment Self-Check 1.1 I. TRUE OR FALSE Directions: Read each statement below carefully. Write TRUE if the statement is correct and FALSE if the statement is not correct on your separate answer sheet. 1. Using a larger electrode diameter can cause melt through/ burn through. 2. Travelling too fast will make the bead face narrow with pointing ripple. 3. If the current is too low, the electrode melts too fast. 4. Quality or sound weld is the result of correct current, constant voltage, travel speed, electrode angle and correct electrode size. 5. In fillet weld, electrode angle is not necessary for preventing undercut and under fill. 6. Welding is the process of joining together two pieces of metal so that bonding takes place at their original boundary surfaces. 7. Electrode circumference is based on the thickness of the base metal, the welding position, and the type of joint to be weld. 8. Each type of electrode has recommended amperage ranges for optimum performance. 9. High amperage could also cause the electrode coating to overheat and break down. 10. Arc length is the distance from the tip of the electrode core wire to the electrode handle. 13
What is it? Lesson Information 1.2 Safe Welding Practices What are the safety practices that should be observed when doing shielded metal arc welding? The following are suggested practices and tips that will help to eliminate shop accidents when arc welding. 1. Wear a welding mask. Wear leather or welding gloves at all times when arc welding to protect against hot electrodes, particles of spatter and slag, or the metal being welded. Welding Mask Welding Gloves Safety Helmet Source: https://www.alibaba.com/trade 2. Wear safety shoes to protect your feet and ankles from burns caused by weld spatter. Safety Shoes Source: https://www.alibaba.com/trade 14
3. Do not wear clothing with turned up cuffs. Keep your collar and pockets buttoned. Do not wear ragged, oily or greasy clothing. Never weld when your body is exposed, as when not wearing a shirt, or wearing a short-sleeved shirt or shorts. If welding apron is not available, wear cover all clothing rather than cotton. Cover all does not ignite as readily and provides better protection from heat. Leather Jacket Full Body Harness Source: https://www.alibaba.com/trade 4. Inspect welding cables for broken insulation and frayed conductors. Check electrode holder and ground clamps for positive connections before beginning to weld. Loose connections and grounds may prove dangerous. Provide a dry wooden platform to stand on or wear rubber soled shoes where there are damp floors. Source: www.MillerWelds.com 15
5. Clear all flammable materials away from the welding area before beginning to weld. Flying sparks from the spatter may ignite flammable material several feet from the welding operation. Clear the welding area of rags, straw, paper, shavings, and other flammable items before starting to weld. Flammable Sparks Source: www.MillerWelds.com 6. Keep matches, lighters, papers, and cellophane wrappers out of pockets as these items ignite quickly and/or may explode. Explode Source: www.MillerWelds.com 7. Turn on an exhaust system or industrial fan before beginning to weld. Welding fumes soon spread to all parts of the shop and may be injurious when inhaled. Take special measures to avoid noxious fumes that occur when welding or cutting metals containing zinc. Inhaling zinc fumes will cause you to feel ill for several hours after welding. Injured Fumes Cut Hands Source: www.MillerWelds.com 8. Do not strike an arc before covering face and eyes with the protective welding mask. The ultraviolet light rays given off by the arc are the same as those transmitted by sunlight, except that they are more intense and concentrated. Exposure to these rays will cause a severe burn. Eye irritation and burn will result if your eyes are not shielded. Protective Equipment Source: www.MillerWelds.com 16
9. Protect other workers by using a welding screen to enclose your area. Warn persons standing nearby, by saying “cover”, to cover their eyes when you are ready to strike an arc. 10. Never look directly at the arc without protecting your eyes. The rays can penetrate through closed eyelids if you are welding at close range. Do not wear contact lenses while welding or around a welder. 11. Do not weld barrels, tanks or other containers which may have held combustible material. These operations are best performed by professional welders. 12. Do not chip slag from a weld unless your eyes and those of others near you are protected by safety glass. Safety Glass Respirator Source: https://www.alibaba.com/trade 13. Be alert for fires at all times because when the operator’s welding mask is lowered, clothing may catch fire without being noticed. Use your senses of touch, smell, and hearing to indicate that something is wrong. In case of a clothing fire, strip off the clothing if possible. Do not run, as running fans the flames, instead, wrap yourself in a fire blanket, or improvise with a coat or a piece of canvas. If there is nothing at hand to wrap in, drop to the floor and roll slowly. Ear Muff Source: https://www.alibaba.com/trade 14. Handle all hot metals with tongs or pliers to prevent burning your hands or gloves. Place all hot metals where no one will come in contact with. Develop the habit of feeling all metals cautiously before picking them up. Do not leave hot metals where anyone may pick them up or step on them. 15. Guard against saturation of clothing by perspiration or moisture. This increases the shock hazard. 16. Disconnect the welding machine when repairing or adjusting it. 17. Always unplug the welding machine and put all equipment away when you have finished for the day. 18. In case of eye or skin burns, get first-aid treatment. Report immediately to the instructor all burns and injuries. 19. Protect fuel tanks and fuel lines with wet sheet asbestos when welding near motors or power units. The paint on machinery also may start to burn from the heat of welding. 17
Assessment Self-Check 1.2 I. TRUE or FALSE Directions: In the following suggested welding practices and tips listed below, answer T if the statement is TRUE and F if it is FALSE. Write your answers on your separate answer sheet. 1. Wear a welding helmet. 2. Wear leather or special fabric gloves at all times when arc welding to protect from hot electrodes, particles of spatter and slag, or the metal being welded. 3. Wear high-top shoes to protect your feet and ankles from burns caused by weld spatter. 4. Wear clothing with turned up cuffs. 5. Keep your collar and pockets unbuttoned. 6. Do not wear ragged, oily or greasy clothing. 7. Never weld when your body is exposed, as when not wearing a shirt, or wearing a short-sleeved shirt or shorts. 8. Wool does not ignite as readily and provides better protection from heat. 9. Inspect welding cables for broken bones and frayed conductors. 10. Check electrode holder and ground clamps for positive connections before beginning to weld. II. Multiple Choice: Determine the appropriate Personal Protective Equipment (PPE) to be used. Write your answers on your separate answer sheet. 1. They protect feet from hot sparks or falling objects. a. Welding sleeves c. Safety glass b. Safety shoes d. Welding gloves 2. It protects the body from hot sparks. a. Leather Jacket c. Cover all b. Safety glass d. Respirator 3. It is a Personal Protective Equipment (PPE) that is used in working heights. a. Leggings c. Full body harness b. Welding Mask d. Safety glass 4. It is used to protect arms from falling flux or hot sparks. a. Welding mask c. Welding sleeve b. Leggings d. Safety apron 5. It is a working suit that is used in workplace as whole body protection from sparkling of equipment. a. Full body harness c. Safety shoes b. Cover all d. Safety apron 18
What is it? Lesson Information 1.3 5S of Good Housekeeping What is the 5S system? 1. SEIRI - SORT • Taking out and disposing unnecessary items. • Unneeded items are thrown away or disposed. Source: http://www.oshc.dole.gov.ph/images/5S.jpg 2. SEITON – SYSTEMATIZE • Organizing of necessary items in good order and easy access. • Items in the workplace are arranged for ease of access and repeated use. Source: http://www.oshc.dole.gov.ph/images/5S.jpg 19
3. SEISO- SWEEP • Cleaning of the workplace after usage or even if things are not dirty. Source: http://www.oshc.dole.gov.ph/images/5S.jpg 4. SEIKETSU- SANITIZE/STANDARDIZE • Maintaining the workplace in high standard of housekeeping and sanitation. • Disinfection prevents the spread of microorganism that cannot be seen with your naked eyes. Source: http://www.oshc.dole.gov.ph/images/5S.jpg 5. SHITSUKE – SELF DISCIPLINE • Doing things spontaneously without being told. • Even if you have the knowledge and skills but you do not practice self-discipline, they are still considered as useless. Source: http://www.oshc.dole.gov.ph/images/5S.jpg 20
Assessment Self-Check 1.3 Directions: Give an idea of the following based on your own understanding. Write your answers on your separate answer sheet. 1. Sort _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ 2. Systematize _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ 3. Sweep _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ 4. Standardize _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ 5. Self-Discipline ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ 21
What is it? Lesson Information 1.4 Acceptable (and Unacceptable) Weld Profiles Source: http://nattesting.com/acceptable_weld.htm 22
Assessment Self-Check 1.4 Matching Type Directions: Match the pictures of Column A with the words or group of words in column B. Write only the letter of your choice on your separate answer sheet. Item Column A Letter Column B No. 1 a Desirable fillet weld profiles 2 b Acceptable fillet weld profiles 3 c Insufficient throat 4 d Excessive convexity 5 e Excessive undercut 23
6 f Overlap 7 g Insufficient leg 8 h Incomplete fusion 9 i Butt joint-equal thickness plate 10 1/16 in. (1.6mm) j Butt joint-unequal 1/8 in. (3mm) thickness plate 3/16 in. (5mm) k Butt joint-Excessive 11 convexity 12 l Butt joint- insufficient throat 24
13 m Butt joint-excessive undercut 14 n Butt joint-overlap 15 o Maximum convexity 25
What is it? Lesson Information 1.5 Weld Defects, Causes and Remedies What are Welding Defects? Welding defects are generated in a welding job due to the faulty or poor technique used by the inexperienced or unskilled welder or due to fundamental difficulties in the welding operation. An ideal weld or good weld should be such that adequate fusion exists between the filler metal and edge preparation together with good penetration. Types of Welding Defects: Welding defects are broadly classified into two categories, and these are: 1. External welding defects (Defects occur on the upper surface of the welded work). 2. Internal welding defects (Defects occur under the surface of the welded work). I. External Welding Defects: The various types of external defects with their causes and remedies are listed below: A. Weld Crack This is the most unwanted defect of all the other welding defects. Welding cracks can be present at the surface, inside of the weld material or at the heat affected zones. Source: www.theweldingmaster.com Crack can also appear at different temperatures: 1. Hot Crack – It is more prominent during crystallization of weld joints where the temperature can rise more than 10,000-degree Celsius. 2. Cold Crack – This type of crack occurs at the end of the welding process where the temperature is quite low. Sometimes cold crack is visible several hours after welding or even after few days. 26
Causes of Weld Crack: 1. Poor ductility of the given base metal 2. The presence of residual stress can cause a crack on the weld metal. 3. The rigidity of the joint which makes it difficult to expand or contract the metals. 4. If there is high content on sulphur and carbon then also the cracks may appear. 5. Using hydrogen as a shielding gas while welding ferrous materials. Remedies for Weld crack: 1. Using appropriate materials may decrease the chances of crack. 2. Preheating the weld and reducing the cooling speed joint helps in reducing crack. 3. Reduce the gap between the weld joints by using reasonable weld joints. 4. While welding releases the clamping force slowly which increases fill to capacity of welding material. B. Undercut When the base of metal melts away from the weld zone, then a groove is formed in the shape of a notch, then this type of defect is known as undercut. It reduces the fatigue strength of the joint. Source: www.theweldingmaster.com Causes of Undercut: 1. If the arc voltage is very high then this defect may occur. 2. If we use the wrong electrode or if the angle of the electrode is wrong, then also the defect may form. 3. Using a large electrode is also not advisable. 4. High electrode speed is also one of the reasons for this defect. Remedies for Undercut: 1. Reduce the arc length or lower the arc voltage. 2. Keep the electrode angle from 30 to 45 degree with the standing leg. 3. The diameter of the electrode should be small. 4. Reduce the travel speed of the electrode. 27
C. Spatter When some metal drops are expelled from the weld and remain stuck to the surface, then this defect is known as spatter. Source: www.MillerWelds.com Causes of Spatter: 1. High welding current can cause this defect. 2. The longer the arc the more chances of getting this defect. 3. Incorrect polarity 4. Improper gas shielded may also cause this defect. Remedies for Spatter: 1. Reducing the arc length and welding current 2. Using the right polarity and according to the conditions of the welding 3. Increasing the plate angle and using proper gas shielding D. Porosity Porosity refers to small cavities or holes resulting from gas pockets in weld metal. Source: www.MillerWelds.com Causes of Porosity: 1. It occurs when the electrode is not coated properly. 2. Using a longer arc may also increase its chances. 3. Increased welding currents. 4. Rust or oil on the welding surface. Remedies for Porosity: 1. Proper selection of the electrode 2. Decreasing the welding current 3. Using smaller arc and slowing the process to allow the gases to escape 4. Remove rust or oil from the surface and use a proper technique 28
E. Overlap When the weld face extends beyond the weld toe, then this defect occurs. In this condition the weld metal rolls and forms an angle less than 90 degrees. Source: www.theweldingmaster.com Causes of Overlap: 1. Improper welding technique 2. By using large electrodes this defect may occur. 3. High welding current Remedies for Overlap: 1. Use a proper technique for welding. 2. Use small electrode. 3. Less welding current. F. Distortion Distortion means contraction of weld metal during welding that forces base metal to move. Source: www.MillerWelds.com Causes of Distortion: 1. A great number of passes with small diameter electrodes 2. Slow arc travel speed 3. High residual stresses in the plate to be welded 4. Using improper welding sequences Remedies of Distortion: 1. Use the proper amount of weld metal as per the requirement of the joint. It will reduce the contraction forces. 2. Use an appropriate number of weld passes. 3. Place the weld near the neutral axis. 4. Use proper welding sequences. G. Burn-Through 29
Burn- Through refers to weld metal melting completely through base metal resulting in holes where no metal remains. Source: www.MillerWelds.com Cause of Burn-Through: 1. Excessive heat input Remedies of Burn-Through: 1. Select lower amperage. Use smaller electrode. 2. Increase and/or maintain steady travel speed. II. Internal Welding Defects: The various types of internal defects with their causes and remedies are listed below: A. Slag Inclusion If there is any slag in the weld, then it affects the toughness and metal weldability of the given material. This decreases the structural performance of the weld material. Slag is formed on the surface of the weld or between the welding turns. Source: www.theweldingmaster.com Causes of Slag: 1. Slag is formed if the welding current density is very small, as it does not provide the required amount of heat for melting the metal surface. 2. If the welding speed is too fast then also slag may occur. 3. If the edge of the weld surface is not cleaned properly then also slag may form. 4. Improper welding angle and travel rate of welding rod Remedies for Slag Inclusion: 1. Increase the current density. 30
2. Adjust the welding speed so that the slag and weld pool do not mix with each other. 3. Clean the weld edges and remove the slags of previous weld layers. 4. Have a proper electrode angle and travel rate. B. Incomplete Fusion Incomplete fusion occurs when the welder does not accurately weld the material and the metal pre solidifies which leads to a gap which is not filled with the molten metal. Source: www.theweldingmaster.com Causes of Incomplete fusion: 1. It occurs because of the low heat input. 2. When the weld pool is very large and runs ahead of the arc. 3. When the angle of the joint is too low. 4. Incorrect electrode and torch angle may also lead to incomplete fusion. 5. Improper bead position Remedies for Incomplete Fusion: 1. Increasing the welding current and decreasing the travel speed helps in removing the chances of incomplete fusion. 2. Reducing the deposition rate. 3. Increasing the joint angle. 4. Try to position the electrode and torch angle properly so that the edges of the plate melt away. 5. Positioning the bead properly so that the sharp edges with other beads can be avoided. 31
C. Incompletely Filled Groove or Incomplete Penetration These defects occur only in the butt welds where the groove of the metal is not filled completely. It is also called as incomplete penetration defect. Source: www.theweldingmaster.com Causes of an Incomplete Filled Groove: 1. Less deposition of the weld metal 2. Use of improper size of the electrode 3. Improper welding technique Remedies for Incomplete Filled Groove: 1. More deposition of the weld metal. 2. Use a proper size of the electrode. 3. By using a proper welding technique. 32
Assessment Self-Check 1.5 Multiple Choice: Directions: Read and analyze the statement carefully. Choose the correct answer and write the letter only on your separate answer sheet. 1. ______________________ are generated in a welding job due to the faulty or poor technique used by the inexperienced or unskilled welder or due to fundamental difficulties in the welding operation. a. Spatter c. Penetration b. Porosity d. Welding Defects 2. ____________________ occurs when the depth of the welded joint is insufficient. a. Incomplete Penetration c. Penetration b. Porosity d. Welding Defects 3. ____________________ is defined as the distance from the base plate top surface to the maximum extent of the weld nugget. a. Spatter c. Penetration b. Porosity d. Welding Defects 4. ____________________ is a group of small voids and blowholes are comparatively bigger isolated holes or cavities. a. Spatter c. Penetration b. Porosity d. Welding Defects 5. ____________________ is the small metal particles that are thrown out of the arc during welding and get deposited on the base metal around the weld bead along its length. a. Spatter c. Penetration b. Porosity d. Welding defects 6. __________________ is the change in the shape and difference between the position of two plates before and after welding due to the temperature gradient present at various points along the joints. a. Groove c. Distortion b. Hot tear d. Undercut 7. _________________ is a kind of weld defect which forms a groove in the parent metal along with the sides of the weld bead. a. Groove c. Distortion b. Hot tear d. Undercut 8. ________________________ reduces the thickness of the plate and also reduces the strength of the weld. a. Groove c. Distortion b. Hot tear d. Undercut 9. ________________ is also known as solidification cracking state. a. Groove c. Distortion b. Hot tear d. Undercut 10. ___________________ cracking is due to tearing of the grain boundaries of weld metal before complete solidification has taken place and metal is still in the plastic state. a. Groove c. Distortion b. Solidification d. Undercut 33
What is it? Lesson Information 1.6 Perform Root Pass and Multi-Layer Deposit in Flat Position Things to Take Note in Arc Welding Prepare the Metal to be Welded Arc welding is more tolerant to slightly rusty metal than other electric welding processes but at the least, you should remove any paint, grease, rust, or other contaminants with steel brush, sandpaper or angle grinder to avoid weld contamination or inclusion. Source: https://www.nccer.org 34
Attach Clamps on Work Pieces (Steel Plate) and Grounding Ensure there is a clean location so that the electrical circuit can be completed with minimal resistance at the ground location. Again, rust or paint will interfere with the grounding of your work piece, making it difficult to create an arc when you begin welding. Perform Tack for temporary joint of two metals. Source: www.MillerWelds.com 35
Select the correct electrode and amperage range for the work you are attempting. Insert the electrode into the insulated holder. Set amperage at levels recommended by the electrode manufacturer. As an example, 1⁄4 inch (0.6 cm) plate steel can be welded effectively using an E6011, 1⁄8 inch (0.3 cm) electrode, at between 80-100 amps. Source: www.MillerWelds.com 36
Electrode Angle (Lead Angle) When welding on the work piece, the rod should be angled around 10 to 20 degrees from vertical and pulled in the direction towards the welder. The angle of the rod prevents the slag overtaking the rod (inclusions in the weld will occur if welding is carried over the slag). Use your spare hand to support the top of the electrode to improve control of the electrode if necessary. Source: www.MillerWelds.com Arc Length The arc length is the distance between the electrode and the weld pool. It should be roughly the same as the diameter of the electrode. You will get used to the arc length after some practices. The arc length can be easily determined by the sound and visible light from the arc. The arc should be kept short and hide the majority of the light from the weld without pushing the electrode into the slag pool. A good short arc length will result in a consistent sharp crackling sound. The appearance of the completed weld will provide further clues. Source: www.MillerWelds.com 37
Maintaining Lead Angle and Arc Length As the welding electrode gets shorter during the weld process, it takes a minded effort to reduce the length of the arc. Excessive arc length will lead to an unstable arc with excess heat and undercutting. This is one of the most common mistakes by beginners. The angle of the electrode should be maintained over the length of the weld. Practice is necessary to avoid decreasing the lead angle as the weld progresses, as this can lead to slag inclusions and even cause the arc to stall. The easy approach to maintain electrode angle is to focus on moving the electrode holder rather than the electrode as the weld progresses. First Weld Pass Source: www.MillerWelds.com Note: View this link for hands on presentation https://www.youtube.com/watch?v=HOG2ypThBpc Second Weld Pass 38
Source: www.MillerWelds.com Third Weld Pass Source: www.MillerWelds.com Complete Weld Pass Source: www.MillerWelds.com Note: View this link for hands on presentation https://youtu.be/rb72AT-YK0Y Note: Performing weld passes depends on the thickness of the Based Metal and applying waving patterns that best suited to your performance. 39
Slag After welding, you may want to remove the slag and clean up your weld. Chip off the slag and steel brush the weld to remove any foreign material and remaining slag. Ensure eye protection is worn as the brittle slag can fly off to distance. A clean weld after grinding is easier to examine for any welding defects. Source: https://weldguru.com/smaw-tips-techniques/ 40
Visual Examination After Welding- Completed Weldment The trainer is expected to determine that weldment conforms to the working drawing and specifications for which it is designed and constructed. The weld must all be made to the size specified. The following items must be considered: 1. All welds should be inspected to see that they do not have any of the following defects: a. Surface cracks b. Crater cracks or underfill c. Surface porosity d. Incomplete root penetration e. Undercut f. Underfill on face, groove (concave) g. Excessive face reinforcement, groove (convex) h. Overlap i. Misalignment (high-low) j. Arc strikes k. Excessive spatter 2. Other weldment defects that must be checked: a. Warpage – beyond allowable or acceptable limits b. Base metal defect – scabs or seams in the base metal c. Backing welds – a question about quality of root fusion 41
Testing the Weld Weld Strength Test Diagram Test Welds Using a Ballpeen Hammer in the direction shown below Weakness can be Due to Porosity (holes in the weld), Incorrect Heat or Fast Travel Speed. Use a hammer to strike the joint on the material welded to the base. The weld should bend slightly and not break. Breakage could be due to too many holes (porosity) in the weld, or if the weld contains slag. Also note if any of the bevelled area is visible. If it is, this could indicate that the filler material was not fully melted due to traveling too fast with the electrode or by not using enough heat. Source: www.MillerWelds.com 42
Application Performance Task No. 1.6 Activity 1: Hands-on Activity Directions: Follow the procedure given in Lesson Information 1.6. This activity will be done individually and should last only for 2-4 hours. Your uniformity of weld beads will be graded based on the rubric below. Rubric for Uniformity of Weld Beads According to Techniques, Appropriate Conditions, and Welding Standards Performance Criteria Categories/ 5 Points 4 Points 3 Points 1Point Dimensions Smoothness All beads were Most beads Some beads Almost all were smooth were not beads were not and uniformity smooth and and uniform smooth and smooth and uniform uniform of beads uniform Proper use of Used tools and Used tools and Used tools and Unable to use tools and equipment with equipment confidence equipment with equipment with tools and less confidence the help of equipment others properly Application of Effective Application of Application of Application of procedures application of procedure was procedure was procedure was procedures was acceptable inconsistent unacceptable evident Safety work Observed safety Observed Observed Observed habits safety practices at all safety practices safety practices once times most of the practices times sometimes Note: Performing this task will be given by your teacher on specific schedule. 43
Sample Template Republic of th Department o Region X – Nor Division of Mi Poblacion, Lugait, G-11 COMPETENCE SMAW NC II MODULE 1 LE POSITIO PROGRES Name Lesson Lesson Lesson Less Information Information Information Inform 1.2-Safety 1.1- 1.3-5S of 1.4 Fundamenta Welding Good Accep ls of Welding Practices & & Self-Check Self-Check Housekeepin an g & Self- Unacce 1.1 1.2 Check 1.3 Weld Profile Chec 1. Prepared by: Name of the Teacher Subject Teacher 4
he Philippines of Education rthern Mindanao isamis Oriental , Misamis Oriental ESSON 1 WELD CARBON STEEL PLATE IN FLAT ON (1G) SS CHART son Lesson Lesson Generalizati Remarks mation Information Information on 4- 1.5-Welding 1.6-Perform ptable Root Pass nd Defects and Multi- eptable Causes and ding Remedies & Layer Self-Check Deposit & & Self- Performance ck 1.4 1.5 Task 1.6 4
Generalization From all the Lesson Information you have learned, what are your realizations about the following? A. Enumerate the personal protective equipment of a welder. ___________________________________________________________________ ___________________________________________________________________ ___________________________________________________________________ B. How will you apply the 5S in your home? Give each an example. ___________________________________________________________________ ___________________________________________________________________ ___________________________________________________________________ C. Give at least two examples of external and internal welding defects. List down the possible causes and corrective actions in each example. ___________________________________________________________________ ___________________________________________________________________ ___________________________________________________________________ D. In your observation, what is the most applicable electrode in performing root pass on flat position groove weld 1G and why? ___________________________________________________________________ ___________________________________________________________________ ___________________________________________________________________ 45
Posttest Let us determine your learning on the task in Performing Groove Weld on Carbon Steel Plates and Pipes by taking this posttest. I. Multiple Choice: Directions: Read and analyze the statement carefully. Choose the correct answer and write the letter only on your separate answer sheet. 1. Welding standard root face. c. 1.6m a. 1.6mm d. 1.6ft b. 1.6cm 2. In preparation of based metal what is the standard bevel required. a. 2mm c. 37.5degrees b. 3mm d. 1.6cm 3. It is the required range angle of electrode position in based metal. a. Hot tear c. 10-30degrees b. Solidification d. Undercut 4. It refers to organization of necessary items in good order and easy access. a. Seiri (Sort) c. Seiton (Systematize) b. Seiso (Sweep) d. Shitsuke (Self Descipline) 5. It means taking out and disposing unnecessary items. a. Seiri (Sort) c. Seiketsu (Sanitize/Standardize) b. Seiso (Sweep) d. Seiton (Systematize) 6. ________________ is also known as solidification cracking state. a. Hot tear c. Groove b. Distortion d. Undercut 7. ____________________ is defined as the distance from the base plate top surface to the maximum extent of the weld nugget. a. Porosity c. Undercut b. Distortion d. Penetration 8. It is used to protect arms from falling flux or hot sparks. a. Welding mask c. Welding sleeve b. Leggings d. Safety apron 9. It is a working suit that is used in workplace as whole body protection from sparkling of equipment. a. Full body harness c. Safety shoes b. Cover all d. Safety apron 10. They protect feet from hot sparks or falling objects. a. Welding sleeves c. Safety glass b. Safety shoes d. Welding gloves 11. A shallow fusion between weld metal and based metal. a. Spatter c. Penetration b. Porosity d. Incomplete penetration 46
12. _________________ is a kind of weld defect which forms a groove in the parent metal along with the sides of the weld bead. a. Groove c. Distortion b. Hot tear d. Undercut 13. It is cause of not following the welding principle or procedures and lack of skill of a welder. a. Spatter c. Penetration b. Porosity d. Welding defects 14. It is due to excessive heat input and creates hole. a. Burn-through c. Penetration b. Porosity d. Incomplete penetration 15. ____________________ is a group of small voids and blowholes that are comparatively bigger isolated holes or cavities. a. Spatter c. Penetration b. Porosity d. Welding defects 16. It will cause deposited to be narrow, uneven and irregularly rippled and with poor fusion if not follow. a. Current setting c. Length of an Arc b. Speed of travel d. Incomplete penetration 17. This fundamentals is very vital for weld quality and can create blow holes or incomplete fusion. a. Angle of electrode c. Penetration b. Current setting d. Speed of travel 18. It will cause the puddle to be large, with pile up, and a straight ripple pattern if this fundamental is not follow. a. Speed of travel c. Current setting b. Manipulation of electrode d. Length of an arc 19. Reinforcement R should not exceed to ________________. a. 1mm c. 3mm b. 2mm d. 4mm 20. A defects that occur under the surface of the welded work. a. Spatter c. Groove b. External d. Internal 21. A defects occur on the upper surface of the welded work. a. External c. Weld beads b. Internal d. Incomplete penetration 22. It is a welding fundamental that designates the correct electrode size, generally based on metal type and thickness. a. Manipulation of electrode c. Current setting b. Porosity d. Angle of electrode 47
23. ______________________ are generated in a welding job due to the faulty or poor technique used by the inexperienced or unskilled welder or due to fundamental difficulties in the welding operation. a. Spatter c. Penetration b. Welding defects d. Porosity 24. ____________________ occurs when the depth of the welded joint is insufficient. a. Incomplete penetration c. Spatter b. Porosity d. Welding defects 25. ___________________ cracking is due to tearing of the grain boundaries of weld metal before complete hardening has taken place and metal is still in the plastic state. a. Hot tear c. Distortion b. Solidification d. Undercut 48
Self-Check 1.1 Pretest Answer KeyPretest II. Matching Type:49 I. Multiple Choice: TRUE or FALSE 16. b 1. b 1. TRUE 17. a 2. a 2. TRUE 18. b 3. b 3. FALSE 19. a 4. a 4. TRUE 20. d 5. d 5. FALSE 21. c 6. c 6. TRUE 22. a 7. a 7. TRUE 23. c 8. c 8. TRUE 24. b 9. b 9. TRUE 25. b 10. b 10. FALSE 11. d 12. a 13. b 14. d 15. d
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