REVIEWER IN SMAW NC II, Lecture notes of Communications Law

Download REVIEWER IN SMAW NC II and more Lecture notes Communications Law in PDF only on Docsity! Remediation Lesson in SMAW NC II FIRST QUARTER SMAW NC II SHIELDED METAL ARC WELDING (SMAW) NC II The Shielded Metal Arc Welding (SMAW) NC II Qualification consists of competencies that a person must achieve to weld carbon steel plate and pipe components as specified by layout, blueprints, diagrams, work order, welding procedure or oral instructions using shielded metal arc welding equipment. This Qualification conforms with American Welding Society (AWS) D 1.1 Structural Welding Code; American Society of Mechanical Engineers (ASME) IX Boiler and Pressure Vessel Code; American Petroleum Institute (API) 1104 Code for Gas and Oil Pipeline Facilities; and International Standards Organization (ISO) 9606-1 Qualification of Welders for Steel. PIPE WELDING POSITIONS Matching Type: Match column A with column B by writing the letter of the correct answer on the blank provided before each nmber COLUMN A COLUMN B _____1. This position inclines the pipe at a 45° angle to create a sloping surface. The pipe is fixed, as with 5G, and the welder must move around the pipe. This is the most advanced of the four positions and requires a greater level of expertise from the pipe welder. _____2. This position places the pipe upright in a vertical position. The pipe can be rotated along the vertical (Y) axis, with the welder remaining stationary. The welding is performed horizontally on the side of the pipe. ______3. This position places the pipe horizontally. The pipe can be rotated along the horizontal (X) axis, with the welder remaining stationary. The weld is completed on the top of the pipe and is the most basic of the pipe welding positions. ______4. The 5G position places the pipe horizontally but, unlike with the 1G position, the pipe cannot be rotated. Instead, the welder must move around the stationary pipe in a vertical direction to create the weld. A. B. C. D. Welding Positions: Pipe welding has four positions: 1G The horizontal rolled position. In this position the pipe is horizontal and it is being rolled so that you, the welder, are actually in a flat position relative to the pipe. It's the easiest pipe welding position. 5G The horizontal fixed position. The pipe is stationary and not rolling as you weld, which makes it more challenging. Pipe Welding Tips and Procedures: If you can't make a single pass then go with multi-layer beads. The rule of thumb is to use one layer of beads for each one eighth inch wall thickness of the pipe. A common welding technique using the SMAW process is to weave your layer beads. But you should always lay a bead over a cleaned weld to avoid slag being deposited in the filler material. The most common type of joint used for welding together pipe is a butt joint. Very simply, you take two pipes and put them together and now you have a butt joint to weld. But if you are welding thicker walled pipe then you are going to bevel a V or U butt joint. Singles only. PIPE JOINT FIT UP AND PREPARATIONS Pipe Joint Fit Up and Preparation! 1. Remove any material that will negatively affect your weld. That includes any oil or paint, rust or slag, and scale, etc. 2. Be sure that the weld joint is uniform and as smooth as possible on the surface of it. 3. A well cut bevel is crucial to the success of your pipe welding procedure. It must be done properly. 4. You can make a bevel using a grinder or a cutting torch. You can also machine it. You can hand cut bevels using attachments to a grinder, or you can use beveling machines. Using A Cutting Torch For Beveling Pipe: PIPE ALIGNMENT TOOL Pipe Alignment Tool Sample DIY pipe clamp The Tack Weld: If you are welding .5" pipe then you just need 2 tacks welds on opposite sides of each other. 4 tacks are used for pipe that is standard in size. A tack weld needs to have the same penetration and quality as the weld bead you will lay to finish the job. Some say that a three sixteenths electrode is the maximum you should go for multi layering welding for the root pass because if it's bigger you may not get good penetration and fusion of the weld, and without any slag or undercutting of the weld. Using Spacers: A spacer is a commonly used tool for achieving a well aligned joint. A spacer is a piece of metal that has been machined specifically for the joint you are welding. You will also find language referring to spacers as a 'backing ring' or a 'chill ring’ . Spacers are very handy because you can use them for several purposes which include aligning pipe, making tack welds easier, keeping a root opening at the desired amount as you prepare and perform your welding, and keeping slag and spatter from getting in the pipe. How to perform 6G pipe welding using SMAW ESSENTIALS FOR PROPER WELDING PROCEDURES C A L M S Correct Current Correct Arc Length/ Arc Gap Correct Angle Correct electrode movement/ travel speed Correct electrode size WELD DEFECTS a ? (ternal Defect si ay aa a ETI z (et ertaclesnela alts (am tsa) ——! Lack of Fusion Pile maui) De eri Bleu leelCehnda tel cy BIE Tare ert) Bier le Molec iia Ee ea) www.weldingandndt.com 1. CRACKS: It is the most dangerous of all defects. Cracks may be of any size or shape; it can be either microscopic or macroscopic. Cracks may appear anywhere i.e. on the surface, subsurface, at any depth, or at the root. The crack occurs when localized stress exceeds the ultimate Tensile Stress (UTS) of the material. It may propagate within the material. 2. POROSITY & BLOW HOLES: Porosity is a cavity-like discontinuity and occurs due to the entrapment of gases in the molten weld pool. These entrapped gases don’t get a chance to escape from the molten weld pool and hence cause porosity or blowholes. Porosity is basically a small pore or void, whereas, blowholes are comparatively larger hole or cavity. Porosity may be present on the surface or inside the weld metal. Porosity can occur individually or it may occur in groups also (mostly), group of porosity is known as cluster porosity. Gases that are entrapped and cause porosity are mostly Hydrogen, Carbon mono oxide, Carbon dioxide, Nitrogen, and Oxygen. These gases are formed due to the fluxes present on the welding electrode, Moisture, Oil, Grease other foreign contaminants present on the joint, or on the welding electrode or on the filler wire. Insufficient flow of shielding gas also causes porosity in GMAW, FCAW, GTAW & PAW welding processes. 5. LACK OF PENETRATION (INCOMPLETE PENETRATION): When the weld metal doesn’t completely penetrate the joint, then it is called a Lack of Penetration or Incomplete Penetration. It is one of the most dangerous defects since it acts as a stress raiser, and hence crack may originate or propagate from there. 6. LACK OF FUSION (INCOMPLETE FUSION): It is the lack of proper melting (or proper fusion) either between the weld metal with the base metal or one layer of the weld with the other layer. Lack of fusion is also called as Cold lapping or cold shuts. One of the most prominent reasons for the cause of lack of fusion is poor welding techniques. Lack of fusion is an internal defect, but it can occur on the external surface too if the sidewall of parent metal doesn’t get properly fused with the base metal, as shown in the below figure and for this case lack of fusion can also be called as ‘lack of sidewall fusion’. 7. SPATTERS: Spatters are small globular metal droplets (of weld metal) splashed out on the base metal during welding. Spatters stick on the base metal hence can be removed by wire brush or buffing. 10. INCLUSION: Any entrapped solid material (either metallic or non-metallic) in the weld metal, is called as Inclusion. Tungsten, Oxides, Slag, and Flux are some of the common foreign materials which are entrapped in the molten weld pool and form inclusion. WELD DEFECTS SA ROOT PASS i Burn through Incomplete/ Lack of Penetration Poor Penetration Sunog ang Bakal Kulang sa Penetration Kulang sa Penetration Lack/ Incomplete Fusion Improper Tie-Ins Excessive Penetration Hilaw ang welding (Mali ang pagdudugtong) Sobra ang Penetration WELD DEFECTS SA CAPPING/ COVER PASS Wrarpage or distortion Uneven Beads or Ripples Slag Inclusion Pagbaluktot ng Bakal Di-parehas na weld bead o kaliskis Nakasingit na dumi na hindi maalis Undercut Porosity or Pinholes Underfill (May crack sa ilalim) (KUlang sa Pagpupuno) Overlap Excessive Spatter Weaveness of Bead (Sobra and lapad ng pasada ng welding) (Maililiit na talsik ng slag sa labas ng bakal (baluktot na pasada ng welding) Sagot: > Tumigil sa pagwewelding > |-off o patayin ang welding machine > Sabihin sa authorized person o concerned person na nakatalaga para umayos nito. Sagot: >» Mag-welding ayon sa nirekomendang parameters. Ang parameters ay ang tinatawag na essentials of welding: correct current (amperage), correct electrode size, correct arc gap or arc length, correct angle, correct travel speed). o CLAM Bago ang aktuwal na welding, gawin muna ang trial welding sa bakal. lset ang welding machine sa nirekomendang terminal (polarity), amperahe at voltahe. Ang undercut ay ang groove o crater (uka) sa toe ng welding. Kapag may undercut, hindi napupuno ang weld metal ang area na may groove, kaya ang nagiging resulta ay madaling mag-crack sa may toes na bahagi ng weld. Sagot: >» Gumamit ng akmang personal protective equipment > Tamang paghawak ng makina o equipment, mga tools at materials gaya ng welding rod at bakal >» Sapat na kaalaman sa tamang pag-iingat o safety practices. 7. Paano maiiwasan ang electric shock o makuryente habang naqwewelding? Sagot: Lagyan ng ground ang lahat ng electrical equipment at ang work piece of bakal. Gumamit ng recommended na cable size. Siguraduhing lahat ng electrical connections are mahigpit, malinis at tuyo. Panatilihing tuyo ang welding area, mga gamit sa welding at damit sa lahat ng oras. Panatilihing nasa kundisyon ang mga cable at connectors sa lahat ng oras. Iwasan ang open circuit voltage. Ang open circuit voltage nangyayari kapag ang welding machine ay naka-on ngunit wlang kuryenteng dumadaloy sa circuit. Ang open circuit voltage ay ang potential force na available sa para mag-initiate ng daloy ng kuryente kapag ang arc ay inistrike. > Ang malaking welding cable ay nakakonekta sa power source at ang maliit na welding cable ay sa electrode holder. Ang size ng welding cable ay #4 pinakamaliit #3, #2, #1 at palaki #1/0, #2/0, #3/0 at #4/0. >» Magsuot ng welding gloves na hindi dinadaluyan ng kuryente kapag nag-aadjust ng equipment. > Sundin ang mga safety standards sa welding. Sa SMAW may tinatawag na OSHS o Occupational Safety and Health Standards na gaya ng mga sumusunod: > Rule 1100.01: Gas and Electric Arc Welding and Cutting Operations - hindi dapat ginagawa ang mga ito sa mga area na may mga substance na maaaring magliyab o sumabog. > Rule 1100.02: Personal Protective Equipment - ang PPE ay provided by employers. > Rule 1100.03: Welding or Cutting in Confined Spaces - dapat may PPE ang welders dito para hindi makalanghap ng usok at provided ng exhaus at ventilated system. 8. Ano ang dahilan ng weld defect na warpage o distortion? Sagot: >» Ang warpage of distortion ay ang pagbaliktot ng metal during cooling process. Dapat lagyan ng brace o tibayan ang crack weld. 9. Ano ang dahilan ng poor penetration of incomplete fusion? Sagot: > Hindi sapat na root gap. Mababang amperahe ng welding machine. Sobrang bagal ng travel speed at mali ang torch angle o angqulo ng electrode, 10. Paano maiiwasan ang pagkakaroon ng slag inclusion at undercut? > Hindi masyadong malinis ang weld na dahilan ng slag inclusion. >» Mataas na amperahe ang dahilan ng undercut. 11. Kapag ang electrode or welding rod na ginamit ay may moisture o basa, ano ang epekto nito sa weld? > Ang moisture of basa (hamog) sa weld ay nagdudulot ng porosity. 12. Ano ang gagawin mo kapag nakita mo ang iyong kapwa welder na natumba at nawalan ng malay sa isang confined area? Sagot: > Humingi agad ng tulong.