Lesson 1Distortion prevention: stitch welds, backstep technique, clamping, low heat input processes, balanced welding sequence, and pre-bending allowanceExplains warp prevention with stitch welds, backstep, clamps, low heat processes, balanced order, pre-bend for joint shape/thickness.
Stitch welding and skip sequence planningBackstep technique for shrinkage controlUse of clamps, strongbacks, and fixturesLow heat input processes and passesPre-bending and presetting componentsLesson 2How to prevent hot cracking: filler selection, heat input control, bead sequencing, and use of stabilized/low-carbon fillersPreventive steps against hot cracking, filler pick, heat control, bead order, stabilised/low-carbon fillers for solidifying, stress management.
Selecting fillers for proper ferrite balanceUsing stabilized and low-carbon filler gradesHeat input limits and interpass temperatureBead sequencing to spread shrinkagePreheat and cooling control for crack resistanceLesson 3Repair/mitigation of distortion: mechanical straightening, local heating, re-welding strategy, acceptance criteria and rework planningAddresses warp repair, mechanical straight, local heat, re-weld plans, check against limits for fix, rework, or ok-as-is.
Measuring distortion and recording baselinesMechanical jacking, pressing, and peeningLocal heat straightening proceduresRe-welding strategies to counter shrinkageAcceptance criteria and repair documentationLesson 4Distortion and warping mechanisms in circumferential shells and brackets: longitudinal and transverse shrinkage, uneven heat distributionExplores warp in shells/brackets, long/short shrink, uneven heat, joint layout/weld order effects on final shape.
Longitudinal shrinkage around circumferencesTransverse shrinkage and ovality in shellsBracket-induced local bending and twistHeat input distribution around the jointPredicting distortion from weld size and pathLesson 5Three-pronged prevention methods for fusion/penetration defects: joint prep, parameter control, and techniqueDetails joint prep, settings, technique to stop fusion/penetration faults, repeatable setups, checks, procedure papers.
Joint design, bevel angle, and root face selectionRoot opening, land, and fit-up tolerancesCurrent, voltage, and travel speed windowsArc length, electrode angle, and manipulationVerification of fusion with visual and NDT checksLesson 6Repair and post-weld remediation of porosity: grinding, re-weld, vacuum backing if needed, and re-inspectionPost-weld porosity fix, grind bad spots, controlled re-weld, backing/vacuum if needed, re-check for standards.
Identifying porosity extent with NDTGrinding and blending porous regionsRe-welding techniques to avoid repeat poresUse of backing bars or vacuum assistanceFinal inspection, records, and traceabilityLesson 7Hot cracking (solidification cracking/intergranular cracking): root causes in stainless (composition, high sulfur/phosphorus, restraint, heat input)Analyses hot cracking in stainless, linking makeup, impurities, restraint, heat to solidifying/grain cracks, spot risks on site.
Solidification cracking in austenitic stainless weldsIntergranular hot cracking along grain boundariesEffects of sulfur and phosphorus impuritiesInfluence of joint restraint and fit-upHeat input, cooling rate, and crack susceptibilityLesson 8Repair strategies for hot cracking: stop-drill and gouge, re-weld with controlled heat input, post-weld cleaning and inspectionStructured hot crack repair, stop-drill, gouge/grind, controlled re-weld, clean/check to clear cracks fully.
Crack mapping, marking, and extent assessmentStop-drill techniques to arrest crack growthGouging and grinding to sound metalControlled re-weld with adjusted heat inputPost-weld cleaning, NDT, and documentationLesson 9Lack of fusion and lack of penetration: how they occur on circumferential butt joints and filletsClarifies fusion/penetration lacks in round butts/fillets, joint shape, reach, position, technique to fault spots/check areas.
Root fusion problems in pipe butt weldsSidewall fusion loss in narrow groovesLack of penetration in double-sided weldsFillet weld throat and leg size issuesInspection focus zones on circumferential weldsLesson 10Prevention strategies for porosity: cleaning, gas control, travel technique, purge integrity, and weld pool manipulationPractical porosity stops, cleaning, gas/flow, travel, purge checks, pool work to let gases out pre-solid.
Pre-weld cleaning and degreasing proceduresShielding gas composition and flow settingsTorch angle and travel speed for gas escapePurge dams, venting, and leak testingStringer versus weave beads for porosity controlLesson 11Repair methods for lack of fusion/penetration: grind-out, re-weld procedures, preheat/interpass controls, and NDT acceptance limitsOutlines fusion/penetration repairs, grind defects, qualified re-welds, preheat/interpass, NDT limits pre-sign-off.
Locating fusion defects with UT and radiographyGrinding and carbon arc gouging techniquesRe-weld parameters for full penetrationPreheat and interpass temperature controlApplying code NDT acceptance limitsLesson 12Porosity causes in stainless welds: contamination, inadequate shielding, purge failures, and entrapment of gasesExamines porosity in stainless, dirt, poor shield, purge fails, gas trap to pore types, joint/position gas paths.
Surface contaminants and moisture sourcesShielding gas flow, turbulence, and draftsBack purging failures in root passesGas entrapment in deep or narrow groovesRecognizing porosity patterns in radiography
