IIW IWS cheat sheet

SMAW: arc between covered electrode and workpiece; the flux coating generates shielding gas and slag, so no separate gas supply is needed.

GMAW transfer modes: short-circuiting (low current, thin sheet), globular (intermediate), spray (above transition current, argon-rich gas, high deposition), pulsed (controlled spray at low average current).

SAW uses a granular flux blanket and bare wire; typical currents 400-1200 A give high deposition rates, but the process is limited to flat or horizontal positions, mostly mechanised.

TIG/GTAW uses a non-consumable tungsten electrode with separate filler; it is used for thin sections and root passes where cleanliness and control matter. DCEN concentrates heat at the workpiece.

FCAW: tubular wire with internal flux; self-shielded variants need no external gas and tolerate wind, while gas-shielded variants give smoother arcs and lower fume.

Resistance spot welding heat follows Q = I^2 * R * t; current is the dominant variable because heat scales with its square.

Duty cycle: a machine rated 60% at 300 A can run 6 minutes in 10 at 300 A; at 100% duty the permissible current is lower, roughly I100 = I60 * sqrt(0.6).

Shielding gas selection: CO2 gives deep penetration and is cheap; Ar/CO2 mixes (e.g. 80/20) stabilise spray transfer and reduce spatter; argon/helium mixes increase heat input for aluminium and copper.

Carbon equivalent (IIW): CE = C + Mn/6 + (Cu+Ni)/15 + (Cr+Mo+V)/5; values above about 0.40-0.45 raise cold-cracking risk and call for preheat or low-hydrogen practice.

Hydrogen cracking needs three conditions together: diffusible hydrogen, a susceptible hard microstructure, and tensile restraint stress; removing any one prevents it.

Carbon steel HAZ hardening depends on cooling rate (t8/5) and alloy content; faster cooling and higher CE give harder martensite and greater cracking risk.

Austenitic stainless steels: sensitisation occurs when chromium carbides precipitate at grain boundaries in the 450-850 C range, depleting chromium and reducing corrosion resistance; low-carbon grades (304L/316L) limit this.

Duplex stainless steels need balanced ferrite/austenite; excessive heat input or slow cooling promotes sigma phase and embrittlement, so heat input is usually limited to roughly 0.5-2.5 kJ/mm.

Aluminium: the tenacious oxide layer (melting point about 2070 C versus 660 C for the metal) requires AC TIG or reverse-polarity cleaning; high thermal conductivity causes heat-affected distortion.

Hot cracking in welds is driven by solidification segregation; it is controlled by filler choice (e.g. low-sulphur, higher-manganese fillers), weld shape, and reduced restraint.

Preheat reduces cooling rate and hydrogen diffusion time; typical carbon steel preheat is 100-200 C depending on CE and thickness, and interpass temperature is capped for stainless and duplex.

A welded joint is a design element: full-penetration butt welds develop full member strength, while fillet welds transmit load through the throat, effective throat = 0.7 * leg length for a 90-degree fillet.

Fillet weld capacity per unit length: F = 0.7 * a * f_vw, where a is leg length and f_vw is design shear strength of the weld metal.

Weld symbols: a reference line carries the weld symbol; the arrow side is below the line and the other side above; a tail holds process or specification notes.

Butt weld edge preparation: square edges for thin plate, V or U preparations for thicker plate; a root gap and root face control penetration and burn-through.

Distortion control by design: place welds near the neutral axis, balance welds about the centreline, use intermittent or staggered fillets, and minimise weld volume.

Joint types are butt, T, lap, corner, and edge; each has characteristic stress flow, and sudden section changes cause stress concentration and fatigue initiation.

Fatigue design: weld toes and roots are stress raisers; improve fatigue life with smooth toe profiles, grinding, or peening, and avoid attachments transverse to the stress direction.

Structural steel design rules often cap fillet weld leg size by plate thickness (typically not less than the thinner part and limited by edge distance) to avoid melting the plate edge.

A welding procedure specification (WPS) states the variables (process, filler, current range, preheat, position, gas); it is supported by a procedure qualification record (PQR) from a tested coupon.

Essential variables are those whose change invalidates qualification; typical examples are process, base metal group, filler classification, thickness range, position, and heat input.

A welder performance qualification is personal and tests the welder's ability; it is separate from the procedure qualification and is valid only within its stated range.

Fit-up and preparation checks before welding include joint geometry, root gap, cleanliness, and removal of moisture or contamination from the joint faces.

Traceability: filler metals, consumables, and base material certificates are recorded against the joint or assembly so the correct material is verifiable.

Heat input H = (k * U * I) / v, where U is arc voltage, I is current, v is travel speed, and k is an efficiency factor (about 0.8 for SMAW, near 1.0 for SAW).

Nonconformance handling: record the defect, segregate the item, and evaluate repair or concession against the acceptance standard before any rework.

Post-weld heat treatment relieves residual stress and tempers hard microstructures; it is specified by temperature range, holding time, and heating/cooling rates.

Visual inspection is performed first and throughout; it detects surface defects such as undercut, spatter, misalignment, and poor bead profile.

Radiographic testing finds volumetric internal defects (porosity, slag, lack of fusion) but is less sensitive to tight planar cracks oriented parallel to the beam.

Ultrasonic testing detects planar defects and lack-of-fusion well, requires a qualified operator, and is less effective on coarse-grained austenitic welds.

Magnetic particle testing applies only to ferromagnetic materials; it detects surface and near-surface defects and requires the surface to be clean and dry.

Dye penetrant testing detects surface-breaking defects in non-porous materials; it is not suitable for rough or porous surfaces because of false indications.

Acceptance criteria are defined by the applicable standard or specification; the inspector classifies and sizes indications against those limits rather than judging subjectively.

Destructive tests on procedure qualification coupons include tensile, bend, impact, and macro examination; bend tests reveal ductility and fusion defects.

Hydrostatic and pneumatic tests verify pressure integrity; pneumatic testing stores more energy and requires greater exclusion distances and controls.

Welding fume contains metal oxides and process-dependent gases; local exhaust ventilation at the arc is the primary control, and respiratory protection supplements it.

Ozone forms in GMAW and TIG with argon-rich shielding; it is an irritant, and good ventilation plus distance from the plume reduce exposure.

Electric shock risk rises with wet conditions and high open-circuit voltage; no-load voltage limits and dry insulation are key controls.

Arc eye (photokeratitis) results from ultraviolet exposure; welding helmets with correct shade and screens around the work protect welders and bystanders.

Fire prevention: remove combustibles within about 10 m, use fire blankets, and maintain a fire watch after hot work ends because slag retains heat.

Confined-space entry requires atmosphere testing, forced ventilation, a permit, and a standby person; welding gases and shielding gas can displace oxygen.

Cylinder safety: store upright and secured, keep oxygen and fuel gas separated, and never use oil or grease on oxygen fittings.

Radiation and hot spatter: protective clothing, leather gloves, and eye protection are required, and grinding near welding adds noise and dust exposure.

Set current from the electrode or wire manufacturer's range for the diameter, then adjust by arc behaviour: too low gives sticking or poor fusion, too high gives spatter and undercut.

Arc length: a short arc gives better shielding and penetration for SMAW; excessive length causes spatter, porosity, and lost shielding.

Travel angle: for SMAW a drag angle of about 10-15 degrees is typical; for GMAW a push angle improves visibility and bead appearance on thin sheet.

Position technique: flat uses highest current; vertical-up gives better penetration and is favoured for thicker sections; vertical-down is faster on thin sheet with less penetration.

Tack welds should be small, fully fused, and ground or feathered before the main pass; poor tacks are a common source of root defects.

Root pass control: maintain a consistent keyhole in TIG or a steady root gap in SMAW; back purging protects the root of stainless steel from oxidation.

After welding, clean slag and spatter, check bead profile and dimensions, and record any repair; never cover a defect with a subsequent pass.

Electrode storage: low-hydrogen electrodes are kept in heated ovens and used from quivers, because moisture pickup reintroduces hydrogen and cracking risk.

Deposition rate (kg/h) = (wire cross-section area * feed speed * density) * 60; for a given wire, current and feed speed set output.

Arc time and operating factor: operating factor = arc time / total worked time; manual processes are typically 20-40%, mechanised processes higher.

Cost per metre = (labour rate * time per metre) + (filler mass per metre * filler price) + (power cost) + overheads; labour usually dominates for manual welding.

Weld volume for a V butt weld grows with plate thickness squared, so joint design changes can reduce cost more than faster welding.

Planning sequence: define the WPS and qualification needs, plan fit-up and access, then sequence welds to balance distortion and minimise handling.

Supervision verifies that the correct WPS revision, filler batch, and qualified welder are used, and records deviations before work proceeds.

Productivity levers include higher deposition processes (SAW, FCAW), reduced spatter and rework, better fit-up, and minimising non-arc time.

Schedule risk: qualification and testing lead times, consumable delivery, and inspection hold points must be built into the fabrication programme.

A supervisor's daily check covers WPS availability, welder qualification validity, consumable condition, preheat, and environmental conditions (wind, humidity).

Hold points are stages where work cannot proceed until inspection is released; witness points require notification but not necessarily presence.

Production planning balances welding stations, fit-up capacity, and inspection load; a bottleneck at inspection delays the whole programme.

Man-hour estimates derive from weld length, deposition rate, operating factor, and rework allowance; quoting without these gives unreliable costs.

Cost of poor quality includes rework, reinspection, and delay; tracking repair rates per welder and per joint type identifies training needs.

Communication of change: any change to a qualified procedure must be assessed against essential variables and re-qualified or re-approved before use.

Records to retain include WPS, PQR, welder certificates, consumable certificates, inspection reports, and NDT results, for traceability and handover.

Environmental and safety compliance is a supervisory responsibility: permits, ventilation, fire watch, and waste segregation are checked, not assumed.

Before striking an arc, verify polarity and connection: DCEN (electrode negative) concentrates heat at the workpiece for TIG and is common for GMAW; DCEP gives deeper penetration for SMAW.

Set gas flow with a flowmeter at the torch, typically 10-15 L/min for GMAW and TIG; too little causes porosity, too much causes turbulence and entrainment.

For TIG, prepare the tungsten electrode with a ground taper (about 2-2.5 times diameter in length); contamination causes arc wander and inclusions.

Striking and restarting: use a scratch or lift-arc start for TIG, and chip or grind the crater at stops to avoid crater cracks.

Distortion correction by flame or mechanical means is done after inspection approval and within limits set by the specification; uncontrolled straightening can crack welds.

Weld appearance acceptance: uniform ripple, correct leg length and throat, no undercut beyond limits, and smooth transitions at stop/start points.

Consumable matching: use the filler classification specified in the WPS; substituting a higher-strength filler can reduce toughness and ductility.

Environmental limits: wind above about 2 m/s disperses shielding gas in open-site GMAW; use windbreaks or self-shielded processes.

Risk assessment for welding identifies hazards: fume, UV/IR radiation, electric shock, fire, noise, and manual handling; controls follow the hierarchy of elimination, substitution, engineering, administrative, then PPE.

Fume extraction rates and hood position matter more than general ventilation; capture at source before the plume enters the breathing zone.

Hexavalent chromium fume from stainless steel welding is a specific carcinogen hazard; it requires enhanced extraction and health surveillance where exposure is significant.

Gas cylinder identification uses colour and label, but labels are the authoritative identifier; never rely on colour alone.

Hot work permits define the area, fire watch duration, and gas test requirements; the permit is closed only after the area is checked for smouldering material.

PPE for welding: flame-retardant clothing, leather gauntlets, safety footwear, hearing protection during grinding, and a helmet with correct filter shade for the current.

Emergency arrangements include accessible first aid, eyewash for chemical exposure, and a means to isolate power and gas in an incident.

Defect versus discontinuity: a discontinuity is any interruption in the weld; it becomes a defect only when it exceeds the acceptance criteria.

Porosity is rounded gas entrapment, often from moisture, dirt, or lost shielding; it is volumetric and shows clearly on radiographs.

Lack of fusion is planar and often oriented parallel to the fusion face; ultrasonic testing is generally more reliable than radiography for it.

Undercut reduces the throat and acts as a stress raiser; it is assessed by depth and length against the acceptance standard.

Slag inclusion occurs mainly in multi-pass flux processes when slag is not removed between passes; it appears as elongated radiographic indications.

Lamellar tearing occurs in thick restrained T-joints when through-thickness strain tears inclusions; it is mitigated by joint design and material testing.

Hardness testing (e.g. HV10 traverses) verifies HAZ hardness against limits, often 350 HV for carbon steels, as an indicator of cracking risk.

Inspection reports should record the method, standard, acceptance class, location, size of indication, and result, so decisions are auditable.

Solidification cracking susceptibility rises with sulphur and phosphorus and falls with manganese; weld metal composition and shape (depth-to-width ratio) both matter.

Reheat cracking occurs in thick-section low-alloy steels in the coarse-grained HAZ during post-weld heat treatment; it is linked to residual stress and impurity segregation.

Stainless steel weld metal often contains 5-10% delta ferrite to resist solidification cracking; too much ferrite reduces toughness and corrosion resistance.

Aluminium alloys: 6xxx heat-treatable grades lose strength in the HAZ; 5xxx grades are strain-hardened and soften near the weld.

Copper and its alloys conduct heat rapidly, so preheat and high heat input are needed; some alloys are prone to hot cracking from low-melting phases.

Titanium is highly reactive above about 400-600 C; it requires inert gas shielding of the weld, root, and cooling metal to prevent embrittlement.

Cast iron welding needs preheat and controlled cooling to avoid cracking; nickel-based fillers accommodate thermal stress better than steel fillers.

Thermal cutting introduces a hardened, oxidised edge; grinding back to sound metal before welding avoids hydrogen and inclusion pickup.

Weld size selection: for a fillet carrying load P per unit length, required leg a = P / (0.7 * f_vw), then round up to a standard size.

Full joint penetration butt welds are often specified where fatigue or impact loading governs; partial penetration is used where the stress allows.

Access for welding and inspection must be designed in: minimum distances from a weld to an obstruction, and room for a torch, a gauge, and NDT probes.

Restraint increases residual stress; design should allow movement (e.g. sliding connections, weld sequence) rather than fully restraining a shrinking weld.

Weld symbols may include size, length, pitch, and all-around or field-weld marks; misreading them is a common fabrication error.

For tubular joints, the intersection curve and varying groove angle require specific procedures and welder qualification for the geometry.

Bolt versus weld decisions consider inspection access, fatigue, disassembly, and site conditions; a weld is generally stiffer and more fatigue-resistant if detailed well.

Corrosion design: avoid crevices and trapped water at weld details; seal or drain details, and match filler composition to the service environment.

Quality plan structure: define the item, the inspection stages, the method, the acceptance standard, and the responsible person for each stage.

Calibration of measuring and test equipment (gauges, flowmeters, NDT sets) is a prerequisite for valid inspection results.

Material identification and segregation prevent mixing of grades; colour coding or tagging is checked against certificates at receipt and at fit-up.

Welder qualification records must match the process, position, and thickness of the production work; an expired or out-of-range certificate invalidates the weld.

Document control ensures only the current WPS revision is on the shop floor; superseded documents are removed to avoid wrong parameters.

Rework procedures require the same qualification and inspection as original work; repeated repair can degrade material and is limited by specification.

Handover documentation typically includes as-built drawings, WPS/PQR, welder records, NDT reports, and material certificates.

Power source characteristics: constant-current (drooping) sources suit SMAW and TIG, where arc length changes should not swing current widely; constant-voltage sources suit GMAW and FCAW for self-regulating arc length.

DCEP for GMAW gives good penetration and is standard for steel; DCEN is used for some hardfacing and for TIG; AC is used for aluminium TIG to combine cleaning and penetration.

Wire feed speed and current are linked for a given wire diameter; for GMAW, increasing wire feed speed raises current and deposition rate.

Shielding gas flow is set with a regulator and flowmeter; leaks at the torch or hose cause porosity even when the flowmeter reads correctly.

SAW flux must be dry and matched to the wire; recycled flux is screened and checked for contamination and fines.

Plasma cutting uses a constricted arc and gives cleaner edges on stainless and aluminium than oxy-fuel cutting, which relies on oxidation of the steel.

Equipment checks before use: earth return connection, cable insulation, torch condition, gas hoses, and water cooling where fitted.

Estimate weld length from drawings, add for tacks and repairs, then multiply by time per metre to get arc hours; divide by operating factor to get worked hours.

Filler consumption per metre can be estimated as weld cross-section area times density times a loss factor (often 1.05-1.15 for spatter and stubs).

Labour cost dominates manual welding; a 10% improvement in operating factor can outweigh a filler price saving.

Rework rate is a key performance indicator; measuring repairs per 100 m of weld allows targeted training and procedure review.

Inspection hold points must be scheduled into the programme; releasing them late causes idle welding crews and delay costs.

Change control: variations in material, thickness, or joint design affect qualification and cost, so they are assessed formally before acceptance.

Stock control of consumables: low-hydrogen electrodes need ovens and controlled issue, and expired or damp stock is quarantined.

Ventilation design: capture velocity at the arc, duct sizing, and discharge location determine effectiveness; recirculation of filtered air requires appropriate filtration for the contaminants present.

Noise from grinding and plasma cutting often exceeds 85 dB(A); hearing protection and noise reduction at source are required where exposure is high.

Manual handling and posture: welding positions can be awkward, so positioners and benches reduce strain and improve weld quality.

Waste segregation: metal offcuts, spent flux, used electrodes, and packaging are separated; spent flux and slag are not general waste in many jurisdictions.

Energy and gas efficiency: avoid idling power sources, fix leaks, and use the minimum shielding flow that maintains coverage.

Emergency response includes knowing the location of isolation valves for gas manifolds and the main electrical isolator.

Visual weld gauges measure leg length, throat, undercut depth, and crown height; they are simple, fast, and should be used on every weld.

Radiographic film density and image quality indicators (IQIs) verify technique sensitivity; without adequate IQI visibility the film is not acceptable.

Ultrasonic probe frequency and angle are chosen for thickness and defect orientation; calibration blocks verify distance and sensitivity.

Magnetic particle testing uses AC for surface defects and DC for deeper near-surface detection; field direction should be roughly perpendicular to the expected defect.

Penetrant testing dwell and development times follow the product instructions; washing and drying steps affect sensitivity and false indications.

Leak testing methods include bubble immersion, pressure change, and tracer gas; the method is chosen by sensitivity required and component geometry.

Mechanical tests on production test pieces (e.g. bend, nick-break) give a quick check of weld soundness where specified.

The iron-carbon diagram: steels up to about 2.1% C; eutectoid at 0.8% C; austenite transforms to ferrite and pearlite on slow cooling, or martensite on fast cooling.

Continuous cooling transformation (CCT) diagrams predict HAZ microstructure from cooling rate; alloying shifts curves right, making martensite easier to form.

Carbon equivalent formulas differ (IIW, Pcm); Pcm is used for low-carbon micro-alloyed steels where carbon alone underestimates risk.

Stress relief cracking and temper embrittlement affect some low-alloy steels during post-weld heat treatment; the temperature range and time are controlled.

Austenitic stainless steel has higher thermal expansion and lower thermal conductivity than carbon steel, so distortion is greater and heat input is kept low.

Galvanised steel welding produces zinc oxide fume; remove the coating locally and use extraction, because zinc fume causes metal fume fever.

Hydrogen content of consumables is classified (e.g. H5, H10 in millilitres per 100 g of deposited metal); lower hydrogen reduces cracking risk.

Stress concentration factor rises with abrupt geometry change; a smooth weld toe transition lowers it and improves fatigue performance.

Residual stress from shrinkage can reach yield in restrained joints; it affects brittle fracture and dimensional stability rather than static strength alone.

Brittle fracture risk increases with thickness, low temperature, high restraint, and sharp defects; material toughness requirements address this.

Weld distortion types: longitudinal shrinkage, transverse shrinkage, angular distortion, and bowing; each is controlled by sequence, restraint, and heat balance.

For pressure equipment, design codes specify joint efficiency factors, minimum thickness, and required NDT proportions by joint category.

Neutral axis placement of welds and symmetry in built-up sections reduce bowing after welding.

Detailing for inspection: avoid welds on both sides of a plate at the same location where access is impossible.

Preheat verification uses contact thermometers, temperature-indicating crayons, or thermocouples; the measurement is taken near the joint before welding and recorded.

Interpass temperature is checked between passes; exceeding it in stainless or duplex steels can reduce corrosion resistance or toughness.

Consumable control: electrodes are issued in quantities matching the shift, returned unused, and redried only per manufacturer instructions.

Fit-up and dimensional checks use tape, callipers, and templates; recorded values compare against drawing tolerances before welding starts.

Non-destructive testing is scheduled after the specified cooling or heat treatment, not immediately after welding, where delayed cracking is a risk.

Root cause analysis of defects uses records of parameters, welder, consumable batch, and conditions to identify the true cause rather than the symptom.

GMAW troubleshooting: porosity points to gas flow, draughts, or dirty metal; spatter to voltage and inductance settings; poor fusion to low current or fast travel.

SMAW troubleshooting: slag inclusions from poor interpass cleaning; arc blow from magnetic fields, mitigated by changing the earth position or using AC.

TIG troubleshooting: tungsten contamination from touching the pool; porosity from gas flow or moisture; arc wander from a bent or contaminated electrode.

Vertical-up root passes in pipe use a keyhole technique with controlled arc force; the root is inspected before the hot pass is applied.

Heat input control in practice: record current, voltage, and travel speed for critical welds, and calculate H to confirm it is within the WPS range.

Stop/start technique: feather the crater, restart slightly ahead of the previous stop, and inspect the joint for fusion before continuing.

Toolbox talks before a new job cover the WPS, joint details, acceptance criteria, and safety controls specific to that work.

Performance monitoring compares actual arc time, repair rate, and consumption with estimates; deviations trigger investigation, not blame.

Resource levelling: welding stations, fitters, and inspectors are matched to the sequence so that no stage starves the next.

Subcontractor control requires the same WPS, qualification, and inspection standards; certificates are verified before work starts.

Cost of inspection is small relative to the cost of failure; the inspection plan is proportional to the consequence of failure and the joint category.

Lessons learned from completed jobs feed back into estimates, procedures, and training for the next project.

Fume control hierarchy: process substitution (e.g. lower-fume consumables), extraction at source, general ventilation, then respiratory protective equipment as the last barrier.

Exposure monitoring uses personal sampling in the breathing zone; results are compared with occupational exposure limits for the specific substances present.

Electrical safety: use residual current devices, inspect cables and holders, and avoid welding in wet conditions without additional protection.

Compressed gas safety: never use oxygen as a substitute for compressed air, and keep cylinders away from heat and impact.

Hot work near coatings or solvents can generate toxic decomposition products; remove coatings and ventilate before welding.

Training and competence: only trained personnel operate welding equipment, and emergency procedures are practised.

Sampling and extent of testing are set by the specification or code; increasing NDT beyond the required extent does not automatically change acceptance.

Defect sizing matters for fitness-for-service assessment; standards such as BS 7910 use fracture mechanics to judge whether a flaw is acceptable.

Weld mapping records the location, welder, and inspection result for each weld on a drawing, supporting traceability and repair tracking.

Dimensional inspection after welding checks shrinkage and distortion against tolerances; correction is planned before further fabrication.

Test piece preparation for macros: section, grind, and etch to reveal fusion, penetration, and HAZ; the macro is a record of the procedure qualification.

Repeatability: the same NDT method, procedure, and operator qualification are needed for results to be comparable over time.

Weldability is the capacity of a material to be welded into a sound joint under the intended conditions; it depends on composition, thickness, and restraint.

Heat-affected zone softening occurs in work-hardened or heat-treated alloys; strength recovery may require post-weld heat treatment or redesign.

Nitrogen in duplex and austenitic stainless steels stabilises austenite and improves pitting resistance; shielding gas composition can add nitrogen.

Hydrogen pickup sources include moisture in coatings, rust, and damp electrodes; cleanliness and consumable control are the primary defences.

Dissimilar metal joints need filler selection for dilution and thermal expansion mismatch; nickel-based fillers are common for steel-to-stainless joints.

Thermal expansion mismatch between base metal and weld metal causes residual stress and can drive cracking in service.

Design for weldability: specify standard joint details, avoid excessive weld volume, and allow access for the torch and for inspection.

Weld symbols and drawing notes are contractual; queries about ambiguous symbols are resolved before fabrication, not during welding.

Fatigue categories in design codes assign detail categories to joint types; the detail with the lowest category governs the fatigue life.

For seismic or dynamic loading, specify toughness and inspection beyond static requirements, and control weld defects at critical details.

Corrosion allowance and material selection interact with weld details; a weld that traps water becomes a corrosion initiation site.

Tolerances for alignment and gap are specified; exceeding them changes stress distribution and may require re-fit before welding.

Production planning uses a weld map and sequence to balance distortion and access; welds are sequenced from the least to the most restrained.

Consumable traceability links the batch to the weld; a failed batch can then be traced to all affected joints.

Inspection and test plan (ITP) stages typically include material receipt, fit-up, preheat, in-process, final visual, NDT, and post-weld heat treatment.

Records of environmental conditions (temperature, humidity, wind) support decisions about stopping or continuing work.

Training needs analysis uses defect trends and new procedure requirements to target welder development.

Continuous improvement uses data from repairs, NDT results, and cost records to change procedures or designs.

Electrode angle and travel speed control bead shape; a consistent angle and speed give a uniform bead and predictable penetration.

Weaving is limited in width (often to about 2-3 times the electrode diameter) to avoid slag traps and poor fusion at the weave edges.

Multi-pass technique: clean each pass, control interpass temperature, and stagger stop positions to avoid a continuous weak line.

Backing and consumable inserts support the root; ceramic backing gives smooth root formation but must be removed and inspected.

Weld repair: remove the defect to sound metal, re-prepare the groove, and follow the qualified repair procedure; repairs are recorded.

Post-weld cleaning of stainless steel removes heat tint and restores corrosion resistance; mechanical or chemical methods are used per specification.

Key performance indicators include arc time percentage, repair rate, first-time inspection pass rate, and cost per metre of completed weld.

Estimating allowances: add time for fit-up, cleaning, repositioning, and inspection; ignoring these underestimates the job.

Procurement planning matches consumable delivery to the welding sequence; late filler delivery stops production.

Contract awareness: scope, standards, and acceptance criteria are agreed before work; disputes often arise from unclear inspection requirements.

Safety and quality supervision are linked: rushed work with poor access increases both defects and incidents.

Reporting: daily progress and inspection status are recorded so that delays and cost overruns are visible early.

Process selection factors: material, thickness, position, joint access, required quality, deposition rate, and cost.

For thin sheet, low-heat processes (TIG, pulsed GMAW, short-circuit GMAW) reduce burn-through; for thick section, SAW or FCAW gives higher deposition.

Electroslag and electrogas welding are high-deposition processes for vertical thick-section joints; they use a molten slag bath and are limited to specific positions.

Stud welding uses a drawn arc or capacitor discharge; it is fast and is used for shear connectors and attachments.

Laser and electron beam welding give narrow HAZ and deep penetration but need precise fit-up and, for EB, a vacuum.

Equipment maintenance: check cables, torches, and feed rolls; worn liners and rolls cause wire feed variation and arc instability.

Metal fume fever is a short-term flu-like reaction to zinc or copper fume; it is prevented by extraction and by removing coatings before welding.

Carbon monoxide can form in gas-shielded welding and in confined spaces; ventilation and gas monitoring are required.

Fire watch duration after hot work is specified by the permit; smouldering material can ignite hours after the work ends.

PPE compatibility: a welding helmet must fit with respiratory protection and eye protection for grinding without breaking the seal.

Work at height with welding equipment requires securing cables and gas hoses and preventing dropped objects.

Environmental controls include fume filtration before discharge and correct disposal of spent consumables and contaminated materials.

Inspection planning starts at the design stage; the joint category determines the NDT method and extent.

Visual inspection of the root before capping is a key opportunity to detect lack of penetration and burn-through.

Acceptance criteria for undercut, porosity, and slag are numeric; the inspector measures and records rather than approximates.

NDT personnel certification (e.g. levels 1, 2, 3) defines who may perform, interpret, and approve results.

False indications from surface condition are reduced by cleaning before penetrant and magnetic particle testing.

Final inspection verifies dimensions, weld appearance, markings, and documentation before handover.

Cooling rate in the HAZ is influenced by heat input, preheat, thickness, and joint type; thicker sections conduct heat away faster and harden more.

Carbon steel classification: mild steel has low carbon and good weldability; higher-carbon and alloy steels need preheat and low-hydrogen consumables.

Austenitic stainless steel is not hardened by heat treatment; its HAZ issues are sensitisation and hot cracking rather than martensite.

Aluminium oxide must be removed mechanically or by AC cleaning before welding; it also absorbs moisture and causes porosity.

Nickel alloys are sensitive to sulphur and phosphorus; cleanliness of the joint and filler is critical to avoid hot cracking.

Hydrogen cracking can be delayed; inspection after a specified delay (e.g. 24-48 hours) improves detection.

Weld design for fatigue: use full penetration, grind flush, and avoid weld toes at high-stress locations.

Fillet weld minimum size is set by the thicker part to avoid rapid cooling and cracking; maximum size is limited where the weld runs along a plate edge.

Lap joints and eccentricities introduce bending; design should align load paths to avoid secondary moments.

For pressure vessels, joint categories define the required NDT; longitudinal seams generally require more inspection than circumferential seams.

Allowance for shrinkage in fabrication dimensions prevents out-of-tolerance assemblies after welding.

Detailing for corrosion: avoid weld spatter traps and crevices, and specify post-weld treatment where needed.

Welding procedure qualification tests the procedure, not the welder; the PQR records the actual parameters used for the test coupon.

A WPS may cover a range of thicknesses and positions based on the qualification standard's rules.

Welder qualification tests are repeated after a specified period of inactivity or a change in essential variables.

Inspection results feed back into the quality system; repeated defects trigger a review of the WPS or training.

Material certificates (e.g. EN 10204 3.1) verify composition and mechanical properties; they are checked against the specification.

Handover includes as-built records and NDT reports so the owner can maintain and inspect the asset.

Workplace organisation (5S) reduces time lost searching for tools and materials and improves safety.

Job rotation and ergonomics reduce fatigue, which affects weld quality and incident rates.

Production meetings review progress against the plan, inspection status, and any material or resource constraints.

Cost tracking per weld or per assembly identifies where labour and consumables are being consumed.

Training and qualification planning ensures welders are qualified for the processes and positions needed in the programme.

Risk register for fabrication includes qualification delays, material shortages, weather, and inspection hold points.

Set-up checklist: joint preparation, cleanliness, fit-up, earth connection, gas flow, and parameters verified before the first arc.

Tack welds should be inspected and, where specified, removed or ground before the main pass.

For pipe welding, the root is often TIG with a purge; the fill and cap may use SMAW or FCAW.

Travel speed changes affect bead width and penetration; a steady rhythm gives consistent results.

Cleaning between passes removes slag and oxide, which prevents inclusions and lack of fusion.

Post-weld inspection of the finished weld includes dimensions, surface defects, and any specified NDT.

Fume extraction equipment must be maintained and its filters replaced; a blocked filter reduces capture and increases exposure.

Personal protective equipment is checked before use for damage; damaged helmets or gloves are replaced.

Confined-space welding requires continuous monitoring of oxygen and flammable gases, not just an initial test.

Hot work permits are specific to time and place; work outside the permit conditions requires a new permit.

Emergency procedures include evacuation routes, first aid, and shutdown of gas and power.

Waste and emissions from welding are managed according to local environmental requirements.

Inspection records support traceability and are required for handover and for any future repair or modification.

NDT method selection depends on defect type: volumetric methods for porosity and slag, planar methods for cracks and lack of fusion.

Surface preparation affects penetrant and magnetic particle sensitivity; rough surfaces give false indications.

Ultrasonic testing of austenitic welds needs special probes and techniques because of beam scattering.

Radiographic interpretation requires knowledge of weld geometry to distinguish defects from features such as root penetration.

Acceptance decisions are documented with the standard, the class, and the measured size of the indication.

Preheat temperature selection depends on CE, thickness, and hydrogen level; higher CE and thickness need higher preheat.

Interpass temperature limits prevent excessive heat buildup, which can reduce toughness in some steels and cause sensitisation in stainless.

Post-weld heat treatment temperature and time are chosen to relieve stress without degrading properties; excessive temperature can cause embrittlement.

For aluminium, preheating is used mainly to remove moisture and to help heat flow, not to prevent hydrogen cracking as in steel.

Dissimilar joints can suffer carbon migration at elevated temperature; nickel-based fillers reduce this.

Weld metal composition differs from filler due to dilution; the procedure accounts for this in alloy selection.

Design codes specify minimum weld sizes and maximum gaps; exceeding them requires engineering approval.

Weld symbols may include a tail with process and consumable notes; these are read with the drawing notes.

Joint preparation angles affect weld volume and cost; narrower included angles reduce filler consumption.

For fatigue-critical details, specify toe grinding or TIG dressing where the design code permits.

Thermal cutting and edge preparation tolerances affect fit-up and weld quality; they are specified and inspected.

Design should allow for inspection access, including room for NDT equipment and for visual inspection of the root.

Quality control during fabrication includes checking parameters against the WPS and recording any deviation.

Calibration records for welding equipment and measuring instruments support the validity of results.

Material handling and storage prevent damage and contamination; stainless steel is stored separately from carbon steel.

Welder performance is monitored through inspection results and repair rates, and feedback is given promptly.

Documentation of repairs includes the location, cause, method, and inspection result after repair.

Final acceptance requires all inspection stages to be complete and records to be signed off.

Production planning includes the sequence of fit-up, welding, inspection, and any heat treatment.

Resource allocation considers the skill level required for each joint and the availability of qualified welders.

Cost control includes monitoring consumable usage against estimates and investigating large deviations.

Schedule updates reflect inspection results and any rework; rework is planned into the programme rather than treated as a surprise.

Communication of quality requirements to the workforce prevents avoidable defects and rework.

Performance review after project completion identifies improvements for future work.

Power source selection depends on process: constant current for SMAW and TIG, constant voltage for GMAW and FCAW.

Duty cycle and current rating determine the suitable machine for the work; exceeding the duty cycle causes overheating.

Wire feed systems need correct drive rolls and liners for the wire type and diameter to avoid feed problems.

Gas mixing and flow control affect arc stability and weld quality; flowmeters are calibrated and checked.

Equipment grounding and cable condition are checked before use to prevent shock and poor arc performance.

Process automation improves consistency and deposition but requires precise fit-up and parameter control.

Hazard identification for welding covers fume, radiation, fire, electricity, noise, and manual handling.

Control measures are selected in the hierarchy of controls, with PPE as the last line of defence.

Exposure limits are substance-specific; monitoring results are compared with the applicable limits.

Fire prevention includes removing combustibles, using fire blankets, and maintaining a fire watch.

Confined-space entry requires testing, ventilation, and a standby person.

Emergency arrangements include first aid, eyewash, and isolation of power and gas.

Visual inspection is the most widely used method and is performed before, during, and after welding.

Radiographic testing is suited to volumetric defects and gives a permanent record.

Ultrasonic testing is suited to planar defects and thick sections, and requires a qualified operator.

Magnetic particle testing is limited to ferromagnetic materials and detects surface and near-surface defects.

Penetrant testing detects surface-breaking defects in non-porous materials.

Acceptance criteria are defined by the applicable standard, and results are recorded with the method and extent.

Carbon equivalent predicts hardenability and cracking risk; higher values need preheat and low-hydrogen practice.

Hydrogen cracking requires hydrogen, a susceptible microstructure, and restraint; controlling any one prevents it.

Austenitic stainless steels can sensitise in the 450-850 C range; low-carbon grades reduce the risk.

Duplex stainless steels need balanced ferrite and austenite; excessive heat input can form sigma phase.

Aluminium requires removal of the oxide layer and appropriate shielding for sound welds.

Hot cracking is controlled by composition, weld shape, and reduced restraint.

Fillet weld throat is 0.7 times the leg length for a 90-degree fillet; capacity depends on throat and design strength.

Full penetration butt welds are used where full strength and fatigue resistance are required.

Weld symbols indicate size, length, and position; misreading them causes fabrication errors.

Distortion is controlled by balancing welds, using intermittent welds, and sequencing.

Fatigue life is improved by smooth toe profiles and by avoiding abrupt section changes.

Design should provide access for welding and inspection.

A WPS defines the variables for a qualified procedure; a PQR records the qualification test.

Welder qualification is separate from procedure qualification and is specific to the welder.

Essential variables include process, material group, thickness, position, and heat input.

Traceability links materials and consumables to the weld through records and certificates.

Heat input is calculated from current, voltage, and travel speed, and is controlled within the WPS range.

Nonconformances are recorded, evaluated, and resolved before acceptance.

Deposition rate depends on current, wire feed speed, and wire size; higher deposition reduces arc time.

Operating factor is the ratio of arc time to worked time; manual processes have lower operating factors.

Cost per metre includes labour, filler, power, and overheads; labour usually dominates.

Weld volume increases with plate thickness, so joint design affects cost significantly.

Planning includes qualification, inspection hold points, and consumable delivery.

Supervision verifies that the correct WPS, filler, and qualified welder are used.

Current is set from the manufacturer's range and adjusted by arc behaviour.

Arc length affects shielding and penetration; a short arc is generally better for SMAW.

Travel angle and speed control bead shape and penetration.

Position affects current selection: flat uses higher current than vertical or overhead.

Tacks should be small, fused, and cleaned before the main pass.

Cleaning between passes prevents slag inclusions and lack of fusion.

Local exhaust ventilation at the arc is the primary control for welding fume.

Ozone forms in argon-shielded processes and is controlled by ventilation.

Electric shock risk is reduced by dry conditions and insulated equipment.

Arc eye is prevented by correct filter shades and screens.

Fire prevention includes removing combustibles and maintaining a fire watch.

Confined-space entry requires testing, ventilation, and a permit.

Visual inspection detects surface defects and is performed throughout fabrication.

Radiographic testing detects volumetric defects and provides a record.

Ultrasonic testing detects planar defects and is effective in thick sections.

Magnetic particle testing is limited to ferromagnetic materials.

Penetrant testing detects surface-breaking defects in non-porous materials.

Acceptance criteria are defined by the applicable standard and recorded.

Carbon equivalent predicts cracking risk and guides preheat selection.

Hydrogen cracking requires hydrogen, hard microstructure, and restraint.

Sensitisation of austenitic stainless steel occurs in the 450-850 C range.

Duplex stainless steels are sensitive to excessive heat input and sigma phase.

Aluminium requires oxide removal and appropriate shielding.

Hot cracking is controlled by composition, weld shape, and restraint.

Fillet weld throat is 0.7 times leg length for a 90-degree fillet.

Full penetration butt welds provide full strength and fatigue resistance.

Weld symbols indicate size, length, and position.

Distortion is controlled by balancing welds and sequencing.

Fatigue life is improved by smooth toe profiles.

Design should provide access for welding and inspection.

A WPS defines variables for a qualified procedure; a PQR records the qualification test.

Welder qualification is separate from procedure qualification.

Essential variables include process, material group, thickness, position, and heat input.

Traceability links materials and consumables to the weld.

Heat input is calculated from current, voltage, and travel speed.

Nonconformances are recorded and resolved before acceptance.

Deposition rate depends on current, wire feed speed, and wire size.

Operating factor is the ratio of arc time to worked time.

Cost per metre includes labour, filler, power, and overheads.

Weld volume increases with plate thickness and affects cost.

Planning includes qualification, inspection hold points, and delivery.

Supervision verifies the correct WPS, filler, and qualified welder.

Current is set from the manufacturer's range and adjusted by arc behaviour.

Arc length affects shielding and penetration.

Travel angle and speed control bead shape and penetration.

Position affects current selection.

Tacks should be small, fused, and cleaned.

Cleaning between passes prevents inclusions and lack of fusion.