Weldment Standards and Joints Catalog
Encyclopedic catalog for designing, specifying, fabricating, and inspecting welded structures: joint geometries (butt, T, lap, corner, edge); weld types (fillet, groove CJP/PJP, plug, slot, surfacing, resistance); AWS A2.4 + ISO 2553 weld symbols; codes (AWS D1.x, ASME Section IX, API 1104, ISO 15614/15613, EN 1090, AS 1554, CSA W47/W59, GOST 14771); inspection methods (VT, UT, PAUT+TOFD, RT, MT, PT); processes (SMAW, GMAW, GTAW, FCAW, SAW, ESW, OFW, PAW, LBW/EBW, FSW, RW); HAZ, CE, preheat/interpass, and PWHT. Filler-metal classification through AWS A5 + EN ISO 17632/18276 etc.
1. Joint Type Master Classification (AWS A3.0M / A3.0:2020)
| Joint | Description | Common processes |
|---|---|---|
| Butt | Two members in approx same plane edge-to-edge | SMAW, GMAW, GTAW, FCAW, SAW, EBW, LBW |
| T-joint | Two members perpendicular forming T | SMAW, GMAW, FCAW, GTAW |
| Lap | Two overlapping members | GMAW, FCAW, RW (spot/seam), brazing |
| Corner | Members meeting at corner (~90°) | GMAW, GTAW, SAW |
| Edge | Edges of members meeting (sheet metal) | GTAW, RW, LBW |
2. Butt-Joint Edge Preparations
| Preparation | Sketch / angle | Thickness range | Use |
|---|---|---|---|
| Square (open or closed) | I-groove | ≤ 6 mm (open root); ≤ 3 mm (closed) | Thin plate / sheet |
| Single-V | 60-75° included (carbon), 70-80° (stainless) | 4-30 mm | Most common single-side access |
| Double-V (X) | 60° each side; balanced or asymmetric | 12-100 mm | Two-side access reduces filler ~50% vs V |
| Single-U | 8-12° bevel + 6-10 mm root radius | 18-100 mm | Heavy section single-side; reduces filler |
| Double-U (H) | mirror of U | 38-300 mm | Thick plate two-side; reactor + boiler |
| Single-J | one side beveled (J shape) | 18-100 mm | T-joint with full penetration on one side |
| Double-J | mirror of J | 38-300 mm | T-joint with double-side access |
| Single-bevel | one side beveled, other square | 4-30 mm | T-joint full penetration |
| Double-bevel (K) | both sides beveled, one member | 12-100 mm | T-joint full penetration two-side access |
| Flare-V | two convex edges (tube/round bar) | 3-25 mm | Tube + sheet metal lap |
| Flare-bevel | one convex edge + one flat | 3-25 mm | Tube to plate |
| Compound (combo bevel + J + radius) | special | thick + heavy | Pressure vessel / nuclear |
Root opening (root gap): 0-6 mm depending on prep + process; typical 2-3 mm for SMAW V-groove on plate. Root face (land): 0-3 mm; reduces burn-through risk; eliminated where backing strip / backgouge used. Backing: ceramic, copper, or steel strip allows higher current and full root penetration.
3. Weld Types
3.1 Fillet Weld
Triangular section deposited at intersection of two surfaces ~90°.
| Designation | Notes |
|---|---|
| Single fillet | One side only |
| Double fillet | Both sides |
| Continuous | Run full length |
| Intermittent | Skip pattern (e.g., 50-150 = 50 mm weld every 150 mm pitch) |
| Chain | Aligned both sides |
| Staggered | Offset both sides |
| Convex / Flat / Concave | Profile contour |
Throat dimension a (effective): for equal-leg fillet, a = 0.707 × leg length. Strength of fillet ≈ throat × length × shear stress.
3.2 Groove Weld
| Type | Description |
|---|---|
| Complete Joint Penetration (CJP) | Full thickness fused (root to face) — preferred for primary load + cyclic |
| Partial Joint Penetration (PJP) | Defined depth less than full thickness |
| Square groove | Square edges with root opening |
| V-groove | V-shaped prep |
| Bevel groove | Single beveled edge (other square) |
| U-groove | U-shaped prep |
| J-groove | J-shaped prep |
| Flare groove | Flared edges (tube/bar) |
CJP requires either two-side access (V or X) or single-side with backing or backgouge + back-weld.
3.3 Plug + Slot Weld
Plug: fills circular hole. Slot: fills elongated hole. Used as substitute for fasteners or to fuse internal stiffener through outer plate. Per AWS D1.1 Section 2.
3.4 Surfacing / Cladding
| Type | Process | Application |
|---|---|---|
| Wear surfacing (hardfacing) | SMAW, GMAW, FCAW, GTAW + Cr-Cb-Mo-W-C electrodes; PTAW for premium | Mining (truck bed liners, dragline buckets, mill liners), agriculture (plow shares, harvester) |
| Corrosion overlay | SAW + strip, ESW, or GTAW with austenitic SS / Inconel 625 / 825 over carbon steel base | Refinery hot HC vessels, sour service, sea water |
| Buttering (transition layer) | GTAW or SMAW depositing intermediate filler before dissimilar joint completion | Dissimilar-metal welds (CS to SS, low-alloy to Ni-base) |
3.5 Resistance Welds
| Type | Description |
|---|---|
| Spot weld | Single fused nugget through faying surfaces under electrode pressure |
| Seam weld | Continuous nugget formed by rolling electrode wheels |
| Projection weld | Spot weld localized by raised projection on one part (nut on plate, panel-to-tube) |
| Flash butt weld | End-butt with brief arc-flash + forging (rail, chain, large rings) |
| Upset butt weld | Pure resistance + forging without flash (wire, bar) |
4. Weld Symbols (AWS A2.4:2020 / ISO 2553:2019)
4.1 AWS A2.4 Layout
$\boxed{\text{Tail (process, spec, ref)};;\text{flag};;\text{arrow side / other side};;\text{reference line};;\text{arrow}}$
- Arrow side: weld on side arrow points to
- Other side: weld on opposite side
- Both sides: symbol on both sides of reference line
- Weld-all-around: circle at junction of arrow + reference line
- Field weld: flag (filled triangle) at junction
- Specific weld dimensions in/around the basic weld symbol
Basic weld symbols (placed above/below reference line):
| Symbol | Weld type |
|---|---|
| Triangle (right angle) | Fillet |
| V | V-groove |
| Bevel | Bevel-groove (vertical bar + angled leg) |
| U | U-groove |
| J | J-groove |
| Square | Square-groove |
| Circle | Plug or spot |
| Rectangle | Slot or seam |
| Open V | Flare-V groove |
| Bevel + V | Flare-bevel groove |
| Stud weld | Hexagon |
Supplementary:
| Symbol | Meaning |
|---|---|
| Flush (—) | Flush finish |
| Convex (⌒) | Convex contour |
| Concave (⌣) | Concave contour |
| C | Chipping |
| G | Grinding |
| M | Machining |
| R | Rolling |
| H | Hammering |
| Backing bar (rectangle on reference line) | Backing strip required |
| Spacer (square) | Spacer required |
| Melt-through (semicircle on reference line) | Full melt-through required |
4.2 ISO 2553 Layout
ISO uses System A (reference line + arrow, like AWS but other side mirrored to dashed reference line) and System B (no dashed line, “other side” via inverted symbol). Symbol shapes match AWS in most cases; differences:
- ISO uses different conventions for combined symbols (e.g., bevel + fillet)
- Filler-metal / process references in tail differ
- Designation of intermittent welds slightly different format
Both standards specify weld size by leg (fillet) or depth-of-bevel (groove). Effective throat a is now derivable from either.
5. Welding Codes by Region + Industry
5.1 AWS D1.x — Structural Welding (US)
| Code | Material | Title |
|---|---|---|
| AWS D1.1/D1.1M:2020 | Carbon + low-alloy steel | Structural Welding Code — Steel |
| AWS D1.2/D1.2M:2024 | Aluminum | Structural Welding Code — Aluminum |
| AWS D1.3/D1.3M:2018 | Sheet steel | Structural Welding Code — Sheet Steel |
| AWS D1.4/D1.4M:2018 | Reinforcing steel | Structural Welding Code — Reinforcing Steel |
| AWS D1.5/D1.5M:2020 | Steel | Bridge Welding Code (with AASHTO) |
| AWS D1.6/D1.6M:2017 | Stainless steel | Structural Welding Code — Stainless Steel |
| AWS D1.7/D1.7M:2010 | Steel | Guide for Strengthening + Repair of Existing Structures |
| AWS D1.8/D1.8M:2021 | Carbon + low-alloy steel | Structural Welding Code — Seismic Supplement (with AISC 341) |
| AWS D1.9/D1.9M:2015 | Titanium | Structural Welding Code — Titanium |
Other AWS:
- AWS D17.1/D17.1M:2024 — Aerospace fusion welding (replaces MIL-STD-1595)
- AWS D17.2/D17.2M — Aerospace resistance welding
- AWS D14.x — Industrial machinery (cranes, presses, off-road)
- AWS D15.1 — Railroad welding
- AWS D3.6M — Underwater welding (Class A/B/O hyperbaric)
5.2 ASME — Pressure Vessels + Boilers + Piping
| Section | Topic |
|---|---|
| ASME BPVC Section I | Power boilers |
| ASME BPVC Section III | Nuclear components (Divisions 1, 2, 3 / 5) |
| ASME BPVC Section VIII Div 1 | Pressure vessels (workhorse) |
| ASME BPVC Section VIII Div 2 | Alternative rules (analysis-based design) |
| ASME BPVC Section VIII Div 3 | Vessels > 70 MPa (10 ksi) |
| ASME BPVC Section IX | Welding + brazing + fusing qualifications (QW / QB / QF) |
| ASME BPVC Section II | Materials (Part A ferrous, B nonferrous, C welding rods + electrodes, D properties) |
| ASME B31.1 | Power piping |
| ASME B31.3 | Process piping (chemical + refinery) |
| ASME B31.4 | Liquid pipeline |
| ASME B31.5 | Refrigeration piping |
| ASME B31.8 | Gas pipeline |
| ASME B31.9 | Building services piping |
| ASME B31.12 | Hydrogen piping |
| ASME PCC-1 | Bolted flange joint assembly |
| ASME PCC-2 | Repair of pressure equipment + piping |
5.3 API — Oil and Gas
| Code | Topic |
|---|---|
| API 1104 | Welding pipelines + related facilities (oil + gas) |
| API 510 | Pressure vessel inspection / repair / alteration / re-rating |
| API 570 | Piping inspection / repair / alteration / re-rating |
| API 653 | Tank inspection / repair / alteration / reconstruction (above-ground storage) |
| API 650 / 620 | Welded storage tanks |
| API 12 | Field welded tanks |
| API RP 582 | Welding guidelines for chemical, oil + gas |
| API RP 577 | Welding inspection + metallurgy |
5.4 ISO — International
| Standard | Topic |
|---|---|
| ISO 15614 (parts 1-14) | Welding procedure qualification (WPQR) |
| ISO 15613 | WPQR by pre-production welding test |
| ISO 9606 (parts 1-5) | Qualification of welders (1 = steel, 2 = Al, 3 = Cu, 4 = Ni, 5 = Ti/Zr) |
| ISO 14731 | Welding coordination (Tasks + responsibilities; IWE / IWT / IWS / IWP qualification) |
| ISO 3834 (parts 1-6) | Quality requirements for fusion welding (1=full, 2=comprehensive, 3=standard, 4=elementary) |
| ISO 17636 | RT testing of welds |
| ISO 17640 | UT testing of welds |
| ISO 17638 | MT testing of welds |
| ISO 3452 | PT testing |
| ISO 17643 | ET testing |
| ISO 5817 | Quality levels for imperfections (B = stringent, C = intermediate, D = moderate) |
5.5 EN — Europe
| Code | Topic |
|---|---|
| EN 1090-1 | Execution of steel + Al structures — Conformity assessment |
| EN 1090-2 | Steel structures (Execution Classes EXC1-EXC4) |
| EN 1090-3 | Aluminum structures |
| EN 1090-4/-5 | Cold-formed steel + Al |
| EN 13445 | Unfired pressure vessels |
| EN 13480 | Metallic industrial piping |
| EN 12952 | Water-tube boilers |
| EN 12953 | Shell boilers |
5.6 National / Regional
| Code | Country | Topic |
|---|---|---|
| AS 1554.1-7 | AU | Steel + Al + Stainless structural |
| AS/NZS 3992 | AU/NZ | Pressure equipment welding |
| CSA W47.1 | CA | Certification of companies for fusion welding of steel |
| CSA W47.2 | CA | Certification of companies for fusion welding of Al |
| CSA W59 | CA | Welded steel construction (metal arc) |
| CSA W178 | CA | Certification of welding inspectors + practice |
| JIS Z 3801 / 3805 / 3811 | JP | Welder qualification |
| JIS Z 3604 / 3214 | JP | Welding of specific structures |
| GOST 14771-76 | RU | Gas-shielded arc welding |
| GOST 14098 | RU | Welded joints of rebar |
| GOST 5264-80 | RU | Manual arc welding joint types |
| KS B 0801 series | KR | — |
| GB 50661 | CN | Welding of steel structures |
| IS 9595 / IS 1182 | IN | Welding |
6. Welding Inspection — NDE
6.1 Methods Overview (see ndt-methods T3 for deep dive)
| Method | What it finds | Best for | Limit |
|---|---|---|---|
| VT (Visual) | Surface discontinuities, weld profile, undercut, overlap, crater, arc strike | All — required preceding test method | Surface only |
| PT (Penetrant, dye) | Surface-breaking cracks, porosity | Non-magnetic materials (SS, Al, Ni) | Surface only |
| MT (Magnetic Particle) | Surface + near-surface cracks | Ferromagnetic only (CS, low-alloy) | <6 mm subsurface |
| UT (Ultrasonic, pulse-echo) | Volumetric (cracks, LF, LP, slag, porosity) | All thicknesses 6-300 mm | Operator + access dependent |
| PAUT (Phased Array UT) | Volumetric with steered beams + electronic focusing | Welds 6-300 mm; replaces RT in many applications | Setup + cost |
| TOFD (Time-of-Flight Diffraction) | Crack tip diffraction (height-sized) | Combined with PAUT for code-compliant alternatives to RT | Surface + near-surface dead zone |
| RT (Radiography) | Volumetric (porosity, slag, LF, LP) — gold standard | Pressure vessels; CJP welds | Cost, safety, time, no through-thickness crack-height info |
| Digital RT (DR, CR) | Same as RT, with digital detector | Replacing film | — |
| CT (Computed Tomography) | 3D volumetric | Specialty (aerospace turbine blades, AM parts) | Cost, size limit |
| ET (Eddy Current) | Surface cracks (mainly conductive metals) | Tube + boiler tubes, aerospace skin | Conductivity-dependent |
| AE (Acoustic Emission) | Active defect monitoring (in-service growth) | Pressure-vessel re-qualification | Requires loading |
| IR Thermography | Internal voids + bond defects | Composites, electronics | — |
| Leak test (bubble, mass spec) | Through-leaks | Pressure vessels, vacuum | Through-only |
6.2 Inspector Certification
- AWS QC1 / CWI (Certified Welding Inspector) — US
- AWS B5.1 (CWI), B5.2 (CWS), B5.16 (CWE) qualification specs
- AWS B5.4 — Specification for the qualification of welding instructors
- ASNT SNT-TC-1A — Recommended practice for NDT personnel; Level I/II/III
- ISO 9712 — Qualification + certification of NDT personnel
- ASNT CP-189 — Standard for qualification + certification of NDT personnel (US, complementary to TC-1A)
- ASNT ACCP — Central Certification Program (cross-industry recognition)
- EN 473 → ISO 9712 — EU NDT cert
- PCN (UK), COFREND (FR), DGZfP (DE) — national bodies under ISO 9712
- IIW IWE / IWT / IWS / IWP — International Welding Engineer / Technologist / Specialist / Practitioner (ISO 14731)
6.3 NDE Acceptance Criteria
| Code | Section | Notes |
|---|---|---|
| AWS D1.1 Table 6.1 | Visual acceptance — statically loaded | Undercut, weld profile, cracks, porosity |
| AWS D1.1 Table 6.2 | UT acceptance — statically loaded | Compact / linear defects |
| AWS D1.1 Table 6.3 | UT acceptance — cyclically loaded (fatigue) | Tighter than 6.2 |
| AWS D1.1 Annex K | PAUT alternative to D1.1 Section 6 conventional UT | |
| AWS D1.5 Section 6 | Bridge welding (cyclic, fracture-critical) | AASHTO supplement |
| ASME VIII Div 1 UW-51 | RT acceptance for full RT | Slag, porosity, cracks, LF, LP |
| ASME VIII Div 1 UW-52 | RT acceptance for spot RT | Reduced scope |
| ASME VIII Div 1 Appendix 12 | UT acceptance | Volumetric |
| ASME V Article 4 | UT examination methodology | |
| ASME V Article 2 | RT examination methodology | |
| API 1104 Section 9 | Pipeline weld acceptance (length + depth of imperfections) — alternative criteria 9.3 ECA | |
| ISO 5817 B / C / D | Quality levels per defect type | |
| ISO 10675-1 | RT acceptance per ISO 5817 | |
| ISO 11666 | UT acceptance per ISO 5817 | |
| ISO 23279 | UT characterization of indications |
6.4 Engineering Critical Assessment (ECA / BS 7910)
Alternative fitness-for-service criterion: defect acceptable if it cannot grow to critical size in service life. Required by API 1104 9.3 + pipeline / offshore for girth welds; methodology via BS 7910 / API 579 / FITNET.
7. Weld Discontinuities + Defects (AWS A3.0)
| Discontinuity | Cause | Fix |
|---|---|---|
| Porosity (clustered, scattered, linear, piping) | Moisture, contamination, gas-shield loss, electrode condition | Re-dry electrode (E7018: 230-260°C × 2 hr), clean joint, increase shielding |
| Slag inclusion | Failure to clean between passes, electrode angle, low travel speed | Inter-pass cleaning (wire brush, grinder), proper electrode angle |
| Tungsten inclusion (GTAW) | Tungsten tip touched puddle, wrong polarity | Lift-arc, AC for Al, regrind, replace tungsten |
| Lack of Fusion (LF) | Insufficient heat, contamination, wrong electrode angle, fast travel | Increase amperage, slow travel, clean |
| Lack of Penetration (LP) / Incomplete penetration | Root face too thick, root gap too narrow, low current | Adjust prep, increase current/heat |
| Undercut | Excessive current, wrong angle, fast travel | Reduce current, dwell at edge |
| Overlap (cold lap) | Insufficient heat / penetration, wrong angle | Adjust technique |
| Cracks — longitudinal | High restraint + hydrogen + hardness; centerline solidification | Lower H₂ electrode, preheat, lower CE, slower cooling |
| Cracks — transverse | Hydrogen induced; high-restraint | Same |
| Cracks — crater | Improper crater fill at termination | Backfill crater, use crater-fill feature on power source |
| Cracks — root | Solidification, restraint, LP | Increase root opening, control heat |
| Cracks — toe | Stress concentration, hydrogen, undercut | Grind smooth, preheat, low-H₂ electrode |
| Cracks — underbead (HAZ) | Hydrogen embrittlement of hard HAZ | Preheat, low-H electrode, PWHT |
| Cracks — hot (solidification, stainless + Ni) | Segregation, high stress on cooling | Lower heat input, use grade with ferrite (308L 4-10 FN), control restraint |
| Lamellar tearing | Through-thickness restraint on rolled plate with sulfur stringers | Low-S “Z-grade” plate (Z25, Z35) per EN 10164 |
| Crater pipe | Sudden arc termination | Crater fill / back-step |
| Spatter | Excessive current, magnetic blow | Reduce current, change polarity, anti-spatter compound |
| Burn-through (melt-through) | Excess heat, thin material, wide gap | Lower current, faster travel, backing strip |
| Arc strike | Tip touched parent metal outside weld zone | Critical: grind out + verify with MT/PT |
| Convex / concave profile | Improper bead profile | Profile per code (e.g., AWS D1.1 Fig 5.4) |
8. Welding Processes
8.1 SMAW (Shielded Metal Arc Welding, Stick) — AWS A5.1, A5.5
Coated stick electrode; DCEP (most), DCEN, AC.
| AWS A5.1 | Description | Position | Coating |
|---|---|---|---|
| E6010 | Cellulose, deep-penetration root pass, all positions, DCEP | All | Cellulose |
| E6011 | Cellulose, AC option of E6010 | All | Cellulose |
| E6013 | Rutile, easy starting, light penetration, sheet metal | All | Rutile |
| E7014 | Iron-powder rutile, faster deposition | All | Rutile + Fe powder |
| E7018 | Low-hydrogen iron-powder, structural workhorse, requires oven-stored or re-baked | All | Low-H + Fe powder |
| E7024 | Heavy iron-powder, flat fillet only | Flat | Rutile + Fe powder |
| E7028 | Iron-powder low-H, flat | Flat | Low-H + Fe powder |
| E7048 | Low-H for vertical-down (pipeline) | All incl V-down | Low-H |
Low-alloy AWS A5.5:
- E7018-A1 (½Mo), E8018-B2 (1¼Cr-½Mo), E9018-B3 (2¼Cr-1Mo), E8018-C3 (1Ni), E10018-D2 (Mn-Mo), E11018-M (high-strength, mil)
8.2 GMAW (Gas Metal Arc Welding, MIG/MAG) — AWS A5.18, A5.28
Solid wire on spool fed continuously; shielding gas externally (Ar, Ar+CO2, Ar+O2, CO2).
| AWS A5.18 | Composition | Service |
|---|---|---|
| ER70S-2 | Si-Mn-Ti-Zr-Al deoxidizers | Rusty / mill-scale plate (GTAW + GMAW) |
| ER70S-3 | Si-Mn (mid) | General purpose mid-cleanliness plate |
| ER70S-4 | Si-Mn (higher) | More tolerance for surface oxide |
| ER70S-6 | Higher Si + Mn (highest) | Workhorse GMAW, GMAW-STT root + open-root pipeline; tolerates poor cleanliness |
| ER70S-G | Custom (any composition complying with tensile) | OEM proprietary |
| ER80S-D2 | Mn-Mo | Higher tensile + impact |
| ER90S-G / ER100S-G / ER110S-G | High-strength tailored | Special structural |
Transfer modes:
| Mode | Voltage / current | Use |
|---|---|---|
| Short-circuit (Short-arc) | <22 V / 50-180 A | Out-of-position, thin material, root pass |
| Globular | 22-25 V / 180-220 A (CO2 typical) | Heritage; high spatter |
| Spray | >25 V + Ar-rich, > transition current (~200-250 A for 1.2 mm) | Flat + horizontal fillet, high deposition |
| Pulsed-spray (GMAW-P) | Pulsed peak/background | All positions, low heat input avg, modern workhorse |
| Surface-Tension Transfer (STT, Lincoln) | Controlled droplet detachment | Pipe root open-root |
| Cold Metal Transfer (CMT, Fronius) | Coordinated wire retraction at droplet detachment | Aluminum, thin sheet, root pass, brazing |
| RMD (Regulated Metal Deposition, Miller) | Similar to STT | Pipe root |
8.3 GTAW (Gas Tungsten Arc Welding, TIG) — AWS A5.18, A5.28, A5.9, A5.16
Non-consumable tungsten electrode + separately added filler rod (or autogenous, no filler).
| Tungsten | Use |
|---|---|
| 2% thoriated (red, AWS EWTh-2) | DCEN steel + SS — heritage; thorium is radioactive (low) |
| 2% ceriated (orange, EWCe-2) | DCEN steel + SS modern, no radioactivity |
| 1.5% lanthanated (gold, EWLa-1.5) | DCEN + AC universal modern (replaces thoriated + ceriated) |
| 2% lanthanated (blue, EWLa-2) | Same as above, higher current |
| Pure tungsten (green, EWP) | AC Al heritage (balls into hemisphere) |
| Zirconiated (brown, EWZr-1) | AC Al — clean weld pool |
Filler rod for GTAW commonly same wire as GMAW (ER70S-2 for steel — extra deoxidizers handle GTAW’s lower turbulence and any back-side oxidation). Stainless: ER308L / ER316L / ER309L (dissimilar). Al: ER4043 / 4047 (Si), ER5356 (Mg). Ni-base: ERNiCr-3 (Inconel 82), ERNiCrMo-3 (625).
8.4 FCAW (Flux-Cored Arc Welding) — AWS A5.20, A5.29
Tubular wire with internal flux; gas-shielded (FCAW-G) or self-shielded (FCAW-S).
| AWS A5.20 | Description |
|---|---|
| E71T-1C/M | Rutile gas-shielded, all-position, low-spatter workhorse |
| E70T-1C/M | Rutile gas-shielded, flat + horizontal |
| E71T-8 | Self-shielded, all-position, low-hydrogen |
| E70T-G / E71T-G | General, custom proprietary |
| E71T-11 | Self-shielded general purpose (light structural) |
| E70T-4 | Self-shielded, high deposition flat |
A5.29 covers low-alloy (E81T1-K2, E91T1-K2, E110T5-K3 etc.).
8.5 SAW (Submerged Arc Welding) — AWS A5.17, A5.23
Continuous wire under granular flux; flat + horizontal only, high deposition rate. Used for pressure vessel longitudinal + circumferential, large beam, ship plate, pipe mill, tank.
| AWS A5.17 wire | Description |
|---|---|
| EM12K | Med-Mn-Si killed (workhorse) |
| EH12K | Higher-Mn killed |
| EL12 | Low-Mn |
| Flux: F7A2-EM12K | Combined wire+flux classification |
8.6 ESW + EGW (Electroslag + Electrogas)
Vertical-only, single-pass thick plate (50-400 mm). ESW = consumable electrode in flux pool; EGW = consumable wire in gas-shielded pool. Used for heavy ship plate, T-joints (girders), pressure vessels.
8.7 OFW (Oxy-Fuel — Oxyacetylene)
Heritage gas welding (3160°C neutral OA flame); largely replaced for production but still used for repair, brazing, plumbing, ornamental.
8.8 PAW (Plasma Arc Welding)
Constricted arc through orifice; keyhole at higher current. Aerospace tube, instrument, thin sheet. Microplasma: <15 A precision.
8.9 LBW + EBW (Laser + Electron Beam)
Deep narrow welds with minimal HAZ; aerospace turbine blade, transmission gear, sensor housing. Auto powertrain mass-production (gear-to-shaft).
8.10 FSW (Friction Stir Welding)
Rotating tool plunged into joint; solid-state weld. Aluminum + Cu + Mg + Ti + steel. Aerospace (rocket tanks SLS, Falcon 9, Vega), high-speed train bodies, marine aluminum hulls, EV battery trays.
8.11 RW (Resistance Welding)
| Type | Service |
|---|---|
| Resistance spot weld (RSW) | Auto body sheet; >5000 spots per vehicle |
| Resistance seam weld (RSEW) | Fuel tank, exhaust pipe |
| Projection weld | Nut to panel, panel to tube |
| Flash butt | Rail joints, chain, rim |
| Upset butt | Wire-to-wire |
8.12 Stud Welding
| Process | Service |
|---|---|
| Drawn-arc (DASW) | Headed studs to beams (Nelson studs on composite beam), > Ø6 mm |
| Capacitor-discharge (CDSW) | Small studs to sheet (Ø3-8 mm), no flux/ferrule, no marking |
OEMs: Nelson Stud Welding (Doncasters), Stanley Engineered Fastening Tucker, Image Industries, Köster, Sunbird.
8.13 Hybrid Processes
| Process | Combination | Use |
|---|---|---|
| Hybrid Laser-Arc (HLAW) | Laser + GMAW | Shipyard thick plate, pipe-mill |
| Tandem GMAW | Two wires through one torch | Pipe mill, ship plate (productivity) |
| TIG-Hot Wire | GTAW + resistance-heated filler wire | Cladding |
9. Heat-Affected Zone (HAZ) — Metallurgy + Cracking
9.1 HAZ Zones
| Region | Peak temperature | Microstructure | Hardness |
|---|---|---|---|
| Fusion zone (FZ) / weld metal | > T_melt | Cast solidification (as-deposited) | depends |
| Coarse-grained HAZ (CGHAZ) | 1100-1400°C | Coarse austenite → martensite/bainite on cool | hardest, most-crack-prone |
| Fine-grained HAZ (FGHAZ) | 900-1100°C | Recrystallized + refined | moderate |
| Intercritical HAZ (ICHAZ) | 700-900°C | Partial austenite (mixed) | variable |
| Subcritical HAZ (SCHAZ) | 500-700°C | Tempered base | low-moderate |
| Unaffected base | < 500°C | Original | base |
9.2 Carbon Equivalent (CE) — Hardenability + Hydrogen-Cracking Risk
IIW (CE-IIW): $CE = C + Mn/6 + (Cr+Mo+V)/5 + (Ni+Cu)/15$
Yurioka (CE_N): more accurate for low-C, low-alloy modern steels
Pcm (Ito-Bessyo, for high-strength low-alloy): $Pcm = C + Si/30 + (Mn+Cu+Cr)/20 + Ni/60 + Mo/15 + V/10 + 5B$
| CE-IIW | Crack-risk class | Pre-heat |
|---|---|---|
| < 0.40 | Low | usually none required |
| 0.40-0.50 | Moderate | 100-150°C (depending on thickness, H₂, restraint) |
| 0.50-0.60 | High | 150-200°C + low-H electrode |
| > 0.60 | Very high | 200-300°C + low-H + slow cool + PWHT |
9.3 Preheat + Interpass
Codes (AWS D1.1 Table 5.8, EN 1011-2, ISO/TR 17671-2) specify min preheat by:
- Steel grade (per material category)
- Thickness
- Process (heat input)
- H₂ class of consumable
| AWS D1.1 H₂ class | Hydrogen content (ml/100g of weld metal) |
|---|---|
| H4 | ≤4 |
| H8 | ≤8 |
| H16 | ≤16 |
Low-H electrodes (E7018, E8018, E9018 etc.) must be from sealed cans; once opened, must be stored in 120°C+ holding oven; re-bake at 230-260°C × 2 hr if exposed to >50% humidity.
Interpass temperature: minimum (to prevent under-cooled HAZ cracking) and maximum (to prevent over-tempering / softening of quench-tempered base, particularly Q&T 690-960 grades).
9.4 Postweld Heat Treatment (PWHT)
| Purpose | Method |
|---|---|
| Stress relief | 595-705°C (1100-1300°F) typical for CS + low-alloy; soak time 1 hr per 25 mm thickness; per ASME VIII Div 1 UCS-56 |
| Hydrogen-bake | 200-300°C × hours; for crack-sensitive joints |
| Tempering | 565-700°C — restores toughness in martensitic HAZ |
| Solution anneal | Austenitic SS: 1010-1120°C + water quench |
| Quench + temper (Q&T) | Heat-treat after weld (rare) |
PWHT exempt when: thickness < some threshold per code (e.g., ASME VIII Div 1 UCS-56 allows CS exempt up to certain thickness with preheat).
Local heating (induction blanket, resistance heating ceramic pads, or full furnace) acceptable per ASME VIII / API 510 with thermocouples + heat-treat report.
10. Procedure + Welder Qualification
10.1 Documentation Hierarchy
| Document | Purpose |
|---|---|
| WPS (Welding Procedure Specification) | Recipe a welder follows: process, joint, material, filler, gas, position, current, preheat, etc. |
| PQR (Procedure Qualification Record) | Test-weld records demonstrating WPS produces sound welds per code |
| WPQR (Welding Procedure Qualification Record) | ISO equivalent |
| WQR / WPQ (Welder Performance Qualification) | Per-welder test verifying welder can deposit per WPS |
| Manufacturer’s NDE / Inspection Report | Production record |
| MTR (Mill Test Report) / CMTR | Base + filler metal certification |
| MTC (Material Test Certificate) | EN 10204 type 2.1 / 2.2 / 3.1 / 3.2 traceability |
ASME Section IX QW-200 (WPS+PQR), QW-300 (welder qualification), QW-360 (operator qualification — for SAW, ESW, machine GMAW).
Essential / supplementary essential / non-essential variables per ASME IX define when re-qualification is required vs not.
10.2 EN ISO Equivalents
| ASME IX | EN ISO |
|---|---|
| WPS | pWPS → WPS |
| PQR | WPQR per ISO 15614 |
| Welder qual | ISO 9606 |
| Operator qual | ISO 14732 |
11. Filler-Metal Classification Summary (AWS A5.x)
| AWS A5 | Covers |
|---|---|
| A5.1 | CS SMAW |
| A5.2 | Iron + steel rods (OFW) |
| A5.3 | Al SMAW |
| A5.4 | Stainless SMAW |
| A5.5 | Low-alloy SMAW |
| A5.6 | Cu + Cu-alloy SMAW |
| A5.7 | Cu + Cu-alloy GMAW + GTAW rods |
| A5.8 | Brazing filler |
| A5.9 | Stainless GMAW + GTAW + SAW wires + electrodes |
| A5.10 | Al + Al-alloy GMAW + GTAW |
| A5.11 | Ni + Ni-alloy SMAW |
| A5.12 | Tungsten electrodes for GTAW + PAW |
| A5.13 | Surfacing SMAW electrodes |
| A5.14 | Ni + Ni-alloy GMAW + GTAW |
| A5.15 | Cast iron SMAW + OFW |
| A5.16 | Ti + Ti-alloy GMAW + GTAW |
| A5.17 | CS SAW (wire + flux) |
| A5.18 | CS GMAW (solid + composite) |
| A5.19 | Mg + Mg-alloy GMAW + GTAW |
| A5.20 | CS FCAW |
| A5.21 | Surfacing GMAW + GTAW |
| A5.22 | Stainless FCAW |
| A5.23 | Low-alloy SAW |
| A5.24 | Zr + Zr-alloy GMAW + GTAW |
| A5.25 | CS ESW |
| A5.26 | CS EGW |
| A5.28 | Low-alloy GMAW + GTAW + LBW |
| A5.29 | Low-alloy FCAW |
| A5.30 | Consumable inserts (GTAW back purge ring) |
| A5.31 | Brazing fluxes |
| A5.32 | Shielding gases |
| A5.34 | Ni + Ni-alloy FCAW |
| A5.36 | CS + Low-alloy FCAW + Metal-cored (new combined classification) |
EN ISO filler classifications (parallel system): ISO 2560 (SMAW CS), ISO 14341 (GMAW CS solid), ISO 17632 (FCAW CS), ISO 14171 (SAW CS), ISO 18276 (FCAW high-strength), ISO 3580 (SMAW heat-resistant), ISO 14343 (GMAW/SAW SS), ISO 18274 (Ni-alloy), ISO 18273 (Al), etc.
12. Equipment OEMs
| OEM | Country | Strengths |
|---|---|---|
| Lincoln Electric | US | SMAW + GMAW + FCAW + SAW power sources, consumables — global leader |
| ESAB (Colfax) | SE/US | Process power sources + consumables (Filarc, OK Autrod, OK Tubrod) |
| Miller Electric (ITW) | US | SMAW, GMAW, GTAW, plasma cutting (Pipeworx, XMT, Dynasty, Maxstar) |
| Hobart Brothers (ITW) | US | Filler metals (FabCO, FabCOR, ER70S-6) |
| Fronius | AT | Premium GMAW + GTAW (TransSteel, TransPuls, MagicWave); CMT (Cold Metal Transfer) |
| Kemppi | FI | GMAW + GTAW (Master M, X8 Mig Welder, FastMig); WiseSeries control |
| EWM | DE | GMAW + GTAW (Phoenix, Picotig, Tetrix) |
| Hyundai Welding | KR | Consumables |
| Kobelco / Kobe Steel | JP | FCAW + SMAW + SAW consumables (Premiarc + Familiarc) |
| Voestalpine Böhler Welding | AT | High-end consumables (Böhler, UTP, Avesta, Soudokay) |
| Welspun, JFE, JSW | IN/JP | LSAW/HSAW line-pipe SAW |
| Lincoln-Smitweld (now Lincoln) | NL | low-H rod heritage |
| OTC Daihen | JP | GMAW + GTAW + robotics |
| Yaskawa Motoman | JP | Welding robots |
| ABB | CH | Welding robots + power sources |
| KUKA | DE | Welding robots |
| FANUC | JP | Welding robots |
| Comau | IT | Welding robots |
| ARO Welding Technologies (now Aro Welding ARO Group) | FR | Resistance welding guns + transformers (auto body) |
| TJ Snow | US | Resistance welding equipment |
| AMADA | JP | Laser cutting + welding + bending |
| TRUMPF | DE | LBW, fiber + disk lasers (TruDisk, TruLaser) |
| IPG Photonics | US | Fiber laser sources |
| nLight + Coherent + Lumentum | US | Fiber + diode laser sources |
| Sciaky | US | EBW + Electron Beam Additive Manufacturing (EBAM) |
| PTR-Precision Technologies | US | EBW systems |
| Stir-Tech | UK | FSW |
| TWI | UK | FSW (inventor of FSW process 1991); also Friction-stir spot welding (FSSW) |
| Bond Technologies | US | FSW for industrial |
| Hitachi / Mazak / Bond | JP/US | FSW equipment |
13. Common Pitfalls
- Specifying CJP for fillet-only joints without two-side access or backing: NDE acceptance hard or impossible; consider PJP if loading allows
- Using E7018 from opened can not stored in oven: moisture ingress → hydrogen-induced cracking in 24-72 hr; always re-bake or use sealed-bag consumables
- Welding A514/Q&T high-strength steel without preheat or with H-rich electrode: HAZ cracking common in 70-150 hr post-weld; AWS D1.1 + A5.5 H4/H8 mandatory
- Galvanized steel welded without grinding zinc off: zinc-fume toxicity + porosity; grind ≥25 mm back, ventilate
- Stainless welded with no back-purge on tube: sugar-coated heat-tinted root (Cr-depletion) → corrosion failure; argon back-purge for 304/316/duplex
- Duplex 2205 with excessive heat input: ferrite-austenite phase balance shifts to high ferrite, low toughness + high corrosion; control heat input 0.5-2.5 kJ/mm
- Aluminum welded without acetone wipe + stainless wire brush: hydrogen porosity; clean within 24 hr of welding
- Mixing SS filler grades: 308L on 316 sometimes substituted — over-alloy expensive; under-alloy (e.g., 308L on 904L) destroys corrosion resistance
- Welding 7000-series aluminum with 4043 filler: cracks; use 5356 or 5183
- Carbon-steel filler on austenitic SS for dissimilar joint: martensite forms → embrittlement; use ER309L or Ni-base ERNiCr-3
- Skipping inter-pass cleaning on SAW or FCAW: slag inclusion guaranteed
- PWHT temperature exceeded: tempering loss in Q+T base — softening or cracking; check with thermocouple
- Welder qualification expired without re-qualification log: per ASME IX QW-322, requalification needed if process not used for 6 months
- WPS / PQR essential variables changed without re-qual: invalid procedure; check QW-253 (SMAW), QW-256 (GMAW), QW-255 (SAW) variable lists
- Cold-cracking risk from restraint not accounted for: e.g., crane bracket weld restrained on all four edges + 25-mm thick + high CE → 200°C preheat + slow cool + PWHT mandatory
- Lamellar tearing in T-joints on rolled plate with sulfur stringers: specify Z-grade plate (EN 10164 Z25 / Z35) or change joint to reduce through-thickness strain
- RT acceptance applied to non-CJP weld: standard RT acceptance only valid for CJP; PJP needs alternate criteria or UT
- TOFD dead-zone not understood: near-surface defects missed; combine with PAUT pulse-echo
- AWS D1.1 vs D1.5 confusion for bridge: D1.5 is mandatory for AASHTO bridges, more stringent than D1.1
- Repair-weld on field pressure vessel without API 510 procedure: in-service repair requires API 510 + NB-23 (National Board Inspection Code) + qualified WPS + PQR for repair