IS 9595:1992 is the Indian Standard (BIS) for recommendations for metal arc welding of carbon and carbon manganese steels. This standard provides recommendations for the manual metal arc welding (MMAW) of carbon and carbon-manganese steels. It covers parent materials, selection of welding consumables, joint preparation, preheating requirements based on Carbon Equivalent (CE) and thickness, welding procedures, and inspection to ensure sound weld quality.
Provides recommendations for manual, semi-automatic, and automatic metal arc welding of carbon and carbon manganese steels.
IS 9595 specifies recommendations for metal arc welding of carbon and carbon manganese steels — the structural welding code for India covering processes (SMAW manual electrode, SAW submerged arc, GMAW MIG/MAG, FCAW flux-cored, GTAW TIG), welding procedure qualification, welder qualification, weld design, inspection, and acceptance.
Use IS 9595 when: - Fabricating any structural steel work covered by IS 800:2007 - Building / industrial steel structures (PEB, warehouses, offices, factories) - Bridge fabrication (IRC:24:2010, IRC:22:2008) - Pressure vessel fabrication (with additional ASME / IS 2825 provisions) - Pipeline welding (with additional API / IS 4353 provisions) - Storage tank construction (oil tanks, water tanks) - Handrails, fences, gratings, ladders - Repair welding on existing steel structures
IS 9595 covers manual + semi-automatic + automatic arc welding processes. Other welding processes (gas welding, resistance welding) have separate codes; IS 9595 is the dominant structural welding code in India.
Key companion: IS 822:1970 — Code of Procedure for Inspection of Welds. IS 9595 + IS 822 together form the welding QA/QC framework.
1. Shielded Metal Arc Welding (SMAW / Manual / 'stick electrode'): - Most common for site fabrication, repair, small batch work - Electrode: coated rod (E6013 mild steel general; E7018 low-hydrogen for high-strength steels) - Position: all-position; portable - Heat input: medium - Use: structural connections, pipe welds, repair, on-site work
2. Submerged Arc Welding (SAW): - Electrode wire fed continuously under granular flux - High deposition rate; mechanised - Position: flat (1G) only - Use: long longitudinal seams (beams, plates, column flanges)
3. Gas Metal Arc Welding (GMAW / MIG / MAG): - Continuous wire electrode + shielding gas (Ar / CO₂ / Ar+CO₂ mix) - Higher deposition than SMAW; lower heat than SAW - Position: all-position with proper technique - Use: high-volume shop fabrication, structural fillets, sheet metal
4. Flux-Cored Arc Welding (FCAW): - Tubular wire with internal flux - Self-shielded or gas-shielded variants - Higher deposition than SMAW; portable - Use: site structural welding, ship building, plate fabrication
5. Gas Tungsten Arc Welding (GTAW / TIG): - Non-consumable tungsten electrode + Ar shielding + filler rod - Low heat input; high quality; slower - Use: thin plate, stainless steel, root passes of pipe welding
Welding consumables for carbon / C-Mn steels:
| Steel grade (IS 2062) | Recommended electrode (SMAW) | Filler wire (GMAW / FCAW) | |---|---|---| | E 250 (Fe 410 W) | E6013 (general) or E7018 (low-H) | ER70S-6 | | E 300 / E 350 | E7018 low-hydrogen | ER70S-6 | | E 410 / E 450 (high-strength) | E11018 / E12018 low-hydrogen | ER80S / ER90S |
Number convention: 'E70-XX' = 70 ksi tensile strength; 'XX' = position + flux type code.
Weld preparation: - Cleanliness: free of mill scale, rust, oil, paint, moisture (causes porosity) - Bevel angles: 45-60° single V; 60-70° double V; depends on plate thickness - Root gap: 1-3 mm (depends on process, position) - Backing: ceramic / copper / steel for single-side full penetration
Heat input control: - Q (kJ/mm) = (V × A × 60) / (1000 × travel speed mm/min) - Typical structural: 1.0-2.0 kJ/mm - Higher = wider HAZ, slower cooling, lower hardness - Lower = narrower HAZ, faster cooling, higher hardness (risk of cracking in high-CE steels)
Pre-heat (for high-CE steels or thick sections): - E 250 at < 25 mm thick: usually no preheat needed - E 250 at > 50 mm: 50-100 °C preheat - High-strength steels (E 410+): 100-200 °C preheat per CE calculation - CE = C + Mn/6 + (Cr+Mo+V)/5 + (Ni+Cu)/15 - Preheat = f(CE, plate thickness) per IS 9595 table
Post-Weld Heat Treatment (PWHT): - Required for thick welds in high-strength steels (avoid HAZ embrittlement) - Typical: 600-650 °C, hold 1 hr per 25 mm thickness, slow cool - PWHT optional for E 250 normal-thickness; mandatory for pressure vessels
Welder qualification (per IS 7307 / IS 7310): - Test plate welded by candidate; macro-etch, bend, tensile tests - Qualifies welder for specific position + process + thickness range - Re-qualification: every 6 months OR after major change in process
WPS (Welding Procedure Specification): - Document specifying welding parameters for a specific joint geometry + process + material combination - Must be qualified by procedure qualification record (PQR) - WPS approved by client / consultant before production welding starts
Visual inspection (mandatory for every weld): - Surface cracks: not acceptable - Undercut: ≤ 1 mm depth (or per project spec) - Porosity: ≤ 1.5 mm dia, isolated; not clusters - Convexity / concavity: per AWS / IS spec - Spatter: removed; not acceptable on finished weld - Reinforcement: 0.5-3 mm above plate surface (single V); 1-3 mm (fillet)
Non-destructive testing (NDT) — selection per criticality:
| NDT method | Detects | Use | |---|---|---| | Visual (VT) | Surface cracks, undercut, porosity | All welds | | Magnetic Particle (MT) | Surface + near-surface cracks (ferromagnetic only) | Critical structural welds | | Dye Penetrant (PT) | Surface cracks | Non-ferromagnetic (stainless), accessible welds | | Ultrasonic (UT) | Internal defects (cracks, lack of fusion, lack of penetration, slag) | Critical butt welds, thick plates | | Radiographic (RT) | Internal defects (similar to UT but image record) | Pressure vessels, pipeline, tank butt welds |
Sample size for NDT: - Critical structures (bridges, tanks, pressure vessels): 100 % UT or RT - General buildings: 5-25 % spot UT for butt welds; 100 % visual + 10 % MT for fillets - Routine fabrication: 5 % spot check
Defects (per IS 9595 + ASME / AWS): - Lack of fusion: not acceptable in critical welds - Lack of root penetration: per joint design - Slag inclusion: ≤ 3 mm dia, isolated - Tungsten inclusion (TIG): not acceptable - Cracks: not acceptable in any weld
Distortion control: - Tack weld pattern - Welding sequence (alternating sides on long welds) - Pre-bending of plates (counter-balance) - Post-weld straightening (heat shrinking, mechanical)
1. No WPS / PQR for critical welds. Welder skill alone is insufficient for high-criticality work; must follow qualified procedure. Develop and approve WPS before production. 2. Welder not qualified for the specific position / thickness. Welder qualified for 1G (flat) attempts 4G (overhead) — defects guaranteed. Strictly enforce welder qualification scope. 3. Wrong electrode for steel grade. E6013 used on E 410 high-strength steel — under-strength weld. Match electrode tensile to steel. 4. No moisture control on low-hydrogen electrodes. E7018 / E11018 absorb moisture from air; cause hydrogen-induced cracking (HAZ cracks). Bake at 350-450 °C; store in heated cabinet at 100-150 °C; use within 4 hr of opening. 5. No pre-heat on thick high-CE steel. HAZ cools too fast, cracks. Apply pre-heat per IS 9595 table. 6. Cleaning skipped — paint / oil / mill scale on weld zone. Causes porosity, lack of fusion, slag inclusion. Wire-brush + grinder + degrease before welding. 7. Excessive heat input. Wide HAZ, slow cooling, may degrade base metal properties. Control voltage, current, travel speed. 8. Inadequate joint preparation. Bevel angle wrong, root gap inconsistent — leads to lack of penetration, lack of fusion. Use jig / template for repeatable preparation. 9. Tack welds left as full welds. Tack welds are brittle (rapid cool, shallow penetration); leaving them in final weld = failure point. Either remove + re-weld or design tacks as integral. 10. NDT missed on critical butt welds. Internal defects undetected; failure in service. Specify NDT per criticality. 11. Inadequate welder training for new processes. Welder skilled in SMAW attempts FCAW without training — defects. Provide formal training + qualification. 12. Field welding at low temperature without preheat. Below 5 °C ambient, condensation forms; HAZ cracking risk. Pre-heat to drive off moisture; consider postponement. 13. No record of welding parameters. No traceability if defect emerges. Record per-weld: WPS reference, welder ID, electrode batch, parameters, NDT results.
Steel fabrication cascade:
1. Design (IS 800:2007) — connection types, weld sizes, location of welds. 2. Detailed drawings — fabrication shop drawings with weld symbols (per IS 813 weld symbol convention). 3. WPS / PQR development: - Identify each unique joint geometry × material × process combination - Develop WPS for each - Qualify by PQR (Procedure Qualification Record): test weld + macro-etch + tensile + bend 4. Welder qualification — each welder qualified for the positions / processes / thicknesses they will weld. 5. Material procurement — base steel (IS 2062), electrodes, gases, fluxes. 6. Material storage — moisture-controlled storage of low-hydrogen electrodes; heated rod oven. 7. Joint preparation — cutting, beveling, cleaning. 8. Production welding (this code, IS 9595) — per WPS: - Pre-heat per CE table - Tack welding - Root pass - Fill / cap passes - Temperature monitoring - Visual inspection between passes 9. Inspection (IS 822:1970): - Visual on every weld - NDT per criticality + sample size - Defect rectification (grind out + re-weld) 10. Post-Weld Heat Treatment (if required) — controlled heating, holding, cooling. 11. Surface treatment — galvanising, painting, fire-protection coating. 12. Erection — site welding for connections not made in shop. 13. As-built records — WPS used, welder ID, NDT certificates.
IS 9595 has been the workhorse welding code in India for over 30 years. Modern practice supplements with AWS D1.1 / D1.5 references for bridge / critical work; IS 9595 remains the local technical baseline.
| Parameter | IS Value | International | Source |
|---|---|---|---|
| Bend Test Mandrel Diameter (t=specimen thickness) | 4t for steels with yield strength < 360 N/mm². | 4t for parent material with elongation A ≥ 20%. | ISO 15614-1:2017 |
| Qualified Thickness Range (Multi-run butt weld, 't' = test piece thickness) | For t > 12mm, the qualified range is generally 5mm to 2t. | For t from 3 to 30mm, the qualified range is 0.5t to 2t. | ISO 15614-1:2017 |
| Heat Input Control | Heat input to be recorded, but a specific qualification range (e.g., +/- %) is not defined. | Qualified range for Level 2 is from -20% to +25% of the heat input recorded on the PQR. | ISO 15614-1:2017 |
| PWHT Holding Temperature (Carbon Steel) | Typically recommended as 580°C - 620°C. | 595°C - 650°C (1100°F - 1200°F) for P-No. 1 materials. | AWS D1.1:2020 |
| Material Grouping | Based on Indian Standard steel specifications (e.g., IS 2062). | Based on a numerical grouping system as per ISO/TR 15608. | ISO 15614-1:2017 |
| Number of Bend Tests (Plate butt weld, t ≥ 12mm) | 4 bend tests (typically side bends). | 4 transverse side bend tests. | ISO 15614-1:2017 |