Two repair philosophies
Welding joins metals by fusion (over 1500 °C at the arc), creating a metallurgical continuity. Cold bonding joins by chemical adhesion (epoxy or polymer curing at ambient temperature), creating a high-strength mechanical bond. Both methods have distinct application domains — one does not systematically replace the other.
Detailed comparison table
Here are the technical and economic criteria that tip the choice from one method to the other on an industrial site:
- Mechanical strength: weld = 400-600 MPa (steel); bond = 200-300 kg/cm² in shear (sufficient for most applications)
- Hot work: weld = permit required, fire-watch, area isolation; bond = no permit, no fire risk
- ATEX zones: weld = forbidden or complex waiver; bond = authorized
- Cast iron / hardened steels: weld = cracking risk; bond = no metallurgical risk
- Lead time: weld = 1-3 days with rebalancing; bond = 4-24 h, no rebalancing
- Distortion: weld = risk on thin sheets; bond = no distortion
- Material cost: weld = high (electrodes, gas, electricity); bond = moderate (epoxy mastic)
- Standards compliance: weld = ASME IX; bond = ASME PCC-2, ISO 24817, API 510/653
When to choose cold bonding
Cold bonding stands out in five specific contexts: (1) ATEX-classified zone where welding is forbidden, (2) cast-iron or hardened-steel part sensitive to cracking, (3) emergency repair during a short outage, (4) complex geometry hard to weld, (5) need to avoid any thermal-distortion risk on a precision part.
When welding remains necessary
Welding remains irreplaceable for high dynamic loads (vibrations, repeated shocks), service temperatures > 200 °C (where epoxies degrade), high-pressure leak-tight joints needing metallurgical continuity, and structural repairs per ASME Section VIII or CSA W59 codes.
Total cost compared (tank example)
To repair a 10 cm × 10 cm corrosion hole on a process tank (6 mm steel): welding costs about $2,500-4,000 (welder mobilization, hot-work permit, drain-purge, fire-watch, 8-12 h labour, inspection). Cold bonding costs about $800-1,500 (surface prep, epoxy mastic, application, 4-6 h labour, inspection). That is a 60-65 % gap in favour of bonding, excluding downtime savings.
Conclusion
The « cold bonding vs welding » debate has no universal winner — it has a right choice by context. For most emergency repairs, in ATEX zones or on sensitive parts, epoxy cold bonding offers an unbeatable cost/lead-time/HSE ratio, with recognized regulatory compliance.
Hicham M, P Eng, PMP
Engineer and project manager (PMP) at Induscoat Canada. Over 16 years of experience in industrial coatings, composite repairs and wear protection on mining, energy and petrochemical sites in Canada and internationally.