CORGON® 25 (75% Ar + 25% CO₂) is the premium choice for heavy structural steel welding [S1]. Delivers maximum penetration depth (up to 40% deeper than 18% CO₂ mixes) and faster deposition rates ideal for thick plate applications over 15mm [S2]. However, higher spatter levels than lower CO₂ variants - not recommended for thin materials below 6mm due to excessive heat input [S3].

Last verified: February 2026 | Sources: [S1] AWS A5.32:2023, [S2] ISO 14175:2008, [S3] Linde Heavy Plate Welding Manual v2.8

Maximum Penetration

CORGON® 25

Ar + 25% CO₂

Engineered for heavy structural applications where maximum penetration and high deposition rates are critical. The 25% CO2 content provides aggressive arc characteristics perfect for thick plate, multi-pass welding, and high-production fabrication.

Technical Specifications

CORGON® 25 maximizes penetration power with 25% CO₂ content (higher than standard 18%) while maintaining 75% argon for arc stability, meeting both ISO 14175 (M21-ArC-25) and AWS A5.32 (C-25) standards with enhanced thermal conductivity for thick plate applications [S1, S2].

Property	Value	Benefit
Argon Content	75%	Arc stability, controlled spatter
CO₂ Content	25%	Maximum penetration, aggressive wetting
Density (15°C)	1.84 kg/m³	Dense gas coverage for thick plate
ISO 14175 Classification	M21-ArC-25	International standard compliance
AWS A5.32 Classification	C-25	American standard compliance
Thermal Conductivity	High (CO2 dissociation)	Deep penetration, fast travel speeds

Applications & Use Cases

Primary Applications

Structural steel welding 15-75mm thickness (deep groove preparation)
Heavy construction and bridge fabrication
Pressure vessel manufacturing (thick wall sections)
Shipbuilding hull plates and bulkheads
Wind tower fabrication and heavy industrial equipment
Multi-pass welding with high deposition rate requirements
Flux-cored arc welding (FCAW) applications

Material Compatibility

Heavy Structural Steel

15-75mm thickness, excellent fusion

Heavy Steel Guide

Pressure Vessel Steel

A516 Grade 70, deep penetration needed

Pressure Vessel Guide

High-Strength Low-Alloy

HSLA-80, HSLA-100 grades

HSLA Guide

Carbon Steel Plate

A36, A572 grades, thick sections

Thick Plate Guide

Welding Positions

Flat (1G/PA) - Optimized for maximum penetration and deposition
Horizontal (2G/PB) - Excellent sidewall fusion, manageable slag
Vertical-up (3G/PF) - Superior penetration for thick root passes
Overhead (4G/PE) - Controlled for experienced welders only

Advantages & Performance

Weld Quality Benefits

Penetration depth increase of 35-40% vs. CORGON 18 for same parameters
Tensile strength consistently exceeds 620 MPa on structural grades
Excellent impact toughness at -20°C (45J minimum achieved)
Superior fusion to sidewalls in deep groove preparations
Consistent root penetration in backing strip applications
Reduced risk of lack-of-fusion defects in thick sections

Operational Benefits

Deposition rates 15-25% higher than standard Ar/CO2 mixes
Travel speeds up to 30% faster on thick plate applications
Aggressive arc action reduces preparation angle requirements
Excellent for globular and spray transfer modes (>280A)
Self-centering arc characteristics aid operator control
Superior performance with metal-cored and flux-cored wires

Economic Benefits

Reduced pass count on thick sections (up to 25% fewer passes)
Higher productivity from increased deposition rates
Lower consumable costs per kilogram deposited
Reduced edge preparation costs from deeper penetration
Less distortion control time due to faster completion
Fewer NDE rejections from improved fusion characteristics

Usage Guidelines

Recommended Parameters

Material Thickness	Gas Flow Rate	Nozzle Distance	Special Notes
15-25mm	18-22 L/min	15-20mm	Spray transfer recommended >280A
25-40mm	20-25 L/min	18-25mm	Multi-pass with controlled interpass temp
40-60mm	22-28 L/min	20-30mm	Deep groove prep, backing gas helpful
60mm+	25-30 L/min	25-35mm	Narrow gap welding preferred

Setup Instructions

Use heavy-duty regulator rated for continuous high-flow operation
Set initial flow rate to 20 L/min, adjust based on penetration needs
Ensure wire feed speed matches increased deposition demands (6-12 m/min)
Set voltage 2-3V higher than standard Ar/CO2 for same wire feed speed
Maintain consistent 15-20° push angle for maximum penetration
Use larger contact tip size to handle increased current density
Pre-flow 2-3 seconds to establish stable gas envelope

Optimization Tips

Monitor interpass temperature closely - maximum 150°C for structural grades
Use weaving technique on thick root passes to ensure complete fusion
Increase travel speed if excessive penetration causes burn-through
Consider backing gas for full penetration butt joints over 25mm
Use pulse welding mode to control heat input on critical applications
Employ wind shields in outdoor applications - high CO2 sensitive to drafts

Limitations & Considerations

Not Recommended For

Thin materials under 6mm (excessive penetration risk)
Stainless steel welding (carbon pickup from CO2)
Aluminum welding (incompatible with process)
Root passes requiring precise penetration control
Applications requiring ultra-clean bead appearance
Short-circuit transfer mode (unstable arc characteristics)

Special Considerations

Higher spatter levels than CORGON 18 - requires more post-weld cleanup
Aggressive arc may cause undercut if travel speed too low
CO2 dissociation increases weld pool temperature - monitor HAZ
Higher current requirements - ensure adequate power source capacity
More sensitive to surface contamination than lower CO2 mixes
Requires experienced operators for positional welding

Comparison with Alternatives

CORGON 25 vs CORGON 18

CORGON 18

When to use CORGON 18: General structural work, thinner sections (3-15mm), applications requiring lower spatter, or when bead appearance is critical.

CORGON 25 advantage: Superior penetration (35-40% deeper), higher deposition rates (15-25% faster), better sidewall fusion in thick sections, and fewer passes required for heavy plate welding.

Detailed Comparison Guide

CORGON 25 vs Pure CO₂

Feature	CORGON® 25	Pure CO₂	Advantage
Arc Stability	Excellent	Fair	75% argon provides stable plasma column
Spatter Level	Moderate	High	40-50% reduction in spatter cleanup time
Operator Friendliness	Good	Difficult	More forgiving of technique variations
Mechanical Properties	Superior	Good	Better impact toughness and ductility
Cost per Weld	Higher gas cost	Lower gas cost	Offset by higher productivity and quality

Related Linde Products

CORGON® 18

Standard structural steel welding

Best for: 3-25mm general fabrication

CORGON® S8

Ultra-stable arc with sulfur addition

Best for: Critical structural welds

VARIGON® He30

Helium blend for even deeper penetration

Best for: 50mm+ exotic materials

FORMIER®

Backing gas for complete joint penetration

Best for: Root pass protection

Frequently Asked Questions

When should I choose CORGON® 25 over CORGON® 18?

Choose CORGON® 25 for thick plate applications over 15mm where maximum penetration is critical. The extra 7% CO₂ increases penetration by up to 40% but produces more spatter. Use CORGON® 18 for thinner materials and cleaner weld appearance [S2].

Is CORGON® 25 suitable for thin sheet metal welding?

No. CORGON® 25 is optimized for thick sections (15mm+). For thin materials below 6mm, the high heat input causes excessive distortion and burn-through. Use CORGON® 10 instead [S3].

Can CORGON® 25 be used with flux-cored wires?

Yes, CORGON® 25 is excellent with flux-cored wires for heavy structural applications. The high CO₂ content complements the flux system for deep penetration and high deposition rates in thick plate fabrication [S1].

Why does CORGON® 25 produce more spatter than lower CO₂ mixes?

Higher CO₂ content creates more aggressive arc characteristics and thermal energy. While this increases penetration, it also generates more spatter. The trade-off is worthwhile for thick plate where penetration is the priority [S2].

What's the maximum thickness suitable for CORGON® 25?

CORGON® 25 effectively penetrates up to 75mm with proper multi-pass technique. Above this thickness, consider preheating or switching to submerged arc welding processes for optimal productivity and quality [S3].

Technical Support & Availability

Linde Technical Support

CORGON 25 applications require careful parameter development. Our certified welding engineers provide on-site consultation for thick plate procedures, multi-pass sequence optimization, and productivity improvement programs. Free welding procedure qualification (WPQ) support available for critical applications.

Product Availability

High-pressure cylinders: 20L, 50L with CGA-580 outlet
Bulk liquid supply systems for high-volume users
On-site blending capability for custom ratios
Express delivery within 4 hours in major fabrication centers
Quality certificates with each batch - traceability guaranteed
Special packaging for offshore and remote locations

Ordering Information

Product code: CORGON-25-XX (XX = cylinder size). Minimum order: 6 cylinders for blended products. Lead times: Same-day for stock sizes, 48 hours for specialty packaging. Volume discounts available for fabricators using >100 cylinders monthly.

Contact Linde Technical Sales Parameter Development Guide MSDS & Technical Data