Thermal Processing
Nitrogen Generator for Heat Treating, Annealing, and Belt Furnaces
On-site nitrogen helps minimize oxidation and surface degradation during annealing, hardening, and other heat-treating processes.
Purity range
System types
Payback period
Service life
Heat treating, annealing, and other thermal metal-processing operations require a controlled, oxygen-free atmosphere to prevent surface oxidation, scaling, and discoloration. Delivered nitrogen is expensive when heat-treating cycles run 16 hours daily or more, and cylinder swaps create downtime.
On-site nitrogen generation reduces cost and supply-chain delays by producing ultra-high purity nitrogen directly at your furnace. Purities from 99.99% to 99.9995% support bright annealing of stainless steel, sintering of powder-metallurgy and metal-injection-molded (MIM) parts, brazing atmospheres, and continuous belt furnace purge cycles.
Below, we explain the atmospheres that heat treating demands, compare furnace types and their nitrogen requirements, and answer common questions about system sizing and payback.
On-site nitrogen in action
On-site nitrogen feeding an Elnik debinding/sintering furnace
Furnace purge cycle running on generated nitrogen
Elnik furnace install with on-site nitrogen feed
Atmospheres for heat treating
Inert blanketing for carbon steel annealing
Pure nitrogen at 99.5% to 99.9% purity protects carbon steel during annealing by helping minimize oxidation and scaling. Nitrogen backfill into the furnace chamber displaces oxygen, creating an inert environment throughout the thermal cycle.
Bright annealing of stainless steel
Stainless steel annealing often requires 99.99% or higher purity nitrogen mixed with small amounts of hydrogen (added separately). On-site nitrogen generation supplies the bulk inert gas while hydrogen is introduced in controlled ratios, helping minimize oxidation and supporting the bright surface finish.
Sintering atmospheres for powder metallurgy and MIM
Powder-metallurgy sintering (including metal-injection molding) relies on ultra-high purity nitrogen at 99.99% to 99.9995%. On-site generation delivers the clean, consistent atmosphere these processes demand without the cost and complexity of bulk supply or small cylinders.
Brazing atmospheres
Brazing furnaces use nitrogen as the primary carrier gas, often at 99.99% purity. On-site generation supplies nitrogen in continuous high volumes, eliminating downtime from cylinder changes and supporting multi-part batch cycles at full production pace.
Continuous purge volumes for belt furnaces
Belt furnaces running 16 to 24 hours daily consume hundreds of SCFH of nitrogen. On-site systems scale to these volumes, delivering steady-state purge flow at the exact purity the thermal process requires, with full control and zero supply risk.
Furnace types and nitrogen requirements
| Furnace Type | Typical N2 Flow | Purity Required | Atmosphere Recipe |
|---|---|---|---|
| Belt furnace | 200 to 800 SCFH | 99.5% to 99.99% | Continuous purge; inert blanket or endothermic mix |
| Box furnace | 50 to 300 SCFH | 99.9% to 99.99% | Batch cycles; inert backfill |
| Mesh-belt furnace | 300 to 600 SCFH | 99.9% to 99.9995% | Sintering; continuous flow with tight purity control |
| Pusher furnace | 100 to 400 SCFH | 99.5% to 99.99% | Continuous; annealing or brazing mix |
Heat treating applications
Powder metallurgy sintering
On-site nitrogen at 99.99% to 99.9995% purity supports powder-metallurgy sintering cycles without supply interruption or cost escalation.
Metal-injection molding (MIM)
MIM sintering demands ultra-high purity nitrogen. On-site generation supports consistent atmosphere control throughout debinding and sintering.
Bright annealing
Stainless steel and specialty alloy annealing require precisely controlled nitrogen-hydrogen mixes. On-site nitrogen provides the bulk gas with hydrogen blended on-site in exact ratios.
Hardening and tempering
Carbon steel hardening cycles use nitrogen blankets to help minimize decarburization and surface degradation. Belt and batch furnaces run continuously without supply worry.
Brazing furnaces
Continuous brazing ovens demand high nitrogen volumes at consistent purity. On-site systems eliminate cylinder swaps and deliver the flow industrial production requires.
Copper and aluminum annealing
Soft and non-ferrous metal annealing relies on inert nitrogen atmospheres. On-site generation helps minimize oxidation while supporting continuous operation.
Frequently asked questions
What purity nitrogen does heat treating require?
Purity depends on the process. Carbon steel annealing typically uses 99.5% to 99.9% nitrogen. Bright annealing of stainless steel requires 99.99% or higher nitrogen mixed with controlled hydrogen. Powder metallurgy sintering and MIM demand 99.99% to 99.9995% purity. We recommend analyzing your furnace specifications or contacting us with your process details for exact purity sizing.
Why is dew point critical for heat treating?
Moisture in the furnace atmosphere causes hydrogen embrittlement, surface discoloration, and chemical reactions with the workpiece. On-site nitrogen generators require a high-quality upstream air dryer to reduce dew point to -40°F or lower. This helps minimize moisture entering the furnace chamber and supports a clean, stable thermal atmosphere.
Can nitrogen and hydrogen mixes be generated on-site?
Nitrogen yes, hydrogen no. On-site systems generate pure nitrogen. Hydrogen is introduced separately from a bulk supply or small cylinders and blended on-site in precise ratios. This approach is cost-effective because the bulk of the atmosphere is generated on-site while hydrogen (a specialty gas) is sourced in smaller volumes.
What is the payback period for a belt furnace system?
A belt furnace consuming 500 SCFH of nitrogen at 16 hours daily generates significant ongoing nitrogen costs when supplied via cylinders, dewars, or bulk delivery. Switching to on-site generation typically delivers up to 90% gas-cost savings, with most belt furnace systems paying back in 12 to 14 months. Contact us with your current nitrogen consumption and costs for a custom ROI analysis.
Can existing furnaces be retrofitted with on-site nitrogen?
Yes. Retrofits are common. The generator system sits outside or adjacent to the furnace. Stainless steel supply lines run from the generator to the furnace inlet, replacing the existing cylinder or bulk inlet. Installation takes one to three days depending on space and piping runs. We handle engineering and sizing for retrofits as part of the quoting process.
How do I size a nitrogen generator for my furnace?
We need your furnace nitrogen flow rate (SCFH), required purity, duty cycle (hours per day), and current gas supply cost. These inputs determine the generator size, compressed air requirement, and payback timeline. Most heat-treating furnaces consume 100 to 800 SCFH. Send us your specifications or your current nitrogen invoice and we will size a system.
What is the relationship between surface oxidation and nitrogen purity?
Lower nitrogen purity (residual oxygen) directly causes surface oxidation and scaling during heat treating. The higher the required surface finish (bright, unscaled, clean), the higher the nitrogen purity needed. Bright annealing of stainless or high-carbon alloys demands 99.99% or better. General annealing tolerates 99.5% to 99.9%. Always match purity to your quality requirements.
How long does installation take and what is the typical cost?
Installation typically takes one to three days depending on space, piping layout, and electrical hookup. System costs range from approximately $20,000 for small box furnaces to $200,000+ for high-flow belt furnace systems. The payback period is typically 12 to 14 months when replacing bulk or cylinder gas. Request a formal quote with your specifications and we will provide a complete project estimate.
Budgeting a system
Heat treating and annealing systems span Medium to Large tiers depending on flow and dewpoint requirements. See pricing for every system size we build.