# Nitrogen

Nitrogen supply forms, purity specifications and process limits for inerting, cutting and welding, with compressed-gas and cryogenic handling distinctions.

Reviewed: 2026-11-01

Tags: consumables, gases, nitrogen, cutting, welding

Hypertherm's **XPR170** specifies **99.99% nitrogen**, clean, dry and oil-free, at **181 standard liters/minute**. Inlet pressure measured during flow is **7.5 ±0.4 bar** for **Core/CorePlus/VWI** and **8.3 ±0.4 bar** for **OptiMix**. The same table calls for **less than 8.6 bar at the inlet with no flow** to prevent system alerts. Verify both conditions for the installed console. [Hypertherm, *XPR170 process-gas requirements*](https://xnet.hypertherm.com/docs/en/XPR170_IM/bur1747689615639.html)

Nitrogen supports selected cutting, welding and atmosphere-control operations. Woikoski gives a boiling point near −196°C at 0.101 MPa. Qualify nitrogen compatibility with the actual hot material and process. [Woikoski, *AWOlaser nitrogen*](https://www.woikoski.fi/en/gases/welding-gases/awolaser-nitrogen/)

## Specify the gas that reaches the process

A purchase specification should identify nitrogen content, the basis of that content, critical impurities and supply form. A named example is **Blended Products Nitrogen 5.0**, whose technical sheet `ELS-TDS-0-001 | V2 | 140823` specifies:

| Parameter | Supplier specification |
| --- | --- |
| Nitrogen **plus inert rare gases** | >99.999% by volume |
| Moisture | <2 ppm by volume |
| Oxygen | <3 ppm by volume |
| Other typical trace elements | THC <0.5 ppm; CO₂ <1.0 ppm; CO <1.0 ppm, all by volume |

The distinction between guaranteed contents and “other typical” values is part of the specification. The sheet's code is printed in the document; its later upload directory is not its revision date. Its inclusion of inert rare gases also matters when comparing this product with a specification requiring molecular N₂ alone. [Blended Products, *Nitrogen 5.0 technical data sheet*](https://blendedproducts.com/wp-content/uploads/2025/05/ELS_TDS_0_001_Nitrogen_5.0_V2_140823.pdf)

Grade labels such as “5.0,” “laser” or “high purity” are useful procurement shorthand only when accompanied by the supplier's limits. A process can be sensitive to oxygen, water or hydrocarbons independently of the headline purity. Linde's laser-cutting guidance, for example, links oxygen contamination to yellowed stainless-steel edges and additional dross, and states its own minimum nitrogen specification for laser cutting as **99.998%**. This is Linde's application specification, not a universal minimum for every nitrogen use. [Linde, *Laser cutting with LASERLINE*](https://www.linde-gas.com/processes/thermal-cutting/laser-cutting)

## Inerting and blanketing

Inerting reduces the oxygen available to a process by replacing its atmosphere with a suitable gas. Effectiveness depends on enclosure, air ingress, mixing and continued supply, rather than the cylinder label alone. The UK's HSE describes inerting for enclosed plant and emphasizes monitoring oxygen and flammable gas/vapor concentrations, supply reliability and backup arrangements. An open vessel exposed to changing air ingress cannot be assumed to remain inert because nitrogen is flowing nearby. [HSE, *Inerting technical measures*](https://www.hse.gov.uk/comah/sragtech/techmeasinerting.htm)

Define the required process atmosphere for the particular substance, temperature and operating state. There is no general purge duration or residual-oxygen target suitable for every vessel. A low-oxygen atmosphere intended to protect a product or suppress combustion is also dangerous to people. Treat process-atmosphere control and safe entry as separate requirements; successful inerting does not establish a breathable atmosphere. [HSE, *Inerting technical measures*](https://www.hse.gov.uk/comah/sragtech/techmeasinerting.htm)

## Cutting and welding are material-specific

In laser fusion cutting, nitrogen assist gas blows laser-melted material from the kerf without supplying oxygen-combustion heat. Linde identifies stainless steel, aluminum and aluminum alloys as common applications. Gas purity, laser capability and the accepted edge condition belong together in selection. Do not transfer an oxygen-cutting program or a published nitrogen pressure example to another machine, nozzle or thickness without the applicable cutting data. [Linde, *Laser cutting with LASERLINE*](https://www.linde-gas.com/processes/thermal-cutting/laser-cutting)

Use the installed XPR170 console’s pressure at the stated nitrogen flow and purity. Check gas quality at delivery and flowing pressure at the inlet. [Hypertherm, *XPR170 process-gas requirements*](https://xnet.hypertherm.com/docs/en/XPR170_IM/bur1747689615639.html)

For welding, distinguish torch shielding, deliberate nitrogen additions and root backing. BOC's shielding-gas guide describes **Specshield 2.5% N₂ in argon** for TIG welding duplex stainless steels to help balance weld-metal microstructure. Its backing-gas table permits nitrogen for specified carbon/low-alloy and stainless categories while excluding high-strength fine-grained steels; the text requires that materials not be susceptible to nitrogen attack. This does not authorize pure nitrogen as a universal substitute for argon, particularly on an unspecified alloy. Use the qualified procedure, filler and base-material recommendations for the actual joint. [BOC, *Shielding gas: The right gas working for you*, pp. 17, 22–23](https://www.boconline.co.uk/wcsstore/IE_BOC_Industrial_Ntl_Store/pdf/downloads/shielding-gas-brochure410_80125.pdf)

## Supply, generation and delivery

Delivered compressed gas, cryogenic supply and on-site generation require different equipment arrangements. Atlas Copco describes both **pressure-swing adsorption (PSA)** and membrane nitrogen generation from compressed air. PSA uses an adsorbent to preferentially remove oxygen. Generator capability must be evaluated at the selected purity and actual feed conditions, rather than treating the highest advertised flow and highest purity as simultaneous ratings. [Atlas Copco, *Nitrogen generators*](https://www.atlascopco.com/en-us/compressors/products/nitrogen-generators)

The **NGP+ 8–130** datasheet, bearing a **2023 copyright**, illustrates the tradeoff: NGP 8+ capacity is **18.2 m³/h at 95%**, but **1.9 m³/h at 99.999%**, under the sheet's stated conditions. Its flow reference is **20°C, 1 bar absolute and 0% relative humidity**, even though the table uses Nm³/h. It defines nitrogen purity as **100% minus oxygen content** and separately specifies outlet air-quality class. Preserve those definitions when comparing another supply or analyzer reading; an oxygen measurement alone is not a full impurity analysis. [Atlas Copco, *NGP+ 8–130 datasheet*](https://www.atlascopco.com/content/dam/atlas-copco/local-countries/mexico/compressor-technique/files-and-pdf/NGP%2B8-130%20EN.pdf)

Water concentration and dew point also require a stated basis. Pressure dew point is the temperature where water condenses at operating pressure, and differs from atmospheric dew point. Specify where dryness is measured and which pressure applies. A dry gas source does not by itself verify every downstream connection or the final delivered atmosphere. [Atlas Copco, *Selecting a compressed-air dryer*](https://www.atlascopco.com/en-ae/compressors/wiki/compressed-air-articles/choosing-a-dryer)

## Compressed and cryogenic hazards

Airgas **SDS 001040**, revised **March 28, 2025**, classifies gaseous nitrogen as compressed gas and a simple asphyxiant. It requires adequate ventilation, pressure-rated compatible equipment and backflow prevention, and warns that nitrogen can cause suffocation without warning. Secure cylinders upright, protect them from damage and use the correct connection rather than improvising adapters. Neither the absence of odor nor nitrogen's presence in normal air establishes that a release is safe. [Airgas, *Nitrogen SDS*, version 21.06](https://www.airgas.com/msds/001040.pdf)

Airgas **SDS 001188**, revised **May 5, 2025**, adds refrigerated-liquid hazards: cryogenic burns, frostbite and cold-induced material brittleness. It calls for cold-insulating gloves and eye/face protection and prohibits trapping liquid in closed piping without pressure relief. Liquid-service equipment, vaporization and relief arrangements must suit cryogenic operation; a compressed-gas regulator specification alone does not establish that suitability. Both supply forms can displace oxygen as gas enters the surrounding area. [Airgas, *Nitrogen, Refrigerated Liquid SDS*, version 1.05](https://www.airgas.com/msds/001188.pdf)

## Related references

[Laser cutting](../../processes/laser-cutting.md) · [Cutting and shaping processes](../../processes/shaping/index.md) · [Welding methods](../../processes/welding-methods/index.md)