# Argon-helium shielding mixtures

Binary argon–helium welding gases: composition, process selection, arc behavior, gas delivery, and application limits.

Reviewed: 2026-11-01

Tags: consumables, gases, welding, shielding-gas

Linde **VARIGON He30** is **30% helium, balance argon**, on an ideal volume-fraction basis equivalent to mole fraction. The product sheet identifies **DIN EN ISO 14175 I3-ArHe-30** and lists aluminum MIG and TIG. Verify whether the offered blend is binary or contains deliberate dopants, and qualify the actual arc and heat input. [Linde VARIGON He30 product sheet, pp. 1–2](https://static.prd.echannel.linde.com/wcsstore/DE_REC_Industrial_Gas_Store/datasheets/pds/varigon_he_30.pdf)

## Identity and specification

Argon–helium blends shield the pool and hot tungsten in GTAW. Composition affects starting, arc stability and heat input. Specify the blend in the welding procedure. [Miller, shielding gas in TIG welding](https://www.millerwelds.com/en-us/resources/knowledge-hub/tig-welding/how-to/best-practices-for-proper-shielding-gas-in-tig-welding)

The cited German VARIGON He30 sheet has a printed issue date of **21 April 2008**. Confirm the current local supply specification before purchasing. [Linde VARIGON He30 product sheet, pp. 1–2](https://static.prd.echannel.linde.com/wcsstore/DE_REC_Industrial_Gas_Store/datasheets/pds/varigon_he_30.pdf)

The classification is a useful ordering identifier, but obtain composition tolerances, impurity limits, certification requirements, cylinder connection, and delivery form from the supplier's applicable specification. A product name or nominal percentage alone leaves those procurement details unresolved. An SDS describes hazards and handling; it is not a substitute for a gas-quality certificate or a qualified welding procedure. [Linde product sheet](https://static.prd.echannel.linde.com/wcsstore/DE_REC_Industrial_Gas_Store/datasheets/pds/varigon_he_30.pdf); [Linde India He30 SDS, sections 1–3](https://assets.linde.com/-/media/global/apac/linde-india-limited/msds/sds-varigon--he30_tcm526-135477-v004_tcm526-661114.pdf)

## Process and material selection

| Application | Useful starting distinction | Boundary |
| --- | --- | --- |
| GTAW/TIG | Argon favors reliable starting; helium additions increase thermal transfer. | Establish blend suitability with the actual machine, electrode, joint, and WPS. |
| Aluminum GMAW/MIG | Helium additions can help transfer heat into highly conductive workpieces. | Recheck arc length and welding parameters after changing gas. |
| Other alloys or transfer modes | Use the applicable filler-metal and equipment gas recommendation. | An aluminum blend is not an automatic substitute for a steel or stainless-steel gas. |

Miller attributes argon's good high-frequency starts to its lower ionization potential. Helium has higher thermal conductivity and can support greater heat input, faster travel, or deeper penetration, while its higher ionization potential makes starting less consistent. Increasing helium therefore introduces a tradeoff rather than a universally better gas. [Miller TIG guidance](https://www.millerwelds.com/en-us/resources/knowledge-hub/tig-welding/how-to/best-practices-for-proper-shielding-gas-in-tig-welding)

For aluminum, Hobart's guide gives different example blends: **75% He/25% Ar for MIG**, but **25% He/75% Ar for TIG**, and warns that helium above 25% may cause TIG arc instability. These are that guide's application recommendations, not a universal ceiling for every TIG system. It also notes increased gas consumption and cost, and potentially more discoloration from magnesium burnoff at higher arc temperatures. [Hobart aluminum welding guide, shielding gases](https://www.hobartbrothers.com/resources/technical-guides/aluminum-welding-guide/welding-procedures-shielding-gases-used-for-mig-and-tig-welding/)

Keep **binary blends separate from products containing deliberate dopants**. Linde's aluminum GMAW portfolio includes argon–helium products with small active additions as well as binary blends; its discussion describes dopants up to 0.05% to stabilize particular aluminum arcs. A similarly named product with a suffix may consequently have different chemistry. Linde also says helium or dopant additions can require voltage adjustments to recover the intended arc length. Neither a brand family nor an unchanged machine program establishes interchangeability. [Linde aluminum GMAW process guidance](https://www.linde-gas.com/processes/welding/aluminum-alloys)

## Delivery and shielding conditions

**A flow indication is meaningful only with its gas calibration and operating conditions.** For example, CONCOA's 5237 regulator has separate argon and helium scales: the listed unit covers 10–60 SCFH argon and 30–200 SCFH helium. These are instrument ranges, not recommended welding flows. Separate scales demonstrate why an argon reading cannot simply be reused for helium or a blend. Select a meter specified for the mixture, or obtain the instrument manufacturer's applicable correction; do not treat pure-gas scales as a validated blend calibration. Record whether the reported flow is standard volumetric flow and which reference conditions apply. [CONCOA 5237 product specifications](https://www.concoa.com/products/5237-series-point-of-use-regulator)

Set and verify delivery with gas actually flowing through the installed system. As a specific equipment example, the **Kemppi X5 FastMig manual 1920960, revision 2612**, instructs users to install the torch before testing, flush the previous gas with the Gas test function, and then measure and adjust using the built-in rotameter or an external meter/regulator. Its general flow guidance depends on nozzle size and, for MIG, current. A cylinder regulator setting alone does not establish that the complete delivery path is working. Follow the actual equipment's connection, purge, and gas-test instructions after a cylinder or mixture change. [Kemppi gas installation and test instructions](https://userdoc.kemppi.com/om/x5-fastmig/en/content/topics/b_installation/cables/installing_gas.htm)

Excessive flow can entrain air through turbulence; insufficient flow leaves hot metal or tungsten exposed. Cup geometry, gas-lens arrangement, and surrounding conditions affect coverage. Establish flow and preflow/postflow settings for the actual setup. [Miller TIG shielding guidance](https://www.millerwelds.com/en-us/resources/knowledge-hub/tig-welding/how-to/best-practices-for-proper-shielding-gas-in-tig-welding)

## Practical selection example

For an aluminum MIG job suffering inadequate fusion, VARIGON He30 is a candidate for evaluation. Compare its composition with the WPS and equipment requirements; verify meter calibration, flush the previous gas, and trial the adjusted arc on representative joints. Assess fusion, penetration, porosity, bead shape, and starting using the job's acceptance criteria. Linde identifies improved heat transfer as a reason to add helium, but also identifies surface condition and alloy combinations as independent causes of arc problems. [Linde aluminum process guidance](https://www.linde-gas.com/processes/welding/aluminum-alloys); [Kemppi delivery checks](https://userdoc.kemppi.com/om/x5-fastmig/en/content/topics/b_installation/cables/installing_gas.htm)

## Gas quality and handling

Keep gas-quality requirements tied to the application. For example, Hobart's aluminum guide specifies minimum purities of **99.997% for argon** and **99.995% for helium**, with respective maximum dew points of **−76°F** and **−71°F**. These are that guide's requirements for its stated welding context; they do not establish the guaranteed impurity specification of every commercial mixture. [Hobart aluminum guide](https://www.hobartbrothers.com/resources/technical-guides/aluminum-welding-guide/welding-procedures-shielding-gases-used-for-mig-and-tig-welding/)

“Inert” does not mean safe to breathe. Linde India's VARIGON He30 SDS, **revision 01 dated 1 January 2022**, identifies oxygen displacement/asphyxiation and high-pressure gas hazards. It calls for ventilation, pressure-rated equipment, protection from physical damage, and secured upright storage. Use the current SDS for the supplied product and jurisdiction, together with the site's cylinder and ventilation arrangements; the shielding gas SDS does not cover all hazards created by welding. [Linde India He30 SDS, sections 2 and 7](https://assets.linde.com/-/media/global/apac/linde-india-limited/msds/sds-varigon--he30_tcm526-135477-v004_tcm526-661114.pdf)

## Related reference

[Welding methods](../../processes/welding-methods/index.md)