Helium — What It Is and Why It Matters
Helium is an inert shielding gas used in welding, primarily in blends with argon, to increase arc energy and heat input. Helium has higher thermal conductivity than argon, producing a hotter, wider arc that improves wetting and penetration — particularly beneficial for thick aluminum, copper, and heavy stainless steel sections.
Pure helium is rarely used alone (it produces an erratic arc and requires high flow rates due to its low density). Argon-helium blends (typically 25-75% helium) combine helium's heat with argon's arc stability. A 75% argon / 25% helium blend is common for TIG welding thicker aluminum, while higher helium percentages are used for heavy copper and nickel alloy welding.
Helium is significantly more expensive than argon and rising in cost due to global supply constraints. Its lighter-than-air density also requires higher flow rates for adequate coverage, increasing gas consumption. Despite the cost, helium-argon blends are essential for specific high-performance applications where pure argon cannot deliver enough heat.
Frequently Asked Questions
When should I add helium to my shielding gas?
Add helium when you need more heat input without increasing amperage — typically for welding thick aluminum (over 1/4"), copper alloys, and heavy stainless sections. A 75% argon / 25% helium blend is a good starting point. The increased arc energy improves fusion and reduces the tendency for lack-of-fusion defects in thick, conductive materials.
Why is helium so expensive?
Helium is a non-renewable resource extracted primarily as a byproduct of natural gas production. Global supply has tightened as traditional sources deplete and demand increases for industrial, medical, and scientific applications. Prices have roughly tripled over the past decade.