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Frequently Asked Questions

How do you select a shielding gas?

Nov 22, 2019, 13:58 PM
Title : How do you select a shielding gas?

There are a variety of gas blends that can be chosen for MIG, TIG, or Flux Cored Welding applications.

To make a well-informed selection, a number of approaches can be used, but all are based on a basic understanding of the requirements for the finished weldment.

Questions that need to be answered first may include:

  • How important is weld appearance?
  • Is spatter near the weld area a concern?
  • Is deep penetration required or should penetration be limited to minimize burn- through of the joint?
  • Is there a concern about the amount of welding fume generated and should it be reduced?

Depending on the requirements for the finished weld, a number of other questions might be asked as well.

To select a gas blend, the following four-step process can be followed:

  1. Consider the material type – carbon steel, stainless steel, aluminum, nickel alloys, copper alloys or other non-ferrous materials
  2. Know the base material thickness and understand its condition – clean, oily, scaled, etc.
  3. Determine the welding position as this will impact the type of process/metal transfer you plan to utilize. Process selection may be further impacted by the availability of equipment, operator skills and desired productivity.
  4. Review the requirements of the job. Consult the selection chart to determine the gas blend that provides the best performance for the application at hand.

Simple, isn’t it? This selection process should help you make a good first attempt at matching the best shielding gas to your application. Refinement may be needed depending on the specific equipment and skills available. Other needs may have to be identified as work progresses. For further information on Praxair’s Star™ family of shielding gases, please consult your local Praxair representative.

Gas Metal Arc Welding (GMAW or MIG)

Material TypeThicknessConditionTransfer ModeShielding Gas RecommendedTravel SpeedWeld AppearancePenetrationSpatter ReductionFume Reduction
Mild Steel22 to 10 ga
(0.9-2.5mm)
cleanshort-circuitStarGold C-25GEEEG
Mild Steel22 to 10 ga
(0.9-2.5mm)
minor scale/oilshort-circuitStarGold C-25,
Stargon
GEEGG
Mild Steel22 to 10 ga
(0.9-2.5mm)
cleanpulsedMIG Mix Gold,
StarGold C-25
EEGEE
Mild Steel1/8" - 1/2"
(3.2-12.7mm)
cleanshort & sprayStargon, MIG Mix Gold,
StarGold C-10 to C-15
EEGGE
Mild Steel1/8" - 1/2"
(3.2-12.7mm)
minor scale/oilsprayStarGold C-10 to C-15,
HeliStar CS
GGGEG
Mild Steel1/8" - 1/2"
(3.2-12.7mm)
cleanpulsedStarGold C-5,
MIG Mix Gold
EEGEE
Mild Steel1/8" - 1/2"
(3.2-12.7mm)
cleanspray & pulsedStarGold O-5EGFEE
Mild SteelOver 1/2"
(12.7mm)
cleanspray & pulsedStarGold C-10* to C-15EGGEE
Mild SteelOver 1/2"
(12.7mm)
light scale/oilspray & pulsedHeliStar CS*EEEGG
Mild Steel (coated)22-16 ga
(0.9-1.6mm)
galvanizedshort arcStarGold C-25**GGGFP
Mild Steel (coated)22-16 ga
(0.9-1.6mm)
galvanizedspray*
Si-bronze only
ArgonEEFEF
Stainless Steel16-10 ga
(1.6-2.5mm)
cleanshort-circuitHeliStar A-1025,
HeliStar SS
GGEGF
Stainless Steel11 ga - 1/2"
(2.3-12.7mm)
cleansprayHeliStar SS,
StarGold C-2 to C-5
EEGGG
Stainless Steel11 ga - 1/2"
(2.3-12.7mm)
cleanspray & pulsedStarGold O-2EFFGG
Stainless Steel16 ga - 1/2"
(1.6-12.7mm)
cleanpulsedHeliStar SSGEGEG
Low Alloy Steel16 ga - 1/2"
(1.6-12.7mm)
cleanshort-circuitStargon,
MIG Mix Gold
GGGGG
Low Alloy Steel16 ga - 1/2"
(1.6-12.7mm)
cleanspray & pulsedStargon, MIG Mix Gold,
StarGold C-5 to C-10
EEEEG
Low Alloy Steel16 ga - 1/2"
(1.6-12.7mm)
cleanpulsedStarGold O-5GGFEE
Aluminum AlloysAll ThicknessescleanpulsedArgonGGFEG
Aluminum AlloysAll ThicknessescleansprayArgon, HeliStar A-25,
A-50, A-75
EEEGF
Copper AlloysAll Thicknessescleanpulsed & sprayArgonGFFGE
Copper AlloysAll Thicknessescleanpulsed & sprayHeliStar A-25, A-50EGGGG
Nickel AlloysAll Thicknessescleanpulsed, spray mechanizedHeliStar A-25, A-50, SSEEGGG

Performance Measures: E=Excellent, F=Fair, G=Good, P=Poor

* 0.045 to 0.063 wire diameter recommended

** ER70S3 wire recommended

Flux-Cored & Metal-Cored Arc Welding

Material TypeThicknessConditionTransfer ModeShielding Gas RecommendedTravel SpeedDeposition EfficiencyWeld AppearancePenetrationSpatter ReductionFume Reduction*
Mild Steel14 - 10 ga
(1.8-2.5mm)
cleanglobularStarGold C-25, C-40, C-50EGEGGG
Mild Steel14 - 10 ga
(1.8-2.5mm)
some oxideglobularStarGold C-25, C-40, C-50GGGGGF
Mild Steel1/4" - 1/2"
(6.4-12.7mm)
cleanglobularStarGold C-25, C-40, C-50EGEGGG
Mild Steel1/4" - 1/2"
(6.4-12.7mm)
cleanglobularCO2GGGEFP
Mild Steel1/4" - 1/2"
(6.4-12.7mm)
cleanspray**StarGold C-10 to C-15,
MIG Mix Gold
EEEFEE
Mild Steel1/4" - 1/2"
(6.4-12.7mm)
some oxideglobularStarGold C-25, C-50EGGGGG
Mild Steel1/4" - 1/2"
(6.4-12.7mm)
some oxideglobularCO2GFGEFP
Mild Steel1/4" - 1/2"
(6.4-12.7mm)
some oxidespray**StarGold C-10 to C-15,
MIG Mix Gold
EEGFEE
Mild Steelover 1/2"
(12.7mm)
cleanglobularStarGold C-25, C-50GGEGGG
Mild Steelover 1/2"
(12.7mm)
cleanglobularCO2GFGEFP
Mild Steelover 1/2"
(12.7mm)
cleanspray**StarGold C-10 to C-15,
MIG Mix Gold
GEEFEE
Mild Steelover 1/2"
(12.7mm)
some oxideglobularStarGold C-25, C-50FFGGFF
Mild Steelover 1/2"
(12.7mm)
some oxideglobularCO2FFFEFP
Mild Steelover 1/2"
(12.7mm)
some oxidespray**StarGold C-10 to C-15,
MIG Mix Gold
FEGFEG

Performance Measures: E=Excellent, F=Fair, G=Good, P=Poor

* Welding fume varies with wire chemistry selected.

** Metal-cored wire recommended.

Gas Tungsten Arc Welding (GTAW or TIG)

Material TypeConditionTransfer ModeShielding Gas RecommendedTravel SpeedPenetrationColor MatchFume ReductionArc Stability
Mild SteelcleanmanualArgonFGGEE
Stainless SteelcleanmanualArgonPGFEE
Stainless SteelcleanmechanizedHeliStar A-25FGGEG
Austentic SS
(300 Series)
slight oxidemanualHydroStar H-2, H-5FGEEG
Austentic SS
(300 Series)
slight oxidemechanizedHydroStar H-5, H-10GGEEG
Aluminum AlloyscleanmanualArgon, HeliStar A-75FEEEG
Aluminum AlloyscleanmechanizedHeliStar A-25, A-50GEEEF
Copper AlloyscleanmanualArgonFFGEE
Copper AlloyscleanmechanizedHeliStar A-25, A-50GGGEG
NickelcleanmanualArgonPGFEE

Performance Measures: E=Excellent, F=Fair, G=Good, P=Poor

Note: Thickness foil to 1/8". Base metal thickness greater than 1/8" can be more effectively joined with MIG.

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