Welding
Shielding gas flow rate
In short
The shielding gas flow rate depends on the process and the material. In MIG/MAG, the EWM rule gives Q = 10 to 12 × wire Ø in L/min; in TIG, a fixed range of 5 to 10 L/min of argon. The calculation also suggests the recommended gas and its alternatives, with their ISO 14175 class.
Calculation
Example calculated with the tool’s default values.
Inputs
- I want to
- Choose a gas and its flow
- Process
- MIG / MAG, solid wire (131, 135)
- Material
- Plain and low-alloy steel
- Wire diameter (MIG/MAG, flux-cored)
- 1 mm
- Environment
- Sheltered from draughts
Results
- Suggested flow
- 11.0 L/minmiddle of the range
Worked example
Every value in this section belongs to the example, calculated with the tool’s default values.
Other results of the example
- Flow, low
- 10.0 L/min
- Flow, high
- 12.0 L/min
- Recommended gas
- ISO 14175 M21 – ArC – 20Ar 80 + CO2 20 vol. % M21: very good penetration and sidewall fusion, especially on thick material (4 to 12 mm and up); the CO2 helps cope with oil, moisture or rust; in return more spatter and slag islands (BOC).
- Alternative 1
- ISO 14175 M21 – ArC – 25Ar 75 + CO2 25 vol. % Sheet 0.9 to 2.5 mm in short-circuit (Linde StarGold C-25); above 20 % CO2: short-circuit and some flux-cored wires (Linde); Miller table with 75 % Ar / 25 % CO2.
- Alternative 2
- ISO 14175 M24 – ArCO – 12/2Ar 86 + CO2 12 + O2 2 vol. % M24 (Ar + 12 % CO2 + 2 % O2): low spatter, high speeds on 2 to 12 mm, smooth welds with good sidewall fusion (BOC).
- Alternative 3
- ISO 14175 M14 – ArCO – 5/2Ar 93 + CO2 5 + O2 2 vol. % M14 (Ar + 5 % CO2 + 2 % O2): thin sheet 0.6 to 5 mm, stable arc, little spatter, low heat input; on thick material, risk of lack of sidewall fusion (BOC).
- Alternative 4
- ISO 14175 M20 – ArC – 8Ar 92 + CO2 8 vol. % M20 (Ar + 8 % CO2): Messer Ferroline C8 range; Linde quotes 5 to 10 % CO2 for spray and pulsed on 1.6 to 12.7 mm.
- Alternative 5
- ISO 14175 C1 – CCO2 100 vol. % C1 (pure CO2): Miller table at 35 CFH; Linde lists it for flux-cored on thick sections; more spatter and fume than mixtures (Linde).
- Indicative values from gas and equipment makers: they do not replace the qualified WPS or the wire / electrode datasheet.
- Too high a flow creates turbulence that also impairs shielding: more is not better (Lorch).
Step-by-step calculation
Flow rule
Q = k × wire Ø
10.0 to 12.0 × 1.0 mm = 10.0 to 12.0 L/min
Flow used
Q = (min + max) / 2
11.0 L/min
ISO 14175 classes quoted
ISO 14175:2008 table 2
M21 = Ar + CO2 15–25 % ; M24 = Ar + CO2 5–15 + O2 0.5–3 % ; M14 = Ar + CO2 0.5–5 + O2 0.5–3 % ; M20 = Ar + CO2 5–15 % ; C1 = CO2 100 %
How to use it
- Pick the process: MIG/MAG solid wire, gas-shielded flux-cored wire, or TIG.
- Pick the material: steel, austenitic stainless, duplex, aluminium, or copper and alloys.
- Enter the wire diameter for MIG/MAG or flux-cored (no effect in TIG).
- Set the environment: sheltered or draughty.
- Read the suggested flow in L/min (in "Decode a mixture" mode: the ISO 14175 class of the composition).
Frequently asked questions
What is the shielding gas flow rate for MIG welding?
The EWM rule gives 10 to 12 × wire Ø in L/min. With a 1.0 mm wire on steel, that is 10 to 12 L/min, so 11 L/min suggested when sheltered. The calculation also quotes the Lorch rule as a cross-check: MAG Ø × 11.5, MIG Ø × 13.5.
What is the TIG shielding gas flow rate?
In TIG, the calculation uses the EWM range of 5 to 10 L/min of argon, as a guideline depending on nozzle diameter and draughts; the suggested flow is the middle of the range when sheltered and the top of the range in a draught. On aluminium, the Linde TIG table gives 9.4 to 16.5 L/min depending on thickness and position.
How is the welding gas flow rate calculated?
For MIG/MAG and flux-cored wire, the flow is a multiple of the wire diameter: Q = k × wire Ø, then the middle of the range (low + high) / 2 when sheltered, or the top of the range in a draught. For TIG, the range is fixed by the maker data, whatever the wire.
Which shielding gas for MAG welding on steel?
The recommended gas is M21 – ArC – 20 (Ar 80 + CO2 20): very good penetration and sidewall fusion, more spatter. Alternatives quoted: M21 – ArC – 25, M24 – ArCO – 12/2, M14 – ArCO – 5/2 for thin sheet, M20 – ArC – 8 and pure CO2 (C1).
Should the flow go up in a draught?
The calculation then takes the top of the range, but above all advises a windshield: beyond the top of the range, the flow creates turbulence that impairs shielding (Lorch). With helium, a light gas, set a higher flow than with pure argon (EWM).
Limits
Indicative results, taken from gas and equipment maker documents (EWM, Lorch, Linde, BOC, Messer, Miller) and ISO 14175:2008: they replace neither the qualified WPS nor the wire or electrode datasheet. Process / material pairs missing from the sourced tables are refused (for example flux-cored wire on aluminium). Self-shielded flux-cored wires use no gas.
Sources
- EWM : gaz de protection TIG et MIG/MAG : Specialised knowledge, shielding gases (débits en L/min) (link)
- Lorch : réglage du débit MIG/MAG : Règle Ø fil × 11,5 (MAG) / × 13,5 (MIG) (link)
- Miller : paramètres MIG (gaz et débit) : Choix des paramètres de soudage au MIG (link)
- BOC / Linde : gamme de gaz de soudage : The right gas working for you (link)
- Messer : gaz de soudage MAG / TIG / MIG alu : Welding gases, tableaux par procédé (link)
- Linde : choix d’un gaz de protection : How to Select a Shielding Gas ; TIG Welder Gases (link)
- ISO 14175:2008 : gaz de soudage : Tableau 2, classification (link)
- Règle de débit retenue : EWM : 10 à 12 × Ø du fil en L/min. Recoupement Lorch : MAG Ø × 11,5, MIG Ø × 13,5 ; Miller : 35 CFH (≈ 16,5 L/min) sur acier.