Shielding gas tips and best practices for quality welds
While choosing the right shielding gas is an important step, the following best practices will also help you produce better results.
Tip 1: Ensure proper setup and flow rate
Purge valve before attaching regulator: Before you hook up the shielding gas, twist open the valve on top of the canister to let a small amount of gas out and then close the valve again. This cleans out the connection, so when you attach the regulator there are no contaminants like dust that can get into the welding system. Then, make sure you attach the regulator as instructed in the owner’s manual. Typically, a regulator has two dials. The right one will control the gas cylinder, and the left one will control the gas flow rate.
Set flow rate according to welding process: For MIG short-circuit welding it’s recommended to use a 25 to 35 cubic feet per hour (cfh) gas flow rate. TIG welding typically runs a lower flow rate, while MIG processes using other transfer modes (other than short-circuit transfer) can run slightly higher than 35 cfh.
A flow rate that is too low will introduce porosity into the weld because there isn’t enough coverage to protect the puddle. A flow rate that is too high wastes gas and can also produce an eddy current that results in turbulence, introducing atmospheric contaminants into the weld that cause porosity.
Use wind blocks for outdoor welding: Anytime you’re welding outdoors with a gas-shielded process, try to set up a wind block or tent to prevent the wind from blowing the gas away.

An example of porosity in a weld.
Tip 2: Check all power source connections
If you experience issues with gas coverage, the first troubleshooting step is to check all of your connections on the back of your power source. On many multiprocess welding power sources, there are two different gas ports: one for TIG and one for MIG. Be sure you are connected to the right port. Then check that your cfh is set properly.
If you’re still not getting shielding gas after taking these steps, check that the MIG gun is seated properly in the drive system. Without proper seating, the gas exits at the drive system rather than making its way through the end of the MIG gun. Also, consider using an external flow meter on the MIG gun. This will monitor the cfh rate you’re getting at the end of the gun.
Tip 3: Clean the consumables
The consumables in your MIG gun include the contact tip, diffuser and nozzle. The nozzle directs the shielding gas to cover the weld puddle. However, as you weld, spatter and debris can clog the nozzle. If there is too much spatter buildup, it can disrupt the shielding gas coverage. Be sure to occasionally remove the nozzle and use pliers or another tool to remove any excess buildup.
Tip 4: Adjust Contact-Tip-to-Work Distance (CTWD)
Another troubleshooting tip to try if you’re running into shielding gas issues is to adjust your CTWD. If you’re welding too far away from the work surface, you might be losing shielding gas before it gets to the weld puddle. Try moving the end of the gun closer to the base material. While it depends on several factors, 1/4 inch to 5/8 inch is a standard recommended CTWD.