If you own or run a business in which welding is an integral part of the manufacturing process you know one of your recurrent expenses is your shielding gas. Very few manufacturing facilities, big or small, have excellent control of gas usage. Most end up using twice as much than necessary, and in some cases three or more times as much. The good news is that this problem can be addressed quickly and easily and will result in a direct positive impact to your bottom line.
There are countless ways in which gas can be wasted, but here are the four main ways in which this happens.
- Excessive flow
- Gas surges
Leaks are very hard to detect since you can’t see them, you can’t smell them and most of the time you can hear them. Shops that have a central system (bulk delivery) for gas are at risk due to the number of joints that are present in the piping system. However, leaks can be present in hoses that are in disrepair, faulty regulators, faulty solenoids in welding machines, bad gun connections, etc.
It is not feasible to get a spray bottle with water and soap and check all the joints in a central system. Pipes are usually at ceiling height and it would take forever to do so. Not to mention the safety hazard it presents. The best way is by using an infrared detection device or ultrasound detector. This is a service you would need to hire and in most cases has to be done when the plant is not running production. This can be very disruptive to your manufacturing so before you do this, run your numbers to see if you have a leak. This is explained at the bottom of this post. Finding the leaks is the hard part, fixing them is relatively simple.
A common misconception is that if 40cfh of gas is good then 80cfh is better. Unfortunately this is hardly ever the case. We walk into many welding shops and we see flowmeters that are being run wide open.
There are cases in which we need to run above the recommended range of 35-50cfh. Some instances are:
- Need to run extended electrical stickout in hard to reach areas
- There is a draft of air that cannot be stopped and proper shielding with screens is not feasible
- A bigger nozzle is being used
- Compensating for leaks in the gun or gas hose (temporary fix only)
Please note that even in these cases you rarely need more than 60cfh. Having a welding procedure that specifies the gas flow rate is essential, but your welders need to understand that too much flow is detrimental. When you have too much flow it becomes turbulent and creates a Venturi effect. This will draw atmosphere into the weld puddle, thus negating the benefit of using the shielding gas.
Gas surges occur because when the solenoid on your welding machine closes and the section of hose between your regulator and your solenoid builds up pressure. When you hit the trigger for your next weld the gas bursts out of the gun at flow rates that can exceed 220cfh. It may take anywhere from 1 to 15 seconds for the flow rate to go down to your preset flow rate. If you do a lot of short welds this can be a real killer. You are wasting money with every trigger pull. Fortunately there are devices that eliminate or drastically reduce this surge. The one pictured below has an added benefit. Other than controlling the surge it also controls flow so that it cannot be tampered with.
When a bulk system is in place but usage is extremely low you bulk tanks will experience changes in pressure due to temperature changes. This will cause the tank to bleed off periodically. There is not much you can do about this other than maybe go to cylinders while you are slow. Talk to your gas supplier to see if there are other solutions.
How to determine if you have excessive shielding gas usage
An easy way to determine if you are using more shielding gas than you should is to take a look at your purchases over the past twelve months. Survey your shop and come up with an average wire feed speed for the shop. With that information you can determine your average deposition rate per hour. Divide the total pounds over 12 month by the deposition rate and you get total number of welding hours. Then multiply those hours by 50 (using 50cfh to be conservative, you can use 40 if you want). This will give you total number of cubic feet of gas that it would take to burn that wire. If the number is within 15-30% of the amount of gas purchased over that period of time you are in great shape. If that number starts approaching twice the amount you should be using it will be worth your time to find out where the waste is coming from.