Picking the Right Fuel Gas for Flame Hardening

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As the world’s premier manufacturer of flame hardening systems, we know that product installation and support remain at the top of our customers’ priority lists. We also know that our customers are skilled enough to install a lot of purchased equipment on their plant floor using their own plant maintenance personnel. We do this ourselves too. However, for a flame hardening system, we have found that the machine’s success in production is elevated significantly when we can partner with a plant’s maintenance department to provide the installation, training, and ramp-up. This blog will explore key considerations for you to think about concerning the installation and ramping up of your flame hardening machine before you even buy it.

The most important consideration for successful installation is choosing the fuel gas. You can choose either acetylene, propane, natural gas, propylene, MAPP gas, or other welding fuel gases. Each gas has advantages and disadvantages, so a customer needs to understand which gas will work best for their situation.

For example, natural gas is the least expensive option. But a challenge with natural gas is that your flame hardening system will need 20-30 psi of pressure, which is typically higher than the pressure available at standard natural gas delivery systems. There are workarounds to take advantage of the cost-effective advantages of natural gas, but a customer needs to be aware that those workarounds will be necessary. Another advantage of natural gas is the consistency and availability of the gas. By not using an industrial gas delivered by cylinder, you never have to worry about drops in pressure or running out of gas.

Propylene and MAPP gas burn hotter than natural gas and propane. That makes them a better choice for flame hardening applications. This could be critical when you have a challenging hardness pattern and must achieve strict depth and hardness levels. Propylene and MAPP gas comes in cylinders that allow you to set your pressures at whatever level you need. However, cylinders come with their own challenges. The gas in the cylinder is in liquid form. Pressures can be affected by the temperature surrounding the cylinder, so that the liquid gets colder and denser, or when the levels of liquid get lower in the cylinder. In these cases you end up getting less gas so your pressure is reduced. Some customers add heaters around cylinders to keep the withdrawal rate at the level needed to get the flame hot enough to produce your hardness levels. Obviously, with cylinders you need to always keep a backup in inventory in case the cylinder gets too low during a run. You don’t want to run out of gas during a flame hardening cycle.

Acetylene is probably the hottest burning fuel gas available to us. It’s also been around longer than propylene and MAPP gas. Historically it’s the gas associated with flame hardening because of its hotter temperature. However, its challenge comes with achieving a high enough withdrawal rate. You need several bottles of acetylene banked together in order to get enough delivered to the machine to burn at the necessary temperature. Another drawback is the instability of acetylene. They are shock sensitive and could explode when dropped. Erring on the side of caution, we at Flame Hardening Systems have never recommended acetylene to our customers.

We’ve also been asked whether customers can change their fuel gas and still use their existing flame heads and torches. The answer is yes, you can use any gas with the same torch equipment –except for acetylene. Acetylene torches require flame heads with fewer ports than other heads, and the ports are designed differently. You simply can’t change gases when you set up a system with acetylene. So these are among the reasons we counsel our clients to choose another fuel gas source, even though they may have heard acetylene being associated with flame hardening.

Just as important as the delivery system and choice for fuel gas is the delivery system and choice of source for oxygen. The flames produced during flame hardening are the result of a highly refined mixture and delivery of fuel gas and oxygen at the exact flow rates to produce the desired temperature. That temperature, in turn, austenizes the steel or cast iron part to the hardness level and depth you want. In many ways you can think of a flame hardening system as a controlled, sophisticated delivery of this fuel gas and oxygen mix – but the origin of that mix depends upon the delivery system that you install separately at your own facility. We work with clients closely to ensure their choices will get them the results they need, but I can’t stress it enough that this part of the installation is critical for production success.

That’s it for top considerations of fuel gas for a flame hardening system installation. Next blog we’ll talk about how to set up the oxygen delivery system for a successful operation on your plant floor. I hope this blog continues to help you refine your flame hardening processes and leads you to the results you need. Email me at mark@flametreatingsystems.com or call 919-956-5208 if we can be of any help.



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