How to Select the Proper Materials When Building a Fluid System
Selecting the right fitting and ferrule materials is an important step in building a reliable fluid system. Material compatibility affects corrosion resistance, pressure capability, temperature performance, and long-term system integrity. In this video, you will learn key considerations for choosing fitting and ferrule materials that match your tubing, process media, and operating environment. Understanding how different alloys perform can help reduce maintenance requirements, extend service life, and improve overall system reliability. Swagelok offers a wide range of tube fittings and adapters in materials designed for demanding applications, including corrosion-resistant and high-purity systems. For additional guidance on tubing selection, fitting installation, and material considerations, consult the Swagelok Tube Fitter's Manual and explore the Swagelok Tube Fitting Advantage, which highlights the design features that contribute to leak-tight performance and vibration resistance.
Video Transcript
One of the questions that frequently get asked is what kind of material should I use with different types of material tubing?
What kind of material fittings and ferrules should be used on stainless steel or copper tubing. Generally, we like to suggest you keep like materials with like materials. So, you would use stainless steel ferrules and stainless steel fittings with stainless steel tubing. On copper tubing, you would use brass ferrules and brass fittings. On plastic you want to make sure you always use plastic.
Now the reason for this is that you want to make sure that ferrules are stronger than the tubing you are using. The purpose of the ferrules is to swage on to the tubing and lock into place as you see here the ferrules are permanently in place. If the ferrules are softer than the tubing, then you are not going to get that swaging action.
So if you’re using stainless steel tubing, and brass ferrules and fittings, the brass is going to be softer than the stainless steel and you won’t get the same swaging action as you would if you used like material with like materials. Stainless on stainless. Brass on copper tubing.
There are time you don’t want the swaging action of the ferrules, you don’t want them to lock into place. Say for instance you are using a thermal couple or some other sensor probe and you want to insert the probe into a process line but you don’t want to lock the ferrules into place because you want to be able to remove that sensor probe. Or you’re using glass tubing and you’re afraid that hard metal ferrules will fracture the glass. Then you want to consider using plastic. In this particular case, you might want to consider using Teflon as your front ferrule because it’s the most chemically compatible and perhaps nylon as the back ferrule. Nylon is actually a bit stronger than Teflon and helps to deform the front ferrule. The front ferrule is going to be the only wetted ferrule. So it’s the only one that is actually going to see the process so Teflon would make a good material for that. The nylon would be the back ferrule and help to deform that. In that case when you tighten it down you get a nice seal on to the tubing but you’re not fulling swaging the ferrules onto the tubing and you able to actual pull it back out again.
In summary, we suggest that you try to use like materials with like materials. Stainless steel ferrules and fitting with stainless steel tubing. Brass ferrules and fitting with copper tubing. Plastic ferrules and fitting with plastic tubing. That way you don’t have any problem with dissimilar materials fighting each other and you can always be assured your ferrules are going to swage your tubing.
