There are many factors at play when selecting the right material for your compressed air piping system. Your industry, application(s), environment, desired air quality, set-up size, aesthetics even.
In general you have the choice between Aluminium, Stainless steel and Polyamide.
Aluminum is the standard for any industrial application. It's lightweight and easy to install, but generally comes with a higher initial cost.
Stainless steel piping can be installed in harsh production environments like pharma and health, food and beverages, and process industries.
Polyamide pipes are ideal for workshops with several pneumatic tools.