Traditionally, engineers have specified a variety of piping materials for compressed air systems, including black iron, galvanized steel, copper, stainless steel and even plastic. More recently, aluminum piping has become an option considered by many contractors, architects and engineering firms. Aluminum piping makes sense for compressed air systems in many different applications.
Black iron and galvanized steel pipe are two common types of pipe used for compressed air systems. More than 60% to 70% of all compressed air systems installed today use black iron or galvanized pipe, due to a variety of factors:
Contractors are familiar with these materials.
Material costs are low.
The pipe and compressed air system fittings are readily available.
Steel pipe is rated for high pressure.
There are, however, five key reasons why aluminum piping is a superior material to use for most compressed air installations today, each of which addresses a key disadvantage to traditional pipe systems.
- Lowering Installation Costs
More time is needed to install a compressed air system when using steel pipe compared to installing a system using other materials.
One factor behind this is that steel pipe must be threaded in order to join pipes and install the proper fittings. To properly thread steel pipe, you need special threading equipment and skilled workers to operate it. These workers cost more than unskilled workers, and that also drives up installation costs.
Also remember that threading pipes is dirty work. You need cutting fluids to get a good thread, and that must be cleaned from the pipe before you can start using the system. Threading also creates a lot of debris.
Modifying and maintaining a compressed air system made with steel pipe is more difficult than modifying and maintaining systems built from other materials. One reason for this is that steel pipe is much heavier than other materials. Because steel pipe is so heavy, it requires more labor (read as higher labor costs) to handle the piping while making modifications than it would to make modifications to a system made with other piping materials.
- Minimizing System Leaks
Another issue with threaded connections is that they will inevitably leak. It’s been estimated that eight to 10% of the compressed air in a system will leak through threaded connections. This causes compressors to run harder and longer, driving up utility costs.
- Aluminum Piping Doesn’t Corrode
A common problem with using steel pipe is that moisture inside the system will cause pipes to rust from the inside out. Even if your compressed air system has a moisture trap, there will be some moisture in the system and corrosion will occur. Even galvanized steel pipe will corrode, as not all pipes are galvanized both inside and out.
Corrosion causes several problems, beginning with air flow restricted by a rough inner surface caked with deposits caused by corrosion build up. Additionally, loose scale deposits collect over time and create pressure drops. This makes the air compressor work harder to maintain the pressure of the system. In extreme cases, loose scale can completely clog a line or damage equipment connected to a line. Of course, corrosion and loose scale affects air quality and makes it unsuitable for applications that require clean air.