Advantages & Disadvantages Of Different Piping Material

Pipe Material:
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 the preferred option considered by contractors, architects and engineering firms.

Material	Advantages	Disadvantages	Connection Methods
Black Pipe	Low cost components Readily available Rated to high pressure Established (old) technology	Labor intensive Corrosion problems Prone to leaks Costly to repair Not easily modified Safety concerns	Threaded Welded Grooved Crimped
Galvanized Steel	Low cost components Readily available Rated to high pressure Established (old) technology	Labor intensive Corrosion problems Prone to leaks Costly to repair/Safety concerns Not easily modified	Threaded Welded Grooved Crimped
Copper	Low cost components Readily available Resistant to corrosion Established (old) technology	Labor intensive Prone to leaks Costly to repair Not easily modified Safety concerns	Soldered Quick Connect Crimped
Plastic	Low cost components Readily available Resistant to corrosion Lightweight	Labor intensive Prone to leaks Costly to repair (labor) Incompatibility issues Safety concerns	Welded Grooved Quick connect
Extruded Aluminum	Corrosion resistant/low pressure drop Lightweight/Dimension integrity Resistant to mechanical shocks Easy to install and modify	Material cost Thermal expansion/contraction Lower pressure rating	Welded Grooved Quick connect
Stainless Steel	Corrosion resistant/low pressure drop Chemical Compatibilty Rated to high pressure	Labor intensive Material costs Costly to repair (labor) Safety concerns	Threaded Welded Grooved Crimped Quick Connect

 

Diameter Considerations:
The cost of air mains frequently represents a high proportion of the initial cost of a compressed air system. While smaller diameter pipe will help save on capital cost, the restriction due to the small pipe causes greater pressure drop throughout the system, thus increasing energy consumption. Those higher energy costs can quickly exceed the price of larger diameter piping.

Layout Considerations:
The ideal distribution system provides an optimal supply of compressed air at the required pressure to all locations. The layout of compressed air pipelines, however, creates friction and results in pressure drop. Pressure drop in a compressed air piping system should be no more than 1 to 2% of capacity.

Strategies to Reduce Pressure Drop:

•	Install the air main piping in a loop or grid, so that there are multiple paths for air to travel to any location. Even in a simple loop, there are two paths for air to get to any user. If this halves the flow traveling in each direction around the loop, then pressure drop is reduced to ¼ of the level that would be seen in a single trunk line of the same pipe size.
•	Always use full port valves that do not reduce pipe diameter. Ball valves are preferred, but butterfly valves can be a good choice, as long as the seal materials are compatible with compressed air, moisture, and compressor lubricant.
•	Install isolation valves at many locations in the air mains. This allows small sections of the main to be shut down to accommodate expansions, additional drops, or pipe modifications without shutting down the entire air system. This reduces the temptation to split undersized air drops to many machines whenever an additional drop is required.
•	Install periodic drip legs from the bottom of the air mains. These should be used only for draining contaminants and/or checking air quality. If the system is being installed new, and is not of an easily modified material, consider placing a tee and valve at each pipe coupling, so that an outlet is never more than 10 feet down the air main.
•	Limit use of elbows, minimize changes in the direction of airflow, remove constrictions, reduce excessive pipe lengths and isolate unused compressed air piping because it may be a significant source of air leaks.

It is important to note that improper or incorrectly applied piping and material in an air system can result in mechanical failure, damage, and serious injury or death. For assistance in your next piping layout, please contact us regarding our take-off services.