Choosing the right compressed air pipes for a facility

This guide details traditional and new compressed air piping options to decide what’s the best fit for a project.

By Mitch Halverson March 12, 2024
Courtesy: Velocity Conveyors


Learning Objectives

  • Understand the pros and cons of different compressed air piping materials including black iron, galvanized steel, copper and aluminum.
  • Learn about recent innovations in aluminum and compound piping that provide more flexibility and ease of installation compared to traditional piping solutions.
  • Compare compression fittings versus press fittings for use with aluminum piping systems.

Compressed air insights

  • Traditional compressed air piping materials like black iron, galvanized steel, and copper present challenges such as corrosion, brittleness and heavy weight. These issues demand tailored solutions, complicating system installation and maintenance.
  • Aluminum piping emerges as a modern alternative, offering lightweight installation, corrosion resistance and ease of adjustment. Its reliability surpasses traditional materials, and innovations like semi-flexible compound piping enhance flexibility and simplify installation.
  • Choosing between compression and press fittings for aluminum piping involves trade-offs. Compression fittings are cost-effective, but have lower pressure ratings and susceptibility to outdoor elements.

In the intricate web of plant operations, compressed air piping is used to transport air from compressors to power pneumatic equipment in manufacturing facilities. The reliability and efficiency of compressed air systems is essential for production uptime and plays a pivotal role in powering industry across the nation. Plant engineers, managers and maintenance supervisors understand the critical need for trustworthy air piping solutions and the myriad challenges that often accompany traditional piping materials and methods.

This guide explores the pros and cons of the leading materials, comparing the nuances of black iron, galvanized steel, copper and aluminum piping. It also explores the unique challenges posed by all materials and how solutions such as semi-flexible piping can help overcome issues and better position facilities to maximize compressed air system performance. The guide also focuses on the pros and cons of compression versus press fittings when used for aluminum piping.

Figure 1: Aluminum piping connection to air compressor with compression fittings.

Figure 1: Aluminum piping connection to air compressor with compression fittings. Courtesy: Velocity Conveyors

Five traditional piping challenges

Traditional piping in general comes with many benefits, but there are some common challenges they face regardless of the piping used. Five issues in particular can be a major headache during the installation and monitoring process.

  1. No turnkey solutions. One of the recurring challenges in compressed air systems is the absence of universal solutions. Each problem demands a tailored approach, adding complexity to an already intricate system. This complexity is compounded by the rigidity of traditional materials and the finality of their installation. Hard materials demand exact measurements and permanent connections require perfection or the entire system won’t do the job.

  2. Corrosion leading to leaks. Corrosion remains a persistent nemesis, causing leaks that compromise system efficiency and reliability. The choice of piping material is crucial in mitigating this risk.

  3. Brittle materials and cracking. Materials prone to brittleness can develop cracks over time, leading to potential failures. This poses a significant risk, particularly in demanding industrial environments where high-pressure compressed air continuously flows through compromised piping networks. Experienced industrialists know employee safety is always the number one priority, so durable material that lasts for the long term and doesn’t threaten safety when compromised is crucial.

  4. Heavy materials and increased labor. Dense, traditional materials are notorious for their weight. In some cases, traditional solutions weigh a lot more than their more modern counterparts. This increased weight requires more labor and time for installation. The cumbersome qualities of traditional compressed air pipes increase the amount and time of required labor, potentially keeping the factory floor shut down longer. The installation of heavier objects also can lead to greater employee risk.

  5. Skilled labor and hot work permits. Welding, soldering or brazing needs associated with traditional materials necessitate skilled labor and hot work permits. As a result, the installation of traditional piping materials takes longer and the necessary skilled labor is more expensive. These additions further complicate the installation process and can also keep the factory floor shut down for longer.

Figure 2: Aluminum piping’s lightweight qualities enable safe lines across existing ceiling structures.

Figure 2: Aluminum piping’s lightweight qualities enable safe lines across existing ceiling structures. Courtesy: Velocity Conveyors

Three traditional piping materials for compressed air systems

There are several types of piping materials for compressed air systems. Three of the most common are black iron, galvanized steel and copper. Each comes with its own benefits and drawbacks and the situation should be considered.

1. Black iron

As the widely-used historical incumbent and least expensive option for most compressed air piping systems, black iron is the first thought for many professionals in need of a compressed air piping system.

While it has been an industry go-to, just because it’s the cheapest option upon installation doesn’t mean it won’t end up costing more in the long run. The onset of more modern materials have revealed some clear disadvantages of what used to be the most popular material in compressed air piping.

The most significant downfall of black iron piping is it’s prone to failure over time via rust and corrosion. The uncoated surface of black iron leads to rampant rust formation, causing particulates that can damage pneumatic equipment down the line. Unless the factory is moisture and oil free, corrosion and rust will occur and result in system failure. That failure will occur much faster with black iron than other corrosion-prone piping materials.

Black iron also is inflexible. Once installed, modifying black iron systems requires cutting, welding and re-pressurizing the system. This demands extensive downtime and labor expenses.

2. Galvanized steel

Since black iron and galvanized steel are both made of steel, they are quite heavy. However, galvanized steel’s layer of zinc coating adds additional weight which contributes to many of the same safety and labor problems as black iron. However, the zinc provides one important advantage – corrosion resistance. The zinc layer applied to galvanized steel during the manufacturing process adds decades to the pipe’s lifespan.

The greatest disadvantage of galvanized steel piping is the breakdown of the zinc coating surrounding the steel core. Although this coating adds decades of durability to the integrity of the pipe, over time the zinc breaks down into flakes. These flakes can damage or clog pneumatic equipment, making galvanized steel a hazardous material for systems over time. The flakes can even be dangerous if shot out of a blow gun that’s connected downstream.

3. Copper

As the only traditional piping solution with natural corrosion resistance, copper stands apart for its cleanliness and unique look. However, copper also carries the disadvantages of high material costs and installation labor costs. Copper produces clean, oil-free air that can be ideal for some sensitive equipment, but its higher price tag makes it an inaccessible solution for many.

Copper is the only compressed piping material that requires soldering to connect all pipe sections and fittings together without leaks. This method requires expensive, skilled laborers who, even when working efficiently, take longer than modern solutions.

While the copper look may appeal to many from an aesthetic standpoint, it’s often not the best fit for a factory setting.

PVC not a viable option for compressed air

Thanks to its availability, cheap cost and simplicity of installation, PVC may seem like a viable option. However, PVC is not approved by OSHA and should never be used to transport compressed air or other pressurized gases.

PVC has been prohibited for the transportation of compressed air by OSHA because of the significant risk of pipe failure and subsequent shattering that can cause significant harm to workers. Equipment failure can strike no matter how well prepared a facility is. While other materials can burst, none shatter into dangerous ballistic shrapnel like PVC does.

Two reasons behind the rise of aluminum piping

The newest alternative for compressed air piping boasts the most attractive value proposition in a factory, or even private workshop setting. Advanced aluminum piping delivers solutions to the most pressing compressed air system problems.

1. It’s lightweight and has a low installation risk

The lightweight properties of aluminum compared to steel or copper alternatives make installation a breeze. This allows for less installation labor, as one person can lay more piping in less time than large teams installing alternative materials with more complex installation methods.

Aluminum piping also allows for faster, simpler adjustments in the future. These adjustments can even be made by in-house staff. No soldering, welding or brazing means no hot work permits or specialized, outsourced labor.

2. Corrosion-proof reliability

Before aluminum piping, eventual piping failure and replacement was an inevitability decision-makers had to include in their extended budget forecasts. Aluminum piping doesn’t just withstand corrosion, it also ensures lifelong corrosion resistance without flakes or other particulates coming off the piping and harming equipment or employees.

The reliability risk of aluminum piping doesn’t come from internal breakdown via corrosion, but external damage via impact or vibration. Although aluminum piping is made to withstand the pressure of compressed air transport, it’s naturally more susceptible to physical impact. Additionally, the melting point of aluminum (1,221 °F) is lower than copper (1,984 °F) and steel (2,500 °F), making aluminum an unusable material in certain high-heat applications.

Figure 3: Aluminum piping with press fitting.

Figure 3: Aluminum piping with press fitting. Courtesy: RapidAir

Semi-flexible compound piping

Recently innovated compound piping couples lightweight aluminum with an external polymer coating. This new form factor enables flexibility and bend radiuses that aren’t possible with other compressed air piping solutions. The semi-flexibility eases installs (no exact measurements required) along the twists and turns of the production line.

Choosing between compression or press fittings for aluminum piping

Purpose-built for aluminum systems, traditional compression style and modern engineered press options for aluminum piping provide leak-free reliability combined with unmatched installation speed when compared to traditional material fittings. Both methods have their own pros and cons based on application needs.

Compression fittings

Generally less expensive than press fittings, compression fittings require simple tools and skills for installation that can be learned quickly. This makes compression fittings a great choice for a large array of applications, from large-scale factory installations to DIY garage installations. Compression fittings are also repairable if leaks occur via re-tightening. Two disadvantages of compression fittings are their relatively low-pressure rating when compared to the alternative, and their susceptibility to the elements when used outdoors over the long term.

Press fittings

Through a unique process of pressing directly on the aluminum piping, pipe sections join in seconds without separate fasteners or adjustment. This represents a genuine breakthrough for compressed air piping install efficiency. Press fittings stainless steel material give them a sleek, metallic look that comes with inherent corrosion resistance, making them the superior option for installations that are subject to the elements. Press fittings also are capable of handling higher PSI than compression fittings.

Figure 4: Semi-flexible compound aluminum piping is designed to withstand burial in dirt or concrete.

Figure 4: Semi-flexible compound aluminum piping is designed to withstand burial in dirt or concrete. Courtesy: RapidAir

Using compressed air in the field

When David Boyette, owner of Velocity Conveyors, a mechanical installer meeting manufacturing needs throughout the east coast, needed compressed air, he turned to aluminum piping. When Boyette founded the company in 2017, he relied on black iron piping around filters and compressors, but soon made the switch to aluminum. Since switching, installation efficiency has increased with less labor and less time on site.

“An installation that used to take us weeks now takes days,” Boyette said. “Working with black iron pipe took longer, was harder to measure out exactly right and is prone to rust. Now, I’m able to get the same, or more, amount of work done each day with less labor than before.”

During a recent installation project, Boyette and his crew of three were tasked with installing 2,000 ft of conveyor. Thanks to the ease of installation of aluminum pipe, Boyette was able to install 750 ft of the piping by himself, giving his team the leeway they needed to install the conveyor on time and on budget.

Figure 5: David Boyette, owner of Velocity Conveyors.

Figure 5: David Boyette, owner of Velocity Conveyors. Courtesy: Velocity Conveyors

Choosing the right option

As with everything in the industrial space, efficiency is key and aluminum piping is the most reliable, cost-effective and easy-to-install solution. With the onset of malleable aluminum piping with a compound coating, the gap between new and traditional solutions has widened.

Author Bio: Mitch Halverson, product sales manager, RapidAir Compressed Air Products