AIRnet vs Traditional Compressed Air Pipework for an Expanding Factory

The extension is drawn, the machines are ordered, and the pipework quote is based on today’s flow. Twelve months later, another production cell changes the duty. An AIRnet vs traditional compressed air pipework decision for an expanding factory must cover that future load, not just the first installation.

Anglian Compressors, a Branch of Atlas Copco Compressors, assesses the choice against bore size, pressure loss, material limits, installation access and compliance. All three routes can work. The useful question is which one still works after the factory changes.

Bore First, Material Second

Pipe material cannot rescue an undersized distribution system. The design must start with peak simultaneous air demand, required pressure at the point of use and the resistance created by the complete route.

Equivalent length matters here. Every bend, tee, valve, filter and connection adds resistance beyond the measured straight-line distance. A ring main may give air more than one route to a user, while a long dead leg concentrates the entire pressure loss in one direction.

The Health and Safety Executive gives a clear design reference. As a general guide, pressure loss between the receiver and the most remote user should not exceed 5% of the required pressure, subject to an upper value of 0.3 bar. Its HSG39 compressed-air safety guidance (hse.gov.uk) also says pipework should be generously sized for foreseeable expansion.

Design Inputs for Future Demand

Generous sizing does not mean selecting an arbitrary oversize bore. It means calculating against credible future duty rather than adding an unexplained percentage. The design inputs should include:

• Current average and peak free air delivery demand
• Minimum pressure required by the most sensitive process
• Simultaneous demand from machines that can run together
• Straight lengths and the equivalent length of fittings
• Planned production cells, shifts and process changes
• Air quality and pressure dew point requirements
• Ambient, process and cleaning temperatures
• Isolation requirements and available shutdown windows

Our air compressor pipework installation work starts by measuring these conditions, then calculating the bore and routing the main around the factory’s likely development. The output is a phased layout with connection points, isolation zones and pressure-loss calculations that procurement and engineering teams can review.

Worked Example: Sizing for the Future Flow

Take an existing peak demand of 60 l/s FAD, rising to 100 l/s after expansion, over an equivalent route length of 150 m at approximately 7 barg. Using a published empirical sizing equation, a 37 mm internal bore loses about 0.237 bar today but 0.610 bar at the future flow. A 46 mm bore loses about 0.080 bar today and 0.205 bar after expansion.

The 37 mm option passes the HSE 0.3 bar guide at current demand and fails it once the new cell is connected. The 46 mm option stays below 0.3 bar in both scenarios.

These are illustrative bores for pipes around 40 mm and 50 mm outside diameter. The final design must use the selected product’s actual internal diameter, not its nominal size, and add fittings and treatment losses.

The Case for Traditional Pipework

“Traditional pipework” can mean several systems. For this comparison, it refers mainly to site-fabricated carbon steel or galvanised steel installed using threaded, flanged or welded connections. Existing copper and process stainless steel systems need separate assessment because their jointing methods and material limits differ.

Where Familiar Fabrication Wins

Traditional steel remains a rational choice where the factory already has a documented steel standard, established supports and engineers equipped to modify it. Retaining the same material can simplify spares, inspection and repair arrangements. It may also be required in zones where the site specification calls for welded fabrication, additional mechanical protection or a pipe grade selected for a particular temperature.

A sound existing main does not need replacing simply because a modular alternative is available. If measurements confirm that its bore supports future demand and its internal condition is known, extending the installed system may create less disruption than replacing the entire distribution network.

The Limits on a Growing Site

Every new branch normally involves cutting, threading, flanging or welding. That affects labour, access and shutdown planning, particularly when the main crosses active production areas. Hot-work controls may also shape how and when a welded extension can be completed.

Carbon steel condition is another variable. Condensate can corrode the internal surface and create scale, which changes the effective bore and introduces particulate contamination downstream. The initial pipe diameter may still look adequate on a drawing while the operating system behaves differently.

Traditional pipework can serve an expanding factory well. Its case depends heavily on the condition and capacity of what is already there.

The Case for AIRnet Aluminium

AIRnet aluminium is designed for compressed-air distribution using a modular push-fit coupling system. It removes the threading and welding stages associated with traditional steel, which changes the practical cost of adding branches even when the original installation prices appear close.

Expansion Without Rebuilding the Main

A planned take-off can be included for a future machine before that machine arrives. Later alterations can use matched components rather than fabricated joints, reducing the amount of work carried out beside operating lines. The low mass of aluminium also makes larger-bore sections easier to handle when routes pass through congested service areas or at high level.

Aluminium does not produce rust scale. Its internal bore avoids the corrosion mechanism that can progressively change an untreated carbon steel line. That helps preserve the pressure-loss assumptions used during design, provided the system is installed, supported and operated within its specification.

The limitation is application fit. Aluminium should not be selected solely because the factory expects to expand. Pipe temperature, external environment, chemical exposure, mechanical risk and the compatibility of every seal and fitting still govern the specification.

Manufacturer Limits for AIRnet Aluminium

AIRnet aluminium is published in sizes from 20 to 158 mm outside diameter. The manufacturer’s maximum working pressure is 16 barg, except the 158 mm range at 13 barg, with a temperature range of -20°C to 80°C. The installed system must operate within the lowest rating of every pipe, fitting, valve, seal and transition.

The 2023 assembly guide adds limits. Fittings in direct ultraviolet light must be shielded, the pipe cannot be buried in soil without a watertight PVC sleeve, and vibration should not be transmitted into the main. It is not for conveying finished products such as food, chemicals or cement, fittings marked non-reusable cannot be reused, and the fittings and tools are proprietary.

Higher Temperatures Shift the Case to AIRnet Stainless Steel

AIRnet stainless steel addresses environments where aluminium’s temperature or material limits are inadequate. The manufacturer sheet gives 304L sizes from 15 to 108 mm, with 316L available for part of the range, a maximum working pressure of 16 bar and a temperature range of -20°C to 120°C. That 120°C ceiling, against aluminium’s 80°C, gives designers a wider operating envelope for hot process areas and exposed sections.

Stainless steel also suits installations where corrosion resistance is a primary material requirement. That may include areas subject to aggressive cleaning regimes, external moisture or process conditions that justify stainless construction. The exact grade, seals and fittings must still be checked against the substances present on site.

A hybrid system is often technically legitimate. Aluminium may serve the general ring main, with AIRnet stainless steel used through higher-temperature or demanding process zones. The transition must be designed as part of one pressure system, not treated as an improvised connection between two otherwise independent packages.

No article can settle chemical compatibility from the words “washdown area” alone. Cleaning agents, concentration, contact time and temperature can reverse an otherwise reasonable material choice.

Side-by-Side: Where the Differences Affect the Plant

Decision Criterion	AIRnet Aluminium	AIRnet Stainless Steel	Traditional Steel Pipework
Factory expansion	Modular branches and alterations	Modular option for demanding sections	Usually requires site fabrication
Internal corrosion	Does not form rust scale	High corrosion resistance	Condition depends on material, treatment and condensate exposure
Manufacturer ratings	16 barg (13 barg at 158 mm), -20°C to 80°C, 20 to 158 mm OD	16 bar, -20°C to 120°C, 15 to 108 mm, 304L/316L	Depends on pipe grade, joints and site specification
Installation activity	No threading or welding	Uses matched system components	May involve threading, flanging, welding and hot-work controls
Existing-system integration	Straightforward where AIRnet is already installed	Useful as a defined specialist section	Can be the simplest match for a sound legacy main
Future change cost	Planned take-offs reduce later alteration work	Useful where later changes face environmental constraints	Access and fabrication can make each extension a separate project
Compliance	Requires engineered sizing and change control	Requires engineered sizing and change control	Requires engineered sizing and change control

Pressure Loss Becomes an Operating Cost

A distribution main that meets the pressure requirement at commissioning can fail after additional demand is connected. Flow rises, friction loss increases and the most remote process receives less pressure. Raising compressor discharge pressure may mask the symptom, but it makes every connected compressor work against a higher pressure.

The Carbon Trust states that reducing system pressure by 10% can yield approximately 5% energy savings in suitable conditions, according to its compressed-air guidance (carbontrust.com). The reverse relationship explains why compensating for an undersized main at the compressor is an expensive habit.

In the sizing example, the 46 mm bore avoids 0.405 bar of loss at the future flow. If discharge pressure falls by the same amount, that is 5.79% of 7 barg, giving a screening saving of 2.89% under the Carbon Trust relationship. On a 75 kW compressor running 4,000 hours a year (300,000 kWh), that comes to about 8,670 kWh, or approximately £1,457 a year at 16.8 p/kWh, the provisional DESNZ Q4 2025 average UK manufacturing price excluding Climate Change Levy.

That figure holds only if discharge pressure is reduced, the controls turn lower pressure into lower power and your contracted tariff resembles the published average.

Material choice influences how easy the system is to extend, but bore and routing determine whether the extension performs.

Condensate Still Needs Its Own Design

Neither aluminium nor stainless steel removes moisture from compressed air. Dryers, drains, filters and correctly routed pipework remain responsible for keeping condensate away from processes and pneumatic equipment.

The material decision changes what happens when moisture reaches the distribution system. Traditional carbon steel may corrode internally, while aluminium and stainless steel remove that particular failure mechanism. Our guide to water in compressed air lines covers the upstream causes and treatment options.

A corrosion-resistant main is not a substitute for the required pressure dew point.

Compliance Does Not Disappear With a Modular System

Fast assembly does not turn an extension into an informal maintenance job. Where the installation forms part of a pressure system covered by the Pressure Systems Safety Regulations 2000, the change must be considered against the system’s design and examination arrangements.

HSE guidance on PSSR Regulation 13 (hse.gov.uk) says modifications and repairs should be assessed against the original specification, future duty, system integrity, protective devices and the Written Scheme of Examination. An extension can alter flow, pressure behaviour, isolation arrangements and the boundaries covered by the scheme.

The practical sequence is to review the proposed duty, complete the pressure-loss calculation, check the design pressure and component compatibility, then confirm whether the Written Scheme of Examination needs updating. Our guide to UK compressed air regulations explains the wider responsibilities around compressed-air equipment.

The HSE sources cited here apply to Great Britain. Northern Ireland has separate, substantially parallel Pressure Systems Safety Regulations (Northern Ireland) 2004.

Installation Quality Can Override the Material Choice

A correctly selected material can still underperform if the route creates unnecessary bends, the supports allow movement or the ring main cannot be isolated in usable sections. Drainage, thermal movement, connection loads and access for later inspection all belong in the installation design.

Expansion points need deliberate positions. A capped branch placed behind fixed machinery is technically present and operationally useless. The same applies to isolation valves that stop half the factory when one production cell needs alteration.

The Brinkley-Propeller project provides a finished example of a new compressed-air system designed around the facility rather than treated as a collection of pipes and fittings. That system-level view matters more as each production phase is added.

What to Ask For in a Tender

No public UK-wide £/metre threshold shows where AIRnet becomes cheaper than steel, because layout, access and shutdown conditions dominate quotations. Request like-for-like tenders on the same hydraulic duty, with these items priced separately:

• Pipe by actual bore, plus fittings, drops and transitions
• Valves, drains, supports and impact protection
• Access, hot-work controls and shutdown hours
• Testing, commissioning, drawings and Written Scheme of Examination review
• Spares, specialist tools and future branch unit rates

Evaluate each bid at the lowest initial demand, the approved expansion demand and with one side of the ring main isolated. Simple payback is the incremental capital cost divided by the annual energy, maintenance and downtime saving. Show avoided shutdown separately from energy so an assumed production-loss value does not hide inside one figure.

The Verdict: AIRnet Pipework vs Steel by Factory Scenario

Choose AIRnet aluminium for accessible modular expansion, AIRnet stainless steel for higher-temperature or demanding environments, and traditional steel where legacy integration or site standards justify fabrication.

AIRnet aluminium has the clearest operational case when the factory expects regular layout changes and wants to minimise threading, welding and future alteration work. AIRnet stainless steel becomes the stronger option where temperature or environmental conditions exceed the aluminium specification.

Traditional steel remains credible when the existing main is sound, correctly sized and supported by an established site standard. Replacing it without measuring condition, demand and pressure loss would be specification by preference rather than evidence.

A hybrid layout may prove more appropriate than any single-material answer. Ask our team to survey and size the proposed extension before procurement. Provide the current compressor and dryer details, logged demand, required point-of-use pressure, layout drawings, future machine schedule, environmental conditions and shutdown constraints. We’ll turn those inputs into a phased pipework design for your factory in the East of England or surrounding regions.