Stainless steel for Data Centre cooling

The rapid growth of AI has driven the widespread adoption of liquid cooling in data centres, for which Stainless steel has proven to be a critical material. Stainless offers a multitude of benefits specific to the performance of liquid cooling systems, including corrosion resistance, mechanical strength, cleanliness, and a low lifetime cost, maximising efficiency.

Keep reading to learn why liquid cooling has become a necessity in modern data centres, how liquid cooling works, where Stainless steel is used, its benefits in detail and our stock at Stirlings.

Stainless steel liquid cooling components in fabrication.

The rise of AI and the difference with traditional computing

The launch of generative AI in the early 2020s has seen an explosion of adoption worldwide in a very short amount of time. Notably, these AI servers use GPUs rather than CPUs, allowing them to do the complex computing required for AI tasks.

Unlike the CPUs (Central Processing Units) of regular computing, which previously had around 18-18 cores, and in more modern chips have around 64-128 cores, AI models require thousands of high-performance GPUs (Graphics Processing Units). These GPUs contain 384 to over 16,000 cores each to process massive amounts of data simultaneously.

Changing requirements and the consequences of inadequate data centre cooling

Although GPUs are more energy efficient in terms of performance per watt, their computing capability means they consume much more wattage and produce much more heat than any previousgeneration of computer chip.

An AI data centre can produce roughly 100 MW of continuous heat per hour, which is comparable to 100,000 household electric heaters operating continuously at 1 kW each per hour. Comparatively, cooling capacity on this level would require about 29,000 domestic air conditioners each providing 3.5 kW of cooling per hour.

Removing this extreme heat generated by GPUs is essential, as it can result in:

Reduced hardware performance
Component failure
Shortened equipment lifespan
Unexpected downtime

Traditional industrial HVAC systems are still essential for facility cooling, but they are not solely adequate or efficient enough for cooling this level of heat output. High density GPU rack cooling requires a much more targeted approach: liquid cooling. Did you know, water transfers heat roughly 3,500 times more efficiently than air by volume?

What is liquid cooling

This video gives a short summary on direct-to-chip liquid cooling, with a visual demonstration on how it works:

In brief, direct-to-chip data centre liquid cooling works by circulating water or coolant through a closed-loop system to absorb heat directly from GPU chips.

Cooling from start to finish

Liquid cooling uses cold plates mounted directly onto the hottest components. Inside the cold plate are small internal channels through which coolant flows. The heat from the GPU passes directly into the cold plate and into the coolant.

This video shows a demonstration of how cold plates work:

The coolant carries the heat away from the servers, transferring it to the Cooling Distribution Unit (CDU). Inside the CDU, the warm coolant passes through a plate heat exchanger without the two water circuits mixing.

The heat is then rejected outside the building through cooling towers, dry coolers, or other heat-rejection equipment. After releasing its heat, the coolant is cooled and pumped back through the system to repeat the cycle.

This video shows a short demonstration of coolant entering a CDU.

A note on immersion cooling

For most enterprise and hyperscale data centres, direct-to-chip cooling as detailed above is currently the dominant technology because it integrates with conventional rack architectures.

Immersion cooling, for which the entire server is immersed into a bath of dielectric fluid, is growing in specialised environments where heat loads are even higher or maximum energy efficiency is required, such as:

Large AI training clusters
High-performance computing (HPC)
Cryptocurrency mining

There are two main types:

Single-phase immersion

Fluid remains liquid throughout the process
Heated fluid is pumped through a heat exchanger and recirculated

Two-phase immersion

Fluid boils when it contacts hot components
Vapour rises, condenses on a cooling coil, and returns to the tank
Offers exceptional heat transfer but is more complex and expensive

Advantages

Highest cooling performance available
Supports rack densities exceeding 100-200 kW
Eliminates most server fans
Reduces noise and airborne contaminants

Coolants used in liquid cooling systems

Deionised (DI) Water: has dissolved minerals removed, reducing electrical conductivity and minimising scale formation

Advantages:

Excellent heat transfer
Very low mineral content
Reduced scaling
Widely used in high-performance liquid cooling

Water-Glycol Mixtures: water mixed with ethylene glycol or propylene glycol

Advantages:

Freeze protection
Corrosion protection
Biological stability
Longer service life

Although these coolants are mostly water, dissolved oxygen, treatment chemicals, varying temperatures, and flow conditions all contribute to corrosion and require corrosion resistant materials in the fabrication of the cooling system.

Dielectric fluids, including synthetic hydrocarbons, fluorinated fluids, or engineered dielectric oils (specifically for immersion cooling tanks rather than direct-to-chip systems).

Advantages:

Do not conduct electricity
Can safely contact electronic components directly

Stainless steel in liquid cooling

Stainless steel has become the preferred material for many vital components of modern liquid cooling systems thanks to its corrosion resistance, mechanical strength, cleanliness, and long service life.

Corrosion resistance

The corrosion resistance of Stainless helps prevent:

Rust contamination
Internal Pipe degradation
Blockages
Reduced heat transfer
Equipment failure

Leading to a longer life of the system and reduced maintenance and downtime requirements.

Mechanical strength

Direct-to-chip liquid cooling systems operate under significant pressure due to the closed-loop pumping of the coolant.

Stainless steel provides:

Excellent tensile strength
High pressure capability
Resistance to mechanical fatigue
Dimensional stability
Long-term structural integrity

This allows thinner wall sections while maintaining high pressure ratings, reducing weight and therefore cost. Stainless may have a higher initial purchase price than alternatives such as carbon steel, but its total lifecycle cost is often considerably lower.

Cleanliness

Liquid cooling systems depend on maintaining exceptionally clean water, and Stainless contributes virtually no contamination even with constant water looping.

Smooth Stainless surfaces:

Reduce particle accumulation
Minimise biofilm formation
Simplify system cleaning
Maintain consistent flow

Electropolishing can also be used where extremely clean water circuits are required.

Lifetime costs

Over the life of a cooling system, Stainless decreases:

Maintenance
Corrosion repairs
Replacement costs
Downtime
Water contamination issues
Inspection requirements

For facilities operating 24 hours a day, seven days a week, reliability is paramount, and Stainless can achieve this to a much better degree to alternatives such as carbon steel.