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Stainless Steel Liquid Cooling Tube

In the thermal architecture of modern AI data centers and High-Performance Computing (HPC), Stainless Steel Liquid Cooling Tubes and Manifolds act as the indispensable "circulatory system" for computing power. As rack power densities evolve towards 100kW+, liquid cooling has become the ultimate solution for extreme heat flux. Stainless steel tubing, with its superior structural reliability, chemical compatibility, and protection for sensitive electronics, is integrated across all core stages of the cooling system:

  1. CDU (Coolant Distribution Unit) Core System: Stainless steelliquid Cooling tubing is utilized to construct complex heat exchange networks and precision valve assemblies within the CDU. It bridges the Primary Loop (Facility Water) and the Secondary Loop (Clean Coolant), withstanding pressure fluctuations at high flow velocities to ensure precise thermal exchange.
  2. Secondary Loop Infrastructure: The "aseptic zone" of the liquid cooling system. Here, stainless steel tubes deliver coolant to IT equipment. Through advanced Bright Annealing (BA)or Electropolishing (EP), the internal surface (Ra ≤ 0.4μm) effectively inhibits metallic ion leaching, maintaining low coolant conductivity and preventing electrochemical corrosion of critical chips.
  3. Rack-Level Manifolds: Serving as the distribution hub, stainless steel manifolds are deployed vertically at the rear of server racks. Utilizing precision-welded branch ports, they distribute coolant evenly and at constant pressure to every server leaf. Extreme tolerance control (±0.05mm) ensures "leak-free" compatibility with Quick Disconnect (QD) couplings, safeguarding valuable IT assets.
  4. Cold Plate Connection Assemblies: These interface directly with chip-level heat sinks. The mirror-finish internal walls prevent debris from clogging the micron-sized channels within the Cold Plates, ensuring GPUs and CPUs maintain stable operating temperatures even under peak loads.

By utilizing high-purity TP304L/TP316L stainless steel compliant with ASME BPE / 3A Sanitary standards, this liquid cooling solution not only significantly reduces the Power Usage Effectiveness (PUE) but also provides a 15-year long-term operational guarantee for AI computing clusters.

Specifications

Standard

ASME BPE / 3A Sanitary Standards

Material

TP304L (1.4307) / TP316L (1.4404) Austenitic Stainless Steel

Outer Diameter (OD)

DN10 – DN300 ( 12.7 mm – 304.8 mm / 0.5" – 12")

Wall Thickness (WT)

1.0 mm, 1.5 mm, 2.0 mm, 2.5 mm, 3.0 mm (Other thicknesses on request)

WT Tolerance

Typically within ±10%

Surface Finish

Pickled, Mechanically Polished (MP), Electropolished (EP)

Internal Roughness (Ra)

Ra ≤ 0.8 μm (Standard), Optional Ra ≤ 0.6 μm / 0.4 μm (High-purity)

Yield Strength (Rp0.2)

≥ 190 MPa (TP304L); ≥ 200 MPa (TP316L)

Tensile Strength (Rm)

500 – 700 MPa

Elongation (A)

≥ 45% (TP304L); ≥ 40% (TP316L)

Pressure Rating

PN10 – PN25 (Specific ratings depending on size and wall thickness)

Operating Temperature

-196°C to 300°C (Depending on cooling media and environment)

 

 
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Industries

Data Center Cooling System , AI Data Centers, High-Performance Computing
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Standards

Fully compliant with ASTM A270, ASME BPE, and 3A Sanitary Standards. This ensures global interoperability with CDU systems and facilitates seamless safety and environmental audits for data center infrastructures.

High-Purity Materials

Utilizes TP316L (1.4404) or TP304L (1.4307)ultra-low carbon stainless steel. These materials prevent metal ion leaching into aggressive coolants like DI water, maintaining low conductivity and safeguarding GPUs/CPUs from electrochemical corrosion.

Surface Treatment

Employs Mechanical Polishing (MP) or Electropolishing (EP) to achieve Ra ≤ 0.4μm - 0.6μm. Combined with Oil-free degreasing, this finish minimizes flow resistance for PUE optimization and prevents micro-channel clogging in cold plates.

Annealing

Integrated heat treatment in a hydrogen atmosphere with temperatures between 1040°C-1150°C and a dew point ≤ -45°C. This restores the metallurgical structure, eliminates stresses, and ensures a mirror-bright, oxide-free internal surface to minimize contamination.

Quality Testing

Beyond standard hydrostatic tests, we employ Helium Leak Testing and PMI (Positive Material Identification). With tight OD tolerances of ±0.05mm, we guarantee molecular-level zero-leakage and perfect compatibility with Quick Disconnect (QD)

Packaging&Transport

Finished tubes feature sealed ends with dust caps and double-layer anti-static vacuum packaging. This protects against contamination during transit and storage, ensuring products arrive "ready-to-install" for high-cleanliness AI facility environments.

Chemical Composition

Material Performance Comparison
GradeCompositionPREN ValueDI Water StabilityTypical ApplicationSummary
TP304L (1.4307)18Cr-8Ni (Low C)18.0 - 20.0Good for general process waterPrimary loops, facility pipingCost-effective for standard cooling
TP316L (1.4404)16Cr-10Ni-2Mo23.0 - 26.0Excellent; ultra-low leachingSecondary loops, Manifolds, Cold platesHPC Preferred for mission-critical AI safety

Dimensional Tolerances

Stainless Steel Liquid Cooling Tubing Comprehensive Specifications & Pressure Rating
The data in this table strictly complies with ASTM A270 specifications and is suitable for 3-A certified sanitary processing systems.
DNSize (Inch)ODWTOD ToleranceFinish & RaWorking PressureBurst Pressure
DN101/2"12.70 mm1.0 mm± 0.05 mmEP / Ra ≤ 0.25μm24.0 MPa / 240 bar72.0 MPa
DN155/8"15.88 mm1.2 mm± 0.05 mmEP / Ra ≤ 0.25μm22.5 MPa / 225 bar67.5 MPa
DN203/4"19.05 mm1.2 mm± 0.05 mmBA / Ra ≤ 0.4μm18.5 MPa / 185 bar55.5 MPa
DN251"25.40 mm1.65 mm± 0.08 mmBA / Ra ≤ 0.5μm19.5 MPa / 195 bar58.5 MPa
DN321-1/4"31.75 mm1.65 mm± 0.08 mmBA / Ra ≤ 0.5μm15.5 MPa / 155 bar46.5 MPa
DN401-1/2"38.10 mm1.65 mm± 0.10 mmBA / Ra ≤ 0.6μm12.5 MPa / 125 bar37.5 MPa
DN502"50.80 mm2.0 mm± 0.10 mmMP / Ra ≤ 0.8μm11.5 MPa / 115 bar34.5 MPa
DN652-1/2"63.50 mm2.0 mm± 0.12 mmMP / Ra ≤ 0.8μm9.5 MPa / 95 bar28.5 MPa
DN803"76.20 mm2.11 mm± 0.15 mmMP / Ra ≤ 0.8μm8.5 MPa / 85 bar25.5 MPa

Frequently Asked Questions

Why does the 3-A standard specify a precise range for Sulfur content?

In 3-A and ASME BPE systems, sulfur content is strictly controlled between 0.005% and 0.017%. This range is critical for optimizing automated orbital welding performance. Sulfur content below 0.005% can cause inconsistent weld penetration and arc wandering, while content above 0.017% increases the risk of hot cracking. Precise sulfur control ensures uniform, high-quality weld beads, which are essential for crevice-free hygienic systems.

What is the technical difference between Mechanical Polishing (MP) and Electropolishing (EP)?

Mechanical Polishing (MP) uses physical abrasives to reduce surface roughness, typically achieving Ra ≤ 0.5 μm (20 μ-in) for standard 3-A tubes. Electropolishing (EP) is an electrochemical process that removes microscopic peaks from the surface. EP not only achieves a superior finish of Ra ≤ 0.38 μm (15 μ-in) but also creates a chromium-rich passive layer that significantly enhances corrosion resistance and cleanability, making it the standard for high-purity pharmaceutical applications.

How do I choose between TP304L and TP316L for my 3-A piping system?

TP304L is a cost-effective choice suitable for standard food, dairy, and beverage applications with moderate corrosion risks. TP316L contains over 2.0% Molybdenum (Mo), providing much higher resistance to pitting and chloride-induced corrosion. TP316L is highly recommended for processes involving high salt content, acidic media, or aggressive CIP (Clean-in-Place) chemicals. It is the mandatory standard for most biopharmaceutical facilities.

Can 3-A (Imperial) tubing be directly welded to DIN or ISO standard fittings?

No. 3-A tubing follows the Imperial (Inch) system (e.g., 1" = 25.4mm), whereas European DIN (e.g., DN25 = 29mm) or ISO standards have completely different outside diameters. Attempting to weld them together will result in severe internal misalignment and "dead legs," which will fail any hygienic audit. It is vital to ensure that the entire piping system, including tubes, valves, and fittings, follows the same dimensional standard.

Why is "Bright Annealing (BA)" considered essential for 3-A sanitary tubes?

Bright Annealing is an in-line solution treatment performed in a pure hydrogen atmosphere. It eliminates residual welding stresses and fully restores the material’s corrosion resistance without forming oxidation scales. For 3-A tubing, the BA process ensures excellent ductility for flaring or bending while maintaining a scale-free, bright, and ultra-clean internal surface, avoiding the potential contamination risks associated with traditional acid pickling.

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