I. Working Condition Premise
Fixed vibration sources in AI liquid cooling server rooms include continuous operation of circulating water pumps and cabinet cooling fans, generating sustained low-frequency vibration ranging from 10 Hz to 60 Hz. Pump startup/shutdown and valve opening/closing cause instantaneous water hammer shocks. GPU load fluctuations trigger cyclic temperature changes, leading to repeated thermal expansion and contraction of cold plates, valve bodies and pipelines within 15℃~85℃.
Rigid screw locking structures lack elastic allowance. Long-term vibration causes threaded fasteners to rotate loose, while thermal deformation creates assembly clearances and eventually results in slow seal leakage. Cylindrical compression springs realize vibration resistance via axial elastic compensation and vibration energy absorption. Stable preload maintains adequate compression on sealing surfaces to prevent liquid leakage.
II. Anti-Vibration Mechanism
1. Absorb Continuous Vibration to Prevent Fastener Loosening and Pipeline Abrasion
Vibration fully transmits along rigid metal structures to screw threads, leading to gradual self-rotation and loosening of screws over time. Flanges, valve end caps and pipeline plugs adopt combined fastening of screw + compression spring. Vibration energy dissipates through repeated compression and rebound of springs, greatly reducing vibration transmission to threads and avoiding loosened fasteners.
Mass field verification proves that adding compression spring fasteners to pump inlet and outlet pipelines cuts the failure rate of loose joints by more than 70%. Pipeline clips inside cabinets embed compression springs to clamp pipe walls, restricting large displacement of pipelines induced by pump jitter and preventing pipe wall rupture caused by long-term friction between pipelines and cabinet sheet metal.
2. Accommodate Thermal Expansion & Contraction to Eliminate Extra Vibration from Thermal Deformation
Copper tubes and valve bodies produce micron-level axial expansion and contraction under thermal cycling. Compression springs reserve compliant elastic travel: springs compress passively to make room when temperature rises and components elongate; springs rebound actively to replenish compression when temperature drops and components shrink. This eliminates rigid jamming under high temperature and excessive slack wobble under low temperature, avoiding secondary vibration derived from thermal expansion and contraction.
3. Buffer Instant Water Hammer Impact to Mitigate Shock Vibration
Pump startup/shutdown and valve closure generate water hammer. Instantaneous water pressure can reach twice the normal operating pressure accompanied by violent shock vibration. Built-in compression springs of check valves and overflow valves retract briefly under high-pressure impact to cushion shock force. This protects cold plate microchannels from cracking under high-pressure impact and stops joints from loosening and leaking due to intense vibration.
III. Anti-Leakage Implementation Logic
Vibration resistance lays the foundation for long-term leakage prevention. The core anti-leakage logic is to maintain the standard compression ratio of sealing rings and zero clearance on sealing surfaces throughout vibration and temperature fluctuations.
1.Automatic Pressure Compensation by Springs for Sealing Locking upon Minor Fastener Loosening
For fully rigid fastening, slight screw loosening directly reduces compression force on sealing rings and forms leakage gaps. With compression springs installed, even minor thread rotation occurs, spring rebound supplements compression. O-rings and FKM (fluororubber) sealing rings sustain effective compression consistently. Manufacturers completed a 720-hour test under 7 Bar pressure plus continuous vibration: structures with compression springs showed zero leakage throughout the test; rigid structures without springs generally suffered slow leakage.
2.Elastic Tolerance Adaptable to Vibration Offset and Temperature Variation of Rubber Seals
Vibration easily triggers slight eccentricity of valve bodies and plugs; high/low temperature alters hardness and volume of rubber sealing rings. Compression springs offer elastic tolerance to ensure uniform circumferential compression on sealing rings and avoid local insufficient compression. Compatible with two mainstream coolants (ethylene glycol aqueous solution and 3M fluorinated liquid), covering the conventional liquid cooling operating range of -40℃~120℃.
3.Mechanical Limit by Valve Core Springs Prevents Accidental Valve Opening & Leakage under Vibration
Valve cores of UQD blind-mate connectors, check valves and pressure relief valves are pressed against sealing surfaces by compression springs. Spring force compresses valve ports under normal conditions; server room vibration cannot bounce valve cores open. Only positive fluid pressure can push valve cores open for fluid flow. Valves remain closed under vibration and bump conditions to eliminate abnormal leakage. UQD industry specifications explicitly require valve cores not to open spontaneously in vibration tests; spring force of valve compression springs is routinely controlled within 12 N~40 N.
IV. Practical Installation Positions
1. Inside All Types of Liquid Cooling Valves (Most Widely Applied)
Cylindrical compression springs are standard fitted on the rear side of valve cores for check valves, safety relief valves, air vent valves, fluid replenishment valves and shut-off valves of UQD connectors. Springs hold valve cores in place to resist accidental opening under vibration, stabilize pressure and stop dripping. Mass operation and maintenance data confirm spring corrosion and elastic attenuation inside valves are common causes of slow leakage at valve ports.
2. Pipeline Flanges, Maintenance Plugs and Leak-Testing Screws
Cold plate external pipeline flanges, immersion cabinet maintenance ports and air vent screws use screws matched with compression springs to compress sealing components. These sealing points require repeated disassembly and maintenance, and the spring structure guards against thread loosening under long-term vibration.
3. Vibration-Damping Pipeline Supports & Internal Cabinet Pipeline Clips
Long server room pipelines are equipped with spring vibration-damping hangers; internal cabinet routing clips embed compression springs. These components limit pipeline shaking and pipe wall abrasion via passive protection to prevent pipeline rupture and leakage. CCID Consulting industry statistics show large 30 MW compute centers are generally equipped with thousands of liquid cooling vibration-damping hangers with compression springs.
4. Locking Mechanisms for Immersion Cabinet Doors and Pressure Relief Covers
Liquid inside immersion cabinets pressurizes upon heating. Small compression springs are installed on cabinet door latches to compress covers under combined internal pressure and vibration, blocking coolant leakage and volatilization.
V. Material & Compression Stroke Selection Basis
(I) Material Selection Standards Classified by Working Conditions with Clear Prohibited Materials
Applicable standards: JB/T 6655 High-Temperature Resistant Springs, GB/T 23935 General Specification for Cylindrical Helical Springs
|
Working Condition |
Recommended Materials |
Prohibited Materials |
Reasons |
| Ethylene glycol water cooling for cold plates (non-immersed) |
304 stainless steel, 316L stainless steel |
Mild carbon steel |
Aqueous solution corrodes carbon steel; rust residues clog cold plate microchannels; corrosion causes elastic stress relaxation and insufficient sealing compression leading to leakage |
| Full immersion in fluorinated liquid |
316L stainless steel, Hastelloy C276 |
Carbon steel, economy-grade stainless steel |
Fluorinated liquid features weak solubility; ordinary steel suffers corrosion failure after long-term immersion |
| Valves operating continuously above 75℃ |
Inconel Alloy X-750 |
Conventional stainless steel |
Conventional stainless steel undergoes severe stress relaxation under high temperature; Inconel X-750 undergoes hot peening treatment with minor elastic attenuation at high temperature |
Supplementary Rule: Carbon steel springs are only allowed for vibration-damping supports installed at dry external cabinet positions. Carbon steel is strictly forbidden for all springs contacting coolant.
(II) Compression Stroke Strictly Compliant with National Standard Ranges
GB/T 23935 specifies the effective working range of springs accounts for 20%~80% of total deformation. Liquid cooling vibration-resistant sealing uniformly adopts an effective compression stroke of 20%~35%:
Compression ratio below 20%: insufficient preload leads to inadequate sealing ring compression under vibration and high leakage risk;
Compression ratio above 35%: springs approach solid height and lose elastic buffering capacity, equivalent to rigid connection. Vibration resistance fails, and thermal cycling easily triggers leakage.
VI. Common On-Site Pitfalls Summarized from After-Sales Failure Statistics of Spring & Valve Manufacturers
Spring stiffness cannot be arbitrarily selected. Liquid cooling valves commonly adopt stiffness of 3~3.5 N/mm with an 8% stiffness margin reserved to counter long-term stress relaxation. Excessively stiff springs provide insufficient buffering and lose vibration resistance; overly soft springs bear inadequate pressure and cause liquid leakage under high pressure.
Compression springs serving long-term high-temperature environments must undergo hot peening stabilization treatment as required by JB/T 6655. Springs without stabilization heat treatment suffer elastic degradation within 3~6 months, resulting in insufficient sealing surface pressure and slow leakage.
Pump inlet and outlet pipelines cannot rely purely on rigid screw fastening; compression spring vibration dampers are mandatory. These sections are high-incidence leakage points in compute rooms; mainstream renovation schemes all add compression spring buffering structures.
Galvanized carbon steel springs are completely prohibited for immersed components of immersion liquid cooling. Rust generates solid contaminants that pollute fluorinated liquid throughout the cabinet and clog cold plate microchannels of all servers. Meanwhile, spring failure triggers leakage at multiple locations.
VII. Clear Functional Division of Cylindrical Compression Springs, Wave Springs & Canted Coil Springs
Ordinary cylindrical compression springs: suitable for axial reciprocating motion, mainly applied to various valve cores, pipeline fasteners and pipeline supports. Advantages include sufficient axial travel with excellent linear buffering and pressure stabilization. Lacking radial vibration resistance, they are never used for radial sealing involving rotation or plugging/unplugging.
Wave springs: thin in height with uniform multi-point surface compression. Exclusively used for planar compression and heat conduction of GPU cold plates, not applied to valve core structures.
Canted coil springs: realize sealing via radial gripping, matching plug-and-pull sealing of UQD quick connectors, not replacing compression springs for axial valve components.
The three types of springs feature clear application boundaries with dedicated functions without cross misuse.
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