AIINDUSTRY®

Specialty Seals — The Ultimate Solution for Extreme Conditions

Designed for ultra-high temperature, cryogenic, ultra-high pressure, highly corrosive, and ultra-high vacuum extreme conditions. Comprehensive product line covering PTFE/UHMWPE/FFKM spring-energized seals, metal C-rings & O-rings, and hydrogen energy sealing assemblies. Full coverage from -250°C cryogenic to 750°C ultra-high temperature, from ultra-high vacuum to 100 MPa ultra-high pressure.

Back to Sealing Overview

Six Specialty Seal Categories

Full-spectrum sealing for extreme conditions. From spring-energized seals to metal static seals, from cryogenic to ultra-high temperature, from ultra-high vacuum to ultra-high pressure — AIINDUSTRY® finds the optimal sealing solution for every extreme operating condition.

Spring PTFE U-Shape PTFE Jacket + SS Spring

PTFE Spring-Energized Seal

Jacket MaterialVirgin PTFE / Modified PTFE
Spring Material301/304 SS, Elgiloy
Temperature-200 ~ 260°C
PressureVacuum ~ 35 MPa
Media CompatibilityNearly All Chemicals
Cross-SectionU / V / Lip Type

U-shaped PTFE jacket wrapped around a corrosion-resistant metal spring-energizer structure, referencing the classic Trelleborg Variseal® design. PTFE's extremely low friction coefficient (μ<0.05) and full chemical inertness (pH 0–14 full compatibility), combined with stainless steel/Elgiloy spring providing continuous radial force to compensate PTFE creep and wear, achieving wide temperature range (-200~260°C) self-compensation. Jacket cross-section selectable as U, V, or lip type; spring selectable as helical, cantilever, or V-spring for different pressure directions. Suitable for aerospace hydraulic systems, semiconductor process equipment (CVD/PVD), chemical valves, and other extreme media and wide-temperature applications. Service life reaching 10,000+ hours.

Full Chemical Inertness · Wide Temp Range · Self-Compensating · Variseal® Grade
Water Lubrication · Superior Wear Resistance

UHMWPE Spring-Energized Seal

Jacket MaterialUHMWPE
Spring Material301/304 Stainless Steel
Temperature-200 ~ 90°C
PressureVacuum ~ 20 MPa
Frictionμ < 0.07
Optimized MediaWater / Aqueous

UHMWPE (Ultra-High Molecular Weight Polyethylene, MW 3–6 million) jacket with metal spring-energized U-shaped seal structure. UHMWPE offers extreme wear resistance — 4–5× that of PTFE, 6–8× that of PA66 — and very low water absorption (<0.01%), making it particularly suitable for water-lubricated, high-pressure water jet, and hydraulic water system aqueous media applications. Friction coefficient only 0.05–0.07; retains good toughness without embrittlement at -200°C cryogenic temperatures. Volumetric wear rate is 70% lower than PTFE, ideal for aqueous media equipment with long overhaul cycle requirements such as water-jet cutter seals, deep-sea subsea valves, and hydropower equipment.

Superior Wear · Water Lubrication · Ultra-Low Friction · 70% Lower Wear than PTFE
FFKM Jacket + Hastelloy Spring

FFKM Spring-Energized Seal

Jacket MaterialFFKM (Perfluoroelastomer)
Spring MaterialHastelloy C-276
Temperature-20 ~ 320°C
PressureVacuum ~ 35 MPa
Chemical CompatibilityFull (incl. strong acids/solvents)
Key ApplicationsSemi / Chemical / Pharma

FFKM (perfluoroelastomer) U-shaped jacket paired with Hastelloy C-276 corrosion-resistant spring — the premier spring-energized seal solution. FFKM elastomer combines rubber's elastic compensation capability (compression set <15% @ 200°C/70h) with PTFE-grade full chemical compatibility (resistant to strong acids, alkalis, solvents, and plasma). Hastelloy C-276 spring provides stable energizing force in extreme corrosive environments (e.g., HF, HCl gases). Maintains good rebound at 320°C, with short-term peaks up to 330°C. Hardness range Shore A 65–90, customizable by sealing pressure. The preferred solution for the most demanding applications — semiconductor etching (plasma sealing), chemical reactors, and pharmaceutical sterilization equipment.

Full Chemical Compatibility · 320°C High Temp · Extreme Corrosion · Compression Set <15%
Open Inconel / SS316 · Self-Energizing C-Shape

Metal C-Ring Seal

Core MaterialInconel / SS316 / Hastelloy
Temperature-250 ~ 750°C
PressureVacuum ~ 100 MPa
Seal TypeSelf-Energizing Static
Coating OptionsSilver / PTFE / Nickel
ApplicationsAero Engines / Nuclear

C-shaped cross-section hollow metal sealing ring, referencing the classic Wills Rings® design philosophy. The opening faces the system pressure side — media pressure enters the C-cavity to create a self-energizing effect: the higher the pressure, the tighter the seal. Inconel 718/625 or SS316 covers -250~750°C full temperature range; wire diameters from 0.9 to 6.4 mm. Surface coating options include silver plating (up to 400°C, leakage rate down to 10⁻¹² Pa·m³/s level), PTFE coating (chemical corrosion resistance), or nickel plating (economical). The ultimate solution for ultra-high-temperature / ultra-high-pressure static sealing — aero-engine combustion chambers, nuclear reactor pressure vessels, high-temperature reactor flanges. Also suitable for Wills Rings® replacement markets.

Ultra-High Temp 750°C · Self-Energizing · 100 MPa · Wills Rings® Grade
V O-Shape Hollow Metal Ring · Ultra-High Vacuum

Metal O-Ring Seal

Core MaterialInconel / SS316 / Hastelloy
Temperature-200 ~ 500°C
PressureVacuum ~ 70 MPa
Seal TypeElastic Compensation Static
Wall Thickness0.25 ~ 1.6 mm
ApplicationsUHV / Aerospace / Semi

O-shaped cross-section thin-wall hollow metal sealing ring, relying on tube wall elastic deformation for sealing compensation. During installation, the ring is axially compressed 15–25%; the tube wall's elastic rebound provides continuous sealing force, effectively compensating for flange thermal deformation (±0.2 mm) and gap changes caused by temperature fluctuations. Wall thickness adjustable from 0.25 to 1.6 mm to achieve different elastic recovery rates (rebound >5%). Inconel/SS316/Hastelloy grades cover diverse temperature and media requirements. Particularly suitable for ultra-high vacuum systems (leak rate <10⁻¹⁰ Pa·m³/s), semiconductor PVD/CVD coating chambers, spacecraft propulsion sealing, and synchrotron beamlines — scenarios with extreme leakage rate requirements. Both grooved and un-grooved flanges supported.

Ultra-High Vacuum · Elastic Compensation · Ultra-Low Leak Rate · <10⁻¹⁰ Pa·m³/s
H-Resistant Alloy FFKM PTFE H₂ Media Atm. Side Multi-Layer Assembly · Full H₂-Resistant

Hydrogen Energy Seal Assembly

Anti-Embrittlement AlloyInconel / SS316L-High Ni
Sealing ElementsFFKM / PTFE / EPDM
Temperature-250 ~ 150°C
Pressure0 ~ 70 MPa
CoverageProduction/Storage/Transport/Use
Core AdvantageFull-Chain H-Embrittlement Resistant

Multi-layer composite seal assembly, purpose-designed for the entire hydrogen energy chain (PEM/AWE electrolyzers, 70 MPa high-pressure storage tanks, 35/70 MPa refueling stations, fuel cell stacks). Outer Inconel/high-Ni SS316L hydrogen-embrittlement-resistant alloy frame prevents atomic hydrogen permeation and hydrogen embrittlement failure. Inner FFKM/PTFE/EPDM sealing elements provide multi-stage chemical barriers and elastic compensation. Intermediate layer options include metal C-rings/O-rings for enhanced pressure capacity. From liquid hydrogen cryogenic -250°C to refueling station 70 MPa ultra-high pressure, seamless coverage of the hydrogen "production–storage–transport–refueling–use" full chain sealing requirements. Leak rate controlled to 10⁻⁶ Pa·m³/s level, meeting ISO 19880-3 refueling station safety standards.

H-Embrittlement Resistant · Full Chain · -250°C~70MPa · ISO 19880-3

Extreme Condition Selection Matrix

The 5×6 selection matrix below covers five extreme-condition categories — ultra-high temperature, cryogenic, ultra-high pressure, strong corrosion, and ultra-high vacuum — to quickly identify the optimal specialty seal solution.

Extreme ConditionTemp ZonePressureRecommendedProduct Ref.Engineering Basis
Ultra-High Temp> 260°C
Peak 750°C
Vacuum~100 MPaMetal C-Ring Seal
(Wills Rings® Type)
Inconel 718/625
Silver/PTFE Coating
Wire D 0.9~6.4mm
C-shape self-energizing structure — the higher the pressure, the tighter the seal. Inconel material holds at 750°C without deformation. Silver plating provides micro-sealing below 400°C. Preferred for aero-engines and nuclear reactors.
Cryogenic-250 ~ -40°C
Down to LH₂
Vacuum~35 MPaPTFE Spring-Energized
(Variseal® Type)
Metal O-Ring
Virgin PTFE Jacket
VMQ O-ring Energizer
Inconel O-Ring
PTFE non-embrittling at -200°C. VMQ silicone O-ring retains elasticity at -100°C. Metal O-ring provides excellent cryogenic elastic compensation. Preferred combination for LNG/LH₂/LOX equipment sealing.
Ultra-High Pressure-250 ~ 750°C> 70 MPa
Peak 100 MPa
Metal C-Ring Seal
(Wills Rings® Type)
Inconel/SS316
Self-Energizing C-Cavity
100 MPa Certified
C-shaped seal ring — sealing force increases proportionally with pressure; leakage still controllable at 100 MPa. Dedicated solution for deep-sea oil trees and ultra-high-pressure reactor flange sealing.
Strong Corrosion-20 ~ 320°CVacuum~35 MPaFFKM Spring-Energized SealFFKM Jacket
Hastelloy C-276 Spring
pH 0-14 Full
FFKM elastomer full chemical compatibility (strong acids HF/HCl/H₂SO₄, alkalis, solvents, plasma). Hastelloy spring corrosion-resistant. Dedicated for semiconductor etching and chemical reactors.
Ultra-High Vacuum-200 ~ 500°C< 10⁻¹⁰ Pa·m³/sMetal O-Ring SealInconel/SS316
Wall 0.25~1.6mm
Rebound >5%
Thin-wall hollow O-ring elastically compensates flange deformation; leak rate <10⁻¹⁰ Pa·m³/s. Standard UHV solution for semiconductor coating chambers, synchrotron, and aerospace sealing.

Specialty Seal Material Limit Parameters

Core material limit engineering parameters for specialty seals, compiled from Trelleborg TDS datasheets and industry standards. Covers extreme temperature, extreme pressure, helium leak rate, radiation resistance rating, and applicable certification standards — providing quantified engineering decision basis for extreme-condition seal material selection.

MaterialLimit Temp °CLimit Pressure MPaHe Leak Rate Pa·m³/sRadiation GyTypical Standard
PTFE+Inconel 718-250~26035<10⁻¹⁰10⁴ECSS-Q-ST-70
FFKM+Hastelloy C-276-20~32035<10⁻¹⁰10⁵NORSOK M-710
Inconel 718 C-ring-250~750100<10⁻¹²10⁷RCC-M
SS316 O-ring-200~50070<10⁻¹²10⁶ASME BPVC
UHMWPE+SS316-200~9020<10⁻⁸10³ISO 3601
PCTFE-240~12015<10⁻¹⁰BAM (LOX)

Three Steps to the Optimal Seal Solution

Use the Temperature → Pressure → Chemical Media three-step decision chain, combined with the selection matrix above, to precisely match extreme-condition sealing requirements. For multi-factor coupled conditions, contact our engineers for in-depth analysis.

1Identify Temperature Zone (Cryo / Ambient / High-Temp)
2Identify Pressure Grade (Vacuum / Medium / Ultra-High)
3Identify Chemical Compatibility (Corrosive / H-Embrittlement Risk)

Complete Specification Datasheet

The full specialty seal specification datasheet includes groove dimensional tolerances, material property comparisons, surface coating options, leakage rate grades, and installation process requirements for complete engineering data.

Download Specification Datasheet (PDF)

More Sealing Categories

Explore other AIINDUSTRY® sealing categories for a complete sealing solution.

Facing Extreme Conditions? We Can Help.

Tell us your operating parameters — temperature, pressure, media type, leakage rate requirements — and our extreme-condition sealing specialists will recommend the optimal specialty seal solution within 24 hours.

Contact Us →