In harsh-environment energy applications, the sealing of the feedthroughs’ electrical connections represents a potential weak point. Cable feedthroughs that use organic, naturally aging epoxy or ceramic seals which require additional solder interface materials can become porous or develop fissures over time, resulting in leakage and electrical malfunction. To achieve the most reliable performance possible, SCHOTT utilizes superior 'Compression Glass-to-Metal Sealing', which creates a compressive force on the materials that results in durably robust feedthrough seals.

Eternaloc® feedthroughs can be designed to…

Withstand extreme temperatures

Can be designed for operating conditions from -200 to +450°C. Special material combinations even allow up to 1000°C.

Be fully pressure- and explosion-proof

Can be designed to withstand 1300 bar or 20,000 PSI pressure and certified to comply with explosion-proof standards, such as ATEX and IECEx.

Offer excellent electrical performance

Can be designed for more than 13,800 volts and 1,500 amperes, as well as for instrumentation purposes.

Last for decades

Can be designed to offer a qualified lifetime of up to 60 years, delivering maintenance-free reliability that, in turn, reduces recalls and replacements and lowers total cost of ownership.

SCHOTT Eternaloc® Terminal Headers for Liquefied Gas Applications

Gas pressure and extreme temperatures as low as -165°C place incredibly high demands on pumps and other equipment in liquefied gas applications. The requirements are equally high for their electrical terminal header assemblies, particularly since the safety consequences of terminal header failure or leakage can be severe. Thanks to unique compression glass-to-metal sealing technology, Eternaloc® electrical terminal headers are extremely robust, compression-sealed units that provide practically unlimited pressure-proof hermeticity and enhanced safety in cases of accidents. Decades of maintenance-free reliability helps reduce total cost of ownership.

In contrast, other sealing technologies that use organic polymers or ceramics have technical disadvantages that can compromise the integrity of the seal and result in leakage and electrical malfunction, especially when exposed to severe temperature fluctuations over time.


Eternaloc® Terminal Headers for Liquefied Gas Applications Technical Features
 Lifetime Unlimited lifetime of the non-aging pressure barrier
 Temperature resistance Resistant to thermo-shocks, thermo-cycling, and temperature ranges

from -196 °C to + 100 °C or -321 °F to +212 °F

 Pressure resistance  Each product is tested at one-and-a-half times the maximum design pressure,

up to 390 bar

 Electrical rating Medium voltage, low voltage, C&I, and fiber optic penetrations
  Options   Available with
  • Single or double pressure barrier designs
  • Optional attuned electrical systems including conduits, cables, junction boxes and cable glands for connecting with the external electricity supply
  • Optional cryo-cables for use inside the tank
  Dimensions  Fully customizable up to a diameter of 600mm
  Quality assurance
  • 100% final inspection of all products
  • In-house testing capabilities
    -Current / voltage (up to high voltage)
    -Hermeticity (helium mass spectrometer)
    -Insulation resistance
    -Non-destructive tests / investigations (PMI)
    -Pressure Tests up to 160 MPa
    -Cryogenic tests
  • Minimum space impact
  • Easy and low-cost installation utilizing a connector
  • Detailed installation instructions, supervisors, and training support

 SCHOTT Eternaloc® Terminal Headers comply with

  • ATEX

  • IECEx

  • local regulations such as KOSHA, PESO, CU TR, UL, CSA




SCHOTT Eternaloc® Nuclear Electrical Penetration Assemblies

High-quality, hermetically sealed Eternaloc® electrical penetration assemblies (EPAs) from SCHOTT have the capability to deliver the dual benefit of increased safety and reduced total cost of ownership in nuclear power plants.

By utilizing inorganic, non-aging glass seals with significant heat- and radiation-resistant properties, SCHOTT EPAs provide considerable advantages. In contrast, epoxy seals may break down under extreme temperature and pressure. This was observed at the Fukushima Daiichi nuclear power plant disaster in 2011, among other instances.

Eternaloc® Nuclear Electrical Penetration Assemblies Technical Features
Degree of protection
  • IP 54
  • Maintain integrity for several hours in severe accident conditions
  •  Unlimited lifetime of the non-aging pressure barrier
  • Specified lifetime: typically 60 years -> maintenance-free reliability
 Temperature resistance  ≥ 400 °C / 8h (752 degrees Fahrenheit)
 Pressure resistance  ≥ 400 bar (5800 psi)
 Radiation dose  0.5 x 10^6 G
 Electrical rating  Power, low voltage power, C&I, coax / triax and fiber optic penetrations
 Customization options  

Eternaloc® penetration modules for nuclear power plants can be custom-designed with:

  • Connections to tail cables (LOCA-proof sealed by shrinking tubes or elastomer sealing)
  • Tail cables (length and type according to customer specification)
  • Metal housing for protection and support of the cable connections
  • Our latest generation penetrations use receptive modules with mountable nuclear connections, which allow smaller construction sizes and easy on-site installation
  • Fitting reactor vessels and main coolant pump requirements
 Dimensions  2,5" and 4" standard EPA's, custom designs up to 600mm and 250 kg
 Quality assurance
  •  Designed and manufactured according to KTA 3403 or IEEE317 standards (standard for electric penetration assemblies in containment structures for nuclear power generating stations).
  • SCHOTT Eternaloc® penetrations have been stringently tested at Wyle Laboratories in Huntsville, Alabama (USA) and successfully passed an extensive qualification test program per IEEE Standards 317 and 344, including full survivability in conditions analogous to an earthquake reaching a Richter scale magnitude of 12.
 Certifications  NQA-1, ASME NPT and MO, KTA, HAF604




SCHOTT Eternaloc® Compressed Gas Lead-through Plates

To design Eternaloc® lead-through plates for hydrogen gas-cooled generators and other compressed gas applications, SCHOTT utilizes only inorganic and non-aging materials: the feedthroughs consist of a steel flange with the conductors or thermocouples sealed in using compression glass-to-metal sealing technology. The specialty glass acts as the electrical insulator and hermetic seal, which reliably prevents leakage of hydrogen, as well as intrusion of oxygen or moisture.

In contrast, lead-through plates that use organic, naturally aging epoxy seals could compromise the generator’s pressure integrity, resulting in leakage and electrical malfunction.


Eternaloc® Compressed Gas Lead-through Plates Technical Features   Your Benefit

For power supply, signal transmission, and measurements, such as:

  • Temperature

           (RTD= Resistance Temperature Detector, Thermocouple)

  • Vibration
  • Motor speed counting

Available in standard and customized designs

Manufactured according to your requirements, no limitations regarding the type of signal

  • Economy of scale with standard lead-through plate designs
  • Wide variety of selections
 Pressure resistance Withstand high pressure up to 2700 bar Maintain pressure boundary integrity of generator
 Leak-tightness Gas-tight hermeticity is usually tested to pass 10-8 mbar l/s leaking rates, which prevent leakage of hydrogen and intrusion of media into the generator.
  • Safety and efficiency of generator's operation
  • Explosion-proof protection
 Electrical rating
  • High-, medium-, and low-voltage (up to 13800 V) and amperage (up to 1500A) designs
  • Coax and thermocouple wires for measuring equipment available
  • Fiber optic penetration designs possible
Technological variety enables you to equip the whole generator with glass-to-metal sealed feedthroughs
 Quality assurance 100% final inspection of all products Minimizes your efforts for incoming inspection
  • Minimum space impact
  • Easy to install using detailed installation instructions
  • Supervision and training available
Reduces the final weight and bulkiness of generator
  • Unlimited lifetime of non-aging pressure barrier
  • No maintenance required
Contributes to longevity and lower cost of ownership of the generator
 Certifications Certifiable according to international safety standards, including IECEx and ATEX, as well as local regulations, including KOSHA, PESO, CU TU, UL, CSA Customer receives locally and internationally certified product to supply parts worldwide and benefits from SCHOTT's long-term certification experience

SCHOTT Eternaloc® Oil and Gas Connectors, Feedthroughs and Penetrators

Subsea: Years of maintenance-free robustness above 20,000 PSI

Eternaloc® subsea connectors and feedthroughs offer long-term durable protection of subsea tree components, such as wellhead pressure sensors, in high temperature, high pressure (HPHT) conditions. Eternaloc® connectors are available as a complete subsea connector assembly for your application for greater safety, simpler testing and qualification, and space-saving purposes.

Exploration: Made to withstand 35,000 PSI and above

Made with inorganic, non-aging, and ultra-robust glass seals, Eternaloc® exploration connectors are designed to support safe and reliable transmission of valuable data and information provided by sensors in HPHT Wireline, MWD and LWD oil and gas applications. The extreme conditions in drilling applications are prohibitive for lesser-quality materials. For example, connectors using thermoplastic seals are prone to deformation from creepage, leading to an increased risk of seal compromise and component damage. 

Eterenaloc® Oil & Gas Feedthroughs Subsea Connectors Exploration Connectors 
 Temperature resistance For ranges from -170°C to +450°C (-274°F to +842°F) For temperatures in excess of 260°C (500°F)
 Pressure resistance

Years of maintenance-free robustness above 20,000 PSI

  • Design pressure: 20,000 PSI
  • Burst pressure: 50,000 PSI

Ultimate pressure resistance - above 35,000 PSI

  • Design pressure: 35,000 PSI
  • Burst pressure: 50,000 PSI
 Electrical performance Electrical performance up to 13,800 V, 1500 A

Superior insulation resistance under extreme conditions: 

≥10GΩ - with our high-temperature sealing glasses, higher IR can be achieved at 260°C in some circumstances.

 Dimensions Dimensions up to 600 mm diameter, 500 mm height, and 250 kg weight.
  • Long qualified lifetime, typically 30 years
  • Long-term, maintenance-free durability can prevent costly component replacement
  • Remains leak-tight, even after years of use
 Customized options

Fully customizable

  • Large variety of specialty glass materials and metals available, including fiber optic glass.
  • Coax, triax, and fiber optic connections
  • Additional insulating materials available, such as PEEK, PTFE, shrinking tubes, and potting materials. 

Fully customizable

  • Single and multi-pin
  • Male/female connections
  • Custom materials
  • Flexible design and sampling for a variety of applications


Material options

 Metals Glass   Ceramic

Sealing Alloys                                     

  • Kovar
  • Alloy 42
  • Alloy 52 (NiFe47)
  • Cu conductors
  • RTD, Thermocouple

    Sealing Glasses

    • Variety of SCHOTT Glass
    • Crystallizing glass ceramic
    • Optional double glass barrie
    • CRS Cold Rolled
    • Stainless Steel
    • AISI 304/316

    Optical Materials

    • Fiber optic glass

    Alloy 625 / 690

    Additional Insulating Materials
    • PEEK, PTFE
    • Shrinking tubes
    • Potting materials



    Simplifying your processes with less welds

    Eternaloc® connectors are available as a complete subsea connector assembly for your application for greater safety, simpler testing and qualification, and space-saving efforts.

    Oil and Gas 02

    SCHOTT Eternaloc® Submarine Penetration Assemblies

    Reactor integration in submarines requires careful engineering and specialized components. Bulkheads fortified with radiation shields separate the reactor from the rest of the submarine. Electrical pass-through is required into and out of the reactor area for power, instrumentation, and control cables.

    In standard applications, polymers or epoxies can be used to surround and insulate the cables at the pass-through point. But in nuclear applications, where the barrier must remain hermetic for safety and radiation protection, this sealing is insufficient. Here, glass-sealed SCHOTT Eternaloc® bulkhead penetrations deliver resistance to extreme shock, pressure, vibration, and temperature – in some cases as much as 50 times greater than typical submarine component requirements.


    Eternaloc® Submarine Penetration Assemblies  Technical Features
    • Qualified lifetime of up to 40 years
    • Virtually no aging-related wear of the conductors and glass seal
    • Maintenance free throughout entire lifetime: "fit and forget"
     Temperature resistance
    • Flame-retardant
    • Maintains electrical functionality for an extended period at elevated temperatures
     Pressure resistance
    • Extremely pressure resistant
    • High shock resistance against torpedo impact
     Electrical rating

    Power, C&I and fiber optic penetrations including matching connectors designed to customer requirements


     Quality assurance & testing

    SCHOTT electrical penetration assemblies for ships and submarines are manufactured according to the highest quality standards combined with leading engineering know-how and undergo vigorous tests to meet advanced systems specifications:

    • Shock load
    • Burst pressure
    • Hydrostatic pressure
    • Vibration
    • SOLAS Fire Test
    • Short circuit test

    Want to know more? Let's talk

    Whether you need more information, samples, a quote, or advice for a project, I would be delighted to talk to you.

    Contact us
    Ulrich Dirr, Head of Sales Eternaloc®
    Ulrich Dirr

    Head of Sales Eternaloc®