High Pressure Stainless Steel Fittings for Extreme Temperatures

Posted by Vince Lockwood on Thu, Jan 31, 2019 @ 02:08 PM
Vince Lockwood

Posted by Vincent Lockwood 

Corrosive environments and extreme temperatures, high or low, present challenges for everyday fittings, especially in high-pressure applications. JIC fittings in larger sizes do not provide an adequate pressure rating, and O-rings in ORFS connections are susceptible to erosion. Extreme environments require extreme solutions.  

Seal-Lok Xtreme Stainless Steel Fitting

Parker’s ORFS (o-ring face seal) technology has long been a favorite of the fluid and gas handling industry. However, sometimes the severity of temperature conditions or corrosive environments leads to inevitable wear and tear on the elastomeric seals; the more intense the conditions, the more premature the deterioration. In such extreme conditions equipment downtime can be a frequent and expensive issue that may have no obvious solutions. Identifying the need for help in intense circumstances, Parker has engineered a stainless steel variation of the tried and true ORFS technology dubbed Seal-Lok Xtreme.

Seal-Lok Xtreme - Stainless Steel Sealing RingMetal Sealing Ring

A key component of the Seal-Lok Xtreme stainless steel fitting is the use of a patented stainless-steel metal sealing ring which allows operation in a temperature range of -328°F to 1200°F [-200°C to 650°C] at up to 6,000 psi. To achieve such extreme tolerances the entirety of the stainless steel fitting body is manufactured from SAE/AISI 316/316L stainless steel materials, with an added benefit of corrosion resistance.

Seal-Lok Xtreme - Proper Sealing CutawayUnlimited Reusability and Easy Maintenance

Parker’s Seal-Lok Xtreme features unlimited reusability. Additionally, the zero-clearance interface enables quick and easy tube assembly and disassembly coupled with a field-replaceable seal for easy maintenance.

Resistance Galore

Seal-Lok Xtreme stainless steel fittings provide excellent resistance to over-tightening, loosening, and galling. Highly resistant to over-torque, Seal-Lok Xtreme is able to withstand 200% torque above the rated value without any damage to the fitting. This generates the possibility of unlimited reusability, as well as reducing loosening due to vibration. A special dry film used in lubricating the nuts further provides the benefit of reduced galling.


Seal-Lok Xtreme stainless steel fittings are an ideal solution for reliable leak-free power-generation and gas applications. Other applications include:

  • Combustion / Natural gas turbines and CT engines
  • High-temperature engine compartments
  • LNG storage and fueling systems
  • Cryogenic equipment
  • Instrument panels
  • Liquid fuel systems
  • Lube oil systems
  • Instrument panels



Seal-Lok Xtreme stainless steel fittings are available in the following:

  • 45°, 90°, Straight, Cross, and Tee
  • Adaptable to inch tube, metric tube and hose
  • Meets SAE J1453 requirements
  • Meets requirements of ASME B31.1 and BS31.1
  • Available in tube and hose sizes 1/4" to 2" (6mm to 50mm) and pipe sizes up to 2" NPS


How to Order / Nomenclature Details

Parker Seal-Lok Xtreme stainless steel fittings’ nomenclature is similar to traditional Seal-Lok, with the following changes: Add ETS to the end of the part number (to indicate stainless steel sealing compatible). Replace the O (indicating o-ring) with a 9 (indicating metal seals).

Example 1: 8 F59L9-SS ETS, NOT 8 F5OLO-SS (metal seals installed on port and face, instead of o-rings)

Example 2: 6 C6L9-SS ETS, NOT 6 C6LO-SS (metal seals installed on face, instead of o-ring)

Material Note: Seal-Lok Xtreme is available in 316 stainless steel. For other materials please contact the Tube Fittings Division.


“Applications such as liquid natural gas (LNG) and gas combustion turbines often pose challenges to a tube fitting’s elastomeric sealing. Rather than using a standard sealing ring, Seal-Lok Xtreme fittings utilize a patented metal sealing ring that improves sealing dependability against the severe temperature or chemical compatibility issues that reduce the life of elastomeric seals.”

-Ted Amling, Senior Project Engineer, Parker Hannifin Tube Fittings Division

Topics: technical