Unilok Stainless Instrumentation Fittings

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Unilok tube fittings

Unilok stainless instrumentation fittings single-ferrule design creates fast and reliable connections in both analytical and process instrumentation applications and process systems. These fittings are designed and to interchange and intermix with Parker® CPI tube fittings. The following table provides information on the specifications of the Unilok fittings product.

Unilok StainlessInstrumentation Fittings Specifications
Type Single-Ferrule compression fittings
Sizes 1/16 to 1 in.
Maximum Operating Pressure 12,000 psig (825 bar) @ 100° F (38° C)
Temperature Range -325° F to 1200° F (-198° to 648° C)
Materials Stainless steel, carbon steel, brass, Alloy 400, UNS N10276. Other materials are available on request.
Adapters Port connectors, tube stubs, AN fittings, NPT threaded, SAE threaded, BSP threaded (BSPP and BSPT), butt weld, socket weld
Configurations Straights, elbows, tees, crosses, caps, plugs
Special Fittings Dielectric, calibration, bulkhead, inserts, mud dauber, bored-through
Interchange and Intermix

Unilok tube fittings are designed, manufactured, quality controlled and distributed to be totally “interchangeable” with the Parker CPI® brand of tube fittings. The components of both brands are intermixable. The precise manufacturing of both product lines to the most exacting of tolerances under strict quality control procedures ensures the performance, reliability, and safe operation in whatever applications Parker CPI Fittings and SFPG Unilok parts are intermixed in.

Unilok Technology

To deliver leak-proof, reliable connections in instrumentation andUnilok-Technology process tubing systems, Unilok tube fittings are comprised of three precision-machined components: body, ferrule, and nut. The single ferrule design, featuring the spring-like action of the ferrule during make-up, compensates for the differences in tubing materials, thickness and hardness of the tube wall to create leak-tight connections in a broad range of applications.

Through the crucial interaction of the finely machined fitting components with the process tube, a leak-tight seal results. The geometric rotation of the Unilok nut delivers the axial thrust required to coin the ferrule to the outside diameter of the tube. To remove potential stress on an existing system, they have been constructed to eliminate installation torque originating with the fitting to the tubing.

Throughout the rotary action of the nut, the internal surface of the nut comes into contact with the rear surface of the ferrule to axially move the ferrule ahead into the angular section of the fitting body. The leading edge of the ferrule is inserted into the tube to initiate the necessary “bowing” action of the ferrule.

Consequently, the leading edge of the ferrule “locks” on the outside diameter of the tube to finalize the sealing action and connect the tube to the fitting. The resultant “spring-like action” of the ferrule is engineered to help adjust for the systems exposure to variables like vibration.


Unilok tube fitting straight configuration are machined from type 316 stainlessMaterials steel cold-finished bar stock in conformance with ASTM A-276 and ASTM A-479. Tube fitting shapes, elbows, tees and crosses, are machined from close-grained 316 stainless steel forgings in accordance with ASTM A-182. All 316 stainless steel. Unilok components are heat code traceable with certified material test reports (CMTRs) available.

Quality Certification

Unilok tube fittings are manufactured within the tolerances of the SFPG Quality System, which is certified to comply to the ISO 9001:2000 Quality Standard. Additionally, all Unilok tube fittings are manufactured to the technical design specifications and stringent quality control specifications of the SFPG Instrumentation Division. SFPG’s ongoing commitment to quality is illustrated in the company’s personnel, policies, products and service delivery.


Unilok tube fittings are individually packed to ensure the highest levels of quality, safety and cleanliness possible. Product box labelling includes product photos, body material, and the part number. Installation instructions for the product are included in every box.


Unilok tube fittings easy to install using basic hand tools or using automatic installers like the Turn Pro automatic swaging tool.

Approvals and Test Reports

Unilok tube fittings have been tested and/or approved in accordance with the standards of following organizations:

  • American Bureau of Shipping
  • Unilok Tube Fitting Interchange and Intermix Test Report
  • CSA Report
  • Unilok Technical Report
Tools and Accessories

SFPG offers tools and accessories in support of tube fitting assembly and installation, tubing cutting and bending.
To learn more about SFPG’s Unilok stainless steel fittings fill out the quick contact form provided at the bottom of the page.