Duolok Stainless Instrumentation Fittings

DuoLok Stainless Steel

Duolok stainless instrumentation tube fittings incorporate a double-ferrule design to deliver leak-tight operation for both analytical and process instrumentation applications in which leak-tight capability is essential for high quality, productivity and cost control. They are manufactured to intermix and interchange with Swagelok® tube fittings.

DuoLok Stainless Instrumentation Fittings Specifications
Type Compression Tube Fittings
Sizes Fractional: 1/16 to 2 in
Metric: 3 to 25 mm
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, monel. Other materials are available on request.
Adapters NPT, ISO/BSP, SAE/MS, AN, weld ends, port connectors, tube stubs
Configurations Straights, elbows, tees, crosses, caps, plugs
Special Fittings Bored-through, dielectric, calibration, bulkhead, tube inserts
swivel connectors and tee fittings


Tube Fittings Design

Duolok stainless instrumentation fittings are comprised of four precision-machined elements: body, front ferrule, back ferrule, and nut. In make-up, the double-ferrule design, coupled with the staged sequential swaging action of the ferrules, adjusts for differences in tubing materials, hardness, and thickness of the tube wall to ensure leak-tight connections across a broad range of potential applications.


316 stainless steel tube fittings are constructed from cold-finished bar stock in compliance with ASTM A-276 and ASTM A-479. Elbows, tees, and crosses, are machined out of close-grained 316 stainless steel forgings in compliance with ASTM A-182. Certified material test reports (CMTR’s) are available on request for all parts which are also heat code traceable.


Duolok tube fittings are fully assembled and bagged individually in line with the highest standards of quality and cleanliness. The protective bags prevent contamination in the form of tubing burrs, etc. The fittings are packaged in handy, small-lot quantities to simplify procurement and handling. Colour-coded box labels are utilized dependent on the tube fittings’ material. These labels include the part number, material, product description and picture of the product.

Teflon Tape

NPT thread and BSP tapered thread fittings can be purchased with factory installed high-quality teflon tape. Factory-taped fittings lower costs and make sure that the threads are properly taped to ensure leak-tight installations.

Duolok STainless Instrumentation Fittings Installation Training

SFP provides extensive installation training. Courses cover:

  • Selection and assembly
  • Intermixing and interchanging
  • Swaging and quality assurance
  • Remaking and reusing tube fittings
  • Handling cutting and preparing tubing
  • Tube bending
Tools and Accessories

SFP offers the tools and accessories necessary to support tube fitting assembly and installation along with tube cutting, preparations, and bending.

To learn more about SFP’s Duolok stainless instrumentation fittings fill out the quick contact form provided at the bottom of the page.