PTFE Lined Metal Expansion Joint

Unalon Style 9500

The Unalon 9500 series is an expansion joint that combines the properties of metal and PTFE into the most advanced, versatile, expansion joint on the market today.  A PTFE tube is formed into a Stainless Steel, Inconel®, Monel,® or Hastelloy® corrugated tube.

The 9500 Series will:

  • Absorb pipe movement and stress
  • Isolate mechanical vibration
  • Reduce system noise
  • Protect against surge forces
PTFE Lined Metal Expansion Joint


Unlike ordinary solid PTFE of Elastomeric type expansion joints, should up-set conditions exceeding 500◦F occur, series 9500 will maintain it’s pressure carrying capacity up to 1200◦F, adequate time for system shut-down and replacement.


Floating type (150#, 300# or metric). A drill is available in carbon steel, Stainless Steel and nickel alloys or PTFE coated to meet your specific requirements.

Additional Types of Expansion Joints

Lined, Hinged, Dual and Universal Tied

Note: For environmentally corrosive applications; laminated, (multi-ply) bellows as well as the optional features listed below are available.

  • Highly corrosive chemical-petrochemical systems
  • Abrasive industrial process piping systems
  • Power generating and waste water treatment plants
  • Pulp/paper systems and marine services
  • Pollution control systems

Optional Testing Procedures

  • Radiography of longitudinal bellows seam weld
  • (PMI) Positive Material Identification of Bellows
  • Hydro test at 1.5 times the design pressure for 10 minutes

Optional Coatings

  • Four-part epoxy coating for flanges
  • Fluropolymer coated flanges, threaded rod and nuts

Standard Testing Procedures

  • Dye penetrant test of all pressure boundary welds
  • Spark test at 30,000 volts, exceeds industry standard of 10,000 volts

Optional Features

  • Special flange construction, configuration and materials
  • Internal vacuum rings for full vacuum service constructed of Stainless Steel, Nickel Alloys and Tantalum
  • Protective covers available in Stainless Steel and Nickel Alloys
  • Internal flow liners available in Stainless Steel, Nickel Alloys and PTFE

Working temperature from -300◦F to +400◦F

Working Pressure: 50, 150 and 300 PSIG (please specify). For pressure above 300 PSIG, consult factory.

Construction Details


The tube is a single-moulded PTFE leak-proof lining extending flange to flange. The outside of the PTFE tube is etched to adhere to the elastomeric overlay.


This is a high strength woven polyester or Kevlar® reinforcing fabric between the PTFE tube and the cover.

Steel Reinforcements

These are the chemically treated solid round endless rings or high tensile strength helical wire embedded in the carcass. The steel reinforcement provides additional strength for pressure and vacuum service.


This is the exterior elastomeric overlay designed to protect the carcass from external elements.

Special Constructions

Hinged, gimbal and dual. (consult factory)