SecureFlex Single Arch DuPont Kevlar® Reinforced Non-Metallic Expansion Joint


The SecureFlex Van Stone interlocking flanges are compatible to mate with Lap-Joint Stub ends, Raised Face or Flat Full Face type flanges. For other mating flange surfaces (wafer type check or butterfly valves), a full face hard spacer may be required. Consult UNAFLEX® Engineering. The standard floating flanges are 150# drilled epoxy-coated carbon steel. Galvanized, stainless steel and other alloy type materials are also available. DIN-PN-JIS and other non-standard drill patterns customizable to your needs.

Kevlar® wrapped around a solid steel ring in the base of the rubber flange portion eliminates the tire cord from “pulling out” of the flange and provides superior sealing force when compressed against the mating flange during installation. The ring also prevents the distortion of the sealing surface if the installation tolerance is exceeded providing an “extra” margin of safety. Polyester tire cord may be substituted, with customer approval, for sizes 14” and above if design temperature does not exceed 250°F.

Our Flexible Tooling process allows us to manufacture the Expansion Joints to Non-Standard face-to-face dimensions. For smaller dimensions than Standard, design movements may be reduced.

Double and Triple arch expansion joints are also available for greater movement and reduced spring rates. We can also manufacture Concentric and Eccentric Tapers and Offset styles. Sizes up to 144” can be constructed.

Standard control rods that install out-board of the mating flanges are standard. Integral tie rods attached to the floating flanges can also be supplied.

NOTE: Decrease of working pressure for constructions made of Kevlar® above 350°F. Contact UNAFLEX® Engineering for further details.

Bolt Torque Secquence

Bolt Torque Sequence

Finger-tighten all nuts and bolts. With a calibrated torque wrench, tighten each flange connection in a criss-cross pattern (refer to figure). Using this pattern, tighten in 20% increments up to 80% of the final bolt torque. To achieve the final torque value, tighten bolts in a sequential clockwise pattern once around the flange. Maximum recommended torque is suggested for systems that will be operating at or near the maximum pressure and temperature limits of the liner or conveying small molecular gasses.


Re-torquing after the initial installation, we recommend checking the torque of each bolt after 24 hours have elapsed or a temperature cycle or pressure cycle (hydrostatic test) has occurred. Any bolts falling below the recommended value should be retorqued. Values should only be exceeded by 10% increments when necessary to reseal. All torquing on the process system should be done when the system is ambient and cool.

Re-torquing should be performed annually, especially if the system experiences elevated temperatures or extreme temperature swings.

SecureFlex 7000 Available Materials and Temperature Ratings

  • PTFE/TFE/FEP-400°F
  • Viton® FKM/Fluoro-Elastomer-400°F
  • Chlorobutyl-250°F
  • EPDM-250°F
  • Hypalon®-250°F
  • Neoprene-225°F
  • Nitrile-225°F
  • Natural Rubber-180°F
  • Gum Rubber-180°F

White FDA and NSF and Peroxide-Cured Elastomers also available. •300°F rating for EPDM and Chlorobutyl for air service at 50 psi max.

Dimensions and Allowable Movements
*custom face-to-face dimensions available*

chart7000lg NOTES:
  1. Full vacuum construction is available,consult UNAFLEX® Engineering
  2. For higher pressures than shown, consult UNAFLEX® Engineering
  3. Control units (sold separately) must be used when piping is not properly anchored
  4. Safety Shields/Splash Guards recommended.
  5. When mating to FRP-Fiberglass Flat Full Face Flanges, an elastomeric spacer gasket is required. This gasket will distribute the load evenly to the mating flange.
  6. Ranges in the chart are RECOMMENDED Torque Values. The amount of torque required is different for all applications. They can change depending on media, temperature, pressure, mating flange type and surface, material and environmental conditions.

To conform to ASTM F1123-87 Standards, which require a minimum 4:1 safety factor, you must reduce the above working pressures by 25%

Installation Instructions for Non-Metallic Expansion Joints

Service Conditions. Make sure the expansion joint rating for temperature, pressure, vacuum and movements match the system requirements. Contact UNAFLEX® for advice if the system requirements exceed those of the expansion joint selected. Check to make sure the elastomer selected is chemically compatible with the process fluid or gas.

Alignment. Expansion joints are normally not designed to compensate for piping misalignment errors. Piping should be lined up within 1/4”. Misalignment reduces the rated movements of the expansion joint and can induce severe stress and reduce service life. Pipe guides should be installed to keep the pipe aligned and to prevent undue displacement.

Anchoring. Solid anchoring is required wherever the pipeline changes direction, and expansion joints should be located as close as possible to anchor points. If anchors are not used, the pressure thrust may cause excessive movements and damage the expansion joint.

Pipe Support. Piping must be supported so expansion joints do not carry any pipe weight.

Mating Flanges. Install the expansion joint against the mating pipe flanges and install bolts so that the bolt head and washer are against the expansion joint flanges. Flange-to-flange dimensions of the expansion joint must match the breech type opening.

Tightening Bolts. Tighten bolts in stages by alternating around the flange. Torque bolts sufficiently to assure leak-free operation at hydrostatic test pressure. (See Bolt Torque Sequence)

Storage. Ideal storage is a warehouse with a relatively dry, cool location. Store flange face down on a pallet or wooden platform. Do not store other heavy items on top of an expansion joint. Ten-year shelf-life can be expected with ideal conditions. If storage must be outdoors, joints should be placed on wooden platforms and should not be in contact with the ground. Cover with a tarpaulin.

Additional Tips.

Do not insulate over a non-metallic expansion joint; however, if insulation is required, it should be made removable to permit easy access to the flanges. This facilitates periodic inspection of the tightness of the joint bolting.

It is acceptable (but not necessary) to lubricate the expansion joint flanges with a thin film of graphite dispersed in glycerine or water to ease disassembly at a later time.

Do not weld in the near vicinity of a non-metallic joint.

If expansion joints are to be installed underground, or will be submerged in water, contact UNAFLEX® for specific recommendations.

If the expansion joint will be installed outdoors, make sure the cover material will withstand ozone, sunlight, etc. Materials such as Neoprene and Chlorobutyl are recommended. Materials painted with weather resistant paint will give additional ozone and sunlight protection.


Check the tightness of leak-free flanges two or three weeks after installation and re-tighten if necessary.

SecureFlexControl Rod Installation.

A.Assemble expansion joint between pipe flanges to the manufactured face-to-face length of the expansion joint.

WARNING: Expansion joints may operate in pipelines or equipment carrying fluids and/or gases at elevated temperatures and pressures and may transport hazardous materials. Precautions should be taken to protect personnel in the event of leakage or splash. Non-metallic joints should not be installed in inaccessible areas where inspection is impossible. Make sure proper drainage is available in the event of leakage when operating personnel are not available.

B. Assemble control rod plates behind pipe flanges. Flange bolts through the control rod plate must be longer to accommodate the plate. Control rod plates should be equally spaced around the flange. Depending upon the size and pressure rating of the system, 2, 3 or more control rods may be required.

C. Insert control rods through top plate holes. Steel washers are to be positioned at the outer plate surface. An optional rubber washer is positioned between the steel washer and the outer plate surface.

D. If a single nut per unit is furnished, position this not so that there is a gap between the nut and the steel washer. This gap is equal to the joint’s maximum extension (commencing with the nominal face-to-face length). To lock this nut in position, either "stake" the thread in two places or tack weld the nut to the rod. If two jam nuts are furnished for each unit, tighten the two nuts together, so as to achieve a "jamming" effect to prevent loosening.

NOTE: Consult UNAFLEX® if there is any question as to the rated compression and elongation. These two dimensions are critical in setting the nuts and sizing the compression pipe sleeves.

E. If there is a requirement for compression pipe sleeves, ordinary pipe may be used and sized in length to allow the joint to be compressed to its normal limit.

F. For reducer installations, it is recommended that all control rod installations be parallel to the piping.

Location. The expansion joint should always be installed in an accessible location to allow for future inspection or replacement.

Valid XHTML 1.0 Transitional