Non-metallic expansion joints are flexible connectors used in utility and industrial market applications to:
- Absorb movement
- Compensate for thermal expansion
- Reduce vibration in piping systems
Constructed from materials like elastomers, fabrics, and composites, these joints are ideal for systems where metallic joints might corrode or fail under extreme temperature fluctuations.
When selecting a non-metallic expansion joint, consider material properties such as:
- Temperature and chemical resistance
- Ability to withstand pressure and movement
- Special requirements, such as UV and weather resistance
Compatibility with the system’s operational parameters, including pressure ratings and expected movement, is also critical to ensuring long-lasting performance and minimal maintenance.
Effox-Flextor-Mader (EFM) Expansion Joints
Lathrop Trotter is proud to partner with Effox-Flextor-Mader (EFM), a developer of non-metallic expansion joints for utility and industrial applications.
With custom-engineered designs for each application, EFM has provided reliable flexible solutions for service from -40°F to 2100°F (-40°C to 1149°C). EFLEX™ expansion joints reflect the highest engineering standards in the power generation and heavy industrial market. EFM is a DuPont Certified Supplier of VITON® Fluoroelastomer Expansion Joints.
- Elastomeric (up to 400°F, acid resistant)
- EPDM (300°F)
- Fluoroelastomer (Viton or Fluorel, 400°F)
- FSA-DSJ-402-09 & ASTM D6909-09 standards
- Fluoroplastic (up to 600°F continuous, more acid resistant)
- Fluorflex #09, #12, #20 (#9 = 9mm of PTFE chemical barrier)
- Reference FSA-DSJ-403-07 for industry guidelines
- High Temperature Composites (600°F – 2000°F)
- FG7/775, FG7/15, F1000D, F1200D
- Buildup consisting of:
- Outer Layer: Fluoroelastomer belt w/ integral gas seal
- Chemical Barrier: PTFE
- Insulation/Thermal Barrier: Protects cover and vapor barrier from heat degradation. Thermally bonded to the outer substrate to prevent “hot spots”
- Reinforcement: Adds strength and acts as an additional insulator
- Encasement: Binds the belt together and adds strength for handling & service. Belts are sewn and NOT stapled.
Flow Liner
In positive-pressure gas systems with flush mount composite designs, baffles are recommended to extend the life of the expansion joint. In negative pressure systems, a single flow liner is used to prevent the joint from being pulled into the flow, causing the joint to fail prematurely from flutter and erosion.
Double Flow Liner
The double-flow liner is used in systems with large duct movements and elevated temperatures.
Insulation Pillow / Cavity Fill
Higher temperature applications, and applications with particulate, can benefit from the use of an internal insulation pillow, which consists of a wire mesh-wrapped ceramic fiber insulation, fastened in place.
Gas turbine fabric expansion joints are specifically designed to handle the high temperature, high velocity, and rapid temperature rise of gas turbine exhaust gas service.
There are two types of insulation design systems:
- Internal = “Cold” structural frame
- External = “Hot” structural frame
3 basic frame design configurations:
- “Hot to Hot”
- “Hot to Cold” (or Cold to Hot)
- “Cold to Cold”
Expansion joints utilize internal cavity insulation to reduce the temperature at the outer belt. Cavity fill is typically wrapped in high-temperature mesh or screen to prevent “wicking” of material due to suction created by high-velocity duct flow. The cavity pillow is protected and contained by floating “flow liners.” Flow liners are installed in segments, which allow for thermal expansion without binding or buckling.
