Tadpole Flange Gasket and Sealing Strip (TG)
A high-temperature bulb-and-tail sealing profile engineered for flanged expansion joints, shielding composite fabric layers from sharp clamping bar edges and bolt-head pinch shear while ensuring zero leakage in positive-pressure systems.
During expansion joint installation, the fabric belt is compressed between duct flanges and metal clamping bars. When clamping bolts are torqued and duct vibration begins, the sharp inner edge of the clamping bar acts like a guillotine, creating pinch notch tears in the fabric.
The BundleTec Tadpole Flange Gasket (TG) features a resilient bulb core with an extended fabric tail that tucks beneath the clamping bar. The bulb forms a protective bumper along the sharp metal edge to eliminate notch shear, while sealing flange gaps under positive pressures up to +50,000 Pa.
Thermal Duct Expansion & Sizing Engine
Interactively calculate axial and lateral thermal expansion, temperature gradients, and cold setting offsets.
Overview
The Tadpole Flange Gasket (TG) is a specialized sealing and protection profile for flanged fabric expansion joints. Designed with a circular elastic bulb and a flat mounting tail, it distributes clamping bolt forces evenly, covers sharp steel edges, and prevents localized shear failure under continuous industrial vibration.
Applications
- Positive-Pressure Centrifugal & Axial Fan Ductwork
- High-Vibration Ventilation and Process Gas Lines
- Flue Gas Desulfurization (FGD) Scrubber Flange Joints
- Cement Plant & Power Station Clamped Expansion Joints
- All Flanged Non-Metallic Duct Expansion Bellows
Technical Advantages
- Completely prevents clamping bar edges from guillotine-shearing (notch shear) the fabric
- Distributes bolt torque evenly to prevent localized fabric crushing around bolt holes
- Resilient bulb profile ensures zero gas leakage under high positive pressures
- Available with Inconel wire mesh and silicone cores for elasticity up to 600°C
- Fully compliant with FSA-DSJ-402 and RAL-GZ 719 flange assembly guidelines
TG Technical Parameters & Operational Limits
| Bulb Head Diameter | 12 mm to 35 mm (Sized to flange and bar profile) |
| Tail Width Spectrum | 30 mm to 100 mm (Sized to clamping bar width) |
| Operating Temp Range | -50°C to +600°C (Up to +1000°C with ceramic core) |
| Recommended Torque | 45 to 65 Nm compliant with FSA-DSJ-402 |
| Outer Jacketing | PTFE-Coated E-Glass Fabric or Antistatic Aramid |
| Standard Compliance | FSA-DSJ-402 · RAL-GZ 719 Categories I-V |
Tadpole Flange Gasket and Sealing Strip (TG) — Detailed Architectural Design
1. Clamping Shear Stresses & Contact Pressure Distribution
When expansion joint fabric is torqued between steel flanges, unradiused clamping bar edges concentrate extreme shear stresses. Under process vibration, this sharp edge acts like a blade (notch shear failure). Concurrently, positive pressure gas leaks around bolt pitches. The Tadpole gasket simultaneously resolves both mechanical and sealing challenges.
2. Core Metallurgy & Elastic Memory Recovery
The Tadpole bulb core is tailored to process severity: High-recovery solid or sponge silicone for temperatures under 220°C; Inconel 625-clad dense glass fiber rope for 220°C to 550°C; and stainless spring-assisted bio-soluble ceramic fiber for temperatures above 550°C. Jacketing is PTFE-impregnated glass fabric.
3. Fastener Selection & Fastener Head Geometry
Standard hex bolts can pinch and distort fabric corners. BundleTec mandates dome-head or countersunk stainless steel bolts paired with wide heavy washers. This configuration transforms tightening torque into uniform contact pressure (P_contact > 3.5 MPa) across the full perimeter.
4. Plant Case Studies & Corner Radiusing Instructions
On a cement ID fan discharge joint where belts tore every 3 months at the clamping bar edge, retrofitting BundleTec Tadpole gaskets eliminated all tears, yielding 6+ years of uninterrupted service. In rectangular ductwork, mitered corner pieces ensure the bulb transitions without buckling or bunching.
Calculate duct thermal growth and configure the right component →
Input duct cross-section and process temperatures to immediately determine axial and lateral displacement.
Compliant International Quality & Manufacturing Standards
All internal expansion joint components are engineered and fabricated to FSA and RAL-GZ 719 guidelines.
Gütegemeinschaft Weichstoff-Kompensatoren temperature categories 1-5, helium tightness and tensile strength standards.
Fluid Sealing Association FSA-DSJ-401/402 carcass internal hardware, flow liners, and clamping torque allowances.
Directives for static dissipation, equipotential bonding bridges, and explosion protection in Zone 1/21 environments.
Frequently Asked Questions
What is a Tadpole gasket and why is it named "Tadpole"? +
A Tadpole gasket is a custom bulb-and-tail profile consisting of a round resilient core (head) and an extended flat fabric strip (tail). Its resemblance to a tadpole gives it this standardized engineering name.
How does the Tadpole gasket stop clamping bar edge shear? +
The flat tail sits under the clamping bar while the round bulb head rests directly against the bar's sharp inner edge, creating a soft, resilient bumper that prevents the metal edge from touching the fabric.
How does it improve gas tightness in positive pressure systems? +
When clamping bolts are torqued, the resilient bulb compresses to fill micro-imperfections along the flange face, sealing leaks even under pressures exceeding +50,000 Pa.
How are Tadpole gaskets installed around 90-degree duct corners? +
In rectangular duct corners, pre-mitered factory corner segments or radiused transitions are used to prevent the bulb from bunching and creating localized leak paths.