RAL-GZ 719 Standard: Fabric Expansion Joint Quality Assurance & Design Rules
Gütegemeinschaft Weichstoff-Kompensatoren e.V. Quality Specifications, Temperature Tiers & Test Procedures
BundleTec Engineered Standards
RAL-GZ 719 (Gütegemeinschaft Weichstoff-Kompensatoren e.V.) is the premier European benchmark defining quality assurance, raw material classification, helium tightness testing, and mechanical integrity for non-metallic fabric expansion joints.
RAL-GZ 719 Temperature Groups (Groups 1 to 5: 100°C to 1000°C)
The cornerstone of RAL-GZ 719 is its rigorous temperature classification, dividing expansion joints into 5 continuous operating temperature groups with strict material requirements:
Helium Leak Rate Testing Methodology (Q ≤ 1×10⁻³ mbar·l/(s·m))
Per RAL-GZ 719 Section 4.3, non-metallic compensators destined for toxic, acidic, or volatile flue gas service undergo helium mass-spectrometer tightness verification. The maximum allowable leak rate is governed by:
Q = (V · Δp) / (Δt · L_seam) ≤ 1.0 × 10⁻³ [mbar · l / (s · m)] DIN EN ISO 13934-1: F_max ≥ 4000 N / 50 mm Joint/Seam Efficiency: η_seam ≥ 0.85 · F_max
Mechanical Tensile Testing & Seam Strength (DIN EN ISO 13934-1)
Structural textiles are subjected to strip tensile testing per DIN EN ISO 13934-1 to ensure resilience against aerodynamic buffeting and multi-axial displacement forces. Minimum breaking force must exceed 4000 N / 50 mm in both warp and weft directions, with joint/seam retention of at least 85% base tensile capacity.
Construction Types: Type 1 (Belt) & Type 2 (Flanged Cuff) Architectures
RAL-GZ 719 distinguishes between Type 1 (flat cylindrical belt with external clamping bars) and Type 2 (integrated fabric flanged cuffs). When duct velocities exceed 10 m/s or abrasive particulates are present, internal flow sleeves (baffles) and thermal bolster pillows are mandatory design elements.
RAL-GZ 719 Certified Expansion Joint Series
Explore our precision-engineered fabric expansion joints built to RAL-GZ 719 standards: