At RAM Solutions, we developed Spot Weld Couplant Gel to provide high acoustic impedance, improving imaging quality for non-destructive evaluation (NDE) in automotive and aerospace applications. Traditional water-based ultrasonic gels have an acoustic impedance around 1.48 × 10⁶ kg/(m²·s), which is far below that of metals like steel (4.5 × 10⁷ kg/(m²·s)) or aluminum (1.7 × 10⁷ kg/(m²·s)), making them less effective for accurate metal inspections.
While a thin layer of couplant has minimal impact, rough metal surfaces — such as deep indentations at spot welds — can require gel thicknesses up to 1 mm. In these cases, mismatched acoustic impedances can generate strong reflections, reducing image clarity. Couplants with higher impedance that better match the metal significantly improve ultrasonic imaging quality.
Spot Weld Couplant Gel is glycerol-based with a density of 1.18 g/cm³ and an acoustic impedance of 2.39 × 10⁷ kg/(m²·s), closely matching transducer delay lines. This reduces reflections at both the delay line-gel and gel-metal interfaces for clearer ultrasonic signals. Its viscosity (30–40 kcps) prevents sliding on inclined surfaces, and the formulation includes a preservative for a 2-year shelf life and a corrosion inhibitor to protect metal surfaces.
Specifications
Operating Range: -18˚ to 224˚F (-28˚ to 107˚C)
Viscosity: Medium flowable gel
Halogens and Sulfur: Less than 50 ppm pH: 8.0 nominal at 20°C Packaging: Carton of twelve 12 oz / 355 ml bottles Ford Tox #: 518498
Benefits
Safety
Corrosion
Ingredients
Net Quantity
Temperature Range
0° – 60°C (32° – 140°F)