Water ingress in industrial insulation systems is a silent asset killer. Whether in storage tanks, LNG pipelines, or buried process lines, trapped moisture accelerates corrosion under insulation (CUI), degrades thermal performance, and increases operational costs. Traditional inspection methods—such as capacitance probes, neutron backscatter, or manual insulation removal—are either slow, localized, or invasive.
Short-Wave Infrared (SWIR) imaging, enabled by specialized SWIR lenses, offers a powerful non-contact alternative capable of detecting moisture distribution rapidly and accurately across large surface areas.
Why SWIR Works for Moisture Detection
SWIR wavelengths (typically 900–1700 nm) interact strongly with water molecules. Unlike visible light, which primarily captures surface reflectance, SWIR can detect absorption signatures caused by water, even when it is hidden beneath semi-transparent or porous insulation materials such as:
- Mineral wool
- Fiberglass
- Calcium silicate
- Aerogel blankets
- Non-metallic protective claddings
- Coatings and vapor barriers with partial IR transparency
Water exhibits distinct absorption peaks around 970 nm, 1200 nm, 1450 nm, and 1550 nm, which SWIR optics can resolve with high contrast. Dry insulation reflects SWIR efficiently, while wet areas appear darker due to absorption—making leaks and saturation zones immediately visible in thermal-neutral conditions.
**Where SWIR Moisture Detection Delivers the Most Value
1. Corrosion Under Insulation (CUI) Prevention
SWIR moisture maps reveal early saturation long before corrosion becomes detectable by other NDT methods. Insulation can be repaired or dried proactively, reducing unplanned outages.
2. Pipeline Leak Localization
For both buried and above-ground pipelines, SWIR can identify wet trails, insulation pooling, and vapor breakthrough points, even without a temperature difference between water and environment.
3. Tank Roof & Sidewall Insulation Audits
Large vertical or curved surfaces are ideal for SWIR optical inspection, especially when combined with:
- Mobile inspection carts
- Robotic crawlers
- Drone-mounted SWIR cameras
- Boom-arm scanning rigs
This ties into your ongoing focus on tank gauging and inventory integrity systems—SWIR complements radar or servo gauging by validating insulation health, ensuring moisture does not interfere with RF-based sensing or antenna zones.
4. Verification of EMI/RF absorber insulation
Your background interest in microwave absorption glass bubbles and absorber materials is also relevant. Many RF-absorbing insulation layers are partially SWIR-transparent, allowing moisture inside absorber composites to be detected optically without compromising shielding layers.
Implementation Challenges and Lens Considerations
Despite its strengths, SWIR inspection success depends on optical selection and system design. Common challenges include:
- Low signal return from metallic cladding → requires strategic inspection angles or SWIR-transparent polymer covers.
- Vapor barrier coatings reflecting too much → mitigated with high-dynamic-range SWIR lenses and polarization filters.
- Curved tank surfaces causing focus drift → corrected using low-distortion or adaptive-focus SWIR lens assemblies.
- Large inspection zones → benefit from wide-FOV lenses or stitched image mapping.