METAGLAS® Metal-Fused Sight Glass Technology

METAGLAS® metal-fused sight glasses represent the highest standard in process visibility. Developed through precision fusion technology, each unit consists of a sight glass fused into a steel ring, creating a single, inseparable component that delivers exceptional mechanical strength and long-term reliability.

The key to METAGLAS® performance lies in the difference in thermal expansion coefficients between the glass and metal. During fusion, this controlled mismatch generates a powerful compressive stress within the glass, ensuring superior resistance to thermal shock, vibration, and pressure fluctuations.

Mechanical Pre-Stress Advantage

Unlike thermally pre-stressed glasses, the mechanical pre-stress within METAGLAS® components remains stable over time, even under cyclic temperature and pressure loads. This provides significantly higher safety margins and eliminates the risk of spontaneous breakage common with conventionally toughened glass.

Design Flexibility

Through advanced mechanical treatment of the steel ring, METAGLAS® assemblies can be manufactured in a wide variety of constructive configurations. This flexibility supports:

• Circular and rectangular windows for vessel and tank integration
• Clamp, weld-neck, and flange-mounted styles
• Sight flow indicators and flush-mounted sanitary designs
• High-pressure and high-temperature configurations
• Custom geometries for unique process conditions

John Moncrieff Ltd supplies genuine METAGLAS® metal-fused sight glasses as part of our advanced process visibility range — precision-engineered, safety-assured, and fully compliant with international pressure equipment standards.