METAGLAS® Threaded Sight Glasses — Safe, Compact, Ready to Install
METAGLAS® threaded sight glasses deliver the mechanical security of metal-fused, pre-stressed glass in a
compact, screw-in form factor. Ideal for retrofit and OEM builds where fast installation, high integrity
and clear visibility are non-negotiable.
At a glance: Metal-fused glass (no gasket creep at the glass/metal interface) • Low profile, maximum viewing
• Shock, vibration and thermal-shock resilient • Maintenance-free optical seal
Thread Standards & Interfaces
- BSPP / BSPT (ISO 228 / ISO 7)
- NPT (ASME B1.20.1)
- Metric (ISO) and other threads on request
- Face Options: flat or profile to suit housing; O-ring or flat gasket per application
Design & Construction
- Bonding: Glass fused into a machined metal ring, generating permanent compressive pre-stress
- Body Materials: Stainless steel as standard; carbon steel, specials and surface finishes available
- Sealing: O-ring or flat gasket (material to suit media and temperature)
- Temperature/Pressure: Envelope depends on size and materials — provided with quotation
- Finish: Smooth, easy-clean viewing surface; low build height for tight installs
Applications
- Gearboxes, pumps and reservoirs — oil level/condition checks
- Process lines and utilities — water, coolants, non-hazardous chemicals
- Vessels, manifolds, housings — visual inspection points
- Food, beverage, pharma — where compact viewing ports are required
Why METAGLAS® beats conventional glass
- Safety margin: Pre-stressed metal-fused design mitigates rupture risk
- Stability: Resists pressure cycling, vibration and thermal shock
- Longevity: No delamination or creep at the glass/metal interface
- Uptime: Simple screw-in fitment; minimal maintenance
Ordering Checklist
- Thread type & size (BSPP/BSPT/NPT/Metric)
- Pressure & temperature envelope
- Media & cleanliness requirements
- Body material & surface finish
- Seal type and material (O-ring / flat gasket)
- Any certification or documentation pack (PED, material certs)
John Moncrieff Ltd supplies threaded METAGLAS® sight glasses configured to your duty —
engineered for visibility, reliability, and fast installation.
