Rectangular Weld-On Sight Glass Fittings

John Moncrieff’s rectangular weld-on sight glass fittings provide robust, high-clarity visibility into process vessels, tanks, and pipelines. Designed for direct welding either into or onto the vessel wall, these assemblies deliver long-term mechanical integrity, leak-tight performance, and clear process observation in demanding industrial environments.

Each unit is supplied as a complete fabricated assembly, including the rectangular glass plate, sealing gaskets, cover frame, and fastening hardware. This integrated approach simplifies installation, minimises interface risk, and ensures consistent performance across pressure and temperature cycles.

Performance & Design Highlights

• Weld-On Construction: Engineered for permanent integration into vessel walls for maximum stability.
• Temperature Capability: Up to 243 °C with borosilicate MAXOS® glass (to DIN 7081 / BS 3463).
• Pressure Service: High-integrity design suitable for demanding process conditions; high-pressure variants available.
• Viewing Geometry: Typical lengths from 250–1,000 mm, approx. 70 mm wide with an ~18 mm viewing slot.
• Material Options: Manufactured in carbon steel, stainless steel, or special alloys to match process and vessel requirements.
• Glass Types: Available in clear or reflex styles for level indication and process inspection.

Typical Applications

• Liquid level indication on tanks and silos
• Visual inspection of vessel and reactor internals
• Process monitoring in chemical and petrochemical plants
• Pharmaceutical and hygienic systems (material- and seal-dependent)
• General industrial equipment requiring elongated viewing windows

When you need extended viewing length, welded-in integrity, and repeatable performance, John Moncrieff’s rectangular weld-on sight glass fittings provide a proven, engineered solution for critical process visibility.