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Premium Circular Sight Glasses for Reliable Visual Process Monitoring

High-performance circular sight glasses manufactured from borosilicate, soda-lime, and quartz glass with stainless steel, carbon steel, or PTFE-lined bodies. Custom diameters, thicknesses, and connection types for pressure vessels, tanks, and pipelines.

Borosilicate & Quartz Glass Custom Diameters & Thicknesses High Pressure & Temperature Rated

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Industrial Circular Sight Glass - Borosilicate and Stainless Steel

Premium Circular Sight Glass Borosilicate • Sanitary • High Pressure

Up to 300°C / 40 bar

Custom Engineering

🔍 Clear Optical View

✅ ISO 9001 Certified

🔥 High Temperature Rated

📏 Custom Manufacturing

🌎 Worldwide Supply

Circular Sight Glass Technical Specifications

Engineered for reliable visual monitoring in a wide range of industrial processes. Multiple glass and body material options available.

📋 Construction & Material Options

Glass Type	Borosilicate 3.3, Soda-Lime, Quartz
Body Material	304 SS, 316L SS, Carbon Steel, PTFE Lined
Gasket / Seal	PTFE, Viton, EPDM, Silicone, Graphite
Connection Type	Flanged (ANSI/DIN/JIS), Threaded, Weld-in, Clamp
Glass Thickness	6mm – 30mm (custom)
Surface Finish	Ra ≤ 0.8μm for sanitary, electro-polish available

🔬 Performance & Dimensional Data

Diameter Range	25mm to 500mm (1" to 20")
Max Operating Pressure	Up to 40 bar (580 psi) standard; higher on request
Temperature Range	-40°C to +300°C (borosilicate); up to 500°C (quartz)
Glass Type	Tempered or annealed borosilicate
Compliance	PED, 3-A Sanitary, FDA, ATEX optional
Custom Options	Lighting ports, wipers, spray rings, double-glazed

💡 Need a custom circular sight glass?

We design and manufacture complete sight glass assemblies to your exact requirements. Send your drawings, dimensions, or process conditions for expert recommendation.

Why Our Circular Sight Glasses Excel

Every unit is tested and inspected to ensure clear visibility, mechanical strength, and long-term reliability under demanding conditions.

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Superior Optical Clarity

High-transmission borosilicate glass with low distortion provides a clear, unobstructed view of process media and level.

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High Mechanical Strength

Tempered and thick-walled glass options resist pressure, impact, and thermal shock in critical applications.

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Wide Temperature Range

Borosilicate glass handles -40°C to 300°C, while quartz options extend to 500°C for extreme heat applications.

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Fully Customizable

Any diameter, thickness, gasket material, or connection type. Integrated accessories like lighting and wipers available.

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Excellent Chemical Resistance

Borosilicate glass resists acids, alkalis, solvents, and process chemicals. PTFE-lined bodies offer universal compatibility.

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Quick Turnaround & Stock

Standard sizes ship within 24 hours. Custom-engineered sight glasses delivered in 5–10 business days. Rush fabrication available.

Industries & Applications

Circular sight glasses are essential components across numerous process industries for safe visual monitoring.

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Chemical Processing

Reactors, storage tanks, pipelines

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Pharmaceutical

WFI systems, bioreactors, CIP/SIP

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Food & Beverage

Dairy, brewery, edible oil lines

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Oil & Gas

Separators, knockout drums, pipelines

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Power Generation

Boiler drums, condensate tanks, heat exchangers

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Water Treatment

Filtration vessels, dosing systems, storage tanks

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Heavy Industry

Hydraulic reservoirs, gearboxes, lubrication systems

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R&D / Pilot Plants

Experimental reactors, observation windows

Why Engineers Choose OptiView

From initial design to final delivery, we make sourcing circular sight glasses straightforward and reliable.

Circular Sight Glass Manufacturing Facility

✓ Factory-Direct Engineering Support — Work directly with our design team for expert material and configuration recommendations.
✓ Hydrostatic Testing on Every Unit — Each sight glass is pressure-tested at 1.5× rated working pressure and documented with a test certificate.
✓ Material Traceability — Full 3.1 material certificates for all metallic and glass components. Heat numbers traceable to mill origin.
✓ Competitive Project Pricing — Save 20–35% versus major OEM brands. Volume discounts for annual supply agreements.
✓ Global Compliance Expertise — We navigate PED, ASME B31.3, 3-A Sanitary, and ATEX requirements so your order meets local regulations.
✓ No Minimum Order — Single-unit prototypes welcome. Trial orders encouraged to validate quality before bulk commitment.

Quality Certifications & Compliance

Our manufacturing and quality systems adhere to the most rigorous international standards.

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ISO 9001:2015

Quality Management System

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ASME B31.3

Process Piping Code

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3-A Sanitary

Hygienic Equipment

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PED 2014/68/EU

Pressure Equipment

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FDA 21 CFR

Food Contact Materials

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EN 10204 3.1

Material Traceability

Frequently Asked Questions

Quick answers to common questions about our circular sight glasses.

Can you manufacture a circular sight glass to replace an existing unit? +

Yes, we can reverse-engineer a direct replacement from your existing unit. Simply provide the glass diameter, thickness, body material, connection type and size, or send a photo/nameplate. Our engineering team will verify all critical dimensions before production.

What is the typical lead time for custom circular sight glasses? +

Standard custom orders with common materials ship in 5–7 business days. Complex assemblies with specialty alloys (Hastelloy, Monel) or integrated accessories may take 10–14 business days. Rush service within 3 business days is available for urgent requirements. Standard catalog items ship within 24 hours.

Do you offer circular sight glasses with lighting or wiper systems? +

Absolutely. We manufacture complete sight glass assemblies with integrated LED or halogen lighting, rotary wipers (manual or pneumatic), and spray wash rings. These are commonly used in tanks and reactors where the process media can coat the glass surface. Specify your requirements when submitting your inquiry.

What pressure rating do I need for my application? +

The required pressure rating depends on your operating pressure, temperature, and the glass diameter/thickness. As a general guide: borosilicate glass with 10mm–15mm thickness is suitable up to 10 bar (150 psi) for smaller diameters. For higher pressures up to 40 bar (580 psi), we use thicker or tempered glass. Share your process conditions, and our engineers will specify the appropriate configuration.

Do you provide documentation for regulatory compliance? +

Yes. We supply a comprehensive documentation package including hydrostatic test reports, material certificates (EN 10204 3.1), dimensional inspection reports, and surface finish verification. For PED-compliant orders, we provide the full Declaration of Conformity and CE marking. All documentation is included in the price — no hidden fees.

Can I order a single circular sight glass for testing or prototyping? +

Yes, absolutely. We have no minimum order quantity for either standard or custom sight glasses. Single-unit orders are welcome for prototype evaluation, plant trials, or emergency replacements. This is part of our commitment to supporting engineers and maintenance teams at every stage.

Ready to Specify Your Circular Sight Glass?

Submit your requirements and our engineering team will respond with a detailed quotation within 3 business hours.

Free technical consultation & material selection guidance
Competitive factory-direct pricing with volume discounts
3D CAD model or 2D drawing provided for approval before fabrication
No obligation — transparent, itemized quotation

Request Your Quote

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