Stepped Sight Glass | Borosilicate Stepped Edge Sight Glass for Industrial Observation
Product Overview
A stepped sight glass is commonly used as a visual inspection window in process equipment, vessels, and piping. In technical glass literature, stepped edge is listed as a standard edge treatment for sight glass windows, alongside beveled, polished, and grooved edge options.
Product Alias: stepped edge sight glass, borosilicate stepped sight glass, round stepped sight glass, and stepped sight glass disc.
Typical Applications
Stepped sight glass is used where operators need direct visual confirmation of media condition, level, flow, or contamination in closed systems. Published sight glass guidance describes this product family as suitable for equipment exposed to elevated temperature, chemical attack, and pressure, including piping, vessels, chemical reactors, and other industrial systems.
Typical industries include:
- chemical and petrochemical processing
- pharmaceutical and biotech equipment
- food and beverage production
- oil and gas systems
- utility and wastewater applications
Material and Performance
Material Properties
| Property | Value | Source |
|---|---|---|
| Material family | Borosilicate glass 3.3 | |
| Density | 2.23 ± 0.02 g/cm³ | |
| Thermal expansion coefficient (0–300°C) | 3.3 ± 0.1 × 10⁻⁶/K | |
| Softening point | 815 ± 10°C | |
| Strain point | 560 ± 10°C | |
| Bending strength | 160 N/mm² | |
| Young’s modulus | 64 GPa | |
| Hardness | 5.5 Mohs | |
| Working temperature | Up to 280°C | |
| Lower temperature limit | No lower temperature limit stated |
Key Advantages
- secure fit through the stepped edge profile;
- high thermal resistance for industrial process observation;
- strong resistance to water, acids, alkalis, and organic substances;
- ground and polished surfaces for optical clarity and proper seating;
- availability of common custom edge treatments and special dimensions on request.
Technical Specifications
Common Published Size / Pressure Data for Borosilicate DIN 7080 Disc Family
| Outer Size (D × s, mm) | Viewing Diameter (mm) | Nominal Pressure (bar) | Standard |
|---|---|---|---|
| 63 × 10 | 48 | 16 | DIN 7080 |
| 80 × 12 | 65 | 16 | DIN 7080 |
| 100 × 15 | 80 | 16 | DIN 7080 |
| 125 × 15 | 100 | 10 | DIN 7080 |
| 125 × 20 | 100 | 16 | DIN 7080 |
| 150 × 20 | 125 | 10 | DIN 7080 |
| 150 × 25 | 125 | 16 | DIN 7080 |
| 175 × 20 | 150 | 10 | DIN 7080 |
| 175 × 25 | 150 | 16 | DIN 7080 |
| 200 × 20 | 175 | 8 | DIN 7080 |
| 200 × 25 | 175 | 10 | DIN 7080 |
| 200 × 30 | 175 | 16 | DIN 7080 |
| 250 × 25 | 225 | 8 | DIN 7080 |
| 250 × 30 | 225 | 10 | DIN 7080 |
Product Reference Data
| Parameter | Value | Source |
|---|---|---|
| Product type | Stepped sight glass | |
| Common alias | Stepped edge sight glass | |
| Material | Borosilicate glass 3.3 | |
| Edge style | Stepped edge | |
| Surface finish | Ground and polished | |
| Standard family | DIN 7080 | |
| Temperature duty | Up to 280°C | |
| Chemical resistance | Water, acids, alkalis, organic substances | |
| Installation note | Other dimensions can be supplied on request |
Quality Proof and Evidence
- Inspection report — dimensional check, edge quality, and visual inspection;
- Customer case — a real vessel, tank, or reactor installation;
- Test data — pressure, thermal cycling, or chemical resistance results;
- Certificate — only the documents you can actually provide.
FAQ
What is a stepped sight glass?
It is a sight glass disc with a stepped edge profile, used to help the glass fit securely into the sight glass assembly.
Is “stepped edge sight glass” a common search term?
Yes. Technical glass suppliers explicitly list stepped edge as a common sight-glass edge treatment, and buyers often use that phrase when sourcing the glass disc itself.
What material is usually used?
For industrial duty, borosilicate glass 3.3 is the standard choice because of its low thermal expansion and strong chemical durability.
What is the temperature range?
The DIN 7080 borosilicate disc literature states pressure duties up to 280°C and no lower temperature limit in the source datasheet.
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