Tank Weld Sight Glasses
Tank Weldable Sight Glass ZW30 provides clear and direct visualization of processes and product levels inside a container, enabling operators to assess critical characteristics such as color, clarity, and consistency. Material recommendations tailored to your specific application parameters are available upon request.
Weld-On Sight Glass – Applications
This type of tank-weldable hatch allows observation inside process containers in industries such as food and beverage, energy, distillery, chemical, biotechnology, pharmaceutical, and more.

Item | Part name | Material options |
---|---|---|
1 | Cover Flange | Stainless Steel 316L Stainless Steel 304 Carbon Steel w/ anti-corrosion coating |
2 | Weld Pad | Stainless Steel 316L Stainless Steel 304 Carbon Steel w/ anti-corrosion coating |
3 | Sight Glass (max temp) | DIN7080 Tempered Borosilicate (280°C) Quartz, Min. 95% Fused Silica (1450°C) DIN8902 Tempered Soda Lime (150°C) |
4 | Gaskets *(max temp) | Non Asbestos (200°C) Exp Graphite (450°C) Graph/Kevlar (450°C) FKM (260°C) PTFE (260°C) EPDM (140°C) |
5 | Bolts | Stainless Steel 304 |
Sanitary Sight Glass – Installation
The numbers in the following installation instructions refer to the previous diagram. After properly welding the base flange (5) onto the vessel wall, assemble the gasket (3), the sight glass (4), the gasket (3), and the cover flange (2) in that order.
Tighten the bolts (1) according to the torque values specified in the technical information table (always tighten bolts in diametrically opposite pairs).

ID | ZW30-2 | ZW30-3 | ZW30-4 | ZW30-5 | ZW30-6 | ZW30-7 | ZW30-8 |
Visible Diameter (A) | 2” | 3” | 4” | 5” | 6” | 7” | 8” |
Total Diameter (B) | 5” | 6” | 7” | 8-1/2″ | 10” | 11” | 13” |
Flange Thickness Cover (H1) Weld Pad (H2) | 3/4” 1” | 3/4” 1” | 3/4” 1” | 1” 1-1/4” | 1-1/4” 1-1/2” | 1-1/4” 1-1/2” | 1-1/4” 1-1/2” |
Glass Size* Ø Thickness | 3-3/4” 3/4” | 4-3/4” 3/4” | 5-3/4” 1” | 7” 3/4” | 8” 1-1/4” | 9” 1-1/4” | 11” 1-1/4” |
Bolt Circle Diameter (C) | 3-3/8” | 4-3/8” | 6-3/8” | 7-3/4” | 9” | 10” | 12” |
Tightening Torque* (ft/lbs) | 17 | 17 | 19 | 22 | 25 | 28 | 32 |
*Glass sizes are applicable only for tempered borosilicate glass. Please contact us for details on other glass materials.
Our tank sight glasses are designed to provide clear and precise visual inspection in industrial applications, offering efficient monitoring of fluid levels without interrupting processes. Made with high-quality materials, they ensure durability and resistance in demanding environments, making them a reliable option for any type of tank. Furthermore, their easy installation and maintenance provide a practical and efficient solution.
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