Weldable sight glasses for tanks are devices installed in tanks and pressure vessels to allow the visualization of the contents and the processes occurring inside the tank. The oval shape of the sight glass provides a wide viewing area, making it easier for operators to inspect the contents and internal processes of the tank.
Weld Neck Sight Glasses – Applications
These sight glasses are particularly useful in food and beverage processing, as well as in the pharmaceutical, chemical, and other industries where direct observation of the tank’s contents is crucial for controlling and monitoring the process.

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

Weld Neck Sight Glasses – Technical Information | |||
---|---|---|---|
ID | A (Visible Diam) | B (Total Diam) | C (Total thickness) |
3” | 3” (76.20 mm) | 5” (127.00 mm) | 3.5” (88.90 mm) |
4” | 4” (101.6 mm) | 6” (152.40 mm) | 3.5” (88.90 mm) |
5” | 5” (127.00 mm) | 7.5” (190.50 mm) | 4” (101.60 mm) |
6” | 6” (152.40 mm) | 9” (228.60 mm) | 4.5” (114.30 mm) |
7” | 7” (177.80 mm) | 10” (254.00 mm) | 5” (127.00 mm) |
8” | 8” (203.20 mm) | 11” (279.40 mm) | 5” (127.00 mm) |
9” | 9” (228.60 mm) | 12” (304.80 mm) | 6” (152.40 mm) |
Iniflu’s Level Sight Glasses are designed to provide precise and secure monitoring of liquid levels in tanks and industrial systems. Made with high-quality materials, our sight glasses ensure long-lasting durability and resistance to extreme conditions. Discover our range of level sight glasses.
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