Our Products
Weld-On Circular Vessel Sight Glass
The Weld-On Circular Vessel Sight Glass is a DIN 28120 compliant inspection window designed for pressure vessels, reactors, tanks, and process equipment. Featuring a welded base flange, high-strength sight glass, and secure bolted assembly, it provides reliable visual monitoring under pressure, vacuum, and elevated temperature conditions.
Non binding • Usually a response within 24 hours
Certified quality
Technical data
Weld-On Circular Vessel Sight Glass for Pressure Vessels and Process Equipment
The Weld-On Circular Vessel Sight Glass is designed for safe and reliable observation inside pressure vessels, reactors, storage tanks, separators, and industrial process systems.
The assembly consists of a welded base flange, sight glass disc, sealing gaskets, cover flange, and fastening bolts. Once installed, operators can visually inspect liquid levels, mixing processes, reaction conditions, foam formation, crystallization, and product quality without interrupting operation.
Manufactured according to DIN 28120 dimensional standards, the sight glass fitting is suitable for both pressure and vacuum service. Standard pressure ratings include PN10 and PN16 depending on nominal size, with higher pressure configurations available upon request.
Glass options include DIN 7080 borosilicate glass, DIN 8902 tempered soda-lime glass, fused quartz glass, and other specialty materials. Stainless steel 316L, carbon steel, duplex stainless steel, and customized alloys are available for aggressive process environments.
Widely used throughout the chemical, pharmaceutical, petrochemical, food processing, biotechnology, and energy industries, the Weld-On Circular Vessel Sight Glass provides long-term reliability, excellent visibility, and dependable sealing performance.
Weld-On Circular Vessel Sight Glass — Technical Data
| Item | Details |
|---|---|
| Product Overview | Viewing diameter based on DIN 28120 Sight glass fittings are circular flanged ports for welding into or onto a vessel wall. The base and the mating flange are screwed together tightly, with the sight glass disk and an independent gasket to the upper and the lower flange respectively positioned between them. |
| Advantages (Lightweight low profile type for pressureless vessels) | – smaller outer diameter and therefore vessel cutout – shallower height above weld – lower weight – easier to clean – lower cost |
| Viewing diameter | 80 to 225 mm |
| Application | For observation of interior of tanks, silos, stirred vessels, separators, pipelines etc. |
| Operating conditions | Pressure: non-pressurized Temperature: max. 150°C with sodalime glass DIN 8902 max. 280°C with borosilicate glass DIN 7080 higher temperatures on request |
| Possible combinations | Can be combined with Lumistar luminaires when used in explosion hazardous as well as non explosion hazardous areas. The mating flange is then drilled and tapped to suit luminaire mounting bracket. A Lumiglas disc wiper SW 1 and a Lumiglas spray device can also be mounted. |
| Certificates/testing | Depending on customer requirements and at extra cost, can be provided to DIN EN 10204 3.1/3.2 |
Weld-On Circular Vessel Sight Glass — Component Materials
| Item | Part | Material |
|---|---|---|
| 1 | base flange | stainless steel 1.4571 (316 Ti) or other |
| 2 | gasket | KLINGERsil C-4400, Silikon, PTFE or other |
| 3 | sight glass disc | – sodalime glass: toughened DIN 8902 – borosilicate glass: toughened DIN 7080 |
| 4 | mating flange | stainless steel 1.4571 (316 Ti) or other |
| 5 | securing bolts | stainless steel A2 or other |
Dimensions for sight glass fitting in stainless steel, viewing diameter based on DIN 28120
| Size | 1 | 2 | 3 | 4 | 5 | 6 | 7 | |
|---|---|---|---|---|---|---|---|---|
| Nominal diameter | DN | 50 | 80 | 100 | 125 | 150 | 200 | 300 |
| Visible diameter | d1 | 80 | 100 | 125 | 150 | 175 | 225 | 300 |
| Sight glass plate | d2 | 100 | 125 | 150 | 175 | 200 | 250 | 325 |
| s | 10 | 10 | 10 | 10 | 10 | 10 | 15 | |
| Flange | D | 140 | 165 | 190 | 215 | 240 | 290 | 370 |
| k | 120 | 145 | 170 | 195 | 220 | 270 | 345 | |
| h1 | 10 | 10 | 10 | 10 | 10 | 10 | 15 | |
| h2 | 15 | 15 | 15 | 15 | 15 | 15 | 20 | |
| Fastening screws | Anz. | 4 | 8 | 8 | 8 | 8 | 8 | 12 |
| Größe | M 6 | M 6 | M 6 | M 6 | M 6 | M 6 | M 8 | |
| Seals (product contact and atmospheric side) | d1 | 80 | 100 | 125 | 150 | 175 | 225 | 300 |
| d7 | 102 | 127 | 152 | 177 | 202 | 252 | 327 |
KEY FEATURES
DIN 28120 Standard Design
Manufactured according to DIN 28120 dimensions for interchangeability and easy replacement.
Pressure and Vacuum Service
Suitable for PN10–PN16 operating conditions and vacuum applications.
High Temperature Resistance
Supports temperatures up to 280°C with borosilicate glass and up to 500°C with fused quartz glass.
Corrosion Resistant Construction
Available in stainless steel 304, 316L, duplex stainless steel, carbon steel, and special alloys.
Excellent Optical Clarity
Provides distortion-free observation of internal process conditions.
Modular Maintenance Design
Glass discs and gaskets can be replaced without removing the welded base flange.
Custom Manufacturing Service
We provide tailor-made solutions according to drawings or technical requirements.
- Custom diameter
- Custom thickness
- Special pressure design
- Edge polishing
- Optical finishing
- OEM / ODM support
- Custom packaging
TYPICAL APPLICATIONS
- Pressure Vessels
- Chemical Reactors
- Boilers & Steam Systems
- Pipeline Sight Glass Assemblies
- Pharmaceutical Equipment
- Food & Beverage Processing
- Industrial Observation Ports
FAQ
A: The design is based on DIN 28120, one of the most widely used standards for circular vessel sight glass fittings
A:Standard versions are available for PN10 and PN16 service, with higher-pressure designs available upon request.
A: Yes. The fitting can be designed for both vacuum and pressure applications.
A: Yes. LED and explosion-proof sight glass lights can be mounted to improve vessel visibility.
A: Yes. EN 10204 3.1 and 3.2 inspection certificates can be supplied upon request.
Need Custom Weld-On Circular Vessel Sight Glass Solutuions?
Send us your drawings or technical requirements for fast quotation and engineering support.