ANSI flow sight glass type 620-A

Tubular sight glass with borosilicate glass cylinder for 360° panoramic view

The heart of the ACI Pipe Sight Glass Type 620A is a borosilicate glass 3.3 pipe enclosed between two stainless steel or steel flanges. This design enables Type 620A to provide 360° observation and illumination of the process medium.

The standard version of the tubular sight glass Type 620A is supplied with flat gaskets made of pure PTFE or Teflon, but we also have novaphit MST and soft-material gaskets such as EPDM or NBR in stock. If our standard range of gaskets does not meet your requirements, simply contact us and we will select the perfect special material together with you.

As flange material we use the highly resistant quality stainless steel 1.4571 (AISI 316 Ti, X6CrNiMoTi17-12-2). These flanges are held together and supported by solid threaded studs to ensure the best possible service life of the valve.

For less demanding applications, our Type 620A tubular sight glass can also be supplied with P265GH flanges. Of course, it is also possible to use special materials such as Hastelloy alloys, duplex steel or other high-performance metals.

In small nominal diameters (up to 2 inches) our tubular sight glass type 620A withstands a nominal operating pressure of up to 16 bar without any problems, and up to 4 inches 10 bar is still possible without hesitation!

Since the flange, gasket and glass are precisely matched to each other, the tubular sight glass type 620A is almost completely free of dead space and is therefore well suited for applications that place high demands on cleanliness.

For use in industrial plants in which ongoing work must be expected, especially for installation under or near catwalks, we recommend the installation of one of our impact protection jackets. This simple additional option protects the glass tube against impact from falling parts or tools and you may save yourself an expensive repair or even a catastrophic failure of the plant!

Our tubular sight glasses are fully assembled in our workshop and subjected to a pressure test at 1.5 times the operating pressure. Maintenance after installation is usually not necessary.

Read on for more technical information, detailed product pictures and videos.

Technical data


Flanges: 1.4571 or P265GH / 1.0425 or on request

Screws: A4-70

Glass: borosilicate glass 3.3

Seal: Viton, PTFE, EPDM, graphite or by arrangement.


Tubular flow sight glass with flanges on both sides suitable for flanges to ASME B16.5 class 150 lbs for installation in pipelines.

Nominal size:

1/2" to 8"

Nominal pressure:

class 150 lbs

Operating pressure:
up to 2" max. 16 bar
from 2/1/4" max. 10 bar
from 5" max. 8 bar
from 6" max. 7 bar
from 8" max. 5 bar


max. 300°C (depending on gasket selection)


impact protection jacket


Optional versions are possible.

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ANSI Tubular sight glass Type 620 A