T-Piece (Closed) - Glass

The glass closed-end T-piece makes transparent the point where the line branches at a right angle or where an arm is left blind — the closed end is the area where the most material builds up. Annealing (stress relief) is mandatory for glass parts.

Especially on lines conveying highly abrasive materials (e.g. glass fiber reinforced plastics), the use of a glass Y-connection and/or a closed glass T-piece is recommended — thanks to its transparency, the material flow can be watched as well.

The T-Piece (Closed) provides a side connection to the main line at a right angle (90°); the "closed" type is the variant in which the side arm is cut straight and closed at the end, used for observation/cleaning purposes. There is a copper strip on the outer surface — it provides electrical conductivity (static discharge) at stainless steel transitions.

The closed T: as an observation point

The closed-end T-piece is used at points where the line branches at 90° or where an arm is left blind. The glass body makes this point observable; the closed end is the area of the line where the most material builds up, and being able to see the build-up is a great convenience.

What happens at a blind end

The closed end is a pocket that the flow reaches but cannot continue through. Granulate that enters here cannot get out; over time it builds up, heats up and comes back as residue of the previous material at a color change. Thanks to the transparent body this build-up is noticed and taken into the cleaning plan.

Where it is used

• Arms of lines to be extended in future that are left blind for now
• Points that need access for cleaning and maintenance
• Branch areas where the flow behavior is to be watched

Points to watch

The requirement of being stress relieved (annealed) applies to glass parts; unannealed glass cracks under installation stress. What is more, the closed end also carries load under line pressure — the connecting elements must be chosen accordingly. In environments with a risk of breakage, steel should be preferred to glass.

For other branch geometries you can look at the pipe fittings page.