Parallel double-disc gate valves (30ch6br): design, benefits and limits
The cast-iron parallel double-disc gate valve 30ch6br is one of the most common valves on water and heating networks across the former Soviet Union. Many networks still run on it, and replacements are often like for like. This guide explains the design and where it fits.
TAZ Engineering Team · · 5 min
Design
Two parallel discs with brass or bronze seat rings move inside the body. At the end of the stroke a spreader pushes the discs apart and presses them against the body seats. On opening the discs are released before they lift, so operating force is low and the seats suffer less sliding wear.
The designation 30ch6br means: 30 gate valve, ch grey cast iron, 6 model number, br brass or bronze seats. The electrically actuated version is 30ch906br.
Applications
Cold-water mains, district heating and hot-water systems with moderate parameters: PN 10–16 and up to 225 °C according to the TAZ catalogue. Typically installed in chambers on DN 100–600 mains.
Limits
Grey iron is brittle, so these valves should not be used where pipe bending loads, freezing water in the body or water hammer are possible. Cast-iron gate valves are not used for gas or flammable media.
Alternatives
New cold-water mains usually take ductile-iron resilient-seated gate valves (30ch39r), which are lighter, have no seat pocket and reach rate A tightness. High-parameter heating networks use steel gate valves such as 30s41nzh. For like-for-like replacement, send the face-to-face length and flange data.
Checklist
- medium and temperature
- PN
- DN and face-to-face
- flanges
- pipe loads
- freezing risk
- electric actuator