Fully welded ball valves for district heating and gas
A fully welded ball valve has no body joints, so it cannot leak at body flanges and suits direct burial. It is the standard isolation valve in modern district heating and gas distribution networks.
TAZ Engineering Team · · 6 min
Design
Two steel body halves are welded at the factory. The ball runs in polymer or reinforced seats, and the stem is sealed with O-rings. There is no internal maintenance: at end of life the valve is cut out and a new one is welded in.
Ends and versions
Butt-weld, flanged or combined ends. Buried valves get an extended stem and protective tube so they can be operated from a chamber or from the surface with a key. Large sizes come with a gearbox and an actuator mounting.
District heating parameters
District heating networks typically run up to PN 16–25 and 130–150 °C. Check that the seat material is rated for the continuous supply temperature with margin, and for buried service, that the valve is compatible with pre-insulated pipe systems and corrosion protection.
Gas
Seat tightness is critical for gas: class A under GOST 9544, with no visible leakage, is the usual requirement. The passport must name natural gas as the medium.
Receiving inspection
Check marking, passport, hydrostatic and pneumatic test records, pup length and wall thickness against your pipe. During welding protect the valve from overheating and keep the ball fully open.
Checklist
- DN, PN, temperature
- weld, flanged or combined ends
- extended stem for buried service
- leakage class
- pup wall thickness
- test records