VG-150 Bolted Bonnet Wedge Gate Valve
- Design standard API 600 / ASME B16.34
- Nominal size DN50 – DN400 (NPS 2 – 16)
VG-900
VG-900 Pressure Seal Gate Valve
A pressure seal bonnet gate valve for high pressure steam and boiler feed lines, where a bolted joint becomes the weak point.
- Pressure seal bonnet tightens under line pressure instead of relying on bolt load
- Flexible wedge tolerates body distortion from thermal cycling
- Butt weld ends as standard to remove a flange joint from a hot line
- Graphite sealing ring supplied with every valve as a spare
Specifications
- Design standard
- ASME B16.34 / API 600 pressure seal bonnet
- Nominal size
- DN50 – DN400 (NPS 2 – 16)
- Pressure class
- Class 600 / 900
- Body material
- ASTM A217 WC6, A217 WC9, A216 WCB
- Trim material
- Hardfaced seat and disc facings, 13Cr stem
- End connection
- Butt weld to ASME B16.25; raised face flange to order
- Operating temperature
- -29 °C to +540 °C, alloy body dependent
- Face-to-face
- ASME B16.10
- Actuation
- Bevel gear standard, electric actuator to ISO 5211
- Test practice
- Shell and seat to API 598
Product detail
Above Class 600 a bolted bonnet gets heavy, and the gasket load has to fight the line pressure rather than work with it. The VG-900 uses a pressure seal bonnet instead: the internal pressure pushes the segmented ring against the sealing ring, so the joint gets tighter as the line gets hotter and higher. It is the standard construction on main steam, boiler feed and high pressure condensate.
Where it is used
Boiler feed pump discharge, main steam isolation, high pressure drains and start-up vents. Anywhere the line is hot enough that a bolted joint would relax and need retorquing after the first thermal cycle.
Construction
Flexible wedge rather than solid, so the disc can adjust to a body seat that has moved under thermal load without binding in the closed position. The graphite sealing ring is a wearing part and is supplied in the spares kit. Yoke and stem are sized for the seating force at the full differential, not the average.
Handling and installation
These valves are heavy and the bonnet is not a lifting point. The body carries lifting lugs, and the installation sheet states the orientation and the permitted pipe loads. Fitting one upside down on a horizontal steam line traps condensate above the disc, which is a slow way to damage a good valve.
Enquire about this model
VG-900 Pressure Seal Gate Valve
Include the line size, design pressure, medium and operating temperature and we will confirm the body, trim and end connection for your line.
Send the line size, class, medium and temperature and we will reply with a datasheet.