Double Offset High Performance Butterfly Valve for LNG
The Westad butterfly valve for cryogenic service is designed for tight shut off and throttling service.
The disc movement is double offset. This eliminates concentrated wear points on the sealing ring and extends it’s lifetime. Standard body patterns are flanged and butt welded types.
Butt welded type has extended body to prevent heat conduction to the sealing area during welding installation. An inspection door on top of the body enables easy inspection, maintenance and replacement of inner parts without the need to remove the valve or to cut the pipe.
The primary sealing rings are spring activated and pressure energized to ensure optimal tightness within the full temperature range. The sealing arrangement is fully bi-directional and tested according to the BS 6755-1987 fire safe regulations.
To prevent internal stress in the bonnet during the cool- down period, all bonnet joints are bolted. This bonnet is extended to ensure that the gland area remains free from freezing even for temperatures down to -196 ̊C.
The valve can be installed with the shaft in any direction. The topflange drilling is according to ISO 5211 standards to fit a large range of gears and actuators.
|Temperature range:||-196°C to +200°C|
|Pressure range:||ANSI Class 150 / 300|
|Standard size range:||4" (DN 100) - 48" (DN 1200)|
|Face to face dimensions:||
Butt welded type according to drawing
Butt welded type: Stainless Steel ASTM A351 CF3M
|Disc:||Stainless Steel ASTM A351 CF8M, stellited|
|Shaft:||Stainless Steel AISI 316|
|Nuts and bolts:||Stainless Steel AISI 316|
|Shaft seal:||Grafoil (graphite)|
|Main seal:||Spring activated PTFE (soft) or Helioflex (metal)|